1 // SPDX-License-Identifier: GPL-2.0-only
3 * HyperV Detection code.
5 * Copyright (C) 2010, Novell, Inc.
6 * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
9 #include <linux/types.h>
10 #include <linux/time.h>
11 #include <linux/clocksource.h>
12 #include <linux/init.h>
13 #include <linux/export.h>
14 #include <linux/hardirq.h>
15 #include <linux/efi.h>
16 #include <linux/interrupt.h>
17 #include <linux/irq.h>
18 #include <linux/kexec.h>
19 #include <linux/i8253.h>
20 #include <linux/panic_notifier.h>
21 #include <linux/random.h>
22 #include <asm/processor.h>
23 #include <asm/hypervisor.h>
24 #include <asm/hyperv-tlfs.h>
25 #include <asm/mshyperv.h>
27 #include <asm/idtentry.h>
28 #include <asm/irq_regs.h>
29 #include <asm/i8259.h>
31 #include <asm/timer.h>
32 #include <asm/reboot.h>
34 #include <clocksource/hyperv_timer.h>
37 /* Is Linux running as the root partition? */
38 bool hv_root_partition;
39 EXPORT_SYMBOL_GPL(hv_root_partition);
41 struct ms_hyperv_info ms_hyperv;
42 EXPORT_SYMBOL_GPL(ms_hyperv);
44 #if IS_ENABLED(CONFIG_HYPERV)
45 static void (*vmbus_handler)(void);
46 static void (*hv_stimer0_handler)(void);
47 static void (*hv_kexec_handler)(void);
48 static void (*hv_crash_handler)(struct pt_regs *regs);
50 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_callback)
52 struct pt_regs *old_regs = set_irq_regs(regs);
54 inc_irq_stat(irq_hv_callback_count);
58 if (ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED)
61 set_irq_regs(old_regs);
64 void hv_setup_vmbus_handler(void (*handler)(void))
66 vmbus_handler = handler;
68 EXPORT_SYMBOL_GPL(hv_setup_vmbus_handler);
70 void hv_remove_vmbus_handler(void)
72 /* We have no way to deallocate the interrupt gate */
75 EXPORT_SYMBOL_GPL(hv_remove_vmbus_handler);
78 * Routines to do per-architecture handling of stimer0
79 * interrupts when in Direct Mode
81 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_stimer0)
83 struct pt_regs *old_regs = set_irq_regs(regs);
85 inc_irq_stat(hyperv_stimer0_count);
86 if (hv_stimer0_handler)
88 add_interrupt_randomness(HYPERV_STIMER0_VECTOR, 0);
91 set_irq_regs(old_regs);
94 /* For x86/x64, override weak placeholders in hyperv_timer.c */
95 void hv_setup_stimer0_handler(void (*handler)(void))
97 hv_stimer0_handler = handler;
100 void hv_remove_stimer0_handler(void)
102 /* We have no way to deallocate the interrupt gate */
103 hv_stimer0_handler = NULL;
106 void hv_setup_kexec_handler(void (*handler)(void))
108 hv_kexec_handler = handler;
110 EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
112 void hv_remove_kexec_handler(void)
114 hv_kexec_handler = NULL;
116 EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
118 void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
120 hv_crash_handler = handler;
122 EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
124 void hv_remove_crash_handler(void)
126 hv_crash_handler = NULL;
128 EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
130 #ifdef CONFIG_KEXEC_CORE
131 static void hv_machine_shutdown(void)
133 if (kexec_in_progress && hv_kexec_handler)
137 * Call hv_cpu_die() on all the CPUs, otherwise later the hypervisor
138 * corrupts the old VP Assist Pages and can crash the kexec kernel.
140 if (kexec_in_progress && hyperv_init_cpuhp > 0)
141 cpuhp_remove_state(hyperv_init_cpuhp);
143 /* The function calls stop_other_cpus(). */
144 native_machine_shutdown();
146 /* Disable the hypercall page when there is only 1 active CPU. */
147 if (kexec_in_progress)
151 static void hv_machine_crash_shutdown(struct pt_regs *regs)
153 if (hv_crash_handler)
154 hv_crash_handler(regs);
156 /* The function calls crash_smp_send_stop(). */
157 native_machine_crash_shutdown(regs);
159 /* Disable the hypercall page when there is only 1 active CPU. */
162 #endif /* CONFIG_KEXEC_CORE */
163 #endif /* CONFIG_HYPERV */
165 static uint32_t __init ms_hyperv_platform(void)
168 u32 hyp_signature[3];
170 if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
173 cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
174 &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
176 if (eax >= HYPERV_CPUID_MIN &&
177 eax <= HYPERV_CPUID_MAX &&
178 !memcmp("Microsoft Hv", hyp_signature, 12))
179 return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
184 static unsigned char hv_get_nmi_reason(void)
189 #ifdef CONFIG_X86_LOCAL_APIC
191 * Prior to WS2016 Debug-VM sends NMIs to all CPUs which makes
192 * it difficult to process CHANNELMSG_UNLOAD in case of crash. Handle
193 * unknown NMI on the first CPU which gets it.
