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/random.h>
21 #include <asm/processor.h>
22 #include <asm/hypervisor.h>
23 #include <asm/hyperv-tlfs.h>
24 #include <asm/mshyperv.h>
26 #include <asm/idtentry.h>
27 #include <asm/irq_regs.h>
28 #include <asm/i8259.h>
30 #include <asm/timer.h>
31 #include <asm/reboot.h>
33 #include <clocksource/hyperv_timer.h>
36 /* Is Linux running as the root partition? */
37 bool hv_root_partition;
38 EXPORT_SYMBOL_GPL(hv_root_partition);
40 struct ms_hyperv_info ms_hyperv;
41 EXPORT_SYMBOL_GPL(ms_hyperv);
43 #if IS_ENABLED(CONFIG_HYPERV)
44 static void (*vmbus_handler)(void);
45 static void (*hv_stimer0_handler)(void);
46 static void (*hv_kexec_handler)(void);
47 static void (*hv_crash_handler)(struct pt_regs *regs);
49 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_callback)
51 struct pt_regs *old_regs = set_irq_regs(regs);
53 inc_irq_stat(irq_hv_callback_count);
57 if (ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED)
60 set_irq_regs(old_regs);
63 void hv_setup_vmbus_handler(void (*handler)(void))
65 vmbus_handler = handler;
67 EXPORT_SYMBOL_GPL(hv_setup_vmbus_handler);
69 void hv_remove_vmbus_handler(void)
71 /* We have no way to deallocate the interrupt gate */
74 EXPORT_SYMBOL_GPL(hv_remove_vmbus_handler);
77 * Routines to do per-architecture handling of stimer0
78 * interrupts when in Direct Mode
80 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_stimer0)
82 struct pt_regs *old_regs = set_irq_regs(regs);
84 inc_irq_stat(hyperv_stimer0_count);
85 if (hv_stimer0_handler)
87 add_interrupt_randomness(HYPERV_STIMER0_VECTOR, 0);
90 set_irq_regs(old_regs);
93 /* For x86/x64, override weak placeholders in hyperv_timer.c */
94 void hv_setup_stimer0_handler(void (*handler)(void))
96 hv_stimer0_handler = handler;
99 void hv_remove_stimer0_handler(void)
101 /* We have no way to deallocate the interrupt gate */
102 hv_stimer0_handler = NULL;
105 void hv_setup_kexec_handler(void (*handler)(void))
107 hv_kexec_handler = handler;
109 EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
111 void hv_remove_kexec_handler(void)
113 hv_kexec_handler = NULL;
115 EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
117 void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
119 hv_crash_handler = handler;
121 EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
123 void hv_remove_crash_handler(void)
125 hv_crash_handler = NULL;
127 EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
129 #ifdef CONFIG_KEXEC_CORE
130 static void hv_machine_shutdown(void)
132 if (kexec_in_progress && hv_kexec_handler)
136 * Call hv_cpu_die() on all the CPUs, otherwise later the hypervisor
137 * corrupts the old VP Assist Pages and can crash the kexec kernel.
139 if (kexec_in_progress && hyperv_init_cpuhp > 0)
140 cpuhp_remove_state(hyperv_init_cpuhp);
142 /* The function calls stop_other_cpus(). */
143 native_machine_shutdown();
145 /* Disable the hypercall page when there is only 1 active CPU. */
146 if (kexec_in_progress)
150 static void hv_machine_crash_shutdown(struct pt_regs *regs)
152 if (hv_crash_handler)
153 hv_crash_handler(regs);
155 /* The function calls crash_smp_send_stop(). */
156 native_machine_crash_shutdown(regs);
158 /* Disable the hypercall page when there is only 1 active CPU. */
161 #endif /* CONFIG_KEXEC_CORE */
162 #endif /* CONFIG_HYPERV */
164 static uint32_t __init ms_hyperv_platform(void)
167 u32 hyp_signature[3];
169 if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
172 cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
173 &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
175 if (eax >= HYPERV_CPUID_MIN &&
176 eax <= HYPERV_CPUID_MAX &&
177 !memcmp("Microsoft Hv", hyp_signature, 12))
178 return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
183 static unsigned char hv_get_nmi_reason(void)
188 #ifdef CONFIG_X86_LOCAL_APIC
190 * Prior to WS2016 Debug-VM sends NMIs to all CPUs which makes
191 * it difficult to process CHANNELMSG_UNLOAD in case of crash. Handle
192 * unknown NMI on the first CPU which gets it.
