aboutsummaryrefslogtreecommitdiffstatshomepage
path: root/arch/x86/kernel/cpu/mshyperv.c
blob: e0fd57a8ba840431e1f48dd61c1bc0ffc9fc0d82 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
// SPDX-License-Identifier: GPL-2.0-only
/*
 * HyperV  Detection code.
 *
 * Copyright (C) 2010, Novell, Inc.
 * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
 */

#include <linux/types.h>
#include <linux/time.h>
#include <linux/clocksource.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/hardirq.h>
#include <linux/efi.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kexec.h>
#include <linux/i8253.h>
#include <linux/random.h>
#include <asm/processor.h>
#include <asm/hypervisor.h>
#include <asm/hyperv-tlfs.h>
#include <asm/mshyperv.h>
#include <asm/desc.h>
#include <asm/idtentry.h>
#include <asm/irq_regs.h>
#include <asm/i8259.h>
#include <asm/apic.h>
#include <asm/timer.h>
#include <asm/reboot.h>
#include <asm/nmi.h>
#include <clocksource/hyperv_timer.h>
#include <asm/numa.h>
#include <asm/svm.h>

/* Is Linux running as the root partition? */
bool hv_root_partition;
/* Is Linux running on nested Microsoft Hypervisor */
bool hv_nested;
struct ms_hyperv_info ms_hyperv;

/* Used in modules via hv_do_hypercall(): see arch/x86/include/asm/mshyperv.h */
bool hyperv_paravisor_present __ro_after_init;
EXPORT_SYMBOL_GPL(hyperv_paravisor_present);

#if IS_ENABLED(CONFIG_HYPERV)
static inline unsigned int hv_get_nested_msr(unsigned int reg)
{
	if (hv_is_sint_msr(reg))
		return reg - HV_X64_MSR_SINT0 + HV_X64_MSR_NESTED_SINT0;

	switch (reg) {
	case HV_X64_MSR_SIMP:
		return HV_X64_MSR_NESTED_SIMP;
	case HV_X64_MSR_SIEFP:
		return HV_X64_MSR_NESTED_SIEFP;
	case HV_X64_MSR_SVERSION:
		return HV_X64_MSR_NESTED_SVERSION;
	case HV_X64_MSR_SCONTROL:
		return HV_X64_MSR_NESTED_SCONTROL;
	case HV_X64_MSR_EOM:
		return HV_X64_MSR_NESTED_EOM;
	default:
		return reg;
	}
}

u64 hv_get_non_nested_msr(unsigned int reg)
{
	u64 value;

	if (hv_is_synic_msr(reg) && ms_hyperv.paravisor_present)
		hv_ivm_msr_read(reg, &value);
	else
		rdmsrl(reg, value);
	return value;
}
EXPORT_SYMBOL_GPL(hv_get_non_nested_msr);

void hv_set_non_nested_msr(unsigned int reg, u64 value)
{
	if (hv_is_synic_msr(reg) && ms_hyperv.paravisor_present) {
		hv_ivm_msr_write(reg, value);

		/* Write proxy bit via wrmsl instruction */
		if (hv_is_sint_msr(reg))
			wrmsrl(reg, value | 1 << 20);
	} else {
		wrmsrl(reg, value);
	}
}
EXPORT_SYMBOL_GPL(hv_set_non_nested_msr);

u64 hv_get_msr(unsigned int reg)
{
	if (hv_nested)
		reg = hv_get_nested_msr(reg);

	return hv_get_non_nested_msr(reg);
}
EXPORT_SYMBOL_GPL(hv_get_msr);

void hv_set_msr(unsigned int reg, u64 value)
{
	if (hv_nested)
		reg = hv_get_nested_msr(reg);

	hv_set_non_nested_msr(reg, value);
}
EXPORT_SYMBOL_GPL(hv_set_msr);

static void (*vmbus_handler)(void);
static void (*hv_stimer0_handler)(void);
static void (*hv_kexec_handler)(void);
static void (*hv_crash_handler)(struct pt_regs *regs);

DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_callback)
{
	struct pt_regs *old_regs = set_irq_regs(regs);

	inc_irq_stat(irq_hv_callback_count);
	if (vmbus_handler)
		vmbus_handler();

	if (ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED)
		apic_eoi();

	set_irq_regs(old_regs);
}

void hv_setup_vmbus_handler(void (*handler)(void))
{
	vmbus_handler = handler;
}

void hv_remove_vmbus_handler(void)
{
	/* We have no way to deallocate the interrupt gate */
	vmbus_handler = NULL;
}

