1 .. SPDX-License-Identifier: GPL-2.0
3 ===================================================================
4 The Definitive KVM (Kernel-based Virtual Machine) API Documentation
5 ===================================================================
10 The kvm API is a set of ioctls that are issued to control various aspects
11 of a virtual machine. The ioctls belong to the following classes:
13 - System ioctls: These query and set global attributes which affect the
14 whole kvm subsystem. In addition a system ioctl is used to create
17 - VM ioctls: These query and set attributes that affect an entire virtual
18 machine, for example memory layout. In addition a VM ioctl is used to
19 create virtual cpus (vcpus) and devices.
21 VM ioctls must be issued from the same process (address space) that was
22 used to create the VM.
24 - vcpu ioctls: These query and set attributes that control the operation
25 of a single virtual cpu.
27 vcpu ioctls should be issued from the same thread that was used to create
28 the vcpu, except for asynchronous vcpu ioctl that are marked as such in
29 the documentation. Otherwise, the first ioctl after switching threads
30 could see a performance impact.
32 - device ioctls: These query and set attributes that control the operation
35 device ioctls must be issued from the same process (address space) that
36 was used to create the VM.
41 The kvm API is centered around file descriptors. An initial
42 open("/dev/kvm") obtains a handle to the kvm subsystem; this handle
43 can be used to issue system ioctls. A KVM_CREATE_VM ioctl on this
44 handle will create a VM file descriptor which can be used to issue VM
45 ioctls. A KVM_CREATE_VCPU or KVM_CREATE_DEVICE ioctl on a VM fd will
46 create a virtual cpu or device and return a file descriptor pointing to
47 the new resource. Finally, ioctls on a vcpu or device fd can be used
48 to control the vcpu or device. For vcpus, this includes the important
49 task of actually running guest code.
51 In general file descriptors can be migrated among processes by means
52 of fork() and the SCM_RIGHTS facility of unix domain socket. These
53 kinds of tricks are explicitly not supported by kvm. While they will
54 not cause harm to the host, their actual behavior is not guaranteed by
55 the API. See "General description" for details on the ioctl usage
56 model that is supported by KVM.
58 It is important to note that althought VM ioctls may only be issued from
59 the process that created the VM, a VM's lifecycle is associated with its
60 file descriptor, not its creator (process). In other words, the VM and
61 its resources, *including the associated address space*, are not freed
62 until the last reference to the VM's file descriptor has been released.
63 For example, if fork() is issued after ioctl(KVM_CREATE_VM), the VM will
64 not be freed until both the parent (original) process and its child have
65 put their references to the VM's file descriptor.
67 Because a VM's resources are not freed until the last reference to its
68 file descriptor is released, creating additional references to a VM
69 via fork(), dup(), etc... without careful consideration is strongly
70 discouraged and may have unwanted side effects, e.g. memory allocated
71 by and on behalf of the VM's process may not be freed/unaccounted when
78 As of Linux 2.6.22, the KVM ABI has been stabilized: no backward
79 incompatible change are allowed. However, there is an extension
80 facility that allows backward-compatible extensions to the API to be
83 The extension mechanism is not based on the Linux version number.
84 Instead, kvm defines extension identifiers and a facility to query
85 whether a particular extension identifier is available. If it is, a
86 set of ioctls is available for application use.
92 This section describes ioctls that can be used to control kvm guests.
93 For each ioctl, the following information is provided along with a
97 which KVM extension provides this ioctl. Can be 'basic',
98 which means that is will be provided by any kernel that supports
99 API version 12 (see section 4.1), a KVM_CAP_xyz constant, which
100 means availability needs to be checked with KVM_CHECK_EXTENSION
101 (see section 4.4), or 'none' which means that while not all kernels
102 support this ioctl, there's no capability bit to check its
103 availability: for kernels that don't support the ioctl,
104 the ioctl returns -ENOTTY.
107 which instruction set architectures provide this ioctl.
108 x86 includes both i386 and x86_64.
114 what parameters are accepted by the ioctl.
117 the return value. General error numbers (EBADF, ENOMEM, EINVAL)
118 are not detailed, but errors with specific meanings are.
121 4.1 KVM_GET_API_VERSION
122 -----------------------
128 :Returns: the constant KVM_API_VERSION (=12)
130 This identifies the API version as the stable kvm API. It is not
131 expected that this number will change. However, Linux 2.6.20 and
132 2.6.21 report earlier versions; these are not documented and not
133 supported. Applications should refuse to run if KVM_GET_API_VERSION
134 returns a value other than 12. If this check passes, all ioctls
135 described as 'basic' will be available.
144 :Parameters: machine type identifier (KVM_VM_*)
145 :Returns: a VM fd that can be used to control the new virtual machine.
147 The new VM has no virtual cpus and no memory.
148 You probably want to use 0 as machine type.
150 In order to create user controlled virtual machines on S390, check
151 KVM_CAP_S390_UCONTROL and use the flag KVM_VM_S390_UCONTROL as
152 privileged user (CAP_SYS_ADMIN).
154 To use hardware assisted virtualization on MIPS (VZ ASE) rather than
155 the default trap & emulate implementation (which changes the virtual
156 memory layout to fit in user mode), check KVM_CAP_MIPS_VZ and use the
160 On arm64, the physical address size for a VM (IPA Size limit) is limited
161 to 40bits by default. The limit can be configured if the host supports the
162 extension KVM_CAP_ARM_VM_IPA_SIZE. When supported, use
163 KVM_VM_TYPE_ARM_IPA_SIZE(IPA_Bits) to set the size in the machine type
164 identifier, where IPA_Bits is the maximum width of any physical
165 address used by the VM. The IPA_Bits is encoded in bits[7-0] of the
166 machine type identifier.
168 e.g, to configure a guest to use 48bit physical address size::
170 vm_fd = ioctl(dev_fd, KVM_CREATE_VM, KVM_VM_TYPE_ARM_IPA_SIZE(48));
172 The requested size (IPA_Bits) must be:
174 == =========================================================
175 0 Implies default size, 40bits (for backward compatibility)
176 N Implies N bits, where N is a positive integer such that,
177 32 <= N <= Host_IPA_Limit
178 == =========================================================
180 Host_IPA_Limit is the maximum possible value for IPA_Bits on the host and
181 is dependent on the CPU capability and the kernel configuration. The limit can
182 be retrieved using KVM_CAP_ARM_VM_IPA_SIZE of the KVM_CHECK_EXTENSION
185 Creation of the VM will fail if the requested IPA size (whether it is
186 implicit or explicit) is unsupported on the host.
188 Please note that configuring the IPA size does not affect the capability
189 exposed by the guest CPUs in ID_AA64MMFR0_EL1[PARange]. It only affects
190 size of the address translated by the stage2 level (guest physical to
191 host physical address translations).
194 4.3 KVM_GET_MSR_INDEX_LIST, KVM_GET_MSR_FEATURE_INDEX_LIST
195 ----------------------------------------------------------
197 :Capability: basic, KVM_CAP_GET_MSR_FEATURES for KVM_GET_MSR_FEATURE_INDEX_LIST
200 :Parameters: struct kvm_msr_list (in/out)
201 :Returns: 0 on success; -1 on error
205 ====== ============================================================
206 EFAULT the msr index list cannot be read from or written to
207 E2BIG the msr index list is to be to fit in the array specified by
209 ====== ============================================================
213 struct kvm_msr_list {
214 __u32 nmsrs; /* number of msrs in entries */
218 The user fills in the size of the indices array in nmsrs, and in return
219 kvm adjusts nmsrs to reflect the actual number of msrs and fills in the
220 indices array with their numbers.
222 KVM_GET_MSR_INDEX_LIST returns the guest msrs that are supported. The list
223 varies by kvm version and host processor, but does not change otherwise.
225 Note: if kvm indicates supports MCE (KVM_CAP_MCE), then the MCE bank MSRs are
226 not returned in the MSR list, as different vcpus can have a different number
227 of banks, as set via the KVM_X86_SETUP_MCE ioctl.
229 KVM_GET_MSR_FEATURE_INDEX_LIST returns the list of MSRs that can be passed
230 to the KVM_GET_MSRS system ioctl. This lets userspace probe host capabilities
231 and processor features that are exposed via MSRs (e.g., VMX capabilities).
232 This list also varies by kvm version and host processor, but does not change
236 4.4 KVM_CHECK_EXTENSION
237 -----------------------
239 :Capability: basic, KVM_CAP_CHECK_EXTENSION_VM for vm ioctl
241 :Type: system ioctl, vm ioctl
242 :Parameters: extension identifier (KVM_CAP_*)
243 :Returns: 0 if unsupported; 1 (or some other positive integer) if supported
245 The API allows the application to query about extensions to the core
246 kvm API. Userspace passes an extension identifier (an integer) and
247 receives an integer that describes the extension availability.
248 Generally 0 means no and 1 means yes, but some extensions may report
249 additional information in the integer return value.
251 Based on their initialization different VMs may have different capabilities.
252 It is thus encouraged to use the vm ioctl to query for capabilities (available
253 with KVM_CAP_CHECK_EXTENSION_VM on the vm fd)
255 4.5 KVM_GET_VCPU_MMAP_SIZE
256 --------------------------
262 :Returns: size of vcpu mmap area, in bytes
264 The KVM_RUN ioctl (cf.) communicates with userspace via a shared
265 memory region. This ioctl returns the size of that region. See the
266 KVM_RUN documentation for details.
268 Besides the size of the KVM_RUN communication region, other areas of
269 the VCPU file descriptor can be mmap-ed, including:
271 - if KVM_CAP_COALESCED_MMIO is available, a page at
272 KVM_COALESCED_MMIO_PAGE_OFFSET * PAGE_SIZE; for historical reasons,
273 this page is included in the result of KVM_GET_VCPU_MMAP_SIZE.
274 KVM_CAP_COALESCED_MMIO is not documented yet.
276 - if KVM_CAP_DIRTY_LOG_RING is available, a number of pages at
277 KVM_DIRTY_LOG_PAGE_OFFSET * PAGE_SIZE. For more information on
278 KVM_CAP_DIRTY_LOG_RING, see section 8.3.
281 4.6 KVM_SET_MEMORY_REGION
282 -------------------------
287 :Parameters: struct kvm_memory_region (in)
288 :Returns: 0 on success, -1 on error
290 This ioctl is obsolete and has been removed.
299 :Parameters: vcpu id (apic id on x86)
300 :Returns: vcpu fd on success, -1 on error
302 This API adds a vcpu to a virtual machine. No more than max_vcpus may be added.
303 The vcpu id is an integer in the range [0, max_vcpu_id).
305 The recommended max_vcpus value can be retrieved using the KVM_CAP_NR_VCPUS of
306 the KVM_CHECK_EXTENSION ioctl() at run-time.
307 The maximum possible value for max_vcpus can be retrieved using the
308 KVM_CAP_MAX_VCPUS of the KVM_CHECK_EXTENSION ioctl() at run-time.
310 If the KVM_CAP_NR_VCPUS does not exist, you should assume that max_vcpus is 4
312 If the KVM_CAP_MAX_VCPUS does not exist, you should assume that max_vcpus is
313 same as the value returned from KVM_CAP_NR_VCPUS.
315 The maximum possible value for max_vcpu_id can be retrieved using the
316 KVM_CAP_MAX_VCPU_ID of the KVM_CHECK_EXTENSION ioctl() at run-time.
318 If the KVM_CAP_MAX_VCPU_ID does not exist, you should assume that max_vcpu_id
319 is the same as the value returned from KVM_CAP_MAX_VCPUS.
321 On powerpc using book3s_hv mode, the vcpus are mapped onto virtual
322 threads in one or more virtual CPU cores. (This is because the
323 hardware requires all the hardware threads in a CPU core to be in the
324 same partition.) The KVM_CAP_PPC_SMT capability indicates the number
325 of vcpus per virtual core (vcore). The vcore id is obtained by
326 dividing the vcpu id by the number of vcpus per vcore. The vcpus in a
327 given vcore will always be in the same physical core as each other
328 (though that might be a different physical core from time to time).
329 Userspace can control the threading (SMT) mode of the guest by its
330 allocation of vcpu ids. For example, if userspace wants
331 single-threaded guest vcpus, it should make all vcpu ids be a multiple
332 of the number of vcpus per vcore.
334 For virtual cpus that have been created with S390 user controlled virtual
335 machines, the resulting vcpu fd can be memory mapped at page offset
336 KVM_S390_SIE_PAGE_OFFSET in order to obtain a memory map of the virtual
337 cpu's hardware control block.
340 4.8 KVM_GET_DIRTY_LOG (vm ioctl)
341 --------------------------------
346 :Parameters: struct kvm_dirty_log (in/out)
347 :Returns: 0 on success, -1 on error
351 /* for KVM_GET_DIRTY_LOG */
352 struct kvm_dirty_log {
356 void __user *dirty_bitmap; /* one bit per page */
361 Given a memory slot, return a bitmap containing any pages dirtied
362 since the last call to this ioctl. Bit 0 is the first page in the
363 memory slot. Ensure the entire structure is cleared to avoid padding
366 If KVM_CAP_MULTI_ADDRESS_SPACE is available, bits 16-31 of slot field specifies
367 the address space for which you want to return the dirty bitmap. See
368 KVM_SET_USER_MEMORY_REGION for details on the usage of slot field.
370 The bits in the dirty bitmap are cleared before the ioctl returns, unless
371 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is enabled. For more information,
372 see the description of the capability.
374 4.9 KVM_SET_MEMORY_ALIAS
375 ------------------------
380 :Parameters: struct kvm_memory_alias (in)
381 :Returns: 0 (success), -1 (error)
383 This ioctl is obsolete and has been removed.
393 :Returns: 0 on success, -1 on error
397 ======= ==============================================================
398 EINTR an unmasked signal is pending
399 ENOEXEC the vcpu hasn't been initialized or the guest tried to execute
400 instructions from device memory (arm64)
401 ENOSYS data abort outside memslots with no syndrome info and
402 KVM_CAP_ARM_NISV_TO_USER not enabled (arm64)
403 EPERM SVE feature set but not finalized (arm64)
404 ======= ==============================================================
406 This ioctl is used to run a guest virtual cpu. While there are no
407 explicit parameters, there is an implicit parameter block that can be
408 obtained by mmap()ing the vcpu fd at offset 0, with the size given by
409 KVM_GET_VCPU_MMAP_SIZE. The parameter block is formatted as a 'struct
410 kvm_run' (see below).
417 :Architectures: all except ARM, arm64
419 :Parameters: struct kvm_regs (out)
420 :Returns: 0 on success, -1 on error
422 Reads the general purpose registers from the vcpu.
428 /* out (KVM_GET_REGS) / in (KVM_SET_REGS) */
429 __u64 rax, rbx, rcx, rdx;
430 __u64 rsi, rdi, rsp, rbp;
431 __u64 r8, r9, r10, r11;
432 __u64 r12, r13, r14, r15;
438 /* out (KVM_GET_REGS) / in (KVM_SET_REGS) */
450 :Architectures: all except ARM, arm64
452 :Parameters: struct kvm_regs (in)
453 :Returns: 0 on success, -1 on error
455 Writes the general purpose registers into the vcpu.
457 See KVM_GET_REGS for the data structure.
464 :Architectures: x86, ppc
466 :Parameters: struct kvm_sregs (out)
467 :Returns: 0 on success, -1 on error
469 Reads special registers from the vcpu.
475 struct kvm_segment cs, ds, es, fs, gs, ss;
476 struct kvm_segment tr, ldt;
477 struct kvm_dtable gdt, idt;
478 __u64 cr0, cr2, cr3, cr4, cr8;
481 __u64 interrupt_bitmap[(KVM_NR_INTERRUPTS + 63) / 64];
484 /* ppc -- see arch/powerpc/include/uapi/asm/kvm.h */
486 interrupt_bitmap is a bitmap of pending external interrupts. At most
487 one bit may be set. This interrupt has been acknowledged by the APIC
488 but not yet injected into the cpu core.
495 :Architectures: x86, ppc
497 :Parameters: struct kvm_sregs (in)
498 :Returns: 0 on success, -1 on error
500 Writes special registers into the vcpu. See KVM_GET_SREGS for the
510 :Parameters: struct kvm_translation (in/out)
511 :Returns: 0 on success, -1 on error
513 Translates a virtual address according to the vcpu's current address
518 struct kvm_translation {
520 __u64 linear_address;
523 __u64 physical_address;
535 :Architectures: x86, ppc, mips
537 :Parameters: struct kvm_interrupt (in)
538 :Returns: 0 on success, negative on failure.
540 Queues a hardware interrupt vector to be injected.
544 /* for KVM_INTERRUPT */
545 struct kvm_interrupt {
555 ========= ===================================
557 -EEXIST if an interrupt is already enqueued
558 -EINVAL the irq number is invalid
559 -ENXIO if the PIC is in the kernel
560 -EFAULT if the pointer is invalid
561 ========= ===================================
563 Note 'irq' is an interrupt vector, not an interrupt pin or line. This
564 ioctl is useful if the in-kernel PIC is not used.
569 Queues an external interrupt to be injected. This ioctl is overleaded
570 with 3 different irq values:
574 This injects an edge type external interrupt into the guest once it's ready
575 to receive interrupts. When injected, the interrupt is done.
577 b) KVM_INTERRUPT_UNSET
579 This unsets any pending interrupt.
581 Only available with KVM_CAP_PPC_UNSET_IRQ.
583 c) KVM_INTERRUPT_SET_LEVEL
585 This injects a level type external interrupt into the guest context. The
586 interrupt stays pending until a specific ioctl with KVM_INTERRUPT_UNSET
589 Only available with KVM_CAP_PPC_IRQ_LEVEL.
591 Note that any value for 'irq' other than the ones stated above is invalid
592 and incurs unexpected behavior.
594 This is an asynchronous vcpu ioctl and can be invoked from any thread.
599 Queues an external interrupt to be injected into the virtual CPU. A negative
600 interrupt number dequeues the interrupt.
602 This is an asynchronous vcpu ioctl and can be invoked from any thread.
612 :Returns: -1 on error
614 Support for this has been removed. Use KVM_SET_GUEST_DEBUG instead.
620 :Capability: basic (vcpu), KVM_CAP_GET_MSR_FEATURES (system)
622 :Type: system ioctl, vcpu ioctl
623 :Parameters: struct kvm_msrs (in/out)
624 :Returns: number of msrs successfully returned;
627 When used as a system ioctl:
628 Reads the values of MSR-based features that are available for the VM. This
629 is similar to KVM_GET_SUPPORTED_CPUID, but it returns MSR indices and values.
630 The list of msr-based features can be obtained using KVM_GET_MSR_FEATURE_INDEX_LIST
633 When used as a vcpu ioctl:
634 Reads model-specific registers from the vcpu. Supported msr indices can
635 be obtained using KVM_GET_MSR_INDEX_LIST in a system ioctl.
640 __u32 nmsrs; /* number of msrs in entries */
643 struct kvm_msr_entry entries[0];
646 struct kvm_msr_entry {
652 Application code should set the 'nmsrs' member (which indicates the
653 size of the entries array) and the 'index' member of each array entry.
654 kvm will fill in the 'data' member.
663 :Parameters: struct kvm_msrs (in)
664 :Returns: number of msrs successfully set (see below), -1 on error
666 Writes model-specific registers to the vcpu. See KVM_GET_MSRS for the
669 Application code should set the 'nmsrs' member (which indicates the
670 size of the entries array), and the 'index' and 'data' members of each
673 It tries to set the MSRs in array entries[] one by one. If setting an MSR
674 fails, e.g., due to setting reserved bits, the MSR isn't supported/emulated
675 by KVM, etc..., it stops processing the MSR list and returns the number of
676 MSRs that have been set successfully.
685 :Parameters: struct kvm_cpuid (in)
686 :Returns: 0 on success, -1 on error
688 Defines the vcpu responses to the cpuid instruction. Applications
689 should use the KVM_SET_CPUID2 ioctl if available.
691 Note, when this IOCTL fails, KVM gives no guarantees that previous valid CPUID
692 configuration (if there is) is not corrupted. Userspace can get a copy of the
693 resulting CPUID configuration through KVM_GET_CPUID2 in case.
697 struct kvm_cpuid_entry {
706 /* for KVM_SET_CPUID */
710 struct kvm_cpuid_entry entries[0];
714 4.21 KVM_SET_SIGNAL_MASK
715 ------------------------
720 :Parameters: struct kvm_signal_mask (in)
721 :Returns: 0 on success, -1 on error
723 Defines which signals are blocked during execution of KVM_RUN. This
724 signal mask temporarily overrides the threads signal mask. Any
725 unblocked signal received (except SIGKILL and SIGSTOP, which retain
726 their traditional behaviour) will cause KVM_RUN to return with -EINTR.
728 Note the signal will only be delivered if not blocked by the original
733 /* for KVM_SET_SIGNAL_MASK */
734 struct kvm_signal_mask {
746 :Parameters: struct kvm_fpu (out)
747 :Returns: 0 on success, -1 on error
749 Reads the floating point state from the vcpu.
753 /* for KVM_GET_FPU and KVM_SET_FPU */
758 __u8 ftwx; /* in fxsave format */
775 :Parameters: struct kvm_fpu (in)
776 :Returns: 0 on success, -1 on error
778 Writes the floating point state to the vcpu.
782 /* for KVM_GET_FPU and KVM_SET_FPU */
787 __u8 ftwx; /* in fxsave format */
798 4.24 KVM_CREATE_IRQCHIP
799 -----------------------
801 :Capability: KVM_CAP_IRQCHIP, KVM_CAP_S390_IRQCHIP (s390)
802 :Architectures: x86, ARM, arm64, s390
805 :Returns: 0 on success, -1 on error
807 Creates an interrupt controller model in the kernel.
808 On x86, creates a virtual ioapic, a virtual PIC (two PICs, nested), and sets up
809 future vcpus to have a local APIC. IRQ routing for GSIs 0-15 is set to both
810 PIC and IOAPIC; GSI 16-23 only go to the IOAPIC.
811 On ARM/arm64, a GICv2 is created. Any other GIC versions require the usage of
812 KVM_CREATE_DEVICE, which also supports creating a GICv2. Using
813 KVM_CREATE_DEVICE is preferred over KVM_CREATE_IRQCHIP for GICv2.
814 On s390, a dummy irq routing table is created.
816 Note that on s390 the KVM_CAP_S390_IRQCHIP vm capability needs to be enabled
817 before KVM_CREATE_IRQCHIP can be used.
823 :Capability: KVM_CAP_IRQCHIP
824 :Architectures: x86, arm, arm64
826 :Parameters: struct kvm_irq_level
827 :Returns: 0 on success, -1 on error
829 Sets the level of a GSI input to the interrupt controller model in the kernel.
830 On some architectures it is required that an interrupt controller model has
831 been previously created with KVM_CREATE_IRQCHIP. Note that edge-triggered
832 interrupts require the level to be set to 1 and then back to 0.
834 On real hardware, interrupt pins can be active-low or active-high. This
835 does not matter for the level field of struct kvm_irq_level: 1 always
836 means active (asserted), 0 means inactive (deasserted).
838 x86 allows the operating system to program the interrupt polarity
839 (active-low/active-high) for level-triggered interrupts, and KVM used
840 to consider the polarity. However, due to bitrot in the handling of
841 active-low interrupts, the above convention is now valid on x86 too.
842 This is signaled by KVM_CAP_X86_IOAPIC_POLARITY_IGNORED. Userspace
843 should not present interrupts to the guest as active-low unless this
844 capability is present (or unless it is not using the in-kernel irqchip,
848 ARM/arm64 can signal an interrupt either at the CPU level, or at the
849 in-kernel irqchip (GIC), and for in-kernel irqchip can tell the GIC to
850 use PPIs designated for specific cpus. The irq field is interpreted
853 Â bits: | 31 ... 28 | 27 ... 24 | 23 ... 16 | 15 ... 0 |
854 field: | vcpu2_index | irq_type | vcpu_index | irq_id |
856 The irq_type field has the following values:
859 out-of-kernel GIC: irq_id 0 is IRQ, irq_id 1 is FIQ
861 in-kernel GIC: SPI, irq_id between 32 and 1019 (incl.)
862 (the vcpu_index field is ignored)
864 in-kernel GIC: PPI, irq_id between 16 and 31 (incl.)
866 (The irq_id field thus corresponds nicely to the IRQ ID in the ARM GIC specs)
868 In both cases, level is used to assert/deassert the line.
870 When KVM_CAP_ARM_IRQ_LINE_LAYOUT_2 is supported, the target vcpu is
871 identified as (256 * vcpu2_index + vcpu_index). Otherwise, vcpu2_index
874 Note that on arm/arm64, the KVM_CAP_IRQCHIP capability only conditions
875 injection of interrupts for the in-kernel irqchip. KVM_IRQ_LINE can always
876 be used for a userspace interrupt controller.
880 struct kvm_irq_level {
883 __s32 status; /* not used for KVM_IRQ_LEVEL */
885 __u32 level; /* 0 or 1 */
892 :Capability: KVM_CAP_IRQCHIP
895 :Parameters: struct kvm_irqchip (in/out)
896 :Returns: 0 on success, -1 on error
898 Reads the state of a kernel interrupt controller created with
899 KVM_CREATE_IRQCHIP into a buffer provided by the caller.
904 __u32 chip_id; /* 0 = PIC1, 1 = PIC2, 2 = IOAPIC */
907 char dummy[512]; /* reserving space */
908 struct kvm_pic_state pic;
909 struct kvm_ioapic_state ioapic;
917 :Capability: KVM_CAP_IRQCHIP
920 :Parameters: struct kvm_irqchip (in)
921 :Returns: 0 on success, -1 on error
923 Sets the state of a kernel interrupt controller created with
924 KVM_CREATE_IRQCHIP from a buffer provided by the caller.
929 __u32 chip_id; /* 0 = PIC1, 1 = PIC2, 2 = IOAPIC */
932 char dummy[512]; /* reserving space */
933 struct kvm_pic_state pic;
934 struct kvm_ioapic_state ioapic;
939 4.28 KVM_XEN_HVM_CONFIG
940 -----------------------
942 :Capability: KVM_CAP_XEN_HVM
945 :Parameters: struct kvm_xen_hvm_config (in)
946 :Returns: 0 on success, -1 on error
948 Sets the MSR that the Xen HVM guest uses to initialize its hypercall
949 page, and provides the starting address and size of the hypercall
950 blobs in userspace. When the guest writes the MSR, kvm copies one
951 page of a blob (32- or 64-bit, depending on the vcpu mode) to guest
956 struct kvm_xen_hvm_config {
966 If the KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL flag is returned from the
967 KVM_CAP_XEN_HVM check, it may be set in the flags field of this ioctl.
968 This requests KVM to generate the contents of the hypercall page
969 automatically; hypercalls will be intercepted and passed to userspace
970 through KVM_EXIT_XEN. In this case, all of the blob size and address
973 No other flags are currently valid in the struct kvm_xen_hvm_config.
978 :Capability: KVM_CAP_ADJUST_CLOCK
981 :Parameters: struct kvm_clock_data (out)
982 :Returns: 0 on success, -1 on error
984 Gets the current timestamp of kvmclock as seen by the current guest. In
985 conjunction with KVM_SET_CLOCK, it is used to ensure monotonicity on scenarios
988 When KVM_CAP_ADJUST_CLOCK is passed to KVM_CHECK_EXTENSION, it returns the
989 set of bits that KVM can return in struct kvm_clock_data's flag member.
991 The only flag defined now is KVM_CLOCK_TSC_STABLE. If set, the returned
992 value is the exact kvmclock value seen by all VCPUs at the instant
993 when KVM_GET_CLOCK was called. If clear, the returned value is simply
994 CLOCK_MONOTONIC plus a constant offset; the offset can be modified
995 with KVM_SET_CLOCK. KVM will try to make all VCPUs follow this clock,
996 but the exact value read by each VCPU could differ, because the host
1001 struct kvm_clock_data {
1002 __u64 clock; /* kvmclock current value */
1011 :Capability: KVM_CAP_ADJUST_CLOCK
1014 :Parameters: struct kvm_clock_data (in)
1015 :Returns: 0 on success, -1 on error
1017 Sets the current timestamp of kvmclock to the value specified in its parameter.
1018 In conjunction with KVM_GET_CLOCK, it is used to ensure monotonicity on scenarios
1023 struct kvm_clock_data {
1024 __u64 clock; /* kvmclock current value */
1030 4.31 KVM_GET_VCPU_EVENTS
1031 ------------------------
1033 :Capability: KVM_CAP_VCPU_EVENTS
1034 :Extended by: KVM_CAP_INTR_SHADOW
1035 :Architectures: x86, arm, arm64
1037 :Parameters: struct kvm_vcpu_event (out)
1038 :Returns: 0 on success, -1 on error
1043 Gets currently pending exceptions, interrupts, and NMIs as well as related
1048 struct kvm_vcpu_events {
1052 __u8 has_error_code;
1073 __u8 smm_inside_nmi;
1077 __u8 exception_has_payload;
1078 __u64 exception_payload;
1081 The following bits are defined in the flags field:
1083 - KVM_VCPUEVENT_VALID_SHADOW may be set to signal that
1084 interrupt.shadow contains a valid state.
