Add a new x86 VM type, KVM_X86_SW_PROTECTED_VM, to serve as a development
and testing vehicle for Confidential (CoCo) VMs, and potentially to even
become a "real" product in the distant future, e.g. a la pKVM.
The private memory support in KVM x86 is aimed at AMD's SEV-SNP and
Intel's TDX, but those technologies are extremely complex (understatement),
difficult to debug, don't support running as nested guests, and require
hardware that's isn't universally accessible. I.e. relying SEV-SNP or TDX
for maintaining guest private memory isn't a realistic option.
At the very least, KVM_X86_SW_PROTECTED_VM will enable a variety of
selftests for guest_memfd and private memory support without requiring
unique hardware.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <
20231027182217.
3615211-24-seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The new VM has no virtual cpus and no memory.
You probably want to use 0 as machine type.
+X86:
+^^^^
+
+Supported X86 VM types can be queried via KVM_CAP_VM_TYPES.
+
+S390:
+^^^^^
+
In order to create user controlled virtual machines on S390, check
KVM_CAP_S390_UCONTROL and use the flag KVM_VM_S390_UCONTROL as
privileged user (CAP_SYS_ADMIN).
+MIPS:
+^^^^^
+
+To use hardware assisted virtualization on MIPS (VZ ASE) rather than
+the default trap & emulate implementation (which changes the virtual
+memory layout to fit in user mode), check KVM_CAP_MIPS_VZ and use the
+flag KVM_VM_MIPS_VZ.
+
+ARM64:
+^^^^^^
+
On arm64, the physical address size for a VM (IPA Size limit) is limited
to 40bits by default. The limit can be configured if the host supports the
extension KVM_CAP_ARM_VM_IPA_SIZE. When supported, use
64-bit bitmap (each bit describing a block size). The default value is
0, to disable the eager page splitting.
+8.41 KVM_CAP_VM_TYPES
+---------------------
+
+:Capability: KVM_CAP_MEMORY_ATTRIBUTES
+:Architectures: x86
+:Type: system ioctl
+
+This capability returns a bitmap of support VM types. The 1-setting of bit @n
+means the VM type with value @n is supported. Possible values of @n are::
+
+ #define KVM_X86_DEFAULT_VM 0
+ #define KVM_X86_SW_PROTECTED_VM 1
+
9. Known KVM API problems
=========================
};
struct kvm_arch {
+ unsigned long vm_type;
unsigned long n_used_mmu_pages;
unsigned long n_requested_mmu_pages;
unsigned long n_max_mmu_pages;
void kvm_configure_mmu(bool enable_tdp, int tdp_forced_root_level,
int tdp_max_root_level, int tdp_huge_page_level);
+#ifdef CONFIG_KVM_PRIVATE_MEM
+#define kvm_arch_has_private_mem(kvm) ((kvm)->arch.vm_type != KVM_X86_DEFAULT_VM)
+#else
+#define kvm_arch_has_private_mem(kvm) false
+#endif
+
static inline u16 kvm_read_ldt(void)
{
u16 ldt;
#define HF_SMM_INSIDE_NMI_MASK (1 << 2)
# define KVM_MAX_NR_ADDRESS_SPACES 2
+/* SMM is currently unsupported for guests with private memory. */
+# define kvm_arch_nr_memslot_as_ids(kvm) (kvm_arch_has_private_mem(kvm) ? 1 : 2)
# define kvm_arch_vcpu_memslots_id(vcpu) ((vcpu)->arch.hflags & HF_SMM_MASK ? 1 : 0)
# define kvm_memslots_for_spte_role(kvm, role) __kvm_memslots(kvm, (role).smm)
-
-static inline int kvm_arch_nr_memslot_as_ids(struct kvm *kvm)
-{
- return KVM_MAX_NR_ADDRESS_SPACES;
-}
-
#else
# define kvm_memslots_for_spte_role(kvm, role) __kvm_memslots(kvm, 0)
#endif
/* x86-specific KVM_EXIT_HYPERCALL flags. */
#define KVM_EXIT_HYPERCALL_LONG_MODE BIT(0)
+#define KVM_X86_DEFAULT_VM 0
+#define KVM_X86_SW_PROTECTED_VM 1
+
#endif /* _ASM_X86_KVM_H */
If in doubt, say "N".
+config KVM_SW_PROTECTED_VM
+ bool "Enable support for KVM software-protected VMs"
+ depends on EXPERT
+ depends on X86_64
+ select KVM_GENERIC_PRIVATE_MEM
+ help
+ Enable support for KVM software-protected VMs. Currently "protected"
+ means the VM can be backed with memory provided by
+ KVM_CREATE_GUEST_MEMFD.
+
+ If unsure, say "N".
+
config KVM_INTEL
tristate "KVM for Intel (and compatible) processors support"
depends on KVM && IA32_FEAT_CTL
.max_level = KVM_MAX_HUGEPAGE_LEVEL,
.req_level = PG_LEVEL_4K,
.goal_level = PG_LEVEL_4K,
+ .is_private = kvm_mem_is_private(vcpu->kvm, cr2_or_gpa >> PAGE_SHIFT),
};
int r;
return 0;
}
+static bool kvm_is_vm_type_supported(unsigned long type)
+{
+ return type == KVM_X86_DEFAULT_VM ||
+ (type == KVM_X86_SW_PROTECTED_VM &&
+ IS_ENABLED(CONFIG_KVM_SW_PROTECTED_VM) && tdp_enabled);
+}
+
int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
{
int r = 0;
case KVM_CAP_X86_NOTIFY_VMEXIT:
r = kvm_caps.has_notify_vmexit;
break;
+ case KVM_CAP_VM_TYPES:
+ r = BIT(KVM_X86_DEFAULT_VM);
+ if (kvm_is_vm_type_supported(KVM_X86_SW_PROTECTED_VM))
+ r |= BIT(KVM_X86_SW_PROTECTED_VM);
+ break;
default:
break;
}
int ret;
unsigned long flags;
- if (type)
+ if (!kvm_is_vm_type_supported(type))
return -EINVAL;
+ kvm->arch.vm_type = type;
+
ret = kvm_page_track_init(kvm);
if (ret)
goto out;
#define KVM_CAP_MEMORY_FAULT_INFO 232
#define KVM_CAP_MEMORY_ATTRIBUTES 233
#define KVM_CAP_GUEST_MEMFD 234
+#define KVM_CAP_VM_TYPES 235
#ifdef KVM_CAP_IRQ_ROUTING
config KVM_PRIVATE_MEM
select XARRAY_MULTI
bool
+
+config KVM_GENERIC_PRIVATE_MEM
+ select KVM_GENERIC_MEMORY_ATTRIBUTES
+ select KVM_PRIVATE_MEM
+ bool