194 static int hv_nmi_unknown(unsigned int val, struct pt_regs *regs)
196 static atomic_t nmi_cpu = ATOMIC_INIT(-1);
198 if (!unknown_nmi_panic)
201 if (atomic_cmpxchg(&nmi_cpu, -1, raw_smp_processor_id()) != -1)
208 static unsigned long hv_get_tsc_khz(void)
212 rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
217 #if defined(CONFIG_SMP) && IS_ENABLED(CONFIG_HYPERV)
218 static void __init hv_smp_prepare_boot_cpu(void)
220 native_smp_prepare_boot_cpu();
221 #if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS)
226 static void __init hv_smp_prepare_cpus(unsigned int max_cpus)
233 native_smp_prepare_cpus(max_cpus);
236 for_each_present_cpu(i) {
239 ret = hv_call_add_logical_proc(numa_cpu_node(i), i, cpu_physical_id(i));
243 for_each_present_cpu(i) {
246 ret = hv_call_create_vp(numa_cpu_node(i), hv_current_partition_id, i, i);
253 static void __init ms_hyperv_init_platform(void)
255 int hv_host_info_eax;
256 int hv_host_info_ebx;
257 int hv_host_info_ecx;
258 int hv_host_info_edx;
260 #ifdef CONFIG_PARAVIRT
261 pv_info.name = "Hyper-V";
265 * Extract the features and hints
267 ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
268 ms_hyperv.priv_high = cpuid_ebx(HYPERV_CPUID_FEATURES);
269 ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
270 ms_hyperv.hints = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
272 pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, hints 0x%x, misc 0x%x\n",
273 ms_hyperv.features, ms_hyperv.priv_high, ms_hyperv.hints,
274 ms_hyperv.misc_features);
276 ms_hyperv.max_vp_index = cpuid_eax(HYPERV_CPUID_IMPLEMENT_LIMITS);
277 ms_hyperv.max_lp_index = cpuid_ebx(HYPERV_CPUID_IMPLEMENT_LIMITS);
279 pr_debug("Hyper-V: max %u virtual processors, %u logical processors\n",
280 ms_hyperv.max_vp_index, ms_hyperv.max_lp_index);
283 * Check CPU management privilege.
285 * To mirror what Windows does we should extract CPU management
286 * features and use the ReservedIdentityBit to detect if Linux is the
287 * root partition. But that requires negotiating CPU management
288 * interface (a process to be finalized).
290 * For now, use the privilege flag as the indicator for running as
293 if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_CPU_MANAGEMENT) {
294 hv_root_partition = true;
295 pr_info("Hyper-V: running as root partition\n");
299 * Extract host information.
301 if (cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS) >=
302 HYPERV_CPUID_VERSION) {
303 hv_host_info_eax = cpuid_eax(HYPERV_CPUID_VERSION);
304 hv_host_info_ebx = cpuid_ebx(HYPERV_CPUID_VERSION);
305 hv_host_info_ecx = cpuid_ecx(HYPERV_CPUID_VERSION);
306 hv_host_info_edx = cpuid_edx(HYPERV_CPUID_VERSION);
308 pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d\n",
309 hv_host_info_eax, hv_host_info_ebx >> 16,
310 hv_host_info_ebx & 0xFFFF, hv_host_info_ecx,
311 hv_host_info_edx >> 24, hv_host_info_edx & 0xFFFFFF);
314 if (ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
315 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
316 x86_platform.calibrate_tsc = hv_get_tsc_khz;
317 x86_platform.calibrate_cpu = hv_get_tsc_khz;
320 if (ms_hyperv.priv_high & HV_ISOLATION) {
321 ms_hyperv.isolation_config_a = cpuid_eax(HYPERV_CPUID_ISOLATION_CONFIG);
322 ms_hyperv.isolation_config_b = cpuid_ebx(HYPERV_CPUID_ISOLATION_CONFIG);
324 pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
325 ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
328 if (ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) {
329 ms_hyperv.nested_features =
330 cpuid_eax(HYPERV_CPUID_NESTED_FEATURES);
334 * Hyper-V expects to get crash register data or kmsg when
335 * crash enlightment is available and system crashes. Set
336 * crash_kexec_post_notifiers to be true to make sure that
337 * calling crash enlightment interface before running kdump
340 if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE)
341 crash_kexec_post_notifiers = true;
343 #ifdef CONFIG_X86_LOCAL_APIC
344 if (ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
345 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
347 * Get the APIC frequency.