1086 - KVM_VCPUEVENT_VALID_SMM may be set to signal that smi contains a
1089 - KVM_VCPUEVENT_VALID_PAYLOAD may be set to signal that the
1090 exception_has_payload, exception_payload, and exception.pending
1091 fields contain a valid state. This bit will be set whenever
1092 KVM_CAP_EXCEPTION_PAYLOAD is enabled.
1097 If the guest accesses a device that is being emulated by the host kernel in
1098 such a way that a real device would generate a physical SError, KVM may make
1099 a virtual SError pending for that VCPU. This system error interrupt remains
1100 pending until the guest takes the exception by unmasking PSTATE.A.
1102 Running the VCPU may cause it to take a pending SError, or make an access that
1103 causes an SError to become pending. The event's description is only valid while
1104 the VPCU is not running.
1106 This API provides a way to read and write the pending 'event' state that is not
1107 visible to the guest. To save, restore or migrate a VCPU the struct representing
1108 the state can be read then written using this GET/SET API, along with the other
1109 guest-visible registers. It is not possible to 'cancel' an SError that has been
1112 A device being emulated in user-space may also wish to generate an SError. To do
1113 this the events structure can be populated by user-space. The current state
1114 should be read first, to ensure no existing SError is pending. If an existing
1115 SError is pending, the architecture's 'Multiple SError interrupts' rules should
1116 be followed. (2.5.3 of DDI0587.a "ARM Reliability, Availability, and
1117 Serviceability (RAS) Specification").
1119 SError exceptions always have an ESR value. Some CPUs have the ability to
1120 specify what the virtual SError's ESR value should be. These systems will
1121 advertise KVM_CAP_ARM_INJECT_SERROR_ESR. In this case exception.has_esr will
1122 always have a non-zero value when read, and the agent making an SError pending
1123 should specify the ISS field in the lower 24 bits of exception.serror_esr. If
1124 the system supports KVM_CAP_ARM_INJECT_SERROR_ESR, but user-space sets the events
1125 with exception.has_esr as zero, KVM will choose an ESR.
1127 Specifying exception.has_esr on a system that does not support it will return
1128 -EINVAL. Setting anything other than the lower 24bits of exception.serror_esr
1129 will return -EINVAL.
1131 It is not possible to read back a pending external abort (injected via
1132 KVM_SET_VCPU_EVENTS or otherwise) because such an exception is always delivered
1133 directly to the virtual CPU).
1137 struct kvm_vcpu_events {
1139 __u8 serror_pending;
1140 __u8 serror_has_esr;
1141 __u8 ext_dabt_pending;
1142 /* Align it to 8 bytes */
1149 4.32 KVM_SET_VCPU_EVENTS
1150 ------------------------
1152 :Capability: KVM_CAP_VCPU_EVENTS
1153 :Extended by: KVM_CAP_INTR_SHADOW
1154 :Architectures: x86, arm, arm64
1156 :Parameters: struct kvm_vcpu_event (in)
1157 :Returns: 0 on success, -1 on error
1162 Set pending exceptions, interrupts, and NMIs as well as related states of the
1165 See KVM_GET_VCPU_EVENTS for the data structure.
1167 Fields that may be modified asynchronously by running VCPUs can be excluded
1168 from the update. These fields are nmi.pending, sipi_vector, smi.smm,
1169 smi.pending. Keep the corresponding bits in the flags field cleared to
1170 suppress overwriting the current in-kernel state. The bits are:
1172 =============================== ==================================
1173 KVM_VCPUEVENT_VALID_NMI_PENDING transfer nmi.pending to the kernel
1174 KVM_VCPUEVENT_VALID_SIPI_VECTOR transfer sipi_vector
1175 KVM_VCPUEVENT_VALID_SMM transfer the smi sub-struct.
1176 =============================== ==================================
1178 If KVM_CAP_INTR_SHADOW is available, KVM_VCPUEVENT_VALID_SHADOW can be set in
1179 the flags field to signal that interrupt.shadow contains a valid state and
1180 shall be written into the VCPU.
1182 KVM_VCPUEVENT_VALID_SMM can only be set if KVM_CAP_X86_SMM is available.
1184 If KVM_CAP_EXCEPTION_PAYLOAD is enabled, KVM_VCPUEVENT_VALID_PAYLOAD
1185 can be set in the flags field to signal that the
1186 exception_has_payload, exception_payload, and exception.pending fields
1187 contain a valid state and shall be written into the VCPU.
1192 User space may need to inject several types of events to the guest.
1194 Set the pending SError exception state for this VCPU. It is not possible to
1195 'cancel' an Serror that has been made pending.
1197 If the guest performed an access to I/O memory which could not be handled by
1198 userspace, for example because of missing instruction syndrome decode
1199 information or because there is no device mapped at the accessed IPA, then
1200 userspace can ask the kernel to inject an external abort using the address
1201 from the exiting fault on the VCPU. It is a programming error to set
1202 ext_dabt_pending after an exit which was not either KVM_EXIT_MMIO or
1203 KVM_EXIT_ARM_NISV. This feature is only available if the system supports
1204 KVM_CAP_ARM_INJECT_EXT_DABT. This is a helper which provides commonality in
1205 how userspace reports accesses for the above cases to guests, across different
1206 userspace implementations. Nevertheless, userspace can still emulate all Arm
1207 exceptions by manipulating individual registers using the KVM_SET_ONE_REG API.
1209 See KVM_GET_VCPU_EVENTS for the data structure.
1212 4.33 KVM_GET_DEBUGREGS
1213 ----------------------
1215 :Capability: KVM_CAP_DEBUGREGS
1218 :Parameters: struct kvm_debugregs (out)
1219 :Returns: 0 on success, -1 on error
1221 Reads debug registers from the vcpu.
1225 struct kvm_debugregs {
1234 4.34 KVM_SET_DEBUGREGS
1235 ----------------------
1237 :Capability: KVM_CAP_DEBUGREGS
1240 :Parameters: struct kvm_debugregs (in)
1241 :Returns: 0 on success, -1 on error
1243 Writes debug registers into the vcpu.
1245 See KVM_GET_DEBUGREGS for the data structure. The flags field is unused
1246 yet and must be cleared on entry.
1249 4.35 KVM_SET_USER_MEMORY_REGION
1250 -------------------------------
1252 :Capability: KVM_CAP_USER_MEMORY
1255 :Parameters: struct kvm_userspace_memory_region (in)
1256 :Returns: 0 on success, -1 on error
1260 struct kvm_userspace_memory_region {
1263 __u64 guest_phys_addr;
1264 __u64 memory_size; /* bytes */
1265 __u64 userspace_addr; /* start of the userspace allocated memory */
1268 /* for kvm_memory_region::flags */
1269 #define KVM_MEM_LOG_DIRTY_PAGES (1UL << 0)
1270 #define KVM_MEM_READONLY (1UL << 1)
1272 This ioctl allows the user to create, modify or delete a guest physical
1273 memory slot. Bits 0-15 of "slot" specify the slot id and this value
1274 should be less than the maximum number of user memory slots supported per
1275 VM. The maximum allowed slots can be queried using KVM_CAP_NR_MEMSLOTS.
1276 Slots may not overlap in guest physical address space.
1278 If KVM_CAP_MULTI_ADDRESS_SPACE is available, bits 16-31 of "slot"
1279 specifies the address space which is being modified. They must be
1280 less than the value that KVM_CHECK_EXTENSION returns for the
1281 KVM_CAP_MULTI_ADDRESS_SPACE capability. Slots in separate address spaces
1282 are unrelated; the restriction on overlapping slots only applies within
1285 Deleting a slot is done by passing zero for memory_size. When changing
1286 an existing slot, it may be moved in the guest physical memory space,
1287 or its flags may be modified, but it may not be resized.
1289 Memory for the region is taken starting at the address denoted by the
1290 field userspace_addr, which must point at user addressable memory for
1291 the entire memory slot size. Any object may back this memory, including
1292 anonymous memory, ordinary files, and hugetlbfs.
1294 On architectures that support a form of address tagging, userspace_addr must
1295 be an untagged address.
1297 It is recommended that the lower 21 bits of guest_phys_addr and userspace_addr
1298 be identical. This allows large pages in the guest to be backed by large
1301 The flags field supports two flags: KVM_MEM_LOG_DIRTY_PAGES and
1302 KVM_MEM_READONLY. The former can be set to instruct KVM to keep track of
1303 writes to memory within the slot. See KVM_GET_DIRTY_LOG ioctl to know how to
1304 use it. The latter can be set, if KVM_CAP_READONLY_MEM capability allows it,
1305 to make a new slot read-only. In this case, writes to this memory will be
1306 posted to userspace as KVM_EXIT_MMIO exits.
1308 When the KVM_CAP_SYNC_MMU capability is available, changes in the backing of
1309 the memory region are automatically reflected into the guest. For example, an
1310 mmap() that affects the region will be made visible immediately. Another
1311 example is madvise(MADV_DROP).
1313 It is recommended to use this API instead of the KVM_SET_MEMORY_REGION ioctl.
1314 The KVM_SET_MEMORY_REGION does not allow fine grained control over memory
1315 allocation and is deprecated.
1318 4.36 KVM_SET_TSS_ADDR
1319 ---------------------
1321 :Capability: KVM_CAP_SET_TSS_ADDR
1324 :Parameters: unsigned long tss_address (in)
1325 :Returns: 0 on success, -1 on error
1327 This ioctl defines the physical address of a three-page region in the guest
1328 physical address space. The region must be within the first 4GB of the
1329 guest physical address space and must not conflict with any memory slot
1330 or any mmio address. The guest may malfunction if it accesses this memory
1333 This ioctl is required on Intel-based hosts. This is needed on Intel hardware
1334 because of a quirk in the virtualization implementation (see the internals
1335 documentation when it pops into existence).
1341 :Capability: KVM_CAP_ENABLE_CAP
1342 :Architectures: mips, ppc, s390
1344 :Parameters: struct kvm_enable_cap (in)
1345 :Returns: 0 on success; -1 on error
1347 :Capability: KVM_CAP_ENABLE_CAP_VM
1350 :Parameters: struct kvm_enable_cap (in)
1351 :Returns: 0 on success; -1 on error
1355 Not all extensions are enabled by default. Using this ioctl the application
1356 can enable an extension, making it available to the guest.
1358 On systems that do not support this ioctl, it always fails. On systems that
1359 do support it, it only works for extensions that are supported for enablement.
1361 To check if a capability can be enabled, the KVM_CHECK_EXTENSION ioctl should
1366 struct kvm_enable_cap {
1370 The capability that is supposed to get enabled.
1376 A bitfield indicating future enhancements. Has to be 0 for now.
1382 Arguments for enabling a feature. If a feature needs initial values to
1383 function properly, this is the place to put them.
1390 The vcpu ioctl should be used for vcpu-specific capabilities, the vm ioctl
1391 for vm-wide capabilities.
1393 4.38 KVM_GET_MP_STATE
1394 ---------------------
1396 :Capability: KVM_CAP_MP_STATE
1397 :Architectures: x86, s390, arm, arm64
1399 :Parameters: struct kvm_mp_state (out)
1400 :Returns: 0 on success; -1 on error
1404 struct kvm_mp_state {
1408 Returns the vcpu's current "multiprocessing state" (though also valid on
1409 uniprocessor guests).
1411 Possible values are:
1413 ========================== ===============================================
1414 KVM_MP_STATE_RUNNABLE the vcpu is currently running [x86,arm/arm64]
1415 KVM_MP_STATE_UNINITIALIZED the vcpu is an application processor (AP)
1416 which has not yet received an INIT signal [x86]
1417 KVM_MP_STATE_INIT_RECEIVED the vcpu has received an INIT signal, and is
1418 now ready for a SIPI [x86]
1419 KVM_MP_STATE_HALTED the vcpu has executed a HLT instruction and
1420 is waiting for an interrupt [x86]
1421 KVM_MP_STATE_SIPI_RECEIVED the vcpu has just received a SIPI (vector
1422 accessible via KVM_GET_VCPU_EVENTS) [x86]
1423 KVM_MP_STATE_STOPPED the vcpu is stopped [s390,arm/arm64]
1424 KVM_MP_STATE_CHECK_STOP the vcpu is in a special error state [s390]
1425 KVM_MP_STATE_OPERATING the vcpu is operating (running or halted)
1427 KVM_MP_STATE_LOAD the vcpu is in a special load/startup state
1429 ========================== ===============================================
1431 On x86, this ioctl is only useful after KVM_CREATE_IRQCHIP. Without an
1432 in-kernel irqchip, the multiprocessing state must be maintained by userspace on
1433 these architectures.
1438 The only states that are valid are KVM_MP_STATE_STOPPED and
1439 KVM_MP_STATE_RUNNABLE which reflect if the vcpu is paused or not.
1441 4.39 KVM_SET_MP_STATE
1442 ---------------------
1444 :Capability: KVM_CAP_MP_STATE
1445 :Architectures: x86, s390, arm, arm64
1447 :Parameters: struct kvm_mp_state (in)
1448 :Returns: 0 on success; -1 on error
1450 Sets the vcpu's current "multiprocessing state"; see KVM_GET_MP_STATE for
1453 On x86, this ioctl is only useful after KVM_CREATE_IRQCHIP. Without an
1454 in-kernel irqchip, the multiprocessing state must be maintained by userspace on
1455 these architectures.
1460 The only states that are valid are KVM_MP_STATE_STOPPED and
1461 KVM_MP_STATE_RUNNABLE which reflect if the vcpu should be paused or not.
1463 4.40 KVM_SET_IDENTITY_MAP_ADDR
1464 ------------------------------
1466 :Capability: KVM_CAP_SET_IDENTITY_MAP_ADDR
1469 :Parameters: unsigned long identity (in)
1470 :Returns: 0 on success, -1 on error
1472 This ioctl defines the physical address of a one-page region in the guest
1473 physical address space. The region must be within the first 4GB of the
1474 guest physical address space and must not conflict with any memory slot
1475 or any mmio address. The guest may malfunction if it accesses this memory
1478 Setting the address to 0 will result in resetting the address to its default
1481 This ioctl is required on Intel-based hosts. This is needed on Intel hardware
1482 because of a quirk in the virtualization implementation (see the internals
1483 documentation when it pops into existence).
1485 Fails if any VCPU has already been created.
1487 4.41 KVM_SET_BOOT_CPU_ID
1488 ------------------------
1490 :Capability: KVM_CAP_SET_BOOT_CPU_ID
1493 :Parameters: unsigned long vcpu_id
1494 :Returns: 0 on success, -1 on error
1496 Define which vcpu is the Bootstrap Processor (BSP). Values are the same
1497 as the vcpu id in KVM_CREATE_VCPU. If this ioctl is not called, the default
1504 :Capability: KVM_CAP_XSAVE
1507 :Parameters: struct kvm_xsave (out)
1508 :Returns: 0 on success, -1 on error
1517 This ioctl would copy current vcpu's xsave struct to the userspace.
1523 :Capability: KVM_CAP_XSAVE
1526 :Parameters: struct kvm_xsave (in)
1527 :Returns: 0 on success, -1 on error
1536 This ioctl would copy userspace's xsave struct to the kernel.
1542 :Capability: KVM_CAP_XCRS
1545 :Parameters: struct kvm_xcrs (out)
1546 :Returns: 0 on success, -1 on error
1559 struct kvm_xcr xcrs[KVM_MAX_XCRS];
1563 This ioctl would copy current vcpu's xcrs to the userspace.
1569 :Capability: KVM_CAP_XCRS
1572 :Parameters: struct kvm_xcrs (in)
1573 :Returns: 0 on success, -1 on error
1586 struct kvm_xcr xcrs[KVM_MAX_XCRS];
1590 This ioctl would set vcpu's xcr to the value userspace specified.
1593 4.46 KVM_GET_SUPPORTED_CPUID
1594 ----------------------------
1596 :Capability: KVM_CAP_EXT_CPUID
1599 :Parameters: struct kvm_cpuid2 (in/out)
1600 :Returns: 0 on success, -1 on error
1607 struct kvm_cpuid_entry2 entries[0];
1610 #define KVM_CPUID_FLAG_SIGNIFCANT_INDEX BIT(0)
1611 #define KVM_CPUID_FLAG_STATEFUL_FUNC BIT(1) /* deprecated */
1612 #define KVM_CPUID_FLAG_STATE_READ_NEXT BIT(2) /* deprecated */
1614 struct kvm_cpuid_entry2 {
1625 This ioctl returns x86 cpuid features which are supported by both the
1626 hardware and kvm in its default configuration. Userspace can use the
1627 information returned by this ioctl to construct cpuid information (for
1628 KVM_SET_CPUID2) that is consistent with hardware, kernel, and
1629 userspace capabilities, and with user requirements (for example, the
1630 user may wish to constrain cpuid to emulate older hardware, or for
1631 feature consistency across a cluster).
1633 Note that certain capabilities, such as KVM_CAP_X86_DISABLE_EXITS, may
1634 expose cpuid features (e.g. MONITOR) which are not supported by kvm in
1635 its default configuration. If userspace enables such capabilities, it
1636 is responsible for modifying the results of this ioctl appropriately.
1638 Userspace invokes KVM_GET_SUPPORTED_CPUID by passing a kvm_cpuid2 structure
1639 with the 'nent' field indicating the number of entries in the variable-size
1640 array 'entries'. If the number of entries is too low to describe the cpu
1641 capabilities, an error (E2BIG) is returned. If the number is too high,
1642 the 'nent' field is adjusted and an error (ENOMEM) is returned. If the
1643 number is just right, the 'nent' field is adjusted to the number of valid
1644 entries in the 'entries' array, which is then filled.
1646 The entries returned are the host cpuid as returned by the cpuid instruction,
1647 with unknown or unsupported features masked out. Some features (for example,
1648 x2apic), may not be present in the host cpu, but are exposed by kvm if it can
1649 emulate them efficiently. The fields in each entry are defined as follows:
1652 the eax value used to obtain the entry
1655 the ecx value used to obtain the entry (for entries that are
1659 an OR of zero or more of the following:
1661 KVM_CPUID_FLAG_SIGNIFCANT_INDEX:
1662 if the index field is valid
1665 the values returned by the cpuid instruction for
1666 this function/index combination
1668 The TSC deadline timer feature (CPUID leaf 1, ecx[24]) is always returned
1669 as false, since the feature depends on KVM_CREATE_IRQCHIP for local APIC
1670 support. Instead it is reported via::
1672 ioctl(KVM_CHECK_EXTENSION, KVM_CAP_TSC_DEADLINE_TIMER)
1674 if that returns true and you use KVM_CREATE_IRQCHIP, or if you emulate the
1675 feature in userspace, then you can enable the feature for KVM_SET_CPUID2.
1678 4.47 KVM_PPC_GET_PVINFO
1679 -----------------------
1681 :Capability: KVM_CAP_PPC_GET_PVINFO
1684 :Parameters: struct kvm_ppc_pvinfo (out)
1685 :Returns: 0 on success, !0 on error
1689 struct kvm_ppc_pvinfo {
1695 This ioctl fetches PV specific information that need to be passed to the guest
1696 using the device tree or other means from vm context.
1698 The hcall array defines 4 instructions that make up a hypercall.
1700 If any additional field gets added to this structure later on, a bit for that
1701 additional piece of information will be set in the flags bitmap.
1703 The flags bitmap is defined as::
1705 /* the host supports the ePAPR idle hcall
1706 #define KVM_PPC_PVINFO_FLAGS_EV_IDLE (1<<0)
1708 4.52 KVM_SET_GSI_ROUTING
1709 ------------------------
1711 :Capability: KVM_CAP_IRQ_ROUTING
1712 :Architectures: x86 s390 arm arm64
1714 :Parameters: struct kvm_irq_routing (in)
1715 :Returns: 0 on success, -1 on error
1717 Sets the GSI routing table entries, overwriting any previously set entries.
1719 On arm/arm64, GSI routing has the following limitation:
1721 - GSI routing does not apply to KVM_IRQ_LINE but only to KVM_IRQFD.
1725 struct kvm_irq_routing {
1728 struct kvm_irq_routing_entry entries[0];
1731 No flags are specified so far, the corresponding field must be set to zero.
1735 struct kvm_irq_routing_entry {
1741 struct kvm_irq_routing_irqchip irqchip;
1742 struct kvm_irq_routing_msi msi;
1743 struct kvm_irq_routing_s390_adapter adapter;
1744 struct kvm_irq_routing_hv_sint hv_sint;
1749 /* gsi routing entry types */
1750 #define KVM_IRQ_ROUTING_IRQCHIP 1
1751 #define KVM_IRQ_ROUTING_MSI 2
1752 #define KVM_IRQ_ROUTING_S390_ADAPTER 3
1753 #define KVM_IRQ_ROUTING_HV_SINT 4
1757 - KVM_MSI_VALID_DEVID: used along with KVM_IRQ_ROUTING_MSI routing entry
1758 type, specifies that the devid field contains a valid value. The per-VM
1759 KVM_CAP_MSI_DEVID capability advertises the requirement to provide
1760 the device ID. If this capability is not available, userspace should
1761 never set the KVM_MSI_VALID_DEVID flag as the ioctl might fail.
1766 struct kvm_irq_routing_irqchip {
1771 struct kvm_irq_routing_msi {
1781 If KVM_MSI_VALID_DEVID is set, devid contains a unique device identifier
1782 for the device that wrote the MSI message. For PCI, this is usually a
1783 BFD identifier in the lower 16 bits.
1785 On x86, address_hi is ignored unless the KVM_X2APIC_API_USE_32BIT_IDS
1786 feature of KVM_CAP_X2APIC_API capability is enabled. If it is enabled,
1787 address_hi bits 31-8 provide bits 31-8 of the destination id. Bits 7-0 of
1788 address_hi must be zero.
1792 struct kvm_irq_routing_s390_adapter {
1796 __u32 summary_offset;
1800 struct kvm_irq_routing_hv_sint {
1806 4.55 KVM_SET_TSC_KHZ
1807 --------------------
1809 :Capability: KVM_CAP_TSC_CONTROL
1812 :Parameters: virtual tsc_khz
1813 :Returns: 0 on success, -1 on error
1815 Specifies the tsc frequency for the virtual machine. The unit of the
1819 4.56 KVM_GET_TSC_KHZ
1820 --------------------
1822 :Capability: KVM_CAP_GET_TSC_KHZ
1826 :Returns: virtual tsc-khz on success, negative value on error
1828 Returns the tsc frequency of the guest. The unit of the return value is
1829 KHz. If the host has unstable tsc this ioctl returns -EIO instead as an
1836 :Capability: KVM_CAP_IRQCHIP
1839 :Parameters: struct kvm_lapic_state (out)
1840 :Returns: 0 on success, -1 on error
1844 #define KVM_APIC_REG_SIZE 0x400
1845 struct kvm_lapic_state {
1846 char regs[KVM_APIC_REG_SIZE];
1849 Reads the Local APIC registers and copies them into the input argument. The
1850 data format and layout are the same as documented in the architecture manual.
1852 If KVM_X2APIC_API_USE_32BIT_IDS feature of KVM_CAP_X2APIC_API is
1853 enabled, then the format of APIC_ID register depends on the APIC mode
1854 (reported by MSR_IA32_APICBASE) of its VCPU. x2APIC stores APIC ID in
1855 the APIC_ID register (bytes 32-35). xAPIC only allows an 8-bit APIC ID
1856 which is stored in bits 31-24 of the APIC register, or equivalently in
1857 byte 35 of struct kvm_lapic_state's regs field. KVM_GET_LAPIC must then
1858 be called after MSR_IA32_APICBASE has been set with KVM_SET_MSR.
1860 If KVM_X2APIC_API_USE_32BIT_IDS feature is disabled, struct kvm_lapic_state
1861 always uses xAPIC format.
1867 :Capability: KVM_CAP_IRQCHIP
1870 :Parameters: struct kvm_lapic_state (in)
1871 :Returns: 0 on success, -1 on error
1875 #define KVM_APIC_REG_SIZE 0x400
1876 struct kvm_lapic_state {
1877 char regs[KVM_APIC_REG_SIZE];
1880 Copies the input argument into the Local APIC registers. The data format
1881 and layout are the same as documented in the architecture manual.
1883 The format of the APIC ID register (bytes 32-35 of struct kvm_lapic_state's
1884 regs field) depends on the state of the KVM_CAP_X2APIC_API capability.
1885 See the note in KVM_GET_LAPIC.
1891 :Capability: KVM_CAP_IOEVENTFD
1894 :Parameters: struct kvm_ioeventfd (in)
1895 :Returns: 0 on success, !0 on error
1897 This ioctl attaches or detaches an ioeventfd to a legal pio/mmio address
1898 within the guest. A guest write in the registered address will signal the
1899 provided event instead of triggering an exit.
1903 struct kvm_ioeventfd {
1905 __u64 addr; /* legal pio/mmio address */
1906 __u32 len; /* 0, 1, 2, 4, or 8 bytes */
1912 For the special case of virtio-ccw devices on s390, the ioevent is matched
1913 to a subchannel/virtqueue tuple instead.
1915 The following flags are defined::
1917 #define KVM_IOEVENTFD_FLAG_DATAMATCH (1 << kvm_ioeventfd_flag_nr_datamatch)
1918 #define KVM_IOEVENTFD_FLAG_PIO (1 << kvm_ioeventfd_flag_nr_pio)
1919 #define KVM_IOEVENTFD_FLAG_DEASSIGN (1 << kvm_ioeventfd_flag_nr_deassign)
1920 #define KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY \
1921 (1 << kvm_ioeventfd_flag_nr_virtio_ccw_notify)
1923 If datamatch flag is set, the event will be signaled only if the written value
1924 to the registered address is equal to datamatch in struct kvm_ioeventfd.
1926 For virtio-ccw devices, addr contains the subchannel id and datamatch the
1929 With KVM_CAP_IOEVENTFD_ANY_LENGTH, a zero length ioeventfd is allowed, and
1930 the kernel will ignore the length of guest write and may get a faster vmexit.
1931 The speedup may only apply to specific architectures, but the ioeventfd will
1937 :Capability: KVM_CAP_SW_TLB
1940 :Parameters: struct kvm_dirty_tlb (in)
1941 :Returns: 0 on success, -1 on error
1945 struct kvm_dirty_tlb {
1950 This must be called whenever userspace has changed an entry in the shared
1951 TLB, prior to calling KVM_RUN on the associated vcpu.
1953 The "bitmap" field is the userspace address of an array. This array
1954 consists of a number of bits, equal to the total number of TLB entries as
1955 determined by the last successful call to KVM_CONFIG_TLB, rounded up to the
1956 nearest multiple of 64.
1958 Each bit corresponds to one TLB entry, ordered the same as in the shared TLB
1961 The array is little-endian: the bit 0 is the least significant bit of the
1962 first byte, bit 8 is the least significant bit of the second byte, etc.
1963 This avoids any complications with differing word sizes.
1965 The "num_dirty" field is a performance hint for KVM to determine whether it
1966 should skip processing the bitmap and just invalidate everything. It must
1967 be set to the number of set bits in the bitmap.
1970 4.62 KVM_CREATE_SPAPR_TCE
1971 -------------------------
1973 :Capability: KVM_CAP_SPAPR_TCE
1974 :Architectures: powerpc
1976 :Parameters: struct kvm_create_spapr_tce (in)
1977 :Returns: file descriptor for manipulating the created TCE table
1979 This creates a virtual TCE (translation control entry) table, which
1980 is an IOMMU for PAPR-style virtual I/O. It is used to translate
1981 logical addresses used in virtual I/O into guest physical addresses,
1982 and provides a scatter/gather capability for PAPR virtual I/O.
1986 /* for KVM_CAP_SPAPR_TCE */
1987 struct kvm_create_spapr_tce {
1992 The liobn field gives the logical IO bus number for which to create a
1993 TCE table. The window_size field specifies the size of the DMA window
1994 which this TCE table will translate - the table will contain one 64
1995 bit TCE entry for every 4kiB of the DMA window.
1997 When the guest issues an H_PUT_TCE hcall on a liobn for which a TCE
1998 table has been created using this ioctl(), the kernel will handle it
1999 in real mode, updating the TCE table. H_PUT_TCE calls for other
2000 liobns will cause a vm exit and must be handled by userspace.
2002 The return value is a file descriptor which can be passed to mmap(2)
2003 to map the created TCE table into userspace. This lets userspace read
2004 the entries written by kernel-handled H_PUT_TCE calls, and also lets
2005 userspace update the TCE table directly which is useful in some
2009 4.63 KVM_ALLOCATE_RMA
2010 ---------------------
2012 :Capability: KVM_CAP_PPC_RMA
2013 :Architectures: powerpc
2015 :Parameters: struct kvm_allocate_rma (out)
2016 :Returns: file descriptor for mapping the allocated RMA
2018 This allocates a Real Mode Area (RMA) from the pool allocated at boot
2019 time by the kernel. An RMA is a physically-contiguous, aligned region
2020 of memory used on older POWER processors to provide the memory which
2021 will be accessed by real-mode (MMU off) accesses in a KVM guest.
2022 POWER processors support a set of sizes for the RMA that usually
2023 includes 64MB, 128MB, 256MB and some larger powers of two.