/*
 * Routines to do per-architecture handling of stimer0
 * interrupts when in Direct Mode
 */
DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_stimer0)
{
	struct pt_regs *old_regs = set_irq_regs(regs);

	inc_irq_stat(hyperv_stimer0_count);
	if (hv_stimer0_handler)
		hv_stimer0_handler();
	add_interrupt_randomness(HYPERV_STIMER0_VECTOR);
	apic_eoi();

	set_irq_regs(old_regs);
}

/* For x86/x64, override weak placeholders in hyperv_timer.c */
void hv_setup_stimer0_handler(void (*handler)(void))
{
	hv_stimer0_handler = handler;
}

void hv_remove_stimer0_handler(void)
{
	/* We have no way to deallocate the interrupt gate */
	hv_stimer0_handler = NULL;
}

void hv_setup_kexec_handler(void (*handler)(void))
{
	hv_kexec_handler = handler;
}

void hv_remove_kexec_handler(void)
{
	hv_kexec_handler = NULL;
}

void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
{
	hv_crash_handler = handler;
}

void hv_remove_crash_handler(void)
{
	hv_crash_handler = NULL;
}

#ifdef CONFIG_KEXEC_CORE
static void hv_machine_shutdown(void)
{
	if (kexec_in_progress && hv_kexec_handler)
		hv_kexec_handler();

	/*
	 * Call hv_cpu_die() on all the CPUs, otherwise later the hypervisor
	 * corrupts the old VP Assist Pages and can crash the kexec kernel.
	 */
	if (kexec_in_progress && hyperv_init_cpuhp > 0)
		cpuhp_remove_state(hyperv_init_cpuhp);

	/* The function calls stop_other_cpus(). */
	native_machine_shutdown();

	/* Disable the hypercall page when there is only 1 active CPU. */
	if (kexec_in_progress)
		hyperv_cleanup();
}
#endif /* CONFIG_KEXEC_CORE */

#ifdef CONFIG_CRASH_DUMP
static void hv_machine_crash_shutdown(struct pt_regs *regs)
{
	if (hv_crash_handler)
		hv_crash_handler(regs);

	/* The function calls crash_smp_send_stop(). */
	native_machine_crash_shutdown(regs);

	/* Disable the hypercall page when there is only 1 active CPU. */
	hyperv_cleanup();
}
#endif /* CONFIG_CRASH_DUMP */
#endif /* CONFIG_HYPERV */

static uint32_t  __init ms_hyperv_platform(void)
{
	u32 eax;
	u32 hyp_signature[3];

	if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
		return 0;

	cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
	      &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);

	if (eax < HYPERV_CPUID_MIN || eax > HYPERV_CPUID_MAX ||
	    memcmp("Microsoft Hv", hyp_signature, 12))
		return 0;

	/* HYPERCALL and VP_INDEX MSRs are mandatory for all features. */
	eax = cpuid_eax(HYPERV_CPUID_FEATURES);
	if (!(eax & HV_MSR_HYPERCALL_AVAILABLE)) {
		pr_warn("x86/hyperv: HYPERCALL MSR not available.\n");
		return 0;
	}
	if (!(eax & HV_MSR_VP_INDEX_AVAILABLE)) {
		pr_warn("x86/hyperv: VP_INDEX MSR not available.\n");
		return 0;
	}

	return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
}

#ifdef CONFIG_X86_LOCAL_APIC
/*
 * Prior to WS2016 Debug-VM sends NMIs to all CPUs which makes
 * it difficult to process CHANNELMSG_UNLOAD in case of crash. Handle
 * unknown NMI on the first CPU which gets it.
 */
static int hv_nmi_unknown(unsigned int val, struct pt_regs *regs)
{
	static atomic_t nmi_cpu = ATOMIC_INIT(-1);
	unsigned int old_cpu, this_cpu;

	if (!unknown_nmi_panic)
		return NMI_DONE;

	old_cpu = -1;
	this_cpu = raw_smp_processor_id();
	if (!atomic_try_cmpxchg(&nmi_cpu, &old_cpu, this_cpu))
		return NMI_HANDLED;

	return NMI_DONE;
}
#endif

static unsigned long hv_get_tsc_khz(void)
{
	unsigned long freq;

	rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);

	return freq / 1000;
}

#if defined(CONFIG_SMP) && IS_ENABLED(CONFIG_HYPERV)
static void __init hv_smp_prepare_boot_cpu(void)
{
	native_smp_prepare_boot_cpu();
#if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS)
	hv_init_spinlocks();
#endif
}

static void __init hv_smp_prepare_cpus(unsigned int max_cpus)
{
#ifdef CONFIG_X86_64
	int i;
	int ret;
#endif

	native_smp_prepare_cpus(max_cpus);

	/*
	 *  Override wakeup_secondary_cpu_64 callback for SEV-SNP
	 *  enlightened guest.
	 */
	if (!ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
		apic->wakeup_secondary_cpu_64 = hv_snp_boot_ap;
		return;
	}

#ifdef CONFIG_X86_64
	for_each_present_cpu(i) {
		if (i == 0)
			continue;
		ret = hv_call_add_logical_proc(numa_cpu_node(i), i, cpu_physical_id(i));
		BUG_ON(ret);
	}

	for_each_present_cpu(i) {
		if (i == 0)
			continue;
		ret = hv_call_create_vp(numa_cpu_node(i), hv_current_partition_id, i, i);
		BUG_ON(ret);
	}
#endif
}
#endif