195 static int hv_nmi_unknown(unsigned int val, struct pt_regs *regs)
197 static atomic_t nmi_cpu = ATOMIC_INIT(-1);
199 if (!unknown_nmi_panic)
202 if (atomic_cmpxchg(&nmi_cpu, -1, raw_smp_processor_id()) != -1)
209 static unsigned long hv_get_tsc_khz(void)
213 rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
218 #if defined(CONFIG_SMP) && IS_ENABLED(CONFIG_HYPERV)
219 static void __init hv_smp_prepare_boot_cpu(void)
221 native_smp_prepare_boot_cpu();
222 #if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS)
227 static void __init hv_smp_prepare_cpus(unsigned int max_cpus)
234 native_smp_prepare_cpus(max_cpus);
237 for_each_present_cpu(i) {
240 ret = hv_call_add_logical_proc(numa_cpu_node(i), i, cpu_physical_id(i));
244 for_each_present_cpu(i) {
247 ret = hv_call_create_vp(numa_cpu_node(i), hv_current_partition_id, i, i);
254 static void __init ms_hyperv_init_platform(void)
256 int hv_max_functions_eax;
257 int hv_host_info_eax;
258 int hv_host_info_ebx;
259 int hv_host_info_ecx;
260 int hv_host_info_edx;
262 #ifdef CONFIG_PARAVIRT
263 pv_info.name = "Hyper-V";
267 * Extract the features and hints
269 ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
270 ms_hyperv.priv_high = cpuid_ebx(HYPERV_CPUID_FEATURES);
271 ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
272 ms_hyperv.hints = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
274 hv_max_functions_eax = cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS);
276 pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, hints 0x%x, misc 0x%x\n",
277 ms_hyperv.features, ms_hyperv.priv_high, ms_hyperv.hints,
278 ms_hyperv.misc_features);
280 ms_hyperv.max_vp_index = cpuid_eax(HYPERV_CPUID_IMPLEMENT_LIMITS);
281 ms_hyperv.max_lp_index = cpuid_ebx(HYPERV_CPUID_IMPLEMENT_LIMITS);
283 pr_debug("Hyper-V: max %u virtual processors, %u logical processors\n",
284 ms_hyperv.max_vp_index, ms_hyperv.max_lp_index);
287 * Check CPU management privilege.
289 * To mirror what Windows does we should extract CPU management
290 * features and use the ReservedIdentityBit to detect if Linux is the
291 * root partition. But that requires negotiating CPU management
292 * interface (a process to be finalized).
294 * For now, use the privilege flag as the indicator for running as
297 if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_CPU_MANAGEMENT) {
298 hv_root_partition = true;
299 pr_info("Hyper-V: running as root partition\n");
303 * Extract host information.
305 if (hv_max_functions_eax >= HYPERV_CPUID_VERSION) {
306 hv_host_info_eax = cpuid_eax(HYPERV_CPUID_VERSION);
307 hv_host_info_ebx = cpuid_ebx(HYPERV_CPUID_VERSION);
308 hv_host_info_ecx = cpuid_ecx(HYPERV_CPUID_VERSION);
309 hv_host_info_edx = cpuid_edx(HYPERV_CPUID_VERSION);
311 pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d\n",
312 hv_host_info_eax, hv_host_info_ebx >> 16,
313 hv_host_info_ebx & 0xFFFF, hv_host_info_ecx,
314 hv_host_info_edx >> 24, hv_host_info_edx & 0xFFFFFF);
317 if (ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
318 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
319 x86_platform.calibrate_tsc = hv_get_tsc_khz;
320 x86_platform.calibrate_cpu = hv_get_tsc_khz;
323 if (ms_hyperv.priv_high & HV_ISOLATION) {
324 ms_hyperv.isolation_config_a = cpuid_eax(HYPERV_CPUID_ISOLATION_CONFIG);
325 ms_hyperv.isolation_config_b = cpuid_ebx(HYPERV_CPUID_ISOLATION_CONFIG);
327 pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
328 ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
331 if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
332 ms_hyperv.nested_features =
333 cpuid_eax(HYPERV_CPUID_NESTED_FEATURES);
334 pr_info("Hyper-V: Nested features: 0x%x\n",
335 ms_hyperv.nested_features);
339 * Hyper-V expects to get crash register data or kmsg when
340 * crash enlightment is available and system crashes. Set
341 * crash_kexec_post_notifiers to be true to make sure that
342 * calling crash enlightment interface before running kdump
345 if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE)
346 crash_kexec_post_notifiers = true;
348 #ifdef CONFIG_X86_LOCAL_APIC
349 if (ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
350 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
352 * Get the APIC frequency.