2027 /* for KVM_ALLOCATE_RMA */
2028 struct kvm_allocate_rma {
2032 The return value is a file descriptor which can be passed to mmap(2)
2033 to map the allocated RMA into userspace. The mapped area can then be
2034 passed to the KVM_SET_USER_MEMORY_REGION ioctl to establish it as the
2035 RMA for a virtual machine. The size of the RMA in bytes (which is
2036 fixed at host kernel boot time) is returned in the rma_size field of
2037 the argument structure.
2039 The KVM_CAP_PPC_RMA capability is 1 or 2 if the KVM_ALLOCATE_RMA ioctl
2040 is supported; 2 if the processor requires all virtual machines to have
2041 an RMA, or 1 if the processor can use an RMA but doesn't require it,
2042 because it supports the Virtual RMA (VRMA) facility.
2048 :Capability: KVM_CAP_USER_NMI
2052 :Returns: 0 on success, -1 on error
2054 Queues an NMI on the thread's vcpu. Note this is well defined only
2055 when KVM_CREATE_IRQCHIP has not been called, since this is an interface
2056 between the virtual cpu core and virtual local APIC. After KVM_CREATE_IRQCHIP
2057 has been called, this interface is completely emulated within the kernel.
2059 To use this to emulate the LINT1 input with KVM_CREATE_IRQCHIP, use the
2060 following algorithm:
2063 - read the local APIC's state (KVM_GET_LAPIC)
2064 - check whether changing LINT1 will queue an NMI (see the LVT entry for LINT1)
2065 - if so, issue KVM_NMI
2068 Some guests configure the LINT1 NMI input to cause a panic, aiding in
2072 4.65 KVM_S390_UCAS_MAP
2073 ----------------------
2075 :Capability: KVM_CAP_S390_UCONTROL
2076 :Architectures: s390
2078 :Parameters: struct kvm_s390_ucas_mapping (in)
2079 :Returns: 0 in case of success
2081 The parameter is defined like this::
2083 struct kvm_s390_ucas_mapping {
2089 This ioctl maps the memory at "user_addr" with the length "length" to
2090 the vcpu's address space starting at "vcpu_addr". All parameters need to
2091 be aligned by 1 megabyte.
2094 4.66 KVM_S390_UCAS_UNMAP
2095 ------------------------
2097 :Capability: KVM_CAP_S390_UCONTROL
2098 :Architectures: s390
2100 :Parameters: struct kvm_s390_ucas_mapping (in)
2101 :Returns: 0 in case of success
2103 The parameter is defined like this::
2105 struct kvm_s390_ucas_mapping {
2111 This ioctl unmaps the memory in the vcpu's address space starting at
2112 "vcpu_addr" with the length "length". The field "user_addr" is ignored.
2113 All parameters need to be aligned by 1 megabyte.
2116 4.67 KVM_S390_VCPU_FAULT
2117 ------------------------
2119 :Capability: KVM_CAP_S390_UCONTROL
2120 :Architectures: s390
2122 :Parameters: vcpu absolute address (in)
2123 :Returns: 0 in case of success
2125 This call creates a page table entry on the virtual cpu's address space
2126 (for user controlled virtual machines) or the virtual machine's address
2127 space (for regular virtual machines). This only works for minor faults,
2128 thus it's recommended to access subject memory page via the user page
2129 table upfront. This is useful to handle validity intercepts for user
2130 controlled virtual machines to fault in the virtual cpu's lowcore pages
2131 prior to calling the KVM_RUN ioctl.
2134 4.68 KVM_SET_ONE_REG
2135 --------------------
2137 :Capability: KVM_CAP_ONE_REG
2140 :Parameters: struct kvm_one_reg (in)
2141 :Returns: 0 on success, negative value on failure
2145 ====== ============================================================
2146 Â ENOENT Â Â no such register
2147 Â EINVAL Â Â invalid register ID, or no such register or used with VMs in
2148 protected virtualization mode on s390
2149 Â EPERM Â Â Â (arm64) register access not allowed before vcpu finalization
2150 ====== ============================================================
2152 (These error codes are indicative only: do not rely on a specific error
2153 code being returned in a specific situation.)
2157 struct kvm_one_reg {
2162 Using this ioctl, a single vcpu register can be set to a specific value
2163 defined by user space with the passed in struct kvm_one_reg, where id
2164 refers to the register identifier as described below and addr is a pointer
2165 to a variable with the respective size. There can be architecture agnostic
2166 and architecture specific registers. Each have their own range of operation
2167 and their own constants and width. To keep track of the implemented
2168 registers, find a list below:
2170 ======= =============================== ============
2171 Arch Register Width (bits)
2172 ======= =============================== ============
2173 PPC KVM_REG_PPC_HIOR 64
2174 PPC KVM_REG_PPC_IAC1 64
2175 PPC KVM_REG_PPC_IAC2 64
2176 PPC KVM_REG_PPC_IAC3 64
2177 PPC KVM_REG_PPC_IAC4 64
2178 PPC KVM_REG_PPC_DAC1 64
2179 PPC KVM_REG_PPC_DAC2 64
2180 PPC KVM_REG_PPC_DABR 64
2181 PPC KVM_REG_PPC_DSCR 64
2182 PPC KVM_REG_PPC_PURR 64
2183 PPC KVM_REG_PPC_SPURR 64
2184 PPC KVM_REG_PPC_DAR 64
2185 PPC KVM_REG_PPC_DSISR 32
2186 PPC KVM_REG_PPC_AMR 64
2187 PPC KVM_REG_PPC_UAMOR 64
2188 PPC KVM_REG_PPC_MMCR0 64
2189 PPC KVM_REG_PPC_MMCR1 64
2190 PPC KVM_REG_PPC_MMCRA 64
2191 PPC KVM_REG_PPC_MMCR2 64
2192 PPC KVM_REG_PPC_MMCRS 64
2193 PPC KVM_REG_PPC_MMCR3 64
2194 PPC KVM_REG_PPC_SIAR 64
2195 PPC KVM_REG_PPC_SDAR 64
2196 PPC KVM_REG_PPC_SIER 64
2197 PPC KVM_REG_PPC_SIER2 64
2198 PPC KVM_REG_PPC_SIER3 64
2199 PPC KVM_REG_PPC_PMC1 32
2200 PPC KVM_REG_PPC_PMC2 32
2201 PPC KVM_REG_PPC_PMC3 32
2202 PPC KVM_REG_PPC_PMC4 32
2203 PPC KVM_REG_PPC_PMC5 32
2204 PPC KVM_REG_PPC_PMC6 32
2205 PPC KVM_REG_PPC_PMC7 32
2206 PPC KVM_REG_PPC_PMC8 32
2207 PPC KVM_REG_PPC_FPR0 64
2209 PPC KVM_REG_PPC_FPR31 64
2210 PPC KVM_REG_PPC_VR0 128
2212 PPC KVM_REG_PPC_VR31 128
2213 PPC KVM_REG_PPC_VSR0 128
2215 PPC KVM_REG_PPC_VSR31 128
2216 PPC KVM_REG_PPC_FPSCR 64
2217 PPC KVM_REG_PPC_VSCR 32
2218 PPC KVM_REG_PPC_VPA_ADDR 64
2219 PPC KVM_REG_PPC_VPA_SLB 128
2220 PPC KVM_REG_PPC_VPA_DTL 128
2221 PPC KVM_REG_PPC_EPCR 32
2222 PPC KVM_REG_PPC_EPR 32
2223 PPC KVM_REG_PPC_TCR 32
2224 PPC KVM_REG_PPC_TSR 32
2225 PPC KVM_REG_PPC_OR_TSR 32
2226 PPC KVM_REG_PPC_CLEAR_TSR 32
2227 PPC KVM_REG_PPC_MAS0 32
2228 PPC KVM_REG_PPC_MAS1 32
2229 PPC KVM_REG_PPC_MAS2 64
2230 PPC KVM_REG_PPC_MAS7_3 64
2231 PPC KVM_REG_PPC_MAS4 32
2232 PPC KVM_REG_PPC_MAS6 32
2233 PPC KVM_REG_PPC_MMUCFG 32
2234 PPC KVM_REG_PPC_TLB0CFG 32
2235 PPC KVM_REG_PPC_TLB1CFG 32
2236 PPC KVM_REG_PPC_TLB2CFG 32
2237 PPC KVM_REG_PPC_TLB3CFG 32
2238 PPC KVM_REG_PPC_TLB0PS 32
2239 PPC KVM_REG_PPC_TLB1PS 32
2240 PPC KVM_REG_PPC_TLB2PS 32
2241 PPC KVM_REG_PPC_TLB3PS 32
2242 PPC KVM_REG_PPC_EPTCFG 32
2243 PPC KVM_REG_PPC_ICP_STATE 64
2244 PPC KVM_REG_PPC_VP_STATE 128
2245 PPC KVM_REG_PPC_TB_OFFSET 64
2246 PPC KVM_REG_PPC_SPMC1 32
2247 PPC KVM_REG_PPC_SPMC2 32
2248 PPC KVM_REG_PPC_IAMR 64
2249 PPC KVM_REG_PPC_TFHAR 64
2250 PPC KVM_REG_PPC_TFIAR 64
2251 PPC KVM_REG_PPC_TEXASR 64
2252 PPC KVM_REG_PPC_FSCR 64
2253 PPC KVM_REG_PPC_PSPB 32
2254 PPC KVM_REG_PPC_EBBHR 64
2255 PPC KVM_REG_PPC_EBBRR 64
2256 PPC KVM_REG_PPC_BESCR 64
2257 PPC KVM_REG_PPC_TAR 64
2258 PPC KVM_REG_PPC_DPDES 64
2259 PPC KVM_REG_PPC_DAWR 64
2260 PPC KVM_REG_PPC_DAWRX 64
2261 PPC KVM_REG_PPC_CIABR 64
2262 PPC KVM_REG_PPC_IC 64
2263 PPC KVM_REG_PPC_VTB 64
2264 PPC KVM_REG_PPC_CSIGR 64
2265 PPC KVM_REG_PPC_TACR 64
2266 PPC KVM_REG_PPC_TCSCR 64
2267 PPC KVM_REG_PPC_PID 64
2268 PPC KVM_REG_PPC_ACOP 64
2269 PPC KVM_REG_PPC_VRSAVE 32
2270 PPC KVM_REG_PPC_LPCR 32
2271 PPC KVM_REG_PPC_LPCR_64 64
2272 PPC KVM_REG_PPC_PPR 64
2273 PPC KVM_REG_PPC_ARCH_COMPAT 32
2274 PPC KVM_REG_PPC_DABRX 32
2275 PPC KVM_REG_PPC_WORT 64
2276 PPC KVM_REG_PPC_SPRG9 64
2277 PPC KVM_REG_PPC_DBSR 32
2278 PPC KVM_REG_PPC_TIDR 64
2279 PPC KVM_REG_PPC_PSSCR 64
2280 PPC KVM_REG_PPC_DEC_EXPIRY 64
2281 PPC KVM_REG_PPC_PTCR 64
2282 PPC KVM_REG_PPC_DAWR1 64
2283 PPC KVM_REG_PPC_DAWRX1 64
2284 PPC KVM_REG_PPC_TM_GPR0 64
2286 PPC KVM_REG_PPC_TM_GPR31 64
2287 PPC KVM_REG_PPC_TM_VSR0 128
2289 PPC KVM_REG_PPC_TM_VSR63 128
2290 PPC KVM_REG_PPC_TM_CR 64
2291 PPC KVM_REG_PPC_TM_LR 64
2292 PPC KVM_REG_PPC_TM_CTR 64
2293 PPC KVM_REG_PPC_TM_FPSCR 64
2294 PPC KVM_REG_PPC_TM_AMR 64
2295 PPC KVM_REG_PPC_TM_PPR 64
2296 PPC KVM_REG_PPC_TM_VRSAVE 64
2297 PPC KVM_REG_PPC_TM_VSCR 32
2298 PPC KVM_REG_PPC_TM_DSCR 64
2299 PPC KVM_REG_PPC_TM_TAR 64
2300 PPC KVM_REG_PPC_TM_XER 64
2302 MIPS KVM_REG_MIPS_R0 64
2304 MIPS KVM_REG_MIPS_R31 64
2305 MIPS KVM_REG_MIPS_HI 64
2306 MIPS KVM_REG_MIPS_LO 64
2307 MIPS KVM_REG_MIPS_PC 64
2308 MIPS KVM_REG_MIPS_CP0_INDEX 32
2309 MIPS KVM_REG_MIPS_CP0_ENTRYLO0 64
2310 MIPS KVM_REG_MIPS_CP0_ENTRYLO1 64
2311 MIPS KVM_REG_MIPS_CP0_CONTEXT 64
2312 MIPS KVM_REG_MIPS_CP0_CONTEXTCONFIG 32
2313 MIPS KVM_REG_MIPS_CP0_USERLOCAL 64
2314 MIPS KVM_REG_MIPS_CP0_XCONTEXTCONFIG 64
2315 MIPS KVM_REG_MIPS_CP0_PAGEMASK 32
2316 MIPS KVM_REG_MIPS_CP0_PAGEGRAIN 32
2317 MIPS KVM_REG_MIPS_CP0_SEGCTL0 64
2318 MIPS KVM_REG_MIPS_CP0_SEGCTL1 64
2319 MIPS KVM_REG_MIPS_CP0_SEGCTL2 64
2320 MIPS KVM_REG_MIPS_CP0_PWBASE 64
2321 MIPS KVM_REG_MIPS_CP0_PWFIELD 64
2322 MIPS KVM_REG_MIPS_CP0_PWSIZE 64
2323 MIPS KVM_REG_MIPS_CP0_WIRED 32
2324 MIPS KVM_REG_MIPS_CP0_PWCTL 32
2325 MIPS KVM_REG_MIPS_CP0_HWRENA 32
2326 MIPS KVM_REG_MIPS_CP0_BADVADDR 64
2327 MIPS KVM_REG_MIPS_CP0_BADINSTR 32
2328 MIPS KVM_REG_MIPS_CP0_BADINSTRP 32
2329 MIPS KVM_REG_MIPS_CP0_COUNT 32
2330 MIPS KVM_REG_MIPS_CP0_ENTRYHI 64
2331 MIPS KVM_REG_MIPS_CP0_COMPARE 32
2332 MIPS KVM_REG_MIPS_CP0_STATUS 32
2333 MIPS KVM_REG_MIPS_CP0_INTCTL 32
2334 MIPS KVM_REG_MIPS_CP0_CAUSE 32
2335 MIPS KVM_REG_MIPS_CP0_EPC 64
2336 MIPS KVM_REG_MIPS_CP0_PRID 32
2337 MIPS KVM_REG_MIPS_CP0_EBASE 64
2338 MIPS KVM_REG_MIPS_CP0_CONFIG 32
2339 MIPS KVM_REG_MIPS_CP0_CONFIG1 32
2340 MIPS KVM_REG_MIPS_CP0_CONFIG2 32
2341 MIPS KVM_REG_MIPS_CP0_CONFIG3 32
2342 MIPS KVM_REG_MIPS_CP0_CONFIG4 32
2343 MIPS KVM_REG_MIPS_CP0_CONFIG5 32
2344 MIPS KVM_REG_MIPS_CP0_CONFIG7 32
2345 MIPS KVM_REG_MIPS_CP0_XCONTEXT 64
2346 MIPS KVM_REG_MIPS_CP0_ERROREPC 64
2347 MIPS KVM_REG_MIPS_CP0_KSCRATCH1 64
2348 MIPS KVM_REG_MIPS_CP0_KSCRATCH2 64
2349 MIPS KVM_REG_MIPS_CP0_KSCRATCH3 64
2350 MIPS KVM_REG_MIPS_CP0_KSCRATCH4 64
2351 MIPS KVM_REG_MIPS_CP0_KSCRATCH5 64
2352 MIPS KVM_REG_MIPS_CP0_KSCRATCH6 64
2353 MIPS KVM_REG_MIPS_CP0_MAAR(0..63) 64
2354 MIPS KVM_REG_MIPS_COUNT_CTL 64
2355 MIPS KVM_REG_MIPS_COUNT_RESUME 64
2356 MIPS KVM_REG_MIPS_COUNT_HZ 64
2357 MIPS KVM_REG_MIPS_FPR_32(0..31) 32
2358 MIPS KVM_REG_MIPS_FPR_64(0..31) 64
2359 MIPS KVM_REG_MIPS_VEC_128(0..31) 128
2360 MIPS KVM_REG_MIPS_FCR_IR 32
2361 MIPS KVM_REG_MIPS_FCR_CSR 32
2362 MIPS KVM_REG_MIPS_MSA_IR 32
2363 MIPS KVM_REG_MIPS_MSA_CSR 32
2364 ======= =============================== ============
2366 ARM registers are mapped using the lower 32 bits. The upper 16 of that
2367 is the register group type, or coprocessor number:
2369 ARM core registers have the following id bit patterns::
2371 0x4020 0000 0010 <index into the kvm_regs struct:16>
2373 ARM 32-bit CP15 registers have the following id bit patterns::
2375 0x4020 0000 000F <zero:1> <crn:4> <crm:4> <opc1:4> <opc2:3>
2377 ARM 64-bit CP15 registers have the following id bit patterns::
2379 0x4030 0000 000F <zero:1> <zero:4> <crm:4> <opc1:4> <zero:3>
2381 ARM CCSIDR registers are demultiplexed by CSSELR value::
2383 0x4020 0000 0011 00 <csselr:8>
2385 ARM 32-bit VFP control registers have the following id bit patterns::
2387 0x4020 0000 0012 1 <regno:12>
2389 ARM 64-bit FP registers have the following id bit patterns::
2391 0x4030 0000 0012 0 <regno:12>
2393 ARM firmware pseudo-registers have the following bit pattern::
2395 0x4030 0000 0014 <regno:16>
2398 arm64 registers are mapped using the lower 32 bits. The upper 16 of
2399 that is the register group type, or coprocessor number:
2401 arm64 core/FP-SIMD registers have the following id bit patterns. Note
2402 that the size of the access is variable, as the kvm_regs structure
2403 contains elements ranging from 32 to 128 bits. The index is a 32bit
2404 value in the kvm_regs structure seen as a 32bit array::
2406 0x60x0 0000 0010 <index into the kvm_regs struct:16>
2410 ======================= ========= ===== =======================================
2411 Encoding Register Bits kvm_regs member
2412 ======================= ========= ===== =======================================
2413 0x6030 0000 0010 0000 X0 64 regs.regs[0]
2414 0x6030 0000 0010 0002 X1 64 regs.regs[1]
2416 0x6030 0000 0010 003c X30 64 regs.regs[30]
2417 0x6030 0000 0010 003e SP 64 regs.sp
2418 0x6030 0000 0010 0040 PC 64 regs.pc
2419 0x6030 0000 0010 0042 PSTATE 64 regs.pstate
2420 0x6030 0000 0010 0044 SP_EL1 64 sp_el1
2421 0x6030 0000 0010 0046 ELR_EL1 64 elr_el1
2422 0x6030 0000 0010 0048 SPSR_EL1 64 spsr[KVM_SPSR_EL1] (alias SPSR_SVC)
2423 0x6030 0000 0010 004a SPSR_ABT 64 spsr[KVM_SPSR_ABT]
2424 0x6030 0000 0010 004c SPSR_UND 64 spsr[KVM_SPSR_UND]
2425 0x6030 0000 0010 004e SPSR_IRQ 64 spsr[KVM_SPSR_IRQ]
2426 0x6060 0000 0010 0050 SPSR_FIQ 64 spsr[KVM_SPSR_FIQ]
2427 0x6040 0000 0010 0054 V0 128 fp_regs.vregs[0] [1]_
2428 0x6040 0000 0010 0058 V1 128 fp_regs.vregs[1] [1]_
2430 0x6040 0000 0010 00d0 V31 128 fp_regs.vregs[31] [1]_
2431 0x6020 0000 0010 00d4 FPSR 32 fp_regs.fpsr
2432 0x6020 0000 0010 00d5 FPCR 32 fp_regs.fpcr
2433 ======================= ========= ===== =======================================
2435 .. [1] These encodings are not accepted for SVE-enabled vcpus. See
2438 The equivalent register content can be accessed via bits [127:0] of
2439 the corresponding SVE Zn registers instead for vcpus that have SVE
2440 enabled (see below).
2442 arm64 CCSIDR registers are demultiplexed by CSSELR value::
2444 0x6020 0000 0011 00 <csselr:8>
2446 arm64 system registers have the following id bit patterns::
2448 0x6030 0000 0013 <op0:2> <op1:3> <crn:4> <crm:4> <op2:3>
2452 Two system register IDs do not follow the specified pattern. These
2453 are KVM_REG_ARM_TIMER_CVAL and KVM_REG_ARM_TIMER_CNT, which map to
2454 system registers CNTV_CVAL_EL0 and CNTVCT_EL0 respectively. These
2455 two had their values accidentally swapped, which means TIMER_CVAL is
2456 derived from the register encoding for CNTVCT_EL0 and TIMER_CNT is
2457 derived from the register encoding for CNTV_CVAL_EL0. As this is
2458 API, it must remain this way.
2460 arm64 firmware pseudo-registers have the following bit pattern::
2462 0x6030 0000 0014 <regno:16>
2464 arm64 SVE registers have the following bit patterns::
2466 0x6080 0000 0015 00 <n:5> <slice:5> Zn bits[2048*slice + 2047 : 2048*slice]
2467 0x6050 0000 0015 04 <n:4> <slice:5> Pn bits[256*slice + 255 : 256*slice]
2468 0x6050 0000 0015 060 <slice:5> FFR bits[256*slice + 255 : 256*slice]
2469 0x6060 0000 0015 ffff KVM_REG_ARM64_SVE_VLS pseudo-register
2471 Access to register IDs where 2048 * slice >= 128 * max_vq will fail with
2472 ENOENT. max_vq is the vcpu's maximum supported vector length in 128-bit
2473 quadwords: see [2]_ below.
2475 These registers are only accessible on vcpus for which SVE is enabled.
2476 See KVM_ARM_VCPU_INIT for details.
2478 In addition, except for KVM_REG_ARM64_SVE_VLS, these registers are not
2479 accessible until the vcpu's SVE configuration has been finalized
2480 using KVM_ARM_VCPU_FINALIZE(KVM_ARM_VCPU_SVE). See KVM_ARM_VCPU_INIT
2481 and KVM_ARM_VCPU_FINALIZE for more information about this procedure.
2483 KVM_REG_ARM64_SVE_VLS is a pseudo-register that allows the set of vector
2484 lengths supported by the vcpu to be discovered and configured by
2485 userspace. When transferred to or from user memory via KVM_GET_ONE_REG
2486 or KVM_SET_ONE_REG, the value of this register is of type
2487 __u64[KVM_ARM64_SVE_VLS_WORDS], and encodes the set of vector lengths as
2490 __u64 vector_lengths[KVM_ARM64_SVE_VLS_WORDS];
2492 if (vq >= SVE_VQ_MIN && vq <= SVE_VQ_MAX &&
2493 ((vector_lengths[(vq - KVM_ARM64_SVE_VQ_MIN) / 64] >>
2494 ((vq - KVM_ARM64_SVE_VQ_MIN) % 64)) & 1))
2495 /* Vector length vq * 16 bytes supported */
2497 /* Vector length vq * 16 bytes not supported */
2499 .. [2] The maximum value vq for which the above condition is true is
2500 max_vq. This is the maximum vector length available to the guest on
2501 this vcpu, and determines which register slices are visible through
2502 this ioctl interface.
2504 (See Documentation/arm64/sve.rst for an explanation of the "vq"
2507 KVM_REG_ARM64_SVE_VLS is only accessible after KVM_ARM_VCPU_INIT.
2508 KVM_ARM_VCPU_INIT initialises it to the best set of vector lengths that
2511 Userspace may subsequently modify it if desired until the vcpu's SVE
2512 configuration is finalized using KVM_ARM_VCPU_FINALIZE(KVM_ARM_VCPU_SVE).
2514 Apart from simply removing all vector lengths from the host set that
2515 exceed some value, support for arbitrarily chosen sets of vector lengths
2516 is hardware-dependent and may not be available. Attempting to configure
2517 an invalid set of vector lengths via KVM_SET_ONE_REG will fail with
2520 After the vcpu's SVE configuration is finalized, further attempts to
2521 write this register will fail with EPERM.
2524 MIPS registers are mapped using the lower 32 bits. The upper 16 of that is
2525 the register group type:
2527 MIPS core registers (see above) have the following id bit patterns::
2529 0x7030 0000 0000 <reg:16>
2531 MIPS CP0 registers (see KVM_REG_MIPS_CP0_* above) have the following id bit
2532 patterns depending on whether they're 32-bit or 64-bit registers::
2534 0x7020 0000 0001 00 <reg:5> <sel:3> (32-bit)
2535 0x7030 0000 0001 00 <reg:5> <sel:3> (64-bit)
2537 Note: KVM_REG_MIPS_CP0_ENTRYLO0 and KVM_REG_MIPS_CP0_ENTRYLO1 are the MIPS64
2538 versions of the EntryLo registers regardless of the word size of the host
2539 hardware, host kernel, guest, and whether XPA is present in the guest, i.e.
2540 with the RI and XI bits (if they exist) in bits 63 and 62 respectively, and
2541 the PFNX field starting at bit 30.
2543 MIPS MAARs (see KVM_REG_MIPS_CP0_MAAR(*) above) have the following id bit
2546 0x7030 0000 0001 01 <reg:8>
2548 MIPS KVM control registers (see above) have the following id bit patterns::
2550 0x7030 0000 0002 <reg:16>
2552 MIPS FPU registers (see KVM_REG_MIPS_FPR_{32,64}() above) have the following
2553 id bit patterns depending on the size of the register being accessed. They are
2554 always accessed according to the current guest FPU mode (Status.FR and
2555 Config5.FRE), i.e. as the guest would see them, and they become unpredictable
2556 if the guest FPU mode is changed. MIPS SIMD Architecture (MSA) vector
2557 registers (see KVM_REG_MIPS_VEC_128() above) have similar patterns as they
2558 overlap the FPU registers::
2560 0x7020 0000 0003 00 <0:3> <reg:5> (32-bit FPU registers)
2561 0x7030 0000 0003 00 <0:3> <reg:5> (64-bit FPU registers)
2562 0x7040 0000 0003 00 <0:3> <reg:5> (128-bit MSA vector registers)
2564 MIPS FPU control registers (see KVM_REG_MIPS_FCR_{IR,CSR} above) have the
2565 following id bit patterns::
2567 0x7020 0000 0003 01 <0:3> <reg:5>
2569 MIPS MSA control registers (see KVM_REG_MIPS_MSA_{IR,CSR} above) have the
2570 following id bit patterns::
2572 0x7020 0000 0003 02 <0:3> <reg:5>
2575 4.69 KVM_GET_ONE_REG
2576 --------------------
2578 :Capability: KVM_CAP_ONE_REG
2581 :Parameters: struct kvm_one_reg (in and out)
2582 :Returns: 0 on success, negative value on failure
2586 ======== ============================================================
2587 Â ENOENT Â Â no such register
2588 Â EINVAL Â Â invalid register ID, or no such register or used with VMs in
2589 protected virtualization mode on s390
2590 Â EPERM Â Â Â (arm64) register access not allowed before vcpu finalization
2591 ======== ============================================================
2593 (These error codes are indicative only: do not rely on a specific error
2594 code being returned in a specific situation.)
2596 This ioctl allows to receive the value of a single register implemented
2597 in a vcpu. The register to read is indicated by the "id" field of the
2598 kvm_one_reg struct passed in. On success, the register value can be found
2599 at the memory location pointed to by "addr".
2601 The list of registers accessible using this interface is identical to the
2605 4.70 KVM_KVMCLOCK_CTRL
2606 ----------------------
2608 :Capability: KVM_CAP_KVMCLOCK_CTRL
2609 :Architectures: Any that implement pvclocks (currently x86 only)
2612 :Returns: 0 on success, -1 on error
2614 This ioctl sets a flag accessible to the guest indicating that the specified
2615 vCPU has been paused by the host userspace.
2617 The host will set a flag in the pvclock structure that is checked from the
2618 soft lockup watchdog. The flag is part of the pvclock structure that is
2619 shared between guest and host, specifically the second bit of the flags
2620 field of the pvclock_vcpu_time_info structure. It will be set exclusively by
2621 the host and read/cleared exclusively by the guest. The guest operation of
2622 checking and clearing the flag must be an atomic operation so
2623 load-link/store-conditional, or equivalent must be used. There are two cases
2624 where the guest will clear the flag: when the soft lockup watchdog timer resets
2625 itself or when a soft lockup is detected. This ioctl can be called any time
2626 after pausing the vcpu, but before it is resumed.
2632 :Capability: KVM_CAP_SIGNAL_MSI
2633 :Architectures: x86 arm arm64
2635 :Parameters: struct kvm_msi (in)
2636 :Returns: >0 on delivery, 0 if guest blocked the MSI, and -1 on error
2638 Directly inject a MSI message. Only valid with in-kernel irqchip that handles
2653 KVM_MSI_VALID_DEVID: devid contains a valid value. The per-VM
2654 KVM_CAP_MSI_DEVID capability advertises the requirement to provide
2655 the device ID. If this capability is not available, userspace
2656 should never set the KVM_MSI_VALID_DEVID flag as the ioctl might fail.