349 u64 hv_lapic_frequency;
351 rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
352 hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
353 lapic_timer_period = hv_lapic_frequency;
354 pr_info("Hyper-V: LAPIC Timer Frequency: %#x\n",
358 register_nmi_handler(NMI_UNKNOWN, hv_nmi_unknown, NMI_FLAG_FIRST,
362 #ifdef CONFIG_X86_IO_APIC
366 #if IS_ENABLED(CONFIG_HYPERV) && defined(CONFIG_KEXEC_CORE)
367 machine_ops.shutdown = hv_machine_shutdown;
368 machine_ops.crash_shutdown = hv_machine_crash_shutdown;
370 if (ms_hyperv.features & HV_ACCESS_TSC_INVARIANT) {
371 wrmsrl(HV_X64_MSR_TSC_INVARIANT_CONTROL, 0x1);
372 setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
374 mark_tsc_unstable("running on Hyper-V");
378 * Generation 2 instances don't support reading the NMI status from
381 if (efi_enabled(EFI_BOOT))
382 x86_platform.get_nmi_reason = hv_get_nmi_reason;
385 * Hyper-V VMs have a PIT emulation quirk such that zeroing the
386 * counter register during PIT shutdown restarts the PIT. So it
387 * continues to interrupt @18.2 HZ. Setting i8253_clear_counter
388 * to false tells pit_shutdown() not to zero the counter so that
389 * the PIT really is shutdown. Generation 2 VMs don't have a PIT,
390 * and setting this value has no effect.
392 i8253_clear_counter_on_shutdown = false;
394 #if IS_ENABLED(CONFIG_HYPERV)
396 * Setup the hook to get control post apic initialization.
398 x86_platform.apic_post_init = hyperv_init;
399 hyperv_setup_mmu_ops();
400 /* Setup the IDT for hypervisor callback */
401 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_hyperv_callback);
403 /* Setup the IDT for reenlightenment notifications */
404 if (ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT) {
405 alloc_intr_gate(HYPERV_REENLIGHTENMENT_VECTOR,
406 asm_sysvec_hyperv_reenlightenment);
409 /* Setup the IDT for stimer0 */
410 if (ms_hyperv.misc_features & HV_STIMER_DIRECT_MODE_AVAILABLE) {
411 alloc_intr_gate(HYPERV_STIMER0_VECTOR,
412 asm_sysvec_hyperv_stimer0);
416 smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu;
417 if (hv_root_partition)
418 smp_ops.smp_prepare_cpus = hv_smp_prepare_cpus;
422 * Hyper-V doesn't provide irq remapping for IO-APIC. To enable x2apic,
423 * set x2apic destination mode to physical mode when x2apic is available
424 * and Hyper-V IOMMU driver makes sure cpus assigned with IO-APIC irqs
425 * have 8-bit APIC id.
427 # ifdef CONFIG_X86_X2APIC
428 if (x2apic_supported())
432 /* Register Hyper-V specific clocksource */
433 hv_init_clocksource();
437 static bool __init ms_hyperv_x2apic_available(void)
439 return x2apic_supported();
443 * If ms_hyperv_msi_ext_dest_id() returns true, hyperv_prepare_irq_remapping()
444 * returns -ENODEV and the Hyper-V IOMMU driver is not used; instead, the
445 * generic support of the 15-bit APIC ID is used: see __irq_msi_compose_msg().
447 * Note: for a VM on Hyper-V, the I/O-APIC is the only device which
448 * (logically) generates MSIs directly to the system APIC irq domain.
449 * There is no HPET, and PCI MSI/MSI-X interrupts are remapped by the
450 * pci-hyperv host bridge.
452 static bool __init ms_hyperv_msi_ext_dest_id(void)
456 eax = cpuid_eax(HYPERV_CPUID_VIRT_STACK_INTERFACE);
457 if (eax != HYPERV_VS_INTERFACE_EAX_SIGNATURE)
460 eax = cpuid_eax(HYPERV_CPUID_VIRT_STACK_PROPERTIES);
461 return eax & HYPERV_VS_PROPERTIES_EAX_EXTENDED_IOAPIC_RTE;
464 const __initconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
465 .name = "Microsoft Hyper-V",
466 .detect = ms_hyperv_platform,
467 .type = X86_HYPER_MS_HYPERV,
468 .init.x2apic_available = ms_hyperv_x2apic_available,
469 .init.msi_ext_dest_id = ms_hyperv_msi_ext_dest_id,
470 .init.init_platform = ms_hyperv_init_platform,