354 u64 hv_lapic_frequency;
356 rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
357 hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
358 lapic_timer_period = hv_lapic_frequency;
359 pr_info("Hyper-V: LAPIC Timer Frequency: %#x\n",
363 register_nmi_handler(NMI_UNKNOWN, hv_nmi_unknown, NMI_FLAG_FIRST,
367 #ifdef CONFIG_X86_IO_APIC
371 #if IS_ENABLED(CONFIG_HYPERV) && defined(CONFIG_KEXEC_CORE)
372 machine_ops.shutdown = hv_machine_shutdown;
373 machine_ops.crash_shutdown = hv_machine_crash_shutdown;
375 if (ms_hyperv.features & HV_ACCESS_TSC_INVARIANT) {
376 wrmsrl(HV_X64_MSR_TSC_INVARIANT_CONTROL, 0x1);
377 setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
379 mark_tsc_unstable("running on Hyper-V");
383 * Generation 2 instances don't support reading the NMI status from
386 if (efi_enabled(EFI_BOOT))
387 x86_platform.get_nmi_reason = hv_get_nmi_reason;
390 * Hyper-V VMs have a PIT emulation quirk such that zeroing the
391 * counter register during PIT shutdown restarts the PIT. So it
392 * continues to interrupt @18.2 HZ. Setting i8253_clear_counter
393 * to false tells pit_shutdown() not to zero the counter so that
394 * the PIT really is shutdown. Generation 2 VMs don't have a PIT,
395 * and setting this value has no effect.
397 i8253_clear_counter_on_shutdown = false;
399 #if IS_ENABLED(CONFIG_HYPERV)
401 * Setup the hook to get control post apic initialization.
403 x86_platform.apic_post_init = hyperv_init;
404 hyperv_setup_mmu_ops();
405 /* Setup the IDT for hypervisor callback */
406 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_hyperv_callback);
408 /* Setup the IDT for reenlightenment notifications */
409 if (ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT) {
410 alloc_intr_gate(HYPERV_REENLIGHTENMENT_VECTOR,
411 asm_sysvec_hyperv_reenlightenment);
414 /* Setup the IDT for stimer0 */
415 if (ms_hyperv.misc_features & HV_STIMER_DIRECT_MODE_AVAILABLE) {
416 alloc_intr_gate(HYPERV_STIMER0_VECTOR,
417 asm_sysvec_hyperv_stimer0);
421 smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu;
422 if (hv_root_partition)
423 smp_ops.smp_prepare_cpus = hv_smp_prepare_cpus;
427 * Hyper-V doesn't provide irq remapping for IO-APIC. To enable x2apic,
428 * set x2apic destination mode to physical mode when x2apic is available
429 * and Hyper-V IOMMU driver makes sure cpus assigned with IO-APIC irqs
430 * have 8-bit APIC id.
432 # ifdef CONFIG_X86_X2APIC
433 if (x2apic_supported())
437 /* Register Hyper-V specific clocksource */
438 hv_init_clocksource();
442 static bool __init ms_hyperv_x2apic_available(void)
444 return x2apic_supported();
448 * If ms_hyperv_msi_ext_dest_id() returns true, hyperv_prepare_irq_remapping()
449 * returns -ENODEV and the Hyper-V IOMMU driver is not used; instead, the
450 * generic support of the 15-bit APIC ID is used: see __irq_msi_compose_msg().
452 * Note: for a VM on Hyper-V, the I/O-APIC is the only device which
453 * (logically) generates MSIs directly to the system APIC irq domain.
454 * There is no HPET, and PCI MSI/MSI-X interrupts are remapped by the
455 * pci-hyperv host bridge.
457 static bool __init ms_hyperv_msi_ext_dest_id(void)
461 eax = cpuid_eax(HYPERV_CPUID_VIRT_STACK_INTERFACE);
462 if (eax != HYPERV_VS_INTERFACE_EAX_SIGNATURE)
465 eax = cpuid_eax(HYPERV_CPUID_VIRT_STACK_PROPERTIES);
466 return eax & HYPERV_VS_PROPERTIES_EAX_EXTENDED_IOAPIC_RTE;
469 const __initconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
470 .name = "Microsoft Hyper-V",
471 .detect = ms_hyperv_platform,
472 .type = X86_HYPER_MS_HYPERV,
473 .init.x2apic_available = ms_hyperv_x2apic_available,
474 .init.msi_ext_dest_id = ms_hyperv_msi_ext_dest_id,
475 .init.init_platform = ms_hyperv_init_platform,