2658 If KVM_MSI_VALID_DEVID is set, devid contains a unique device identifier
2659 for the device that wrote the MSI message. For PCI, this is usually a
2660 BFD identifier in the lower 16 bits.
2662 On x86, address_hi is ignored unless the KVM_X2APIC_API_USE_32BIT_IDS
2663 feature of KVM_CAP_X2APIC_API capability is enabled. If it is enabled,
2664 address_hi bits 31-8 provide bits 31-8 of the destination id. Bits 7-0 of
2665 address_hi must be zero.
2668 4.71 KVM_CREATE_PIT2
2669 --------------------
2671 :Capability: KVM_CAP_PIT2
2674 :Parameters: struct kvm_pit_config (in)
2675 :Returns: 0 on success, -1 on error
2677 Creates an in-kernel device model for the i8254 PIT. This call is only valid
2678 after enabling in-kernel irqchip support via KVM_CREATE_IRQCHIP. The following
2679 parameters have to be passed::
2681 struct kvm_pit_config {
2688 #define KVM_PIT_SPEAKER_DUMMY 1 /* emulate speaker port stub */
2690 PIT timer interrupts may use a per-VM kernel thread for injection. If it
2691 exists, this thread will have a name of the following pattern::
2693 kvm-pit/<owner-process-pid>
2695 When running a guest with elevated priorities, the scheduling parameters of
2696 this thread may have to be adjusted accordingly.
2698 This IOCTL replaces the obsolete KVM_CREATE_PIT.
2704 :Capability: KVM_CAP_PIT_STATE2
2707 :Parameters: struct kvm_pit_state2 (out)
2708 :Returns: 0 on success, -1 on error
2710 Retrieves the state of the in-kernel PIT model. Only valid after
2711 KVM_CREATE_PIT2. The state is returned in the following structure::
2713 struct kvm_pit_state2 {
2714 struct kvm_pit_channel_state channels[3];
2721 /* disable PIT in HPET legacy mode */
2722 #define KVM_PIT_FLAGS_HPET_LEGACY 0x00000001
2724 This IOCTL replaces the obsolete KVM_GET_PIT.
2730 :Capability: KVM_CAP_PIT_STATE2
2733 :Parameters: struct kvm_pit_state2 (in)
2734 :Returns: 0 on success, -1 on error
2736 Sets the state of the in-kernel PIT model. Only valid after KVM_CREATE_PIT2.
2737 See KVM_GET_PIT2 for details on struct kvm_pit_state2.
2739 This IOCTL replaces the obsolete KVM_SET_PIT.
2742 4.74 KVM_PPC_GET_SMMU_INFO
2743 --------------------------
2745 :Capability: KVM_CAP_PPC_GET_SMMU_INFO
2746 :Architectures: powerpc
2749 :Returns: 0 on success, -1 on error
2751 This populates and returns a structure describing the features of
2752 the "Server" class MMU emulation supported by KVM.
2753 This can in turn be used by userspace to generate the appropriate
2754 device-tree properties for the guest operating system.
2756 The structure contains some global information, followed by an
2757 array of supported segment page sizes::
2759 struct kvm_ppc_smmu_info {
2763 struct kvm_ppc_one_seg_page_size sps[KVM_PPC_PAGE_SIZES_MAX_SZ];
2766 The supported flags are:
2768 - KVM_PPC_PAGE_SIZES_REAL:
2769 When that flag is set, guest page sizes must "fit" the backing
2770 store page sizes. When not set, any page size in the list can
2771 be used regardless of how they are backed by userspace.
2773 - KVM_PPC_1T_SEGMENTS
2774 The emulated MMU supports 1T segments in addition to the
2778 This flag indicates that HPT guests are not supported by KVM,
2779 thus all guests must use radix MMU mode.
2781 The "slb_size" field indicates how many SLB entries are supported
2783 The "sps" array contains 8 entries indicating the supported base
2784 page sizes for a segment in increasing order. Each entry is defined
2787 struct kvm_ppc_one_seg_page_size {
2788 __u32 page_shift; /* Base page shift of segment (or 0) */
2789 __u32 slb_enc; /* SLB encoding for BookS */
2790 struct kvm_ppc_one_page_size enc[KVM_PPC_PAGE_SIZES_MAX_SZ];
2793 An entry with a "page_shift" of 0 is unused. Because the array is
2794 organized in increasing order, a lookup can stop when encoutering
2797 The "slb_enc" field provides the encoding to use in the SLB for the
2798 page size. The bits are in positions such as the value can directly
2799 be OR'ed into the "vsid" argument of the slbmte instruction.
2801 The "enc" array is a list which for each of those segment base page
2802 size provides the list of supported actual page sizes (which can be
2803 only larger or equal to the base page size), along with the
2804 corresponding encoding in the hash PTE. Similarly, the array is
2805 8 entries sorted by increasing sizes and an entry with a "0" shift
2806 is an empty entry and a terminator::
2808 struct kvm_ppc_one_page_size {
2809 __u32 page_shift; /* Page shift (or 0) */
2810 __u32 pte_enc; /* Encoding in the HPTE (>>12) */
2813 The "pte_enc" field provides a value that can OR'ed into the hash
2814 PTE's RPN field (ie, it needs to be shifted left by 12 to OR it
2815 into the hash PTE second double word).
2820 :Capability: KVM_CAP_IRQFD
2821 :Architectures: x86 s390 arm arm64
2823 :Parameters: struct kvm_irqfd (in)
2824 :Returns: 0 on success, -1 on error
2826 Allows setting an eventfd to directly trigger a guest interrupt.
2827 kvm_irqfd.fd specifies the file descriptor to use as the eventfd and
2828 kvm_irqfd.gsi specifies the irqchip pin toggled by this event. When
2829 an event is triggered on the eventfd, an interrupt is injected into
2830 the guest using the specified gsi pin. The irqfd is removed using
2831 the KVM_IRQFD_FLAG_DEASSIGN flag, specifying both kvm_irqfd.fd
2834 With KVM_CAP_IRQFD_RESAMPLE, KVM_IRQFD supports a de-assert and notify
2835 mechanism allowing emulation of level-triggered, irqfd-based
2836 interrupts. When KVM_IRQFD_FLAG_RESAMPLE is set the user must pass an
2837 additional eventfd in the kvm_irqfd.resamplefd field. When operating
2838 in resample mode, posting of an interrupt through kvm_irq.fd asserts
2839 the specified gsi in the irqchip. When the irqchip is resampled, such
2840 as from an EOI, the gsi is de-asserted and the user is notified via
2841 kvm_irqfd.resamplefd. It is the user's responsibility to re-queue
2842 the interrupt if the device making use of it still requires service.
2843 Note that closing the resamplefd is not sufficient to disable the
2844 irqfd. The KVM_IRQFD_FLAG_RESAMPLE is only necessary on assignment
2845 and need not be specified with KVM_IRQFD_FLAG_DEASSIGN.
2847 On arm/arm64, gsi routing being supported, the following can happen:
2849 - in case no routing entry is associated to this gsi, injection fails
2850 - in case the gsi is associated to an irqchip routing entry,
2851 irqchip.pin + 32 corresponds to the injected SPI ID.
2852 - in case the gsi is associated to an MSI routing entry, the MSI
2853 message and device ID are translated into an LPI (support restricted
2854 to GICv3 ITS in-kernel emulation).
2856 4.76 KVM_PPC_ALLOCATE_HTAB
2857 --------------------------
2859 :Capability: KVM_CAP_PPC_ALLOC_HTAB
2860 :Architectures: powerpc
2862 :Parameters: Pointer to u32 containing hash table order (in/out)
2863 :Returns: 0 on success, -1 on error
2865 This requests the host kernel to allocate an MMU hash table for a
2866 guest using the PAPR paravirtualization interface. This only does
2867 anything if the kernel is configured to use the Book 3S HV style of
2868 virtualization. Otherwise the capability doesn't exist and the ioctl
2869 returns an ENOTTY error. The rest of this description assumes Book 3S
2872 There must be no vcpus running when this ioctl is called; if there
2873 are, it will do nothing and return an EBUSY error.
2875 The parameter is a pointer to a 32-bit unsigned integer variable
2876 containing the order (log base 2) of the desired size of the hash
2877 table, which must be between 18 and 46. On successful return from the
2878 ioctl, the value will not be changed by the kernel.
2880 If no hash table has been allocated when any vcpu is asked to run
2881 (with the KVM_RUN ioctl), the host kernel will allocate a
2882 default-sized hash table (16 MB).
2884 If this ioctl is called when a hash table has already been allocated,
2885 with a different order from the existing hash table, the existing hash
2886 table will be freed and a new one allocated. If this is ioctl is
2887 called when a hash table has already been allocated of the same order
2888 as specified, the kernel will clear out the existing hash table (zero
2889 all HPTEs). In either case, if the guest is using the virtualized
2890 real-mode area (VRMA) facility, the kernel will re-create the VMRA
2891 HPTEs on the next KVM_RUN of any vcpu.
2893 4.77 KVM_S390_INTERRUPT
2894 -----------------------
2897 :Architectures: s390
2898 :Type: vm ioctl, vcpu ioctl
2899 :Parameters: struct kvm_s390_interrupt (in)
2900 :Returns: 0 on success, -1 on error
2902 Allows to inject an interrupt to the guest. Interrupts can be floating
2903 (vm ioctl) or per cpu (vcpu ioctl), depending on the interrupt type.
2905 Interrupt parameters are passed via kvm_s390_interrupt::
2907 struct kvm_s390_interrupt {
2913 type can be one of the following:
2915 KVM_S390_SIGP_STOP (vcpu)
2916 - sigp stop; optional flags in parm
2917 KVM_S390_PROGRAM_INT (vcpu)
2918 - program check; code in parm
2919 KVM_S390_SIGP_SET_PREFIX (vcpu)
2920 - sigp set prefix; prefix address in parm
2921 KVM_S390_RESTART (vcpu)
2923 KVM_S390_INT_CLOCK_COMP (vcpu)
2924 - clock comparator interrupt
2925 KVM_S390_INT_CPU_TIMER (vcpu)
2926 - CPU timer interrupt
2927 KVM_S390_INT_VIRTIO (vm)
2928 - virtio external interrupt; external interrupt
2929 parameters in parm and parm64
2930 KVM_S390_INT_SERVICE (vm)
2931 - sclp external interrupt; sclp parameter in parm
2932 KVM_S390_INT_EMERGENCY (vcpu)
2933 - sigp emergency; source cpu in parm
2934 KVM_S390_INT_EXTERNAL_CALL (vcpu)
2935 - sigp external call; source cpu in parm
2936 KVM_S390_INT_IO(ai,cssid,ssid,schid) (vm)
2937 - compound value to indicate an
2938 I/O interrupt (ai - adapter interrupt; cssid,ssid,schid - subchannel);
2939 I/O interruption parameters in parm (subchannel) and parm64 (intparm,
2940 interruption subclass)
2941 KVM_S390_MCHK (vm, vcpu)
2942 - machine check interrupt; cr 14 bits in parm, machine check interrupt
2943 code in parm64 (note that machine checks needing further payload are not
2944 supported by this ioctl)
2946 This is an asynchronous vcpu ioctl and can be invoked from any thread.
2948 4.78 KVM_PPC_GET_HTAB_FD
2949 ------------------------
2951 :Capability: KVM_CAP_PPC_HTAB_FD
2952 :Architectures: powerpc
2954 :Parameters: Pointer to struct kvm_get_htab_fd (in)
2955 :Returns: file descriptor number (>= 0) on success, -1 on error
2957 This returns a file descriptor that can be used either to read out the
2958 entries in the guest's hashed page table (HPT), or to write entries to
2959 initialize the HPT. The returned fd can only be written to if the
2960 KVM_GET_HTAB_WRITE bit is set in the flags field of the argument, and
2961 can only be read if that bit is clear. The argument struct looks like
2964 /* For KVM_PPC_GET_HTAB_FD */
2965 struct kvm_get_htab_fd {
2971 /* Values for kvm_get_htab_fd.flags */
2972 #define KVM_GET_HTAB_BOLTED_ONLY ((__u64)0x1)
2973 #define KVM_GET_HTAB_WRITE ((__u64)0x2)
2975 The 'start_index' field gives the index in the HPT of the entry at
2976 which to start reading. It is ignored when writing.
2978 Reads on the fd will initially supply information about all
2979 "interesting" HPT entries. Interesting entries are those with the
2980 bolted bit set, if the KVM_GET_HTAB_BOLTED_ONLY bit is set, otherwise
2981 all entries. When the end of the HPT is reached, the read() will
2982 return. If read() is called again on the fd, it will start again from
2983 the beginning of the HPT, but will only return HPT entries that have
2984 changed since they were last read.
2986 Data read or written is structured as a header (8 bytes) followed by a
2987 series of valid HPT entries (16 bytes) each. The header indicates how
2988 many valid HPT entries there are and how many invalid entries follow
2989 the valid entries. The invalid entries are not represented explicitly
2990 in the stream. The header format is::
2992 struct kvm_get_htab_header {
2998 Writes to the fd create HPT entries starting at the index given in the
2999 header; first 'n_valid' valid entries with contents from the data
3000 written, then 'n_invalid' invalid entries, invalidating any previously
3001 valid entries found.
3003 4.79 KVM_CREATE_DEVICE
3004 ----------------------
3006 :Capability: KVM_CAP_DEVICE_CTRL
3008 :Parameters: struct kvm_create_device (in/out)
3009 :Returns: 0 on success, -1 on error
3013 ====== =======================================================
3014 ENODEV The device type is unknown or unsupported
3015 EEXIST Device already created, and this type of device may not
3016 be instantiated multiple times
3017 ====== =======================================================
3019 Other error conditions may be defined by individual device types or
3020 have their standard meanings.
3022 Creates an emulated device in the kernel. The file descriptor returned
3023 in fd can be used with KVM_SET/GET/HAS_DEVICE_ATTR.
3025 If the KVM_CREATE_DEVICE_TEST flag is set, only test whether the
3026 device type is supported (not necessarily whether it can be created
3029 Individual devices should not define flags. Attributes should be used
3030 for specifying any behavior that is not implied by the device type
3035 struct kvm_create_device {
3036 __u32 type; /* in: KVM_DEV_TYPE_xxx */
3037 __u32 fd; /* out: device handle */
3038 __u32 flags; /* in: KVM_CREATE_DEVICE_xxx */
3041 4.80 KVM_SET_DEVICE_ATTR/KVM_GET_DEVICE_ATTR
3042 --------------------------------------------
3044 :Capability: KVM_CAP_DEVICE_CTRL, KVM_CAP_VM_ATTRIBUTES for vm device,
3045 KVM_CAP_VCPU_ATTRIBUTES for vcpu device
3046 :Type: device ioctl, vm ioctl, vcpu ioctl
3047 :Parameters: struct kvm_device_attr
3048 :Returns: 0 on success, -1 on error
3052 ===== =============================================================
3053 ENXIO The group or attribute is unknown/unsupported for this device
3054 or hardware support is missing.
3055 EPERM The attribute cannot (currently) be accessed this way
3056 (e.g. read-only attribute, or attribute that only makes
3057 sense when the device is in a different state)
3058 ===== =============================================================
3060 Other error conditions may be defined by individual device types.
3062 Gets/sets a specified piece of device configuration and/or state. The
3063 semantics are device-specific. See individual device documentation in
3064 the "devices" directory. As with ONE_REG, the size of the data
3065 transferred is defined by the particular attribute.
3069 struct kvm_device_attr {
3070 __u32 flags; /* no flags currently defined */
3071 __u32 group; /* device-defined */
3072 __u64 attr; /* group-defined */
3073 __u64 addr; /* userspace address of attr data */
3076 4.81 KVM_HAS_DEVICE_ATTR
3077 ------------------------
3079 :Capability: KVM_CAP_DEVICE_CTRL, KVM_CAP_VM_ATTRIBUTES for vm device,
3080 KVM_CAP_VCPU_ATTRIBUTES for vcpu device
3081 :Type: device ioctl, vm ioctl, vcpu ioctl
3082 :Parameters: struct kvm_device_attr
3083 :Returns: 0 on success, -1 on error
3087 ===== =============================================================
3088 ENXIO The group or attribute is unknown/unsupported for this device
3089 or hardware support is missing.
3090 ===== =============================================================
3092 Tests whether a device supports a particular attribute. A successful
3093 return indicates the attribute is implemented. It does not necessarily
3094 indicate that the attribute can be read or written in the device's
3095 current state. "addr" is ignored.
3097 4.82 KVM_ARM_VCPU_INIT
3098 ----------------------
3101 :Architectures: arm, arm64
3103 :Parameters: struct kvm_vcpu_init (in)
3104 :Returns: 0 on success; -1 on error
3108 ====== =================================================================
3109 Â EINVAL Â Â Â the target is unknown, or the combination of features is invalid.
3110 Â ENOENT Â Â Â a features bit specified is unknown.
3111 ====== =================================================================
3113 This tells KVM what type of CPU to present to the guest, and what
3114 optional features it should have. Â This will cause a reset of the cpu
3115 registers to their initial values. Â If this is not called, KVM_RUN will
3116 return ENOEXEC for that vcpu.
3118 Note that because some registers reflect machine topology, all vcpus
3119 should be created before this ioctl is invoked.
3121 Userspace can call this function multiple times for a given vcpu, including
3122 after the vcpu has been run. This will reset the vcpu to its initial
3123 state. All calls to this function after the initial call must use the same
3124 target and same set of feature flags, otherwise EINVAL will be returned.
3128 - KVM_ARM_VCPU_POWER_OFF: Starts the CPU in a power-off state.
3129 Depends on KVM_CAP_ARM_PSCI. If not set, the CPU will be powered on
3130 and execute guest code when KVM_RUN is called.
3131 - KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
3132 Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
3133 - KVM_ARM_VCPU_PSCI_0_2: Emulate PSCI v0.2 (or a future revision
3134 backward compatible with v0.2) for the CPU.
3135 Depends on KVM_CAP_ARM_PSCI_0_2.
3136 - KVM_ARM_VCPU_PMU_V3: Emulate PMUv3 for the CPU.
3137 Depends on KVM_CAP_ARM_PMU_V3.
3139 - KVM_ARM_VCPU_PTRAUTH_ADDRESS: Enables Address Pointer authentication
3141 Depends on KVM_CAP_ARM_PTRAUTH_ADDRESS.
3142 If KVM_CAP_ARM_PTRAUTH_ADDRESS and KVM_CAP_ARM_PTRAUTH_GENERIC are
3143 both present, then both KVM_ARM_VCPU_PTRAUTH_ADDRESS and
3144 KVM_ARM_VCPU_PTRAUTH_GENERIC must be requested or neither must be
3147 - KVM_ARM_VCPU_PTRAUTH_GENERIC: Enables Generic Pointer authentication
3149 Depends on KVM_CAP_ARM_PTRAUTH_GENERIC.
3150 If KVM_CAP_ARM_PTRAUTH_ADDRESS and KVM_CAP_ARM_PTRAUTH_GENERIC are
3151 both present, then both KVM_ARM_VCPU_PTRAUTH_ADDRESS and
3152 KVM_ARM_VCPU_PTRAUTH_GENERIC must be requested or neither must be
3155 - KVM_ARM_VCPU_SVE: Enables SVE for the CPU (arm64 only).
3156 Depends on KVM_CAP_ARM_SVE.
3157 Requires KVM_ARM_VCPU_FINALIZE(KVM_ARM_VCPU_SVE):
3159 * After KVM_ARM_VCPU_INIT:
3161 - KVM_REG_ARM64_SVE_VLS may be read using KVM_GET_ONE_REG: the
3162 initial value of this pseudo-register indicates the best set of
3163 vector lengths possible for a vcpu on this host.
3165 * Before KVM_ARM_VCPU_FINALIZE(KVM_ARM_VCPU_SVE):
3167 - KVM_RUN and KVM_GET_REG_LIST are not available;
3169 - KVM_GET_ONE_REG and KVM_SET_ONE_REG cannot be used to access
3170 the scalable archietctural SVE registers
3171 KVM_REG_ARM64_SVE_ZREG(), KVM_REG_ARM64_SVE_PREG() or
3172 KVM_REG_ARM64_SVE_FFR;
3174 - KVM_REG_ARM64_SVE_VLS may optionally be written using
3175 KVM_SET_ONE_REG, to modify the set of vector lengths available
3178 * After KVM_ARM_VCPU_FINALIZE(KVM_ARM_VCPU_SVE):
3180 - the KVM_REG_ARM64_SVE_VLS pseudo-register is immutable, and can
3181 no longer be written using KVM_SET_ONE_REG.
3183 4.83 KVM_ARM_PREFERRED_TARGET
3184 -----------------------------
3187 :Architectures: arm, arm64
3189 :Parameters: struct kvm_vcpu_init (out)
3190 :Returns: 0 on success; -1 on error
3194 ====== ==========================================
3195 ENODEV no preferred target available for the host
3196 ====== ==========================================
3198 This queries KVM for preferred CPU target type which can be emulated
3199 by KVM on underlying host.
3201 The ioctl returns struct kvm_vcpu_init instance containing information
3202 about preferred CPU target type and recommended features for it. The
3203 kvm_vcpu_init->features bitmap returned will have feature bits set if
3204 the preferred target recommends setting these features, but this is
3207 The information returned by this ioctl can be used to prepare an instance
3208 of struct kvm_vcpu_init for KVM_ARM_VCPU_INIT ioctl which will result in
3209 VCPU matching underlying host.
3212 4.84 KVM_GET_REG_LIST
3213 ---------------------
3216 :Architectures: arm, arm64, mips
3218 :Parameters: struct kvm_reg_list (in/out)
3219 :Returns: 0 on success; -1 on error
3223 ===== ==============================================================
3224 Â E2BIG Â Â Â Â the reg index list is too big to fit in the array specified by
3225 Â Â Â Â Â Â Â Â Â Â Â Â the user (the number required will be written into n).
3226 ===== ==============================================================
3230 struct kvm_reg_list {
3231 __u64 n; /* number of registers in reg[] */
3235 This ioctl returns the guest registers that are supported for the
3236 KVM_GET_ONE_REG/KVM_SET_ONE_REG calls.
3239 4.85 KVM_ARM_SET_DEVICE_ADDR (deprecated)
3240 -----------------------------------------
3242 :Capability: KVM_CAP_ARM_SET_DEVICE_ADDR
3243 :Architectures: arm, arm64
3245 :Parameters: struct kvm_arm_device_address (in)
3246 :Returns: 0 on success, -1 on error
3250 ====== ============================================
3251 ENODEV The device id is unknown
3252 ENXIO Device not supported on current system
3253 EEXIST Address already set
3254 E2BIG Address outside guest physical address space
3255 EBUSY Address overlaps with other device range
3256 ====== ============================================
3260 struct kvm_arm_device_addr {
3265 Specify a device address in the guest's physical address space where guests
3266 can access emulated or directly exposed devices, which the host kernel needs
3267 to know about. The id field is an architecture specific identifier for a
3270 ARM/arm64 divides the id field into two parts, a device id and an
3271 address type id specific to the individual device::
3273 Â bits: | 63 ... 32 | 31 ... 16 | 15 ... 0 |
3274 field: | 0x00000000 | device id | addr type id |
3276 ARM/arm64 currently only require this when using the in-kernel GIC
3277 support for the hardware VGIC features, using KVM_ARM_DEVICE_VGIC_V2
3278 as the device id. When setting the base address for the guest's
3279 mapping of the VGIC virtual CPU and distributor interface, the ioctl
3280 must be called after calling KVM_CREATE_IRQCHIP, but before calling
3281 KVM_RUN on any of the VCPUs. Calling this ioctl twice for any of the
3282 base addresses will return -EEXIST.
3284 Note, this IOCTL is deprecated and the more flexible SET/GET_DEVICE_ATTR API
3285 should be used instead.
3288 4.86 KVM_PPC_RTAS_DEFINE_TOKEN
3289 ------------------------------
3291 :Capability: KVM_CAP_PPC_RTAS
3294 :Parameters: struct kvm_rtas_token_args
3295 :Returns: 0 on success, -1 on error
3297 Defines a token value for a RTAS (Run Time Abstraction Services)
3298 service in order to allow it to be handled in the kernel. The
3299 argument struct gives the name of the service, which must be the name
3300 of a service that has a kernel-side implementation. If the token
3301 value is non-zero, it will be associated with that service, and
3302 subsequent RTAS calls by the guest specifying that token will be
3303 handled by the kernel. If the token value is 0, then any token
3304 associated with the service will be forgotten, and subsequent RTAS
3305 calls by the guest for that service will be passed to userspace to be
3308 4.87 KVM_SET_GUEST_DEBUG
3309 ------------------------
3311 :Capability: KVM_CAP_SET_GUEST_DEBUG
3312 :Architectures: x86, s390, ppc, arm64
3314 :Parameters: struct kvm_guest_debug (in)
3315 :Returns: 0 on success; -1 on error
3319 struct kvm_guest_debug {
3322 struct kvm_guest_debug_arch arch;
3325 Set up the processor specific debug registers and configure vcpu for
3326 handling guest debug events. There are two parts to the structure, the
3327 first a control bitfield indicates the type of debug events to handle
3328 when running. Common control bits are:
3330 - KVM_GUESTDBG_ENABLE: guest debugging is enabled
3331 - KVM_GUESTDBG_SINGLESTEP: the next run should single-step
3333 The top 16 bits of the control field are architecture specific control
3334 flags which can include the following:
3336 - KVM_GUESTDBG_USE_SW_BP: using software breakpoints [x86, arm64]
3337 - KVM_GUESTDBG_USE_HW_BP: using hardware breakpoints [x86, s390, arm64]
3338 - KVM_GUESTDBG_INJECT_DB: inject DB type exception [x86]
3339 - KVM_GUESTDBG_INJECT_BP: inject BP type exception [x86]
3340 - KVM_GUESTDBG_EXIT_PENDING: trigger an immediate guest exit [s390]
3342 For example KVM_GUESTDBG_USE_SW_BP indicates that software breakpoints
3343 are enabled in memory so we need to ensure breakpoint exceptions are
3344 correctly trapped and the KVM run loop exits at the breakpoint and not
3345 running off into the normal guest vector. For KVM_GUESTDBG_USE_HW_BP
3346 we need to ensure the guest vCPUs architecture specific registers are
3347 updated to the correct (supplied) values.
3349 The second part of the structure is architecture specific and
3350 typically contains a set of debug registers.
3352 For arm64 the number of debug registers is implementation defined and
3353 can be determined by querying the KVM_CAP_GUEST_DEBUG_HW_BPS and
3354 KVM_CAP_GUEST_DEBUG_HW_WPS capabilities which return a positive number
3355 indicating the number of supported registers.
3357 For ppc, the KVM_CAP_PPC_GUEST_DEBUG_SSTEP capability indicates whether
3358 the single-step debug event (KVM_GUESTDBG_SINGLESTEP) is supported.
3360 Also when supported, KVM_CAP_SET_GUEST_DEBUG2 capability indicates the
3361 supported KVM_GUESTDBG_* bits in the control field.
3363 When debug events exit the main run loop with the reason
3364 KVM_EXIT_DEBUG with the kvm_debug_exit_arch part of the kvm_run
3365 structure containing architecture specific debug information.
3367 4.88 KVM_GET_EMULATED_CPUID
3368 ---------------------------
3370 :Capability: KVM_CAP_EXT_EMUL_CPUID
3373 :Parameters: struct kvm_cpuid2 (in/out)
3374 :Returns: 0 on success, -1 on error
3381 struct kvm_cpuid_entry2 entries[0];
3384 The member 'flags' is used for passing flags from userspace.
3388 #define KVM_CPUID_FLAG_SIGNIFCANT_INDEX BIT(0)
3389 #define KVM_CPUID_FLAG_STATEFUL_FUNC BIT(1) /* deprecated */
3390 #define KVM_CPUID_FLAG_STATE_READ_NEXT BIT(2) /* deprecated */
3392 struct kvm_cpuid_entry2 {
3403 This ioctl returns x86 cpuid features which are emulated by
3404 kvm.Userspace can use the information returned by this ioctl to query
3405 which features are emulated by kvm instead of being present natively.
3407 Userspace invokes KVM_GET_EMULATED_CPUID by passing a kvm_cpuid2
3408 structure with the 'nent' field indicating the number of entries in
3409 the variable-size array 'entries'. If the number of entries is too low
3410 to describe the cpu capabilities, an error (E2BIG) is returned. If the
3411 number is too high, the 'nent' field is adjusted and an error (ENOMEM)
3412 is returned. If the number is just right, the 'nent' field is adjusted
3413 to the number of valid entries in the 'entries' array, which is then
3416 The entries returned are the set CPUID bits of the respective features
3417 which kvm emulates, as returned by the CPUID instruction, with unknown
3418 or unsupported feature bits cleared.
3420 Features like x2apic, for example, may not be present in the host cpu
3421 but are exposed by kvm in KVM_GET_SUPPORTED_CPUID because they can be
3422 emulated efficiently and thus not included here.
3424 The fields in each entry are defined as follows:
3427 the eax value used to obtain the entry
3429 the ecx value used to obtain the entry (for entries that are
3432 an OR of zero or more of the following:
3434 KVM_CPUID_FLAG_SIGNIFCANT_INDEX:
3435 if the index field is valid
3439 the values returned by the cpuid instruction for
3440 this function/index combination
3442 4.89 KVM_S390_MEM_OP
3443 --------------------
3445 :Capability: KVM_CAP_S390_MEM_OP
3446 :Architectures: s390
3448 :Parameters: struct kvm_s390_mem_op (in)
3449 :Returns: = 0 on success,
3450 < 0 on generic error (e.g. -EFAULT or -ENOMEM),
3451 > 0 if an exception occurred while walking the page tables
3453 Read or write data from/to the logical (virtual) memory of a VCPU.
3455 Parameters are specified via the following structure::
3457 struct kvm_s390_mem_op {
3458 __u64 gaddr; /* the guest address */
3459 __u64 flags; /* flags */
3460 __u32 size; /* amount of bytes */
3461 __u32 op; /* type of operation */
3462 __u64 buf; /* buffer in userspace */
3463 __u8 ar; /* the access register number */
3464 __u8 reserved[31]; /* should be set to 0 */
3467 The type of operation is specified in the "op" field. It is either
3468 KVM_S390_MEMOP_LOGICAL_READ for reading from logical memory space or
3469 KVM_S390_MEMOP_LOGICAL_WRITE for writing to logical memory space. The
3470 KVM_S390_MEMOP_F_CHECK_ONLY flag can be set in the "flags" field to check
3471 whether the corresponding memory access would create an access exception
3472 (without touching the data in the memory at the destination). In case an
3473 access exception occurred while walking the MMU tables of the guest, the
3474 ioctl returns a positive error number to indicate the type of exception.
3475 This exception is also raised directly at the corresponding VCPU if the
3476 flag KVM_S390_MEMOP_F_INJECT_EXCEPTION is set in the "flags" field.
3478 The start address of the memory region has to be specified in the "gaddr"
3479 field, and the length of the region in the "size" field (which must not
3480 be 0). The maximum value for "size" can be obtained by checking the
3481 KVM_CAP_S390_MEM_OP capability. "buf" is the buffer supplied by the
3482 userspace application where the read data should be written to for
3483 KVM_S390_MEMOP_LOGICAL_READ, or where the data that should be written is
3484 stored for a KVM_S390_MEMOP_LOGICAL_WRITE. When KVM_S390_MEMOP_F_CHECK_ONLY
3485 is specified, "buf" is unused and can be NULL. "ar" designates the access
3486 register number to be used; the valid range is 0..15.
3488 The "reserved" field is meant for future extensions. It is not used by
3489 KVM with the currently defined set of flags.
3491 4.90 KVM_S390_GET_SKEYS
3492 -----------------------
3494 :Capability: KVM_CAP_S390_SKEYS
3495 :Architectures: s390
3497 :Parameters: struct kvm_s390_skeys
3498 :Returns: 0 on success, KVM_S390_GET_KEYS_NONE if guest is not using storage
3499 keys, negative value on error
3501 This ioctl is used to get guest storage key values on the s390
3502 architecture. The ioctl takes parameters via the kvm_s390_skeys struct::
3504 struct kvm_s390_skeys {
3507 __u64 skeydata_addr;
3512 The start_gfn field is the number of the first guest frame whose storage keys
3515 The count field is the number of consecutive frames (starting from start_gfn)
3516 whose storage keys to get. The count field must be at least 1 and the maximum
3517 allowed value is defined as KVM_S390_SKEYS_ALLOC_MAX. Values outside this range
3518 will cause the ioctl to return -EINVAL.
3520 The skeydata_addr field is the address to a buffer large enough to hold count
3521 bytes. This buffer will be filled with storage key data by the ioctl.
3523 4.91 KVM_S390_SET_SKEYS
3524 -----------------------
3526 :Capability: KVM_CAP_S390_SKEYS
3527 :Architectures: s390
3529 :Parameters: struct kvm_s390_skeys
3530 :Returns: 0 on success, negative value on error
3532 This ioctl is used to set guest storage key values on the s390
3533 architecture. The ioctl takes parameters via the kvm_s390_skeys struct.
3534 See section on KVM_S390_GET_SKEYS for struct definition.
3536 The start_gfn field is the number of the first guest frame whose storage keys
3539 The count field is the number of consecutive frames (starting from start_gfn)
3540 whose storage keys to get. The count field must be at least 1 and the maximum
3541 allowed value is defined as KVM_S390_SKEYS_ALLOC_MAX. Values outside this range
3542 will cause the ioctl to return -EINVAL.
3544 The skeydata_addr field is the address to a buffer containing count bytes of
3545 storage keys. Each byte in the buffer will be set as the storage key for a
3546 single frame starting at start_gfn for count frames.
3548 Note: If any architecturally invalid key value is found in the given data then
3549 the ioctl will return -EINVAL.
3554 :Capability: KVM_CAP_S390_INJECT_IRQ
3555 :Architectures: s390
3557 :Parameters: struct kvm_s390_irq (in)
3558 :Returns: 0 on success, -1 on error
3563 ====== =================================================================
3564 EINVAL interrupt type is invalid
3565 type is KVM_S390_SIGP_STOP and flag parameter is invalid value,
3566 type is KVM_S390_INT_EXTERNAL_CALL and code is bigger
3567 than the maximum of VCPUs
3568 EBUSY type is KVM_S390_SIGP_SET_PREFIX and vcpu is not stopped,
3569 type is KVM_S390_SIGP_STOP and a stop irq is already pending,
3570 type is KVM_S390_INT_EXTERNAL_CALL and an external call interrupt
3572 ====== =================================================================
3574 Allows to inject an interrupt to the guest.
3576 Using struct kvm_s390_irq as a parameter allows
3577 to inject additional payload which is not
3578 possible via KVM_S390_INTERRUPT.
3580 Interrupt parameters are passed via kvm_s390_irq::
3582 struct kvm_s390_irq {
3585 struct kvm_s390_io_info io;
3586 struct kvm_s390_ext_info ext;
3587 struct kvm_s390_pgm_info pgm;
3588 struct kvm_s390_emerg_info emerg;
3589 struct kvm_s390_extcall_info extcall;
3590 struct kvm_s390_prefix_info prefix;
3591 struct kvm_s390_stop_info stop;
3592 struct kvm_s390_mchk_info mchk;
3597 type can be one of the following:
3599 - KVM_S390_SIGP_STOP - sigp stop; parameter in .stop
3600 - KVM_S390_PROGRAM_INT - program check; parameters in .pgm
3601 - KVM_S390_SIGP_SET_PREFIX - sigp set prefix; parameters in .prefix
3602 - KVM_S390_RESTART - restart; no parameters
3603 - KVM_S390_INT_CLOCK_COMP - clock comparator interrupt; no parameters
3604 - KVM_S390_INT_CPU_TIMER - CPU timer interrupt; no parameters
3605 - KVM_S390_INT_EMERGENCY - sigp emergency; parameters in .emerg
3606 - KVM_S390_INT_EXTERNAL_CALL - sigp external call; parameters in .extcall
3607 - KVM_S390_MCHK - machine check interrupt; parameters in .mchk
3609 This is an asynchronous vcpu ioctl and can be invoked from any thread.
3611 4.94 KVM_S390_GET_IRQ_STATE
3612 ---------------------------
3614 :Capability: KVM_CAP_S390_IRQ_STATE
3615 :Architectures: s390
3617 :Parameters: struct kvm_s390_irq_state (out)
3618 :Returns: >= number of bytes copied into buffer,
3619 -EINVAL if buffer size is 0,
3620 -ENOBUFS if buffer size is too small to fit all pending interrupts,
3621 -EFAULT if the buffer address was invalid
3623 This ioctl allows userspace to retrieve the complete state of all currently
3624 pending interrupts in a single buffer. Use cases include migration
3625 and introspection. The parameter structure contains the address of a
3626 userspace buffer and its length::
3628 struct kvm_s390_irq_state {
3630 __u32 flags; /* will stay unused for compatibility reasons */
3632 __u32 reserved[4]; /* will stay unused for compatibility reasons */
3635 Userspace passes in the above struct and for each pending interrupt a
3636 struct kvm_s390_irq is copied to the provided buffer.
3638 The structure contains a flags and a reserved field for future extensions. As
3639 the kernel never checked for flags == 0 and QEMU never pre-zeroed flags and
3640 reserved, these fields can not be used in the future without breaking
3643 If -ENOBUFS is returned the buffer provided was too small and userspace
3644 may retry with a bigger buffer.
3646 4.95 KVM_S390_SET_IRQ_STATE
3647 ---------------------------
3649 :Capability: KVM_CAP_S390_IRQ_STATE
3650 :Architectures: s390
3652 :Parameters: struct kvm_s390_irq_state (in)
3653 :Returns: 0 on success,
3654 -EFAULT if the buffer address was invalid,
3655 -EINVAL for an invalid buffer length (see below),
3656 -EBUSY if there were already interrupts pending,
3657 errors occurring when actually injecting the
3658 interrupt. See KVM_S390_IRQ.
3660 This ioctl allows userspace to set the complete state of all cpu-local
3661 interrupts currently pending for the vcpu. It is intended for restoring
3662 interrupt state after a migration. The input parameter is a userspace buffer
3663 containing a struct kvm_s390_irq_state::
3665 struct kvm_s390_irq_state {
3667 __u32 flags; /* will stay unused for compatibility reasons */
3669 __u32 reserved[4]; /* will stay unused for compatibility reasons */
3672 The restrictions for flags and reserved apply as well.
3673 (see KVM_S390_GET_IRQ_STATE)
3675 The userspace memory referenced by buf contains a struct kvm_s390_irq
3676 for each interrupt to be injected into the guest.
3677 If one of the interrupts could not be injected for some reason the
3680 len must be a multiple of sizeof(struct kvm_s390_irq). It must be > 0
3681 and it must not exceed (max_vcpus + 32) * sizeof(struct kvm_s390_irq),
3682 which is the maximum number of possibly pending cpu-local interrupts.
3687 :Capability: KVM_CAP_X86_SMM
3691 :Returns: 0 on success, -1 on error
3693 Queues an SMI on the thread's vcpu.
3695 4.97 KVM_CAP_PPC_MULTITCE
3696 -------------------------
3698 :Capability: KVM_CAP_PPC_MULTITCE
3702 This capability means the kernel is capable of handling hypercalls
3703 H_PUT_TCE_INDIRECT and H_STUFF_TCE without passing those into the user
3704 space. This significantly accelerates DMA operations for PPC KVM guests.
3705 User space should expect that its handlers for these hypercalls
3706 are not going to be called if user space previously registered LIOBN
3707 in KVM (via KVM_CREATE_SPAPR_TCE or similar calls).
3709 In order to enable H_PUT_TCE_INDIRECT and H_STUFF_TCE use in the guest,
3710 user space might have to advertise it for the guest. For example,
3711 IBM pSeries (sPAPR) guest starts using them if "hcall-multi-tce" is
3712 present in the "ibm,hypertas-functions" device-tree property.
3714 The hypercalls mentioned above may or may not be processed successfully
3715 in the kernel based fast path. If they can not be handled by the kernel,
3716 they will get passed on to user space. So user space still has to have
3717 an implementation for these despite the in kernel acceleration.
3719 This capability is always enabled.
3721 4.98 KVM_CREATE_SPAPR_TCE_64
3722 ----------------------------
3724 :Capability: KVM_CAP_SPAPR_TCE_64
3725 :Architectures: powerpc
3727 :Parameters: struct kvm_create_spapr_tce_64 (in)
3728 :Returns: file descriptor for manipulating the created TCE table
3730 This is an extension for KVM_CAP_SPAPR_TCE which only supports 32bit
3731 windows, described in 4.62 KVM_CREATE_SPAPR_TCE
3733 This capability uses extended struct in ioctl interface::
3735 /* for KVM_CAP_SPAPR_TCE_64 */
3736 struct kvm_create_spapr_tce_64 {
3740 __u64 offset; /* in pages */
3741 __u64 size; /* in pages */
3744 The aim of extension is to support an additional bigger DMA window with
3745 a variable page size.
3746 KVM_CREATE_SPAPR_TCE_64 receives a 64bit window size, an IOMMU page shift and
3747 a bus offset of the corresponding DMA window, @size and @offset are numbers
3750 @flags are not used at the moment.
3752 The rest of functionality is identical to KVM_CREATE_SPAPR_TCE.
3754 4.99 KVM_REINJECT_CONTROL
3755 -------------------------
3757 :Capability: KVM_CAP_REINJECT_CONTROL
3760 :Parameters: struct kvm_reinject_control (in)
3761 :Returns: 0 on success,
3762 -EFAULT if struct kvm_reinject_control cannot be read,
3763 -ENXIO if KVM_CREATE_PIT or KVM_CREATE_PIT2 didn't succeed earlier.
3765 i8254 (PIT) has two modes, reinject and !reinject. The default is reinject,
3766 where KVM queues elapsed i8254 ticks and monitors completion of interrupt from
3767 vector(s) that i8254 injects. Reinject mode dequeues a tick and injects its
3768 interrupt whenever there isn't a pending interrupt from i8254.
3769 !reinject mode injects an interrupt as soon as a tick arrives.
3773 struct kvm_reinject_control {
3778 pit_reinject = 0 (!reinject mode) is recommended, unless running an old
3779 operating system that uses the PIT for timing (e.g. Linux 2.4.x).
3781 4.100 KVM_PPC_CONFIGURE_V3_MMU
3782 ------------------------------
3784 :Capability: KVM_CAP_PPC_RADIX_MMU or KVM_CAP_PPC_HASH_MMU_V3
3787 :Parameters: struct kvm_ppc_mmuv3_cfg (in)
3788 :Returns: 0 on success,
3789 -EFAULT if struct kvm_ppc_mmuv3_cfg cannot be read,
3790 -EINVAL if the configuration is invalid
3792 This ioctl controls whether the guest will use radix or HPT (hashed
3793 page table) translation, and sets the pointer to the process table for
3798 struct kvm_ppc_mmuv3_cfg {
3800 __u64 process_table;
3803 There are two bits that can be set in flags; KVM_PPC_MMUV3_RADIX and
3804 KVM_PPC_MMUV3_GTSE. KVM_PPC_MMUV3_RADIX, if set, configures the guest
3805 to use radix tree translation, and if clear, to use HPT translation.
3806 KVM_PPC_MMUV3_GTSE, if set and if KVM permits it, configures the guest
3807 to be able to use the global TLB and SLB invalidation instructions;
3808 if clear, the guest may not use these instructions.
3810 The process_table field specifies the address and size of the guest
3811 process table, which is in the guest's space. This field is formatted
3812 as the second doubleword of the partition table entry, as defined in
3813 the Power ISA V3.00, Book III section 5.7.6.1.
3815 4.101 KVM_PPC_GET_RMMU_INFO
3816 ---------------------------
3818 :Capability: KVM_CAP_PPC_RADIX_MMU
3821 :Parameters: struct kvm_ppc_rmmu_info (out)
3822 :Returns: 0 on success,
3823 -EFAULT if struct kvm_ppc_rmmu_info cannot be written,
3824 -EINVAL if no useful information can be returned
3826 This ioctl returns a structure containing two things: (a) a list
3827 containing supported radix tree geometries, and (b) a list that maps
3828 page sizes to put in the "AP" (actual page size) field for the tlbie
3829 (TLB invalidate entry) instruction.
3833 struct kvm_ppc_rmmu_info {
3834 struct kvm_ppc_radix_geom {
3839 __u32 ap_encodings[8];
3842 The geometries[] field gives up to 8 supported geometries for the
3843 radix page table, in terms of the log base 2 of the smallest page
3844 size, and the number of bits indexed at each level of the tree, from
3845 the PTE level up to the PGD level in that order. Any unused entries
3846 will have 0 in the page_shift field.
3848 The ap_encodings gives the supported page sizes and their AP field
3849 encodings, encoded with the AP value in the top 3 bits and the log
3850 base 2 of the page size in the bottom 6 bits.
3852 4.102 KVM_PPC_RESIZE_HPT_PREPARE
3853 --------------------------------
3855 :Capability: KVM_CAP_SPAPR_RESIZE_HPT
3856 :Architectures: powerpc
3858 :Parameters: struct kvm_ppc_resize_hpt (in)
3859 :Returns: 0 on successful completion,
3860 >0 if a new HPT is being prepared, the value is an estimated
3861 number of milliseconds until preparation is complete,
3862 -EFAULT if struct kvm_reinject_control cannot be read,
3863 -EINVAL if the supplied shift or flags are invalid,
3864 -ENOMEM if unable to allocate the new HPT,
3866 Used to implement the PAPR extension for runtime resizing of a guest's
3867 Hashed Page Table (HPT). Specifically this starts, stops or monitors
3868 the preparation of a new potential HPT for the guest, essentially
3869 implementing the H_RESIZE_HPT_PREPARE hypercall.
3873 struct kvm_ppc_resize_hpt {
3879 If called with shift > 0 when there is no pending HPT for the guest,
3880 this begins preparation of a new pending HPT of size 2^(shift) bytes.
3881 It then returns a positive integer with the estimated number of
3882 milliseconds until preparation is complete.
3884 If called when there is a pending HPT whose size does not match that
3885 requested in the parameters, discards the existing pending HPT and
3886 creates a new one as above.
3888 If called when there is a pending HPT of the size requested, will:
3890 * If preparation of the pending HPT is already complete, return 0
3891 * If preparation of the pending HPT has failed, return an error
3892 code, then discard the pending HPT.
3893 * If preparation of the pending HPT is still in progress, return an
3894 estimated number of milliseconds until preparation is complete.
3896 If called with shift == 0, discards any currently pending HPT and
3897 returns 0 (i.e. cancels any in-progress preparation).
3899 flags is reserved for future expansion, currently setting any bits in
3900 flags will result in an -EINVAL.
3902 Normally this will be called repeatedly with the same parameters until
3903 it returns <= 0. The first call will initiate preparation, subsequent
3904 ones will monitor preparation until it completes or fails.
3906 4.103 KVM_PPC_RESIZE_HPT_COMMIT
3907 -------------------------------
3909 :Capability: KVM_CAP_SPAPR_RESIZE_HPT
3910 :Architectures: powerpc
3912 :Parameters: struct kvm_ppc_resize_hpt (in)
3913 :Returns: 0 on successful completion,
3914 -EFAULT if struct kvm_reinject_control cannot be read,
3915 -EINVAL if the supplied shift or flags are invalid,
3916 -ENXIO is there is no pending HPT, or the pending HPT doesn't
3917 have the requested size,
3918 -EBUSY if the pending HPT is not fully prepared,
3919 -ENOSPC if there was a hash collision when moving existing
3920 HPT entries to the new HPT,
3921 -EIO on other error conditions
3923 Used to implement the PAPR extension for runtime resizing of a guest's
3924 Hashed Page Table (HPT). Specifically this requests that the guest be
3925 transferred to working with the new HPT, essentially implementing the
3926 H_RESIZE_HPT_COMMIT hypercall.
3930 struct kvm_ppc_resize_hpt {
3936 This should only be called after KVM_PPC_RESIZE_HPT_PREPARE has
3937 returned 0 with the same parameters. In other cases
3938 KVM_PPC_RESIZE_HPT_COMMIT will return an error (usually -ENXIO or
3939 -EBUSY, though others may be possible if the preparation was started,
3942 This will have undefined effects on the guest if it has not already
3943 placed itself in a quiescent state where no vcpu will make MMU enabled
3946 On succsful completion, the pending HPT will become the guest's active
3947 HPT and the previous HPT will be discarded.
3949 On failure, the guest will still be operating on its previous HPT.
3951 4.104 KVM_X86_GET_MCE_CAP_SUPPORTED
3952 -----------------------------------
3954 :Capability: KVM_CAP_MCE
3957 :Parameters: u64 mce_cap (out)
3958 :Returns: 0 on success, -1 on error
3960 Returns supported MCE capabilities. The u64 mce_cap parameter
3961 has the same format as the MSR_IA32_MCG_CAP register. Supported
3962 capabilities will have the corresponding bits set.
3964 4.105 KVM_X86_SETUP_MCE
3965 -----------------------
3967 :Capability: KVM_CAP_MCE
3970 :Parameters: u64 mcg_cap (in)
3971 :Returns: 0 on success,
3972 -EFAULT if u64 mcg_cap cannot be read,
3973 -EINVAL if the requested number of banks is invalid,
3974 -EINVAL if requested MCE capability is not supported.
3976 Initializes MCE support for use. The u64 mcg_cap parameter
3977 has the same format as the MSR_IA32_MCG_CAP register and
3978 specifies which capabilities should be enabled. The maximum
3979 supported number of error-reporting banks can be retrieved when
3980 checking for KVM_CAP_MCE. The supported capabilities can be
3981 retrieved with KVM_X86_GET_MCE_CAP_SUPPORTED.
3983 4.106 KVM_X86_SET_MCE
3984 ---------------------
3986 :Capability: KVM_CAP_MCE
3989 :Parameters: struct kvm_x86_mce (in)
3990 :Returns: 0 on success,
3991 -EFAULT if struct kvm_x86_mce cannot be read,
3992 -EINVAL if the bank number is invalid,
3993 -EINVAL if VAL bit is not set in status field.
3995 Inject a machine check error (MCE) into the guest. The input
3998 struct kvm_x86_mce {
4008 If the MCE being reported is an uncorrected error, KVM will
4009 inject it as an MCE exception into the guest. If the guest
4010 MCG_STATUS register reports that an MCE is in progress, KVM
4011 causes an KVM_EXIT_SHUTDOWN vmexit.
4013 Otherwise, if the MCE is a corrected error, KVM will just
4014 store it in the corresponding bank (provided this bank is
4015 not holding a previously reported uncorrected error).
4017 4.107 KVM_S390_GET_CMMA_BITS
4018 ----------------------------
4020 :Capability: KVM_CAP_S390_CMMA_MIGRATION
4021 :Architectures: s390
4023 :Parameters: struct kvm_s390_cmma_log (in, out)
4024 :Returns: 0 on success, a negative value on error
4026 This ioctl is used to get the values of the CMMA bits on the s390
4027 architecture. It is meant to be used in two scenarios:
4029 - During live migration to save the CMMA values. Live migration needs
4030 to be enabled via the KVM_REQ_START_MIGRATION VM property.
4031 - To non-destructively peek at the CMMA values, with the flag
4032 KVM_S390_CMMA_PEEK set.
4034 The ioctl takes parameters via the kvm_s390_cmma_log struct. The desired
4035 values are written to a buffer whose location is indicated via the "values"
4036 member in the kvm_s390_cmma_log struct. The values in the input struct are
4037 also updated as needed.
4039 Each CMMA value takes up one byte.
4043 struct kvm_s390_cmma_log {
4054 start_gfn is the number of the first guest frame whose CMMA values are
4057 count is the length of the buffer in bytes,
4059 values points to the buffer where the result will be written to.
4061 If count is greater than KVM_S390_SKEYS_MAX, then it is considered to be
4062 KVM_S390_SKEYS_MAX. KVM_S390_SKEYS_MAX is re-used for consistency with
4065 The result is written in the buffer pointed to by the field values, and
4066 the values of the input parameter are updated as follows.
4068 Depending on the flags, different actions are performed. The only
4069 supported flag so far is KVM_S390_CMMA_PEEK.
4071 The default behaviour if KVM_S390_CMMA_PEEK is not set is:
4072 start_gfn will indicate the first page frame whose CMMA bits were dirty.
4073 It is not necessarily the same as the one passed as input, as clean pages
4076 count will indicate the number of bytes actually written in the buffer.
4077 It can (and very often will) be smaller than the input value, since the
4078 buffer is only filled until 16 bytes of clean values are found (which
4079 are then not copied in the buffer). Since a CMMA migration block needs
4080 the base address and the length, for a total of 16 bytes, we will send
4081 back some clean data if there is some dirty data afterwards, as long as
4082 the size of the clean data does not exceed the size of the header. This
4083 allows to minimize the amount of data to be saved or transferred over
4084 the network at the expense of more roundtrips to userspace. The next
4085 invocation of the ioctl will skip over all the clean values, saving
4086 potentially more than just the 16 bytes we found.
4088 If KVM_S390_CMMA_PEEK is set:
4089 the existing storage attributes are read even when not in migration
4090 mode, and no other action is performed;
4092 the output start_gfn will be equal to the input start_gfn,
4094 the output count will be equal to the input count, except if the end of
4095 memory has been reached.
4098 the field "remaining" will indicate the total number of dirty CMMA values
4099 still remaining, or 0 if KVM_S390_CMMA_PEEK is set and migration mode is
4104 values points to the userspace buffer where the result will be stored.
4106 This ioctl can fail with -ENOMEM if not enough memory can be allocated to
4107 complete the task, with -ENXIO if CMMA is not enabled, with -EINVAL if
4108 KVM_S390_CMMA_PEEK is not set but migration mode was not enabled, with
4109 -EFAULT if the userspace address is invalid or if no page table is
4110 present for the addresses (e.g. when using hugepages).
4112 4.108 KVM_S390_SET_CMMA_BITS
4113 ----------------------------
4115 :Capability: KVM_CAP_S390_CMMA_MIGRATION
4116 :Architectures: s390
4118 :Parameters: struct kvm_s390_cmma_log (in)
4119 :Returns: 0 on success, a negative value on error
4121 This ioctl is used to set the values of the CMMA bits on the s390
4122 architecture. It is meant to be used during live migration to restore
4123 the CMMA values, but there are no restrictions on its use.
4124 The ioctl takes parameters via the kvm_s390_cmma_values struct.
4125 Each CMMA value takes up one byte.
4129 struct kvm_s390_cmma_log {
4140 start_gfn indicates the starting guest frame number,
4142 count indicates how many values are to be considered in the buffer,
4144 flags is not used and must be 0.
4146 mask indicates which PGSTE bits are to be considered.
4148 remaining is not used.
4150 values points to the buffer in userspace where to store the values.
4152 This ioctl can fail with -ENOMEM if not enough memory can be allocated to
4153 complete the task, with -ENXIO if CMMA is not enabled, with -EINVAL if
4154 the count field is too large (e.g. more than KVM_S390_CMMA_SIZE_MAX) or
4155 if the flags field was not 0, with -EFAULT if the userspace address is
4156 invalid, if invalid pages are written to (e.g. after the end of memory)
4157 or if no page table is present for the addresses (e.g. when using
4160 4.109 KVM_PPC_GET_CPU_CHAR
4161 --------------------------
4163 :Capability: KVM_CAP_PPC_GET_CPU_CHAR
4164 :Architectures: powerpc
4166 :Parameters: struct kvm_ppc_cpu_char (out)
4167 :Returns: 0 on successful completion,
4168 -EFAULT if struct kvm_ppc_cpu_char cannot be written
4170 This ioctl gives userspace information about certain characteristics
4171 of the CPU relating to speculative execution of instructions and
4172 possible information leakage resulting from speculative execution (see
4173 CVE-2017-5715, CVE-2017-5753 and CVE-2017-5754). The information is
4174 returned in struct kvm_ppc_cpu_char, which looks like this::
4176 struct kvm_ppc_cpu_char {
4177 __u64 character; /* characteristics of the CPU */
4178 __u64 behaviour; /* recommended software behaviour */
4179 __u64 character_mask; /* valid bits in character */
4180 __u64 behaviour_mask; /* valid bits in behaviour */
4183 For extensibility, the character_mask and behaviour_mask fields
4184 indicate which bits of character and behaviour have been filled in by
4185 the kernel. If the set of defined bits is extended in future then
4186 userspace will be able to tell whether it is running on a kernel that
4187 knows about the new bits.
4189 The character field describes attributes of the CPU which can help
4190 with preventing inadvertent information disclosure - specifically,
4191 whether there is an instruction to flash-invalidate the L1 data cache
4192 (ori 30,30,0 or mtspr SPRN_TRIG2,rN), whether the L1 data cache is set
4193 to a mode where entries can only be used by the thread that created
4194 them, whether the bcctr[l] instruction prevents speculation, and
4195 whether a speculation barrier instruction (ori 31,31,0) is provided.
4197 The behaviour field describes actions that software should take to
4198 prevent inadvertent information disclosure, and thus describes which
4199 vulnerabilities the hardware is subject to; specifically whether the
4200 L1 data cache should be flushed when returning to user mode from the
4201 kernel, and whether a speculation barrier should be placed between an
4202 array bounds check and the array access.
4204 These fields use the same bit definitions as the new
4205 H_GET_CPU_CHARACTERISTICS hypercall.
4207 4.110 KVM_MEMORY_ENCRYPT_OP
4208 ---------------------------
4213 :Parameters: an opaque platform specific structure (in/out)
4214 :Returns: 0 on success; -1 on error
4216 If the platform supports creating encrypted VMs then this ioctl can be used
4217 for issuing platform-specific memory encryption commands to manage those
4220 Currently, this ioctl is used for issuing Secure Encrypted Virtualization
4221 (SEV) commands on AMD Processors. The SEV commands are defined in
4222 Documentation/virt/kvm/amd-memory-encryption.rst.
4224 4.111 KVM_MEMORY_ENCRYPT_REG_REGION
4225 -----------------------------------
4230 :Parameters: struct kvm_enc_region (in)
4231 :Returns: 0 on success; -1 on error
4233 This ioctl can be used to register a guest memory region which may
4234 contain encrypted data (e.g. guest RAM, SMRAM etc).
4236 It is used in the SEV-enabled guest. When encryption is enabled, a guest
4237 memory region may contain encrypted data. The SEV memory encryption
4238 engine uses a tweak such that two identical plaintext pages, each at
4239 different locations will have differing ciphertexts. So swapping or
4240 moving ciphertext of those pages will not result in plaintext being
4241 swapped. So relocating (or migrating) physical backing pages for the SEV
4242 guest will require some additional steps.
4244 Note: The current SEV key management spec does not provide commands to
4245 swap or migrate (move) ciphertext pages. Hence, for now we pin the guest
4246 memory region registered with the ioctl.
4248 4.112 KVM_MEMORY_ENCRYPT_UNREG_REGION
4249 -------------------------------------
4254 :Parameters: struct kvm_enc_region (in)
4255 :Returns: 0 on success; -1 on error
4257 This ioctl can be used to unregister the guest memory region registered
4258 with KVM_MEMORY_ENCRYPT_REG_REGION ioctl above.
4260 4.113 KVM_HYPERV_EVENTFD
4261 ------------------------
4263 :Capability: KVM_CAP_HYPERV_EVENTFD
4266 :Parameters: struct kvm_hyperv_eventfd (in)
4268 This ioctl (un)registers an eventfd to receive notifications from the guest on
4269 the specified Hyper-V connection id through the SIGNAL_EVENT hypercall, without
4270 causing a user exit. SIGNAL_EVENT hypercall with non-zero event flag number
4271 (bits 24-31) still triggers a KVM_EXIT_HYPERV_HCALL user exit.
4275 struct kvm_hyperv_eventfd {
4282 The conn_id field should fit within 24 bits::
4284 #define KVM_HYPERV_CONN_ID_MASK 0x00ffffff
4286 The acceptable values for the flags field are::
4288 #define KVM_HYPERV_EVENTFD_DEASSIGN (1 << 0)
4290 :Returns: 0 on success,
4291 -EINVAL if conn_id or flags is outside the allowed range,
4292 -ENOENT on deassign if the conn_id isn't registered,
4293 -EEXIST on assign if the conn_id is already registered
4295 4.114 KVM_GET_NESTED_STATE
4296 --------------------------
4298 :Capability: KVM_CAP_NESTED_STATE
4301 :Parameters: struct kvm_nested_state (in/out)
4302 :Returns: 0 on success, -1 on error
4306 ===== =============================================================
4307 E2BIG the total state size exceeds the value of 'size' specified by
4308 the user; the size required will be written into size.
4309 ===== =============================================================
4313 struct kvm_nested_state {
4319 struct kvm_vmx_nested_state_hdr vmx;
4320 struct kvm_svm_nested_state_hdr svm;
4322 /* Pad the header to 128 bytes. */
4327 struct kvm_vmx_nested_state_data vmx[0];
4328 struct kvm_svm_nested_state_data svm[0];
4332 #define KVM_STATE_NESTED_GUEST_MODE 0x00000001
4333 #define KVM_STATE_NESTED_RUN_PENDING 0x00000002
4334 #define KVM_STATE_NESTED_EVMCS 0x00000004
4336 #define KVM_STATE_NESTED_FORMAT_VMX 0
4337 #define KVM_STATE_NESTED_FORMAT_SVM 1
4339 #define KVM_STATE_NESTED_VMX_VMCS_SIZE 0x1000
4341 #define KVM_STATE_NESTED_VMX_SMM_GUEST_MODE 0x00000001
4342 #define KVM_STATE_NESTED_VMX_SMM_VMXON 0x00000002
4344 #define KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE 0x00000001
4346 struct kvm_vmx_nested_state_hdr {
4355 __u64 preemption_timer_deadline;
4358 struct kvm_vmx_nested_state_data {
4359 __u8 vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
4360 __u8 shadow_vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
4363 This ioctl copies the vcpu's nested virtualization state from the kernel to
4366 The maximum size of the state can be retrieved by passing KVM_CAP_NESTED_STATE
4367 to the KVM_CHECK_EXTENSION ioctl().
4369 4.115 KVM_SET_NESTED_STATE
4370 --------------------------
4372 :Capability: KVM_CAP_NESTED_STATE
4375 :Parameters: struct kvm_nested_state (in)
4376 :Returns: 0 on success, -1 on error
4378 This copies the vcpu's kvm_nested_state struct from userspace to the kernel.
4379 For the definition of struct kvm_nested_state, see KVM_GET_NESTED_STATE.
4381 4.116 KVM_(UN)REGISTER_COALESCED_MMIO
4382 -------------------------------------
4384 :Capability: KVM_CAP_COALESCED_MMIO (for coalesced mmio)
4385 KVM_CAP_COALESCED_PIO (for coalesced pio)
4388 :Parameters: struct kvm_coalesced_mmio_zone
4389 :Returns: 0 on success, < 0 on error
4391 Coalesced I/O is a performance optimization that defers hardware
4392 register write emulation so that userspace exits are avoided. It is
4393 typically used to reduce the overhead of emulating frequently accessed
4396 When a hardware register is configured for coalesced I/O, write accesses
4397 do not exit to userspace and their value is recorded in a ring buffer
4398 that is shared between kernel and userspace.
4400 Coalesced I/O is used if one or more write accesses to a hardware
4401 register can be deferred until a read or a write to another hardware
4402 register on the same device. This last access will cause a vmexit and
4403 userspace will process accesses from the ring buffer before emulating
4404 it. That will avoid exiting to userspace on repeated writes.
4406 Coalesced pio is based on coalesced mmio. There is little difference
4407 between coalesced mmio and pio except that coalesced pio records accesses
4410 4.117 KVM_CLEAR_DIRTY_LOG (vm ioctl)
4411 ------------------------------------
4413 :Capability: KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
4414 :Architectures: x86, arm, arm64, mips
4416 :Parameters: struct kvm_clear_dirty_log (in)
4417 :Returns: 0 on success, -1 on error
4421 /* for KVM_CLEAR_DIRTY_LOG */
4422 struct kvm_clear_dirty_log {
4427 void __user *dirty_bitmap; /* one bit per page */
4432 The ioctl clears the dirty status of pages in a memory slot, according to
4433 the bitmap that is passed in struct kvm_clear_dirty_log's dirty_bitmap
4434 field. Bit 0 of the bitmap corresponds to page "first_page" in the
4435 memory slot, and num_pages is the size in bits of the input bitmap.
4436 first_page must be a multiple of 64; num_pages must also be a multiple of
4437 64 unless first_page + num_pages is the size of the memory slot. For each
4438 bit that is set in the input bitmap, the corresponding page is marked "clean"
4439 in KVM's dirty bitmap, and dirty tracking is re-enabled for that page
4440 (for example via write-protection, or by clearing the dirty bit in
4441 a page table entry).
4443 If KVM_CAP_MULTI_ADDRESS_SPACE is available, bits 16-31 of slot field specifies
4444 the address space for which you want to clear the dirty status. See
4445 KVM_SET_USER_MEMORY_REGION for details on the usage of slot field.
4447 This ioctl is mostly useful when KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
4448 is enabled; for more information, see the description of the capability.
4449 However, it can always be used as long as KVM_CHECK_EXTENSION confirms
4450 that KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is present.
4452 4.118 KVM_GET_SUPPORTED_HV_CPUID
4453 --------------------------------
4455 :Capability: KVM_CAP_HYPERV_CPUID (vcpu), KVM_CAP_SYS_HYPERV_CPUID (system)
4457 :Type: system ioctl, vcpu ioctl
4458 :Parameters: struct kvm_cpuid2 (in/out)
4459 :Returns: 0 on success, -1 on error
4466 struct kvm_cpuid_entry2 entries[0];
4469 struct kvm_cpuid_entry2 {
4480 This ioctl returns x86 cpuid features leaves related to Hyper-V emulation in
4481 KVM. Userspace can use the information returned by this ioctl to construct
4482 cpuid information presented to guests consuming Hyper-V enlightenments (e.g.
4483 Windows or Hyper-V guests).
4485 CPUID feature leaves returned by this ioctl are defined by Hyper-V Top Level
4486 Functional Specification (TLFS). These leaves can't be obtained with
4487 KVM_GET_SUPPORTED_CPUID ioctl because some of them intersect with KVM feature
4488 leaves (0x40000000, 0x40000001).
4490 Currently, the following list of CPUID leaves are returned:
4492 - HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS
4493 - HYPERV_CPUID_INTERFACE
4494 - HYPERV_CPUID_VERSION
4495 - HYPERV_CPUID_FEATURES
4496 - HYPERV_CPUID_ENLIGHTMENT_INFO
4497 - HYPERV_CPUID_IMPLEMENT_LIMITS
4498 - HYPERV_CPUID_NESTED_FEATURES
4499 - HYPERV_CPUID_SYNDBG_VENDOR_AND_MAX_FUNCTIONS
4500 - HYPERV_CPUID_SYNDBG_INTERFACE
4501 - HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES
4503 Userspace invokes KVM_GET_SUPPORTED_HV_CPUID by passing a kvm_cpuid2 structure
4504 with the 'nent' field indicating the number of entries in the variable-size
4505 array 'entries'. If the number of entries is too low to describe all Hyper-V
4506 feature leaves, an error (E2BIG) is returned. If the number is more or equal
4507 to the number of Hyper-V feature leaves, the 'nent' field is adjusted to the
4508 number of valid entries in the 'entries' array, which is then filled.
4510 'index' and 'flags' fields in 'struct kvm_cpuid_entry2' are currently reserved,
4511 userspace should not expect to get any particular value there.
4513 Note, vcpu version of KVM_GET_SUPPORTED_HV_CPUID is currently deprecated. Unlike
4514 system ioctl which exposes all supported feature bits unconditionally, vcpu
4515 version has the following quirks:
4517 - HYPERV_CPUID_NESTED_FEATURES leaf and HV_X64_ENLIGHTENED_VMCS_RECOMMENDED
4518 feature bit are only exposed when Enlightened VMCS was previously enabled
4519 on the corresponding vCPU (KVM_CAP_HYPERV_ENLIGHTENED_VMCS).
4520 - HV_STIMER_DIRECT_MODE_AVAILABLE bit is only exposed with in-kernel LAPIC.
4521 (presumes KVM_CREATE_IRQCHIP has already been called).
4523 4.119 KVM_ARM_VCPU_FINALIZE
4524 ---------------------------
4526 :Architectures: arm, arm64
4528 :Parameters: int feature (in)
4529 :Returns: 0 on success, -1 on error
4533 ====== ==============================================================
4534 EPERM feature not enabled, needs configuration, or already finalized
4535 EINVAL feature unknown or not present
4536 ====== ==============================================================
4538 Recognised values for feature:
4540 ===== ===========================================
4541 arm64 KVM_ARM_VCPU_SVE (requires KVM_CAP_ARM_SVE)
4542 ===== ===========================================
4544 Finalizes the configuration of the specified vcpu feature.
4546 The vcpu must already have been initialised, enabling the affected feature, by
4547 means of a successful KVM_ARM_VCPU_INIT call with the appropriate flag set in
4550 For affected vcpu features, this is a mandatory step that must be performed
4551 before the vcpu is fully usable.
4553 Between KVM_ARM_VCPU_INIT and KVM_ARM_VCPU_FINALIZE, the feature may be
4554 configured by use of ioctls such as KVM_SET_ONE_REG. The exact configuration
4555 that should be performaned and how to do it are feature-dependent.
4557 Other calls that depend on a particular feature being finalized, such as
4558 KVM_RUN, KVM_GET_REG_LIST, KVM_GET_ONE_REG and KVM_SET_ONE_REG, will fail with
4559 -EPERM unless the feature has already been finalized by means of a
4560 KVM_ARM_VCPU_FINALIZE call.
4562 See KVM_ARM_VCPU_INIT for details of vcpu features that require finalization
4565 4.120 KVM_SET_PMU_EVENT_FILTER
4566 ------------------------------
4568 :Capability: KVM_CAP_PMU_EVENT_FILTER
4571 :Parameters: struct kvm_pmu_event_filter (in)
4572 :Returns: 0 on success, -1 on error
4576 struct kvm_pmu_event_filter {
4579 __u32 fixed_counter_bitmap;
4585 This ioctl restricts the set of PMU events that the guest can program.
4586 The argument holds a list of events which will be allowed or denied.
4587 The eventsel+umask of each event the guest attempts to program is compared
4588 against the events field to determine whether the guest should have access.
4589 The events field only controls general purpose counters; fixed purpose
4590 counters are controlled by the fixed_counter_bitmap.
4592 No flags are defined yet, the field must be zero.
4594 Valid values for 'action'::
4596 #define KVM_PMU_EVENT_ALLOW 0
4597 #define KVM_PMU_EVENT_DENY 1
4599 4.121 KVM_PPC_SVM_OFF
4600 ---------------------
4603 :Architectures: powerpc
4606 :Returns: 0 on successful completion,
4610 ====== ================================================================
4611 EINVAL if ultravisor failed to terminate the secure guest
4612 ENOMEM if hypervisor failed to allocate new radix page tables for guest
4613 ====== ================================================================
4615 This ioctl is used to turn off the secure mode of the guest or transition
4616 the guest from secure mode to normal mode. This is invoked when the guest
4617 is reset. This has no effect if called for a normal guest.
4619 This ioctl issues an ultravisor call to terminate the secure guest,
4620 unpins the VPA pages and releases all the device pages that are used to
4621 track the secure pages by hypervisor.
4623 4.122 KVM_S390_NORMAL_RESET
4624 ---------------------------
4626 :Capability: KVM_CAP_S390_VCPU_RESETS
4627 :Architectures: s390
4632 This ioctl resets VCPU registers and control structures according to
4633 the cpu reset definition in the POP (Principles Of Operation).
4635 4.123 KVM_S390_INITIAL_RESET
4636 ----------------------------
4639 :Architectures: s390
4644 This ioctl resets VCPU registers and control structures according to
4645 the initial cpu reset definition in the POP. However, the cpu is not
4646 put into ESA mode. This reset is a superset of the normal reset.
4648 4.124 KVM_S390_CLEAR_RESET
4649 --------------------------
4651 :Capability: KVM_CAP_S390_VCPU_RESETS
4652 :Architectures: s390
4657 This ioctl resets VCPU registers and control structures according to
4658 the clear cpu reset definition in the POP. However, the cpu is not put
4659 into ESA mode. This reset is a superset of the initial reset.
4662 4.125 KVM_S390_PV_COMMAND
4663 -------------------------
4665 :Capability: KVM_CAP_S390_PROTECTED
4666 :Architectures: s390
4668 :Parameters: struct kvm_pv_cmd
4669 :Returns: 0 on success, < 0 on error
4674 __u32 cmd; /* Command to be executed */
4675 __u16 rc; /* Ultravisor return code */
4676 __u16 rrc; /* Ultravisor return reason code */
4677 __u64 data; /* Data or address */
4678 __u32 flags; /* flags for future extensions. Must be 0 for now */
4685 Allocate memory and register the VM with the Ultravisor, thereby
4686 donating memory to the Ultravisor that will become inaccessible to
4687 KVM. All existing CPUs are converted to protected ones. After this
4688 command has succeeded, any CPU added via hotplug will become
4689 protected during its creation as well.
4693 ===== =============================
4694 EINTR an unmasked signal is pending
4695 ===== =============================
4699 Deregister the VM from the Ultravisor and reclaim the memory that
4700 had been donated to the Ultravisor, making it usable by the kernel
4701 again. All registered VCPUs are converted back to non-protected
4704 KVM_PV_VM_SET_SEC_PARMS
4705 Pass the image header from VM memory to the Ultravisor in
4706 preparation of image unpacking and verification.
4709 Unpack (protect and decrypt) a page of the encrypted boot image.
4712 Verify the integrity of the unpacked image. Only if this succeeds,
4713 KVM is allowed to start protected VCPUs.
4715 4.126 KVM_X86_SET_MSR_FILTER
4716 ----------------------------
4718 :Capability: KVM_X86_SET_MSR_FILTER
4721 :Parameters: struct kvm_msr_filter
4722 :Returns: 0 on success, < 0 on error
4726 struct kvm_msr_filter_range {
4727 #define KVM_MSR_FILTER_READ (1 << 0)
4728 #define KVM_MSR_FILTER_WRITE (1 << 1)
4730 __u32 nmsrs; /* number of msrs in bitmap */
4731 __u32 base; /* MSR index the bitmap starts at */
4732 __u8 *bitmap; /* a 1 bit allows the operations in flags, 0 denies */
4735 #define KVM_MSR_FILTER_MAX_RANGES 16
4736 struct kvm_msr_filter {
4737 #define KVM_MSR_FILTER_DEFAULT_ALLOW (0 << 0)
4738 #define KVM_MSR_FILTER_DEFAULT_DENY (1 << 0)
4740 struct kvm_msr_filter_range ranges[KVM_MSR_FILTER_MAX_RANGES];
4743 flags values for ``struct kvm_msr_filter_range``:
4745 ``KVM_MSR_FILTER_READ``
4747 Filter read accesses to MSRs using the given bitmap. A 0 in the bitmap
4748 indicates that a read should immediately fail, while a 1 indicates that
4749 a read for a particular MSR should be handled regardless of the default
4752 ``KVM_MSR_FILTER_WRITE``
4754 Filter write accesses to MSRs using the given bitmap. A 0 in the bitmap
4755 indicates that a write should immediately fail, while a 1 indicates that
4756 a write for a particular MSR should be handled regardless of the default
4759 ``KVM_MSR_FILTER_READ | KVM_MSR_FILTER_WRITE``
4761 Filter both read and write accesses to MSRs using the given bitmap. A 0
4762 in the bitmap indicates that both reads and writes should immediately fail,
4763 while a 1 indicates that reads and writes for a particular MSR are not
4764 filtered by this range.
4766 flags values for ``struct kvm_msr_filter``:
4768 ``KVM_MSR_FILTER_DEFAULT_ALLOW``
4770 If no filter range matches an MSR index that is getting accessed, KVM will
4771 fall back to allowing access to the MSR.
4773 ``KVM_MSR_FILTER_DEFAULT_DENY``
4775 If no filter range matches an MSR index that is getting accessed, KVM will
4776 fall back to rejecting access to the MSR. In this mode, all MSRs that should
4777 be processed by KVM need to explicitly be marked as allowed in the bitmaps.
4779 This ioctl allows user space to define up to 16 bitmaps of MSR ranges to
4780 specify whether a certain MSR access should be explicitly filtered for or not.
4782 If this ioctl has never been invoked, MSR accesses are not guarded and the
4783 default KVM in-kernel emulation behavior is fully preserved.
4785 Calling this ioctl with an empty set of ranges (all nmsrs == 0) disables MSR
4786 filtering. In that mode, ``KVM_MSR_FILTER_DEFAULT_DENY`` is invalid and causes
4789 As soon as the filtering is in place, every MSR access is processed through
4790 the filtering except for accesses to the x2APIC MSRs (from 0x800 to 0x8ff);
4791 x2APIC MSRs are always allowed, independent of the ``default_allow`` setting,
4792 and their behavior depends on the ``X2APIC_ENABLE`` bit of the APIC base
4795 If a bit is within one of the defined ranges, read and write accesses are
4796 guarded by the bitmap's value for the MSR index if the kind of access
4797 is included in the ``struct kvm_msr_filter_range`` flags. If no range
4798 cover this particular access, the behavior is determined by the flags
4799 field in the kvm_msr_filter struct: ``KVM_MSR_FILTER_DEFAULT_ALLOW``
4800 and ``KVM_MSR_FILTER_DEFAULT_DENY``.
4802 Each bitmap range specifies a range of MSRs to potentially allow access on.
4803 The range goes from MSR index [base .. base+nmsrs]. The flags field
4804 indicates whether reads, writes or both reads and writes are filtered
4805 by setting a 1 bit in the bitmap for the corresponding MSR index.
4807 If an MSR access is not permitted through the filtering, it generates a
4808 #GP inside the guest. When combined with KVM_CAP_X86_USER_SPACE_MSR, that
4809 allows user space to deflect and potentially handle various MSR accesses
4812 If a vCPU is in running state while this ioctl is invoked, the vCPU may
4813 experience inconsistent filtering behavior on MSR accesses.
4815 4.127 KVM_XEN_HVM_SET_ATTR
4816 --------------------------
4818 :Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO
4821 :Parameters: struct kvm_xen_hvm_attr
4822 :Returns: 0 on success, < 0 on error
4826 struct kvm_xen_hvm_attr {
4841 KVM_XEN_ATTR_TYPE_LONG_MODE
4842 Sets the ABI mode of the VM to 32-bit or 64-bit (long mode). This
4843 determines the layout of the shared info pages exposed to the VM.
4845 KVM_XEN_ATTR_TYPE_SHARED_INFO
4846 Sets the guest physical frame number at which the Xen "shared info"
4847 page resides. Note that although Xen places vcpu_info for the first
4848 32 vCPUs in the shared_info page, KVM does not automatically do so
4849 and instead requires that KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO be used
4850 explicitly even when the vcpu_info for a given vCPU resides at the
4851 "default" location in the shared_info page. This is because KVM is
4852 not aware of the Xen CPU id which is used as the index into the
4853 vcpu_info[] array, so cannot know the correct default location.
4855 KVM_XEN_ATTR_TYPE_UPCALL_VECTOR
4856 Sets the exception vector used to deliver Xen event channel upcalls.
4858 4.128 KVM_XEN_HVM_GET_ATTR
4859 --------------------------
4861 :Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO
4864 :Parameters: struct kvm_xen_hvm_attr
4865 :Returns: 0 on success, < 0 on error
4867 Allows Xen VM attributes to be read. For the structure and types,
4868 see KVM_XEN_HVM_SET_ATTR above.
4870 4.129 KVM_XEN_VCPU_SET_ATTR
4871 ---------------------------
4873 :Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO
4876 :Parameters: struct kvm_xen_vcpu_attr
4877 :Returns: 0 on success, < 0 on error
4881 struct kvm_xen_vcpu_attr {
4889 __u64 state_entry_time;
4891 __u64 time_runnable;
4900 KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO
4901 Sets the guest physical address of the vcpu_info for a given vCPU.
4903 KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO
4904 Sets the guest physical address of an additional pvclock structure
4905 for a given vCPU. This is typically used for guest vsyscall support.
4907 KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR
4908 Sets the guest physical address of the vcpu_runstate_info for a given
4909 vCPU. This is how a Xen guest tracks CPU state such as steal time.
4911 KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_CURRENT
4912 Sets the runstate (RUNSTATE_running/_runnable/_blocked/_offline) of
4913 the given vCPU from the .u.runstate.state member of the structure.
4914 KVM automatically accounts running and runnable time but blocked
4915 and offline states are only entered explicitly.
4917 KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_DATA
4918 Sets all fields of the vCPU runstate data from the .u.runstate member
4919 of the structure, including the current runstate. The state_entry_time
4920 must equal the sum of the other four times.
4922 KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST
4923 This *adds* the contents of the .u.runstate members of the structure
4924 to the corresponding members of the given vCPU's runstate data, thus
4925 permitting atomic adjustments to the runstate times. The adjustment
4926 to the state_entry_time must equal the sum of the adjustments to the
4927 other four times. The state field must be set to -1, or to a valid
4928 runstate value (RUNSTATE_running, RUNSTATE_runnable, RUNSTATE_blocked
4929 or RUNSTATE_offline) to set the current accounted state as of the
4930 adjusted state_entry_time.
4932 4.130 KVM_XEN_VCPU_GET_ATTR
4933 ---------------------------
4935 :Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO
4938 :Parameters: struct kvm_xen_vcpu_attr
4939 :Returns: 0 on success, < 0 on error
4941 Allows Xen vCPU attributes to be read. For the structure and types,
4942 see KVM_XEN_VCPU_SET_ATTR above.
4944 The KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST type may not be used
4945 with the KVM_XEN_VCPU_GET_ATTR ioctl.
4947 5. The kvm_run structure
4948 ========================
4950 Application code obtains a pointer to the kvm_run structure by
4951 mmap()ing a vcpu fd. From that point, application code can control
4952 execution by changing fields in kvm_run prior to calling the KVM_RUN
4953 ioctl, and obtain information about the reason KVM_RUN returned by
4954 looking up structure members.
4960 __u8 request_interrupt_window;
4962 Request that KVM_RUN return when it becomes possible to inject external
4963 interrupts into the guest. Useful in conjunction with KVM_INTERRUPT.
4967 __u8 immediate_exit;
4969 This field is polled once when KVM_RUN starts; if non-zero, KVM_RUN
4970 exits immediately, returning -EINTR. In the common scenario where a
4971 signal is used to "kick" a VCPU out of KVM_RUN, this field can be used
4972 to avoid usage of KVM_SET_SIGNAL_MASK, which has worse scalability.
4973 Rather than blocking the signal outside KVM_RUN, userspace can set up
4974 a signal handler that sets run->immediate_exit to a non-zero value.
4976 This field is ignored if KVM_CAP_IMMEDIATE_EXIT is not available.
4985 When KVM_RUN has returned successfully (return value 0), this informs
4986 application code why KVM_RUN has returned. Allowable values for this
4987 field are detailed below.
4991 __u8 ready_for_interrupt_injection;
4993 If request_interrupt_window has been specified, this field indicates
4994 an interrupt can be injected now with KVM_INTERRUPT.
5000 The value of the current interrupt flag. Only valid if in-kernel
5001 local APIC is not used.
5007 More architecture-specific flags detailing state of the VCPU that may
5008 affect the device's behavior. Current defined flags::
5010 /* x86, set if the VCPU is in system management mode */
5011 #define KVM_RUN_X86_SMM (1 << 0)
5012 /* x86, set if bus lock detected in VM */
5013 #define KVM_RUN_BUS_LOCK (1 << 1)
5017 /* in (pre_kvm_run), out (post_kvm_run) */
5020 The value of the cr8 register. Only valid if in-kernel local APIC is
5021 not used. Both input and output.
5027 The value of the APIC BASE msr. Only valid if in-kernel local
5028 APIC is not used. Both input and output.
5033 /* KVM_EXIT_UNKNOWN */
5035 __u64 hardware_exit_reason;
5038 If exit_reason is KVM_EXIT_UNKNOWN, the vcpu has exited due to unknown
5039 reasons. Further architecture-specific information is available in
5040 hardware_exit_reason.
5044 /* KVM_EXIT_FAIL_ENTRY */
5046 __u64 hardware_entry_failure_reason;
5047 __u32 cpu; /* if KVM_LAST_CPU */
5050 If exit_reason is KVM_EXIT_FAIL_ENTRY, the vcpu could not be run due
5051 to unknown reasons. Further architecture-specific information is
5052 available in hardware_entry_failure_reason.
5056 /* KVM_EXIT_EXCEPTION */
5068 #define KVM_EXIT_IO_IN 0
5069 #define KVM_EXIT_IO_OUT 1
5071 __u8 size; /* bytes */
5074 __u64 data_offset; /* relative to kvm_run start */
5077 If exit_reason is KVM_EXIT_IO, then the vcpu has
5078 executed a port I/O instruction which could not be satisfied by kvm.
5079 data_offset describes where the data is located (KVM_EXIT_IO_OUT) or
5080 where kvm expects application code to place the data for the next
5081 KVM_RUN invocation (KVM_EXIT_IO_IN). Data format is a packed array.
5085 /* KVM_EXIT_DEBUG */
5087 struct kvm_debug_exit_arch arch;
5090 If the exit_reason is KVM_EXIT_DEBUG, then a vcpu is processing a debug event
5091 for which architecture specific information is returned.
5103 If exit_reason is KVM_EXIT_MMIO, then the vcpu has
5104 executed a memory-mapped I/O instruction which could not be satisfied
5105 by kvm. The 'data' member contains the written data if 'is_write' is
5106 true, and should be filled by application code otherwise.
5108 The 'data' member contains, in its first 'len' bytes, the value as it would
5109 appear if the VCPU performed a load or store of the appropriate width directly
5114 For KVM_EXIT_IO, KVM_EXIT_MMIO, KVM_EXIT_OSI, KVM_EXIT_PAPR, KVM_EXIT_XEN,
5115 KVM_EXIT_EPR, KVM_EXIT_X86_RDMSR and KVM_EXIT_X86_WRMSR the corresponding
5116 operations are complete (and guest state is consistent) only after userspace
5117 has re-entered the kernel with KVM_RUN. The kernel side will first finish
5118 incomplete operations and then check for pending signals.
5120 The pending state of the operation is not preserved in state which is
5121 visible to userspace, thus userspace should ensure that the operation is
5122 completed before performing a live migration. Userspace can re-enter the
5123 guest with an unmasked signal pending or with the immediate_exit field set
5124 to complete pending operations without allowing any further instructions
5129 /* KVM_EXIT_HYPERCALL */
5138 Unused. This was once used for 'hypercall to userspace'. To implement
5139 such functionality, use KVM_EXIT_IO (x86) or KVM_EXIT_MMIO (all except s390).
5141 .. note:: KVM_EXIT_IO is significantly faster than KVM_EXIT_MMIO.
5145 /* KVM_EXIT_TPR_ACCESS */
5152 To be documented (KVM_TPR_ACCESS_REPORTING).
5156 /* KVM_EXIT_S390_SIEIC */
5159 __u64 mask; /* psw upper half */
5160 __u64 addr; /* psw lower half */
5169 /* KVM_EXIT_S390_RESET */
5170 #define KVM_S390_RESET_POR 1
5171 #define KVM_S390_RESET_CLEAR 2
5172 #define KVM_S390_RESET_SUBSYSTEM 4
5173 #define KVM_S390_RESET_CPU_INIT 8
5174 #define KVM_S390_RESET_IPL 16
5175 __u64 s390_reset_flags;
5181 /* KVM_EXIT_S390_UCONTROL */
5183 __u64 trans_exc_code;
5187 s390 specific. A page fault has occurred for a user controlled virtual
5188 machine (KVM_VM_S390_UNCONTROL) on it's host page table that cannot be
5189 resolved by the kernel.
5190 The program code and the translation exception code that were placed
5191 in the cpu's lowcore are presented here as defined by the z Architecture
5192 Principles of Operation Book in the Chapter for Dynamic Address Translation
5204 Deprecated - was used for 440 KVM.
5213 MOL uses a special hypercall interface it calls 'OSI'. To enable it, we catch
5214 hypercalls and exit with this exit struct that contains all the guest gprs.
5216 If exit_reason is KVM_EXIT_OSI, then the vcpu has triggered such a hypercall.
5217 Userspace can now handle the hypercall and when it's done modify the gprs as
5218 necessary. Upon guest entry all guest GPRs will then be replaced by the values
5223 /* KVM_EXIT_PAPR_HCALL */
5230 This is used on 64-bit PowerPC when emulating a pSeries partition,
5231 e.g. with the 'pseries' machine type in qemu. It occurs when the
5232 guest does a hypercall using the 'sc 1' instruction. The 'nr' field
5233 contains the hypercall number (from the guest R3), and 'args' contains
5234 the arguments (from the guest R4 - R12). Userspace should put the
5235 return code in 'ret' and any extra returned values in args[].
5236 The possible hypercalls are defined in the Power Architecture Platform
5237 Requirements (PAPR) document available from www.power.org (free
5238 developer registration required to access it).
5242 /* KVM_EXIT_S390_TSCH */
5244 __u16 subchannel_id;
5245 __u16 subchannel_nr;
5252 s390 specific. This exit occurs when KVM_CAP_S390_CSS_SUPPORT has been enabled
5253 and TEST SUBCHANNEL was intercepted. If dequeued is set, a pending I/O
5254 interrupt for the target subchannel has been dequeued and subchannel_id,
5255 subchannel_nr, io_int_parm and io_int_word contain the parameters for that
5256 interrupt. ipb is needed for instruction parameter decoding.
5265 On FSL BookE PowerPC chips, the interrupt controller has a fast patch
5266 interrupt acknowledge path to the core. When the core successfully
5267 delivers an interrupt, it automatically populates the EPR register with
5268 the interrupt vector number and acknowledges the interrupt inside
5269 the interrupt controller.
5271 In case the interrupt controller lives in user space, we need to do
5272 the interrupt acknowledge cycle through it to fetch the next to be
5273 delivered interrupt vector using this exit.
5275 It gets triggered whenever both KVM_CAP_PPC_EPR are enabled and an
5276 external interrupt has just been delivered into the guest. User space
5277 should put the acknowledged interrupt vector into the 'epr' field.
5281 /* KVM_EXIT_SYSTEM_EVENT */
5283 #define KVM_SYSTEM_EVENT_SHUTDOWN 1
5284 #define KVM_SYSTEM_EVENT_RESET 2
5285 #define KVM_SYSTEM_EVENT_CRASH 3
5290 If exit_reason is KVM_EXIT_SYSTEM_EVENT then the vcpu has triggered
5291 a system-level event using some architecture specific mechanism (hypercall
5292 or some special instruction). In case of ARM/ARM64, this is triggered using
5293 HVC instruction based PSCI call from the vcpu. The 'type' field describes
5294 the system-level event type. The 'flags' field describes architecture
5295 specific flags for the system-level event.
5297 Valid values for 'type' are:
5299 - KVM_SYSTEM_EVENT_SHUTDOWN -- the guest has requested a shutdown of the
5300 VM. Userspace is not obliged to honour this, and if it does honour
5301 this does not need to destroy the VM synchronously (ie it may call
5302 KVM_RUN again before shutdown finally occurs).
5303 - KVM_SYSTEM_EVENT_RESET -- the guest has requested a reset of the VM.
5304 As with SHUTDOWN, userspace can choose to ignore the request, or
5305 to schedule the reset to occur in the future and may call KVM_RUN again.
5306 - KVM_SYSTEM_EVENT_CRASH -- the guest crash occurred and the guest
5307 has requested a crash condition maintenance. Userspace can choose
5308 to ignore the request, or to gather VM memory core dump and/or
5309 reset/shutdown of the VM.
5313 /* KVM_EXIT_IOAPIC_EOI */
5318 Indicates that the VCPU's in-kernel local APIC received an EOI for a
5319 level-triggered IOAPIC interrupt. This exit only triggers when the
5320 IOAPIC is implemented in userspace (i.e. KVM_CAP_SPLIT_IRQCHIP is enabled);
5321 the userspace IOAPIC should process the EOI and retrigger the interrupt if
5322 it is still asserted. Vector is the LAPIC interrupt vector for which the
5327 struct kvm_hyperv_exit {
5328 #define KVM_EXIT_HYPERV_SYNIC 1
5329 #define KVM_EXIT_HYPERV_HCALL 2
5330 #define KVM_EXIT_HYPERV_SYNDBG 3
5357 /* KVM_EXIT_HYPERV */
5358 struct kvm_hyperv_exit hyperv;
5360 Indicates that the VCPU exits into userspace to process some tasks
5361 related to Hyper-V emulation.
5363 Valid values for 'type' are:
5365 - KVM_EXIT_HYPERV_SYNIC -- synchronously notify user-space about
5367 Hyper-V SynIC state change. Notification is used to remap SynIC
5368 event/message pages and to enable/disable SynIC messages/events processing
5371 - KVM_EXIT_HYPERV_SYNDBG -- synchronously notify user-space about
5373 Hyper-V Synthetic debugger state change. Notification is used to either update
5374 the pending_page location or to send a control command (send the buffer located
5375 in send_page or recv a buffer to recv_page).
5379 /* KVM_EXIT_ARM_NISV */
5385 Used on arm and arm64 systems. If a guest accesses memory not in a memslot,
5386 KVM will typically return to userspace and ask it to do MMIO emulation on its
5387 behalf. However, for certain classes of instructions, no instruction decode
5388 (direction, length of memory access) is provided, and fetching and decoding
5389 the instruction from the VM is overly complicated to live in the kernel.
5391 Historically, when this situation occurred, KVM would print a warning and kill
5392 the VM. KVM assumed that if the guest accessed non-memslot memory, it was
5393 trying to do I/O, which just couldn't be emulated, and the warning message was
5394 phrased accordingly. However, what happened more often was that a guest bug
5395 caused access outside the guest memory areas which should lead to a more
5396 meaningful warning message and an external abort in the guest, if the access
5397 did not fall within an I/O window.
5399 Userspace implementations can query for KVM_CAP_ARM_NISV_TO_USER, and enable
5400 this capability at VM creation. Once this is done, these types of errors will
5401 instead return to userspace with KVM_EXIT_ARM_NISV, with the valid bits from
5402 the HSR (arm) and ESR_EL2 (arm64) in the esr_iss field, and the faulting IPA
5403 in the fault_ipa field. Userspace can either fix up the access if it's
5404 actually an I/O access by decoding the instruction from guest memory (if it's
5405 very brave) and continue executing the guest, or it can decide to suspend,
5406 dump, or restart the guest.
5408 Note that KVM does not skip the faulting instruction as it does for
5409 KVM_EXIT_MMIO, but userspace has to emulate any change to the processing state
5410 if it decides to decode and emulate the instruction.
5414 /* KVM_EXIT_X86_RDMSR / KVM_EXIT_X86_WRMSR */
5416 __u8 error; /* user -> kernel */
5418 __u32 reason; /* kernel -> user */
5419 __u32 index; /* kernel -> user */
5420 __u64 data; /* kernel <-> user */
5423 Used on x86 systems. When the VM capability KVM_CAP_X86_USER_SPACE_MSR is
5424 enabled, MSR accesses to registers that would invoke a #GP by KVM kernel code
5425 will instead trigger a KVM_EXIT_X86_RDMSR exit for reads and KVM_EXIT_X86_WRMSR
5428 The "reason" field specifies why the MSR trap occurred. User space will only
5429 receive MSR exit traps when a particular reason was requested during through
5430 ENABLE_CAP. Currently valid exit reasons are:
5432 KVM_MSR_EXIT_REASON_UNKNOWN - access to MSR that is unknown to KVM
5433 KVM_MSR_EXIT_REASON_INVAL - access to invalid MSRs or reserved bits
5434 KVM_MSR_EXIT_REASON_FILTER - access blocked by KVM_X86_SET_MSR_FILTER
5436 For KVM_EXIT_X86_RDMSR, the "index" field tells user space which MSR the guest
5437 wants to read. To respond to this request with a successful read, user space
5438 writes the respective data into the "data" field and must continue guest
5439 execution to ensure the read data is transferred into guest register state.
5441 If the RDMSR request was unsuccessful, user space indicates that with a "1" in
5442 the "error" field. This will inject a #GP into the guest when the VCPU is
5445 For KVM_EXIT_X86_WRMSR, the "index" field tells user space which MSR the guest
5446 wants to write. Once finished processing the event, user space must continue
5447 vCPU execution. If the MSR write was unsuccessful, user space also sets the
5448 "error" field to "1".
5453 struct kvm_xen_exit {
5454 #define KVM_EXIT_XEN_HCALL 1
5467 struct kvm_hyperv_exit xen;
5469 Indicates that the VCPU exits into userspace to process some tasks
5470 related to Xen emulation.
5472 Valid values for 'type' are:
5474 - KVM_EXIT_XEN_HCALL -- synchronously notify user-space about Xen hypercall.
5475 Userspace is expected to place the hypercall result into the appropriate
5476 field before invoking KVM_RUN again.
5480 /* Fix the size of the union. */
5485 * shared registers between kvm and userspace.
5486 * kvm_valid_regs specifies the register classes set by the host
5487 * kvm_dirty_regs specified the register classes dirtied by userspace
5488 * struct kvm_sync_regs is architecture specific, as well as the
5489 * bits for kvm_valid_regs and kvm_dirty_regs
5491 __u64 kvm_valid_regs;
5492 __u64 kvm_dirty_regs;
5494 struct kvm_sync_regs regs;
5495 char padding[SYNC_REGS_SIZE_BYTES];
5498 If KVM_CAP_SYNC_REGS is defined, these fields allow userspace to access
5499 certain guest registers without having to call SET/GET_*REGS. Thus we can
5500 avoid some system call overhead if userspace has to handle the exit.
5501 Userspace can query the validity of the structure by checking
5502 kvm_valid_regs for specific bits. These bits are architecture specific
5503 and usually define the validity of a groups of registers. (e.g. one bit
5504 for general purpose registers)
5506 Please note that the kernel is allowed to use the kvm_run structure as the
5507 primary storage for certain register types. Therefore, the kernel may use the
5508 values in kvm_run even if the corresponding bit in kvm_dirty_regs is not set.
5516 6. Capabilities that can be enabled on vCPUs
5517 ============================================
5519 There are certain capabilities that change the behavior of the virtual CPU or
5520 the virtual machine when enabled. To enable them, please see section 4.37.
5521 Below you can find a list of capabilities and what their effect on the vCPU or
5522 the virtual machine is when enabling them.
5524 The following information is provided along with the description:
5527 which instruction set architectures provide this ioctl.
5528 x86 includes both i386 and x86_64.
5531 whether this is a per-vcpu or per-vm capability.
5534 what parameters are accepted by the capability.
5537 the return value. General error numbers (EBADF, ENOMEM, EINVAL)
5538 are not detailed, but errors with specific meanings are.
5547 :Returns: 0 on success; -1 on error
5549 This capability enables interception of OSI hypercalls that otherwise would
5550 be treated as normal system calls to be injected into the guest. OSI hypercalls
5551 were invented by Mac-on-Linux to have a standardized communication mechanism
5552 between the guest and the host.
5554 When this capability is enabled, KVM_EXIT_OSI can occur.
5557 6.2 KVM_CAP_PPC_PAPR
5558 --------------------
5563 :Returns: 0 on success; -1 on error
5565 This capability enables interception of PAPR hypercalls. PAPR hypercalls are
5566 done using the hypercall instruction "sc 1".
5568 It also sets the guest privilege level to "supervisor" mode. Usually the guest
5569 runs in "hypervisor" privilege mode with a few missing features.
5571 In addition to the above, it changes the semantics of SDR1. In this mode, the
5572 HTAB address part of SDR1 contains an HVA instead of a GPA, as PAPR keeps the
5573 HTAB invisible to the guest.
5575 When this capability is enabled, KVM_EXIT_PAPR_HCALL can occur.
5583 :Parameters: args[0] is the address of a struct kvm_config_tlb
5584 :Returns: 0 on success; -1 on error
5588 struct kvm_config_tlb {
5595 Configures the virtual CPU's TLB array, establishing a shared memory area
5596 between userspace and KVM. The "params" and "array" fields are userspace
5597 addresses of mmu-type-specific data structures. The "array_len" field is an
5598 safety mechanism, and should be set to the size in bytes of the memory that
5599 userspace has reserved for the array. It must be at least the size dictated
5600 by "mmu_type" and "params".
5602 While KVM_RUN is active, the shared region is under control of KVM. Its
5603 contents are undefined, and any modification by userspace results in
5604 boundedly undefined behavior.
5606 On return from KVM_RUN, the shared region will reflect the current state of
5607 the guest's TLB. If userspace makes any changes, it must call KVM_DIRTY_TLB
5608 to tell KVM which entries have been changed, prior to calling KVM_RUN again
5611 For mmu types KVM_MMU_FSL_BOOKE_NOHV and KVM_MMU_FSL_BOOKE_HV:
5613 - The "params" field is of type "struct kvm_book3e_206_tlb_params".
5614 - The "array" field points to an array of type "struct
5615 kvm_book3e_206_tlb_entry".
5616 - The array consists of all entries in the first TLB, followed by all
5617 entries in the second TLB.
5618 - Within a TLB, entries are ordered first by increasing set number. Within a
5619 set, entries are ordered by way (increasing ESEL).
5620 - The hash for determining set number in TLB0 is: (MAS2 >> 12) & (num_sets - 1)
5621 where "num_sets" is the tlb_sizes[] value divided by the tlb_ways[] value.
5622 - The tsize field of mas1 shall be set to 4K on TLB0, even though the
5623 hardware ignores this value for TLB0.
5625 6.4 KVM_CAP_S390_CSS_SUPPORT
5626 ----------------------------
5628 :Architectures: s390
5631 :Returns: 0 on success; -1 on error
5633 This capability enables support for handling of channel I/O instructions.
5635 TEST PENDING INTERRUPTION and the interrupt portion of TEST SUBCHANNEL are
5636 handled in-kernel, while the other I/O instructions are passed to userspace.
5638 When this capability is enabled, KVM_EXIT_S390_TSCH will occur on TEST
5639 SUBCHANNEL intercepts.
5641 Note that even though this capability is enabled per-vcpu, the complete
5642 virtual machine is affected.
5649 :Parameters: args[0] defines whether the proxy facility is active
5650 :Returns: 0 on success; -1 on error
5652 This capability enables or disables the delivery of interrupts through the
5653 external proxy facility.
5655 When enabled (args[0] != 0), every time the guest gets an external interrupt
5656 delivered, it automatically exits into user space with a KVM_EXIT_EPR exit
5657 to receive the topmost interrupt vector.
5659 When disabled (args[0] == 0), behavior is as if this facility is unsupported.
5661 When this capability is enabled, KVM_EXIT_EPR can occur.
5663 6.6 KVM_CAP_IRQ_MPIC
5664 --------------------
5667 :Parameters: args[0] is the MPIC device fd;
5668 args[1] is the MPIC CPU number for this vcpu
5670 This capability connects the vcpu to an in-kernel MPIC device.
5672 6.7 KVM_CAP_IRQ_XICS
5673 --------------------
5677 :Parameters: args[0] is the XICS device fd;
5678 args[1] is the XICS CPU number (server ID) for this vcpu
5680 This capability connects the vcpu to an in-kernel XICS device.
5682 6.8 KVM_CAP_S390_IRQCHIP
5683 ------------------------
5685 :Architectures: s390
5689 This capability enables the in-kernel irqchip for s390. Please refer to
5690 "4.24 KVM_CREATE_IRQCHIP" for details.
5692 6.9 KVM_CAP_MIPS_FPU
5693 --------------------
5695 :Architectures: mips
5697 :Parameters: args[0] is reserved for future use (should be 0).
5699 This capability allows the use of the host Floating Point Unit by the guest. It
5700 allows the Config1.FP bit to be set to enable the FPU in the guest. Once this is
5701 done the ``KVM_REG_MIPS_FPR_*`` and ``KVM_REG_MIPS_FCR_*`` registers can be
5702 accessed (depending on the current guest FPU register mode), and the Status.FR,
5703 Config5.FRE bits are accessible via the KVM API and also from the guest,
5704 depending on them being supported by the FPU.
5706 6.10 KVM_CAP_MIPS_MSA
5707 ---------------------
5709 :Architectures: mips
5711 :Parameters: args[0] is reserved for future use (should be 0).
5713 This capability allows the use of the MIPS SIMD Architecture (MSA) by the guest.
5714 It allows the Config3.MSAP bit to be set to enable the use of MSA by the guest.
5715 Once this is done the ``KVM_REG_MIPS_VEC_*`` and ``KVM_REG_MIPS_MSA_*``
5716 registers can be accessed, and the Config5.MSAEn bit is accessible via the
5717 KVM API and also from the guest.
5719 6.74 KVM_CAP_SYNC_REGS
5720 ----------------------
5722 :Architectures: s390, x86
5723 :Target: s390: always enabled, x86: vcpu
5725 :Returns: x86: KVM_CHECK_EXTENSION returns a bit-array indicating which register
5727 (bitfields defined in arch/x86/include/uapi/asm/kvm.h).
5729 As described above in the kvm_sync_regs struct info in section 5 (kvm_run):
5730 KVM_CAP_SYNC_REGS "allow[s] userspace to access certain guest registers
5731 without having to call SET/GET_*REGS". This reduces overhead by eliminating
5732 repeated ioctl calls for setting and/or getting register values. This is
5733 particularly important when userspace is making synchronous guest state
5734 modifications, e.g. when emulating and/or intercepting instructions in
5737 For s390 specifics, please refer to the source code.
5741 - the register sets to be copied out to kvm_run are selectable
5742 by userspace (rather that all sets being copied out for every exit).
5743 - vcpu_events are available in addition to regs and sregs.
5745 For x86, the 'kvm_valid_regs' field of struct kvm_run is overloaded to
5746 function as an input bit-array field set by userspace to indicate the
5747 specific register sets to be copied out on the next exit.
5749 To indicate when userspace has modified values that should be copied into
5750 the vCPU, the all architecture bitarray field, 'kvm_dirty_regs' must be set.
5751 This is done using the same bitflags as for the 'kvm_valid_regs' field.
5752 If the dirty bit is not set, then the register set values will not be copied
5753 into the vCPU even if they've been modified.
5755 Unused bitfields in the bitarrays must be set to zero.
5759 struct kvm_sync_regs {
5760 struct kvm_regs regs;
5761 struct kvm_sregs sregs;
5762 struct kvm_vcpu_events events;
5765 6.75 KVM_CAP_PPC_IRQ_XIVE
5766 -------------------------
5770 :Parameters: args[0] is the XIVE device fd;
5771 args[1] is the XIVE CPU number (server ID) for this vcpu
5773 This capability connects the vcpu to an in-kernel XIVE device.
5775 7. Capabilities that can be enabled on VMs
5776 ==========================================
5778 There are certain capabilities that change the behavior of the virtual
5779 machine when enabled. To enable them, please see section 4.37. Below
5780 you can find a list of capabilities and what their effect on the VM
5781 is when enabling them.
5783 The following information is provided along with the description:
5786 which instruction set architectures provide this ioctl.
5787 x86 includes both i386 and x86_64.
5790 what parameters are accepted by the capability.
5793 the return value. General error numbers (EBADF, ENOMEM, EINVAL)
5794 are not detailed, but errors with specific meanings are.
5797 7.1 KVM_CAP_PPC_ENABLE_HCALL
5798 ----------------------------
5801 :Parameters: args[0] is the sPAPR hcall number;
5802 args[1] is 0 to disable, 1 to enable in-kernel handling
5804 This capability controls whether individual sPAPR hypercalls (hcalls)
5805 get handled by the kernel or not. Enabling or disabling in-kernel
5806 handling of an hcall is effective across the VM. On creation, an
5807 initial set of hcalls are enabled for in-kernel handling, which
5808 consists of those hcalls for which in-kernel handlers were implemented
5809 before this capability was implemented. If disabled, the kernel will
5810 not to attempt to handle the hcall, but will always exit to userspace
5811 to handle it. Note that it may not make sense to enable some and
5812 disable others of a group of related hcalls, but KVM does not prevent
5813 userspace from doing that.
5815 If the hcall number specified is not one that has an in-kernel
5816 implementation, the KVM_ENABLE_CAP ioctl will fail with an EINVAL
5819 7.2 KVM_CAP_S390_USER_SIGP
5820 --------------------------
5822 :Architectures: s390
5825 This capability controls which SIGP orders will be handled completely in user
5826 space. With this capability enabled, all fast orders will be handled completely
5833 - CONDITIONAL EMERGENCY SIGNAL
5835 All other orders will be handled completely in user space.
5837 Only privileged operation exceptions will be checked for in the kernel (or even
5838 in the hardware prior to interception). If this capability is not enabled, the
5839 old way of handling SIGP orders is used (partially in kernel and user space).
5841 7.3 KVM_CAP_S390_VECTOR_REGISTERS
5842 ---------------------------------
5844 :Architectures: s390
5846 :Returns: 0 on success, negative value on error
5848 Allows use of the vector registers introduced with z13 processor, and
5849 provides for the synchronization between host and user space. Will
5850 return -EINVAL if the machine does not support vectors.
5852 7.4 KVM_CAP_S390_USER_STSI
5853 --------------------------
5855 :Architectures: s390
5858 This capability allows post-handlers for the STSI instruction. After
5859 initial handling in the kernel, KVM exits to user space with
5860 KVM_EXIT_S390_STSI to allow user space to insert further data.
5862 Before exiting to userspace, kvm handlers should fill in s390_stsi field of
5874 @addr - guest address of STSI SYSIB
5878 @ar - access register number
5880 KVM handlers should exit to userspace with rc = -EREMOTE.
5882 7.5 KVM_CAP_SPLIT_IRQCHIP
5883 -------------------------
5886 :Parameters: args[0] - number of routes reserved for userspace IOAPICs
5887 :Returns: 0 on success, -1 on error
5889 Create a local apic for each processor in the kernel. This can be used
5890 instead of KVM_CREATE_IRQCHIP if the userspace VMM wishes to emulate the
5891 IOAPIC and PIC (and also the PIT, even though this has to be enabled
5894 This capability also enables in kernel routing of interrupt requests;
5895 when KVM_CAP_SPLIT_IRQCHIP only routes of KVM_IRQ_ROUTING_MSI type are
5896 used in the IRQ routing table. The first args[0] MSI routes are reserved
5897 for the IOAPIC pins. Whenever the LAPIC receives an EOI for these routes,
5898 a KVM_EXIT_IOAPIC_EOI vmexit will be reported to userspace.
5900 Fails if VCPU has already been created, or if the irqchip is already in the
5901 kernel (i.e. KVM_CREATE_IRQCHIP has already been called).
5906 :Architectures: s390
5909 Allows use of runtime-instrumentation introduced with zEC12 processor.
5910 Will return -EINVAL if the machine does not support runtime-instrumentation.
5911 Will return -EBUSY if a VCPU has already been created.
5913 7.7 KVM_CAP_X2APIC_API
5914 ----------------------
5917 :Parameters: args[0] - features that should be enabled
5918 :Returns: 0 on success, -EINVAL when args[0] contains invalid features
5920 Valid feature flags in args[0] are::
5922 #define KVM_X2APIC_API_USE_32BIT_IDS (1ULL << 0)
5923 #define KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK (1ULL << 1)
5925 Enabling KVM_X2APIC_API_USE_32BIT_IDS changes the behavior of
5926 KVM_SET_GSI_ROUTING, KVM_SIGNAL_MSI, KVM_SET_LAPIC, and KVM_GET_LAPIC,
5927 allowing the use of 32-bit APIC IDs. See KVM_CAP_X2APIC_API in their
5928 respective sections.
5930 KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK must be enabled for x2APIC to work
5931 in logical mode or with more than 255 VCPUs. Otherwise, KVM treats 0xff
5932 as a broadcast even in x2APIC mode in order to support physical x2APIC
5933 without interrupt remapping. This is undesirable in logical mode,
5934 where 0xff represents CPUs 0-7 in cluster 0.
5936 7.8 KVM_CAP_S390_USER_INSTR0
5937 ----------------------------
5939 :Architectures: s390
5942 With this capability enabled, all illegal instructions 0x0000 (2 bytes) will
5943 be intercepted and forwarded to user space. User space can use this
5944 mechanism e.g. to realize 2-byte software breakpoints. The kernel will
5945 not inject an operating exception for these instructions, user space has
5946 to take care of that.
5948 This capability can be enabled dynamically even if VCPUs were already
5949 created and are running.
5954 :Architectures: s390
5956 :Returns: 0 on success; -EINVAL if the machine does not support
5957 guarded storage; -EBUSY if a VCPU has already been created.
5959 Allows use of guarded storage for the KVM guest.
5961 7.10 KVM_CAP_S390_AIS
5962 ---------------------
5964 :Architectures: s390
5967 Allow use of adapter-interruption suppression.
5968 :Returns: 0 on success; -EBUSY if a VCPU has already been created.
5970 7.11 KVM_CAP_PPC_SMT
5971 --------------------
5974 :Parameters: vsmt_mode, flags
5976 Enabling this capability on a VM provides userspace with a way to set
5977 the desired virtual SMT mode (i.e. the number of virtual CPUs per
5978 virtual core). The virtual SMT mode, vsmt_mode, must be a power of 2
5979 between 1 and 8. On POWER8, vsmt_mode must also be no greater than
5980 the number of threads per subcore for the host. Currently flags must
5981 be 0. A successful call to enable this capability will result in
5982 vsmt_mode being returned when the KVM_CAP_PPC_SMT capability is
5983 subsequently queried for the VM. This capability is only supported by
5984 HV KVM, and can only be set before any VCPUs have been created.
5985 The KVM_CAP_PPC_SMT_POSSIBLE capability indicates which virtual SMT
5986 modes are available.
5988 7.12 KVM_CAP_PPC_FWNMI
5989 ----------------------
5994 With this capability a machine check exception in the guest address
5995 space will cause KVM to exit the guest with NMI exit reason. This
5996 enables QEMU to build error log and branch to guest kernel registered
5997 machine check handling routine. Without this capability KVM will
5998 branch to guests' 0x200 interrupt vector.
6000 7.13 KVM_CAP_X86_DISABLE_EXITS
6001 ------------------------------
6004 :Parameters: args[0] defines which exits are disabled
6005 :Returns: 0 on success, -EINVAL when args[0] contains invalid exits
6007 Valid bits in args[0] are::
6009 #define KVM_X86_DISABLE_EXITS_MWAIT (1 << 0)
6010 #define KVM_X86_DISABLE_EXITS_HLT (1 << 1)
6011 #define KVM_X86_DISABLE_EXITS_PAUSE (1 << 2)
6012 #define KVM_X86_DISABLE_EXITS_CSTATE (1 << 3)
6014 Enabling this capability on a VM provides userspace with a way to no
6015 longer intercept some instructions for improved latency in some
6016 workloads, and is suggested when vCPUs are associated to dedicated
6017 physical CPUs. More bits can be added in the future; userspace can
6018 just pass the KVM_CHECK_EXTENSION result to KVM_ENABLE_CAP to disable
6021 Do not enable KVM_FEATURE_PV_UNHALT if you disable HLT exits.
6023 7.14 KVM_CAP_S390_HPAGE_1M
6024 --------------------------
6026 :Architectures: s390
6028 :Returns: 0 on success, -EINVAL if hpage module parameter was not set
6029 or cmma is enabled, or the VM has the KVM_VM_S390_UCONTROL
6032 With this capability the KVM support for memory backing with 1m pages
6033 through hugetlbfs can be enabled for a VM. After the capability is
6034 enabled, cmma can't be enabled anymore and pfmfi and the storage key
6035 interpretation are disabled. If cmma has already been enabled or the
6036 hpage module parameter is not set to 1, -EINVAL is returned.
6038 While it is generally possible to create a huge page backed VM without
6039 this capability, the VM will not be able to run.
6041 7.15 KVM_CAP_MSR_PLATFORM_INFO
6042 ------------------------------
6045 :Parameters: args[0] whether feature should be enabled or not
6047 With this capability, a guest may read the MSR_PLATFORM_INFO MSR. Otherwise,
6048 a #GP would be raised when the guest tries to access. Currently, this
6049 capability does not enable write permissions of this MSR for the guest.
6051 7.16 KVM_CAP_PPC_NESTED_HV
6052 --------------------------
6056 :Returns: 0 on success, -EINVAL when the implementation doesn't support
6057 nested-HV virtualization.
6059 HV-KVM on POWER9 and later systems allows for "nested-HV"
6060 virtualization, which provides a way for a guest VM to run guests that
6061 can run using the CPU's supervisor mode (privileged non-hypervisor
6062 state). Enabling this capability on a VM depends on the CPU having
6063 the necessary functionality and on the facility being enabled with a
6064 kvm-hv module parameter.
6066 7.17 KVM_CAP_EXCEPTION_PAYLOAD
6067 ------------------------------
6070 :Parameters: args[0] whether feature should be enabled or not
6072 With this capability enabled, CR2 will not be modified prior to the
6073 emulated VM-exit when L1 intercepts a #PF exception that occurs in
6074 L2. Similarly, for kvm-intel only, DR6 will not be modified prior to
6075 the emulated VM-exit when L1 intercepts a #DB exception that occurs in
6076 L2. As a result, when KVM_GET_VCPU_EVENTS reports a pending #PF (or
6077 #DB) exception for L2, exception.has_payload will be set and the
6078 faulting address (or the new DR6 bits*) will be reported in the
6079 exception_payload field. Similarly, when userspace injects a #PF (or
6080 #DB) into L2 using KVM_SET_VCPU_EVENTS, it is expected to set
6081 exception.has_payload and to put the faulting address - or the new DR6
6082 bits\ [#]_ - in the exception_payload field.
6084 This capability also enables exception.pending in struct
6085 kvm_vcpu_events, which allows userspace to distinguish between pending
6086 and injected exceptions.
6089 .. [#] For the new DR6 bits, note that bit 16 is set iff the #DB exception
6092 7.18 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
6094 :Architectures: x86, arm, arm64, mips
6095 :Parameters: args[0] whether feature should be enabled or not
6099 #define KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE (1 << 0)
6100 #define KVM_DIRTY_LOG_INITIALLY_SET (1 << 1)
6102 With KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE is set, KVM_GET_DIRTY_LOG will not
6103 automatically clear and write-protect all pages that are returned as dirty.
6104 Rather, userspace will have to do this operation separately using
6105 KVM_CLEAR_DIRTY_LOG.
6107 At the cost of a slightly more complicated operation, this provides better
6108 scalability and responsiveness for two reasons. First,
6109 KVM_CLEAR_DIRTY_LOG ioctl can operate on a 64-page granularity rather
6110 than requiring to sync a full memslot; this ensures that KVM does not
6111 take spinlocks for an extended period of time. Second, in some cases a
6112 large amount of time can pass between a call to KVM_GET_DIRTY_LOG and
6113 userspace actually using the data in the page. Pages can be modified
6114 during this time, which is inefficient for both the guest and userspace:
6115 the guest will incur a higher penalty due to write protection faults,
6116 while userspace can see false reports of dirty pages. Manual reprotection
6117 helps reducing this time, improving guest performance and reducing the
6118 number of dirty log false positives.
6120 With KVM_DIRTY_LOG_INITIALLY_SET set, all the bits of the dirty bitmap
6121 will be initialized to 1 when created. This also improves performance because
6122 dirty logging can be enabled gradually in small chunks on the first call
6123 to KVM_CLEAR_DIRTY_LOG. KVM_DIRTY_LOG_INITIALLY_SET depends on
6124 KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE (it is also only available on
6125 x86 and arm64 for now).
6127 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 was previously available under the name
6128 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT, but the implementation had bugs that make
6129 it hard or impossible to use it correctly. The availability of
6130 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 signals that those bugs are fixed.
6131 Userspace should not try to use KVM_CAP_MANUAL_DIRTY_LOG_PROTECT.
6133 7.19 KVM_CAP_PPC_SECURE_GUEST
6134 ------------------------------
6138 This capability indicates that KVM is running on a host that has
6139 ultravisor firmware and thus can support a secure guest. On such a
6140 system, a guest can ask the ultravisor to make it a secure guest,
6141 one whose memory is inaccessible to the host except for pages which
6142 are explicitly requested to be shared with the host. The ultravisor
6143 notifies KVM when a guest requests to become a secure guest, and KVM
6144 has the opportunity to veto the transition.
6146 If present, this capability can be enabled for a VM, meaning that KVM
6147 will allow the transition to secure guest mode. Otherwise KVM will
6148 veto the transition.
6150 7.20 KVM_CAP_HALT_POLL
6151 ----------------------
6155 :Parameters: args[0] is the maximum poll time in nanoseconds
6156 :Returns: 0 on success; -1 on error
6158 This capability overrides the kvm module parameter halt_poll_ns for the
6161 VCPU polling allows a VCPU to poll for wakeup events instead of immediately
6162 scheduling during guest halts. The maximum time a VCPU can spend polling is
6163 controlled by the kvm module parameter halt_poll_ns. This capability allows
6164 the maximum halt time to specified on a per-VM basis, effectively overriding
6165 the module parameter for the target VM.
6167 7.21 KVM_CAP_X86_USER_SPACE_MSR
6168 -------------------------------
6172 :Parameters: args[0] contains the mask of KVM_MSR_EXIT_REASON_* events to report
6173 :Returns: 0 on success; -1 on error
6175 This capability enables trapping of #GP invoking RDMSR and WRMSR instructions
6178 When a guest requests to read or write an MSR, KVM may not implement all MSRs
6179 that are relevant to a respective system. It also does not differentiate by
6182 To allow more fine grained control over MSR handling, user space may enable
6183 this capability. With it enabled, MSR accesses that match the mask specified in
6184 args[0] and trigger a #GP event inside the guest by KVM will instead trigger
6185 KVM_EXIT_X86_RDMSR and KVM_EXIT_X86_WRMSR exit notifications which user space
6186 can then handle to implement model specific MSR handling and/or user notifications
6187 to inform a user that an MSR was not handled.
6189 7.22 KVM_CAP_X86_BUS_LOCK_EXIT
6190 -------------------------------
6194 :Parameters: args[0] defines the policy used when bus locks detected in guest
6195 :Returns: 0 on success, -EINVAL when args[0] contains invalid bits
6197 Valid bits in args[0] are::
6199 #define KVM_BUS_LOCK_DETECTION_OFF (1 << 0)
6200 #define KVM_BUS_LOCK_DETECTION_EXIT (1 << 1)
6202 Enabling this capability on a VM provides userspace with a way to select
6203 a policy to handle the bus locks detected in guest. Userspace can obtain
6204 the supported modes from the result of KVM_CHECK_EXTENSION and define it
6205 through the KVM_ENABLE_CAP.
6207 KVM_BUS_LOCK_DETECTION_OFF and KVM_BUS_LOCK_DETECTION_EXIT are supported
6208 currently and mutually exclusive with each other. More bits can be added in
6211 With KVM_BUS_LOCK_DETECTION_OFF set, bus locks in guest will not cause vm exits
6212 so that no additional actions are needed. This is the default mode.
6214 With KVM_BUS_LOCK_DETECTION_EXIT set, vm exits happen when bus lock detected
6215 in VM. KVM just exits to userspace when handling them. Userspace can enforce
6216 its own throttling or other policy based mitigations.
6218 This capability is aimed to address the thread that VM can exploit bus locks to
6219 degree the performance of the whole system. Once the userspace enable this
6220 capability and select the KVM_BUS_LOCK_DETECTION_EXIT mode, KVM will set the
6221 KVM_RUN_BUS_LOCK flag in vcpu-run->flags field and exit to userspace. Concerning
6222 the bus lock vm exit can be preempted by a higher priority VM exit, the exit
6223 notifications to userspace can be KVM_EXIT_BUS_LOCK or other reasons.
6224 KVM_RUN_BUS_LOCK flag is used to distinguish between them.
6226 7.23 KVM_CAP_PPC_DAWR1
6227 ----------------------
6231 :Returns: 0 on success, -EINVAL when CPU doesn't support 2nd DAWR
6233 This capability can be used to check / enable 2nd DAWR feature provided
6234 by POWER10 processor.
6236 8. Other capabilities.
6237 ======================
6239 This section lists capabilities that give information about other
6240 features of the KVM implementation.
6242 8.1 KVM_CAP_PPC_HWRNG
6243 ---------------------
6247 This capability, if KVM_CHECK_EXTENSION indicates that it is
6248 available, means that the kernel has an implementation of the
6249 H_RANDOM hypercall backed by a hardware random-number generator.
6250 If present, the kernel H_RANDOM handler can be enabled for guest use
6251 with the KVM_CAP_PPC_ENABLE_HCALL capability.
6253 8.2 KVM_CAP_HYPERV_SYNIC
6254 ------------------------
6258 This capability, if KVM_CHECK_EXTENSION indicates that it is
6259 available, means that the kernel has an implementation of the
6260 Hyper-V Synthetic interrupt controller(SynIC). Hyper-V SynIC is
6261 used to support Windows Hyper-V based guest paravirt drivers(VMBus).
6263 In order to use SynIC, it has to be activated by setting this
6264 capability via KVM_ENABLE_CAP ioctl on the vcpu fd. Note that this
6265 will disable the use of APIC hardware virtualization even if supported
6266 by the CPU, as it's incompatible with SynIC auto-EOI behavior.
6268 8.3 KVM_CAP_PPC_RADIX_MMU
6269 -------------------------
6273 This capability, if KVM_CHECK_EXTENSION indicates that it is
6274 available, means that the kernel can support guests using the
6275 radix MMU defined in Power ISA V3.00 (as implemented in the POWER9
6278 8.4 KVM_CAP_PPC_HASH_MMU_V3
6279 ---------------------------
6283 This capability, if KVM_CHECK_EXTENSION indicates that it is
6284 available, means that the kernel can support guests using the
6285 hashed page table MMU defined in Power ISA V3.00 (as implemented in
6286 the POWER9 processor), including in-memory segment tables.
6291 :Architectures: mips
6293 This capability, if KVM_CHECK_EXTENSION on the main kvm handle indicates that
6294 it is available, means that full hardware assisted virtualization capabilities
6295 of the hardware are available for use through KVM. An appropriate
6296 KVM_VM_MIPS_* type must be passed to KVM_CREATE_VM to create a VM which
6299 If KVM_CHECK_EXTENSION on a kvm VM handle indicates that this capability is
6300 available, it means that the VM is using full hardware assisted virtualization
6301 capabilities of the hardware. This is useful to check after creating a VM with
6302 KVM_VM_MIPS_DEFAULT.
6304 The value returned by KVM_CHECK_EXTENSION should be compared against known
6305 values (see below). All other values are reserved. This is to allow for the
6306 possibility of other hardware assisted virtualization implementations which
6307 may be incompatible with the MIPS VZ ASE.
6309 == ==========================================================================
6310 0 The trap & emulate implementation is in use to run guest code in user
6311 mode. Guest virtual memory segments are rearranged to fit the guest in the
6312 user mode address space.
6314 1 The MIPS VZ ASE is in use, providing full hardware assisted
6315 virtualization, including standard guest virtual memory segments.
6316 == ==========================================================================
6321 :Architectures: mips
6323 This capability, if KVM_CHECK_EXTENSION on the main kvm handle indicates that
6324 it is available, means that the trap & emulate implementation is available to
6325 run guest code in user mode, even if KVM_CAP_MIPS_VZ indicates that hardware
6326 assisted virtualisation is also available. KVM_VM_MIPS_TE (0) must be passed
6327 to KVM_CREATE_VM to create a VM which utilises it.
6329 If KVM_CHECK_EXTENSION on a kvm VM handle indicates that this capability is
6330 available, it means that the VM is using trap & emulate.
6332 8.7 KVM_CAP_MIPS_64BIT
6333 ----------------------
6335 :Architectures: mips
6337 This capability indicates the supported architecture type of the guest, i.e. the
6338 supported register and address width.
6340 The values returned when this capability is checked by KVM_CHECK_EXTENSION on a
6341 kvm VM handle correspond roughly to the CP0_Config.AT register field, and should
6342 be checked specifically against known values (see below). All other values are
6345 == ========================================================================
6346 0 MIPS32 or microMIPS32.
6347 Both registers and addresses are 32-bits wide.
6348 It will only be possible to run 32-bit guest code.
6350 1 MIPS64 or microMIPS64 with access only to 32-bit compatibility segments.
6351 Registers are 64-bits wide, but addresses are 32-bits wide.
6352 64-bit guest code may run but cannot access MIPS64 memory segments.
6353 It will also be possible to run 32-bit guest code.
6355 2 MIPS64 or microMIPS64 with access to all address segments.
6356 Both registers and addresses are 64-bits wide.
6357 It will be possible to run 64-bit or 32-bit guest code.
6358 == ========================================================================
6360 8.9 KVM_CAP_ARM_USER_IRQ
6361 ------------------------
6363 :Architectures: arm, arm64
6365 This capability, if KVM_CHECK_EXTENSION indicates that it is available, means
6366 that if userspace creates a VM without an in-kernel interrupt controller, it
6367 will be notified of changes to the output level of in-kernel emulated devices,
6368 which can generate virtual interrupts, presented to the VM.
6369 For such VMs, on every return to userspace, the kernel
6370 updates the vcpu's run->s.regs.device_irq_level field to represent the actual
6371 output level of the device.
6373 Whenever kvm detects a change in the device output level, kvm guarantees at
6374 least one return to userspace before running the VM. This exit could either
6375 be a KVM_EXIT_INTR or any other exit event, like KVM_EXIT_MMIO. This way,
6376 userspace can always sample the device output level and re-compute the state of
6377 the userspace interrupt controller. Userspace should always check the state
6378 of run->s.regs.device_irq_level on every kvm exit.
6379 The value in run->s.regs.device_irq_level can represent both level and edge
6380 triggered interrupt signals, depending on the device. Edge triggered interrupt
6381 signals will exit to userspace with the bit in run->s.regs.device_irq_level
6382 set exactly once per edge signal.
6384 The field run->s.regs.device_irq_level is available independent of
6385 run->kvm_valid_regs or run->kvm_dirty_regs bits.
6387 If KVM_CAP_ARM_USER_IRQ is supported, the KVM_CHECK_EXTENSION ioctl returns a
6388 number larger than 0 indicating the version of this capability is implemented
6389 and thereby which bits in run->s.regs.device_irq_level can signal values.
6391 Currently the following bits are defined for the device_irq_level bitmap::
6393 KVM_CAP_ARM_USER_IRQ >= 1:
6395 KVM_ARM_DEV_EL1_VTIMER - EL1 virtual timer
6396 KVM_ARM_DEV_EL1_PTIMER - EL1 physical timer
6397 KVM_ARM_DEV_PMU - ARM PMU overflow interrupt signal
6399 Future versions of kvm may implement additional events. These will get
6400 indicated by returning a higher number from KVM_CHECK_EXTENSION and will be
6403 8.10 KVM_CAP_PPC_SMT_POSSIBLE
6404 -----------------------------
6408 Querying this capability returns a bitmap indicating the possible
6409 virtual SMT modes that can be set using KVM_CAP_PPC_SMT. If bit N
6410 (counting from the right) is set, then a virtual SMT mode of 2^N is
6413 8.11 KVM_CAP_HYPERV_SYNIC2
6414 --------------------------
6418 This capability enables a newer version of Hyper-V Synthetic interrupt
6419 controller (SynIC). The only difference with KVM_CAP_HYPERV_SYNIC is that KVM
6420 doesn't clear SynIC message and event flags pages when they are enabled by
6421 writing to the respective MSRs.
6423 8.12 KVM_CAP_HYPERV_VP_INDEX
6424 ----------------------------
6428 This capability indicates that userspace can load HV_X64_MSR_VP_INDEX msr. Its
6429 value is used to denote the target vcpu for a SynIC interrupt. For
6430 compatibilty, KVM initializes this msr to KVM's internal vcpu index. When this
6431 capability is absent, userspace can still query this msr's value.
6433 8.13 KVM_CAP_S390_AIS_MIGRATION
6434 -------------------------------
6436 :Architectures: s390
6439 This capability indicates if the flic device will be able to get/set the
6440 AIS states for migration via the KVM_DEV_FLIC_AISM_ALL attribute and allows
6441 to discover this without having to create a flic device.
6443 8.14 KVM_CAP_S390_PSW
6444 ---------------------
6446 :Architectures: s390
6448 This capability indicates that the PSW is exposed via the kvm_run structure.
6450 8.15 KVM_CAP_S390_GMAP
6451 ----------------------
6453 :Architectures: s390
6455 This capability indicates that the user space memory used as guest mapping can
6456 be anywhere in the user memory address space, as long as the memory slots are
6457 aligned and sized to a segment (1MB) boundary.
6459 8.16 KVM_CAP_S390_COW
6460 ---------------------
6462 :Architectures: s390
6464 This capability indicates that the user space memory used as guest mapping can
6465 use copy-on-write semantics as well as dirty pages tracking via read-only page
6468 8.17 KVM_CAP_S390_BPB
6469 ---------------------
6471 :Architectures: s390
6473 This capability indicates that kvm will implement the interfaces to handle
6474 reset, migration and nested KVM for branch prediction blocking. The stfle
6475 facility 82 should not be provided to the guest without this capability.
6477 8.18 KVM_CAP_HYPERV_TLBFLUSH
6478 ----------------------------
6482 This capability indicates that KVM supports paravirtualized Hyper-V TLB Flush
6484 HvFlushVirtualAddressSpace, HvFlushVirtualAddressSpaceEx,
6485 HvFlushVirtualAddressList, HvFlushVirtualAddressListEx.
6487 8.19 KVM_CAP_ARM_INJECT_SERROR_ESR
6488 ----------------------------------
6490 :Architectures: arm, arm64
6492 This capability indicates that userspace can specify (via the
6493 KVM_SET_VCPU_EVENTS ioctl) the syndrome value reported to the guest when it
6494 takes a virtual SError interrupt exception.
6495 If KVM advertises this capability, userspace can only specify the ISS field for
6496 the ESR syndrome. Other parts of the ESR, such as the EC are generated by the
6497 CPU when the exception is taken. If this virtual SError is taken to EL1 using
6498 AArch64, this value will be reported in the ISS field of ESR_ELx.
6500 See KVM_CAP_VCPU_EVENTS for more details.
6502 8.20 KVM_CAP_HYPERV_SEND_IPI
6503 ----------------------------
6507 This capability indicates that KVM supports paravirtualized Hyper-V IPI send
6509 HvCallSendSyntheticClusterIpi, HvCallSendSyntheticClusterIpiEx.
6511 8.21 KVM_CAP_HYPERV_DIRECT_TLBFLUSH
6512 -----------------------------------
6516 This capability indicates that KVM running on top of Hyper-V hypervisor
6517 enables Direct TLB flush for its guests meaning that TLB flush
6518 hypercalls are handled by Level 0 hypervisor (Hyper-V) bypassing KVM.
6519 Due to the different ABI for hypercall parameters between Hyper-V and
6520 KVM, enabling this capability effectively disables all hypercall
6521 handling by KVM (as some KVM hypercall may be mistakenly treated as TLB
6522 flush hypercalls by Hyper-V) so userspace should disable KVM identification
6523 in CPUID and only exposes Hyper-V identification. In this case, guest
6524 thinks it's running on Hyper-V and only use Hyper-V hypercalls.
6526 8.22 KVM_CAP_S390_VCPU_RESETS
6527 -----------------------------
6529 :Architectures: s390
6531 This capability indicates that the KVM_S390_NORMAL_RESET and
6532 KVM_S390_CLEAR_RESET ioctls are available.
6534 8.23 KVM_CAP_S390_PROTECTED
6535 ---------------------------
6537 :Architectures: s390
6539 This capability indicates that the Ultravisor has been initialized and
6540 KVM can therefore start protected VMs.
6541 This capability governs the KVM_S390_PV_COMMAND ioctl and the
6542 KVM_MP_STATE_LOAD MP_STATE. KVM_SET_MP_STATE can fail for protected
6543 guests when the state change is invalid.
6545 8.24 KVM_CAP_STEAL_TIME
6546 -----------------------
6548 :Architectures: arm64, x86
6550 This capability indicates that KVM supports steal time accounting.
6551 When steal time accounting is supported it may be enabled with
6552 architecture-specific interfaces. This capability and the architecture-
6553 specific interfaces must be consistent, i.e. if one says the feature
6554 is supported, than the other should as well and vice versa. For arm64
6555 see Documentation/virt/kvm/devices/vcpu.rst "KVM_ARM_VCPU_PVTIME_CTRL".
6556 For x86 see Documentation/virt/kvm/msr.rst "MSR_KVM_STEAL_TIME".
6558 8.25 KVM_CAP_S390_DIAG318
6559 -------------------------
6561 :Architectures: s390
6563 This capability enables a guest to set information about its control program
6564 (i.e. guest kernel type and version). The information is helpful during
6565 system/firmware service events, providing additional data about the guest
6566 environments running on the machine.
6568 The information is associated with the DIAGNOSE 0x318 instruction, which sets
6569 an 8-byte value consisting of a one-byte Control Program Name Code (CPNC) and
6570 a 7-byte Control Program Version Code (CPVC). The CPNC determines what
6571 environment the control program is running in (e.g. Linux, z/VM...), and the
6572 CPVC is used for information specific to OS (e.g. Linux version, Linux
6575 If this capability is available, then the CPNC and CPVC can be synchronized
6576 between KVM and userspace via the sync regs mechanism (KVM_SYNC_DIAG318).
6578 8.26 KVM_CAP_X86_USER_SPACE_MSR
6579 -------------------------------
6583 This capability indicates that KVM supports deflection of MSR reads and
6584 writes to user space. It can be enabled on a VM level. If enabled, MSR
6585 accesses that would usually trigger a #GP by KVM into the guest will
6586 instead get bounced to user space through the KVM_EXIT_X86_RDMSR and
6587 KVM_EXIT_X86_WRMSR exit notifications.
6589 8.27 KVM_X86_SET_MSR_FILTER
6590 ---------------------------
6594 This capability indicates that KVM supports that accesses to user defined MSRs
6595 may be rejected. With this capability exposed, KVM exports new VM ioctl
6596 KVM_X86_SET_MSR_FILTER which user space can call to specify bitmaps of MSR
6597 ranges that KVM should reject access to.
6599 In combination with KVM_CAP_X86_USER_SPACE_MSR, this allows user space to
6600 trap and emulate MSRs that are outside of the scope of KVM as well as
6601 limit the attack surface on KVM's MSR emulation code.
6603 8.28 KVM_CAP_ENFORCE_PV_CPUID
6604 -----------------------------
6608 When enabled, KVM will disable paravirtual features provided to the
6609 guest according to the bits in the KVM_CPUID_FEATURES CPUID leaf
6610 (0x40000001). Otherwise, a guest may use the paravirtual features
6611 regardless of what has actually been exposed through the CPUID leaf.
6613 8.29 KVM_CAP_DIRTY_LOG_RING
6614 ---------------------------
6617 :Parameters: args[0] - size of the dirty log ring
6619 KVM is capable of tracking dirty memory using ring buffers that are
6620 mmaped into userspace; there is one dirty ring per vcpu.
6622 The dirty ring is available to userspace as an array of
6623 ``struct kvm_dirty_gfn``. Each dirty entry it's defined as::
6625 struct kvm_dirty_gfn {
6627 __u32 slot; /* as_id | slot_id */
6631 The following values are defined for the flags field to define the
6632 current state of the entry::
6634 #define KVM_DIRTY_GFN_F_DIRTY BIT(0)
6635 #define KVM_DIRTY_GFN_F_RESET BIT(1)
6636 #define KVM_DIRTY_GFN_F_MASK 0x3
6638 Userspace should call KVM_ENABLE_CAP ioctl right after KVM_CREATE_VM
6639 ioctl to enable this capability for the new guest and set the size of
6640 the rings. Enabling the capability is only allowed before creating any
6641 vCPU, and the size of the ring must be a power of two. The larger the
6642 ring buffer, the less likely the ring is full and the VM is forced to
6643 exit to userspace. The optimal size depends on the workload, but it is
6644 recommended that it be at least 64 KiB (4096 entries).
6646 Just like for dirty page bitmaps, the buffer tracks writes to
6647 all user memory regions for which the KVM_MEM_LOG_DIRTY_PAGES flag was
6648 set in KVM_SET_USER_MEMORY_REGION. Once a memory region is registered
6649 with the flag set, userspace can start harvesting dirty pages from the
6652 An entry in the ring buffer can be unused (flag bits ``00``),
6653 dirty (flag bits ``01``) or harvested (flag bits ``1X``). The
6654 state machine for the entry is as follows::
6656 dirtied harvested reset
6657 00 -----------> 01 -------------> 1X -------+
6660 +------------------------------------------+
6662 To harvest the dirty pages, userspace accesses the mmaped ring buffer
6663 to read the dirty GFNs. If the flags has the DIRTY bit set (at this stage
6664 the RESET bit must be cleared), then it means this GFN is a dirty GFN.
6665 The userspace should harvest this GFN and mark the flags from state
6666 ``01b`` to ``1Xb`` (bit 0 will be ignored by KVM, but bit 1 must be set
6667 to show that this GFN is harvested and waiting for a reset), and move
6668 on to the next GFN. The userspace should continue to do this until the
6669 flags of a GFN have the DIRTY bit cleared, meaning that it has harvested
6670 all the dirty GFNs that were available.
6672 It's not necessary for userspace to harvest the all dirty GFNs at once.
6673 However it must collect the dirty GFNs in sequence, i.e., the userspace
6674 program cannot skip one dirty GFN to collect the one next to it.
6676 After processing one or more entries in the ring buffer, userspace
6677 calls the VM ioctl KVM_RESET_DIRTY_RINGS to notify the kernel about
6678 it, so that the kernel will reprotect those collected GFNs.
6679 Therefore, the ioctl must be called *before* reading the content of
6682 The dirty ring can get full. When it happens, the KVM_RUN of the
6683 vcpu will return with exit reason KVM_EXIT_DIRTY_LOG_FULL.
6685 The dirty ring interface has a major difference comparing to the
6686 KVM_GET_DIRTY_LOG interface in that, when reading the dirty ring from
6687 userspace, it's still possible that the kernel has not yet flushed the
6688 processor's dirty page buffers into the kernel buffer (with dirty bitmaps, the
6689 flushing is done by the KVM_GET_DIRTY_LOG ioctl). To achieve that, one
6690 needs to kick the vcpu out of KVM_RUN using a signal. The resulting
6691 vmexit ensures that all dirty GFNs are flushed to the dirty rings.
6693 NOTE: the capability KVM_CAP_DIRTY_LOG_RING and the corresponding
6694 ioctl KVM_RESET_DIRTY_RINGS are mutual exclusive to the existing ioctls
6695 KVM_GET_DIRTY_LOG and KVM_CLEAR_DIRTY_LOG. After enabling
6696 KVM_CAP_DIRTY_LOG_RING with an acceptable dirty ring size, the virtual
6697 machine will switch to ring-buffer dirty page tracking and further
6698 KVM_GET_DIRTY_LOG or KVM_CLEAR_DIRTY_LOG ioctls will fail.
6700 8.30 KVM_CAP_XEN_HVM
6701 --------------------
6705 This capability indicates the features that Xen supports for hosting Xen
6706 PVHVM guests. Valid flags are::
6708 #define KVM_XEN_HVM_CONFIG_HYPERCALL_MSR (1 << 0)
6709 #define KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL (1 << 1)
6710 #define KVM_XEN_HVM_CONFIG_SHARED_INFO (1 << 2)
6711 #define KVM_XEN_HVM_CONFIG_RUNSTATE (1 << 2)
6713 The KVM_XEN_HVM_CONFIG_HYPERCALL_MSR flag indicates that the KVM_XEN_HVM_CONFIG
6714 ioctl is available, for the guest to set its hypercall page.
6716 If KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL is also set, the same flag may also be
6717 provided in the flags to KVM_XEN_HVM_CONFIG, without providing hypercall page
6718 contents, to request that KVM generate hypercall page content automatically
6719 and also enable interception of guest hypercalls with KVM_EXIT_XEN.
6721 The KVM_XEN_HVM_CONFIG_SHARED_INFO flag indicates the availability of the
6722 KVM_XEN_HVM_SET_ATTR, KVM_XEN_HVM_GET_ATTR, KVM_XEN_VCPU_SET_ATTR and
6723 KVM_XEN_VCPU_GET_ATTR ioctls, as well as the delivery of exception vectors
6724 for event channel upcalls when the evtchn_upcall_pending field of a vcpu's
6727 The KVM_XEN_HVM_CONFIG_RUNSTATE flag indicates that the runstate-related
6728 features KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR/_CURRENT/_DATA/_ADJUST are
6729 supported by the KVM_XEN_VCPU_SET_ATTR/KVM_XEN_VCPU_GET_ATTR ioctls.