/*
 * When a fully enlightened TDX VM runs on Hyper-V, the firmware sets the
 * HW_REDUCED flag: refer to acpi_tb_create_local_fadt(). Consequently ttyS0
 * interrupts can't work because request_irq() -> ... -> irq_to_desc() returns
 * NULL for ttyS0. This happens because mp_config_acpi_legacy_irqs() sees a
 * nr_legacy_irqs() of 0, so it doesn't initialize the array 'mp_irqs[]', and
 * later setup_IO_APIC_irqs() -> find_irq_entry() fails to find the legacy irqs
 * from the array and hence doesn't create the necessary irq description info.
 *
 * Clone arch/x86/kernel/acpi/boot.c: acpi_generic_reduced_hw_init() here,
 * except don't change 'legacy_pic', which keeps its default value
 * 'default_legacy_pic'. This way, mp_config_acpi_legacy_irqs() sees a non-zero
 * nr_legacy_irqs() and eventually serial console interrupts works properly.
 */
static void __init reduced_hw_init(void)
{
	x86_init.timers.timer_init	= x86_init_noop;
	x86_init.irqs.pre_vector_init	= x86_init_noop;
}

int hv_get_hypervisor_version(union hv_hypervisor_version_info *info)
{
	unsigned int hv_max_functions;

	hv_max_functions = cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS);
	if (hv_max_functions < HYPERV_CPUID_VERSION) {
		pr_err("%s: Could not detect Hyper-V version\n", __func__);
		return -ENODEV;
	}

	cpuid(HYPERV_CPUID_VERSION, &info->eax, &info->ebx, &info->ecx, &info->edx);

	return 0;
}

static void __init ms_hyperv_init_platform(void)
{
	int hv_max_functions_eax;

#ifdef CONFIG_PARAVIRT
	pv_info.name = "Hyper-V";
#endif

	/*
	 * Extract the features and hints
	 */
	ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
	ms_hyperv.priv_high = cpuid_ebx(HYPERV_CPUID_FEATURES);
	ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
	ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);

	hv_max_functions_eax = cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS);

	pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, hints 0x%x, misc 0x%x\n",
		ms_hyperv.features, ms_hyperv.priv_high, ms_hyperv.hints,
		ms_hyperv.misc_features);

	ms_hyperv.max_vp_index = cpuid_eax(HYPERV_CPUID_IMPLEMENT_LIMITS);
	ms_hyperv.max_lp_index = cpuid_ebx(HYPERV_CPUID_IMPLEMENT_LIMITS);

	pr_debug("Hyper-V: max %u virtual processors, %u logical processors\n",
		 ms_hyperv.max_vp_index, ms_hyperv.max_lp_index);

	/*
	 * Check CPU management privilege.
	 *
	 * To mirror what Windows does we should extract CPU management
	 * features and use the ReservedIdentityBit to detect if Linux is the
	 * root partition. But that requires negotiating CPU management
	 * interface (a process to be finalized). For now, use the privilege
	 * flag as the indicator for running as root.
	 *
	 * Hyper-V should never specify running as root and as a Confidential
	 * VM. But to protect against a compromised/malicious Hyper-V trying
	 * to exploit root behavior to expose Confidential VM memory, ignore
	 * the root partition setting if also a Confidential VM.
	 */
	if ((ms_hyperv.priv_high & HV_CPU_MANAGEMENT) &&
	    !(ms_hyperv.priv_high & HV_ISOLATION)) {
		hv_root_partition = true;
		pr_info("Hyper-V: running as root partition\n");
	}

	if (ms_hyperv.hints & HV_X64_HYPERV_NESTED) {
		hv_nested = true;
		pr_info("Hyper-V: running on a nested hypervisor\n");
	}

	if (ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
	    ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
		x86_platform.calibrate_tsc = hv_get_tsc_khz;
		x86_platform.calibrate_cpu = hv_get_tsc_khz;
	}

	if (ms_hyperv.priv_high & HV_ISOLATION) {
		ms_hyperv.isolation_config_a = cpuid_eax(HYPERV_CPUID_ISOLATION_CONFIG);
		ms_hyperv.isolation_config_b = cpuid_ebx(HYPERV_CPUID_ISOLATION_CONFIG);

		if (ms_hyperv.shared_gpa_boundary_active)
			ms_hyperv.shared_gpa_boundary =
				BIT_ULL(ms_hyperv.shared_gpa_boundary_bits);

		hyperv_paravisor_present = !!ms_hyperv.paravisor_present;

		pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
			ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);


		if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) {
			static_branch_enable(&isolation_type_snp);
		} else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_TDX) {
			static_branch_enable(&isolation_type_tdx);

			/* A TDX VM must use x2APIC and doesn't use lazy EOI. */
			ms_hyperv.hints &= ~HV_X64_APIC_ACCESS_RECOMMENDED;

			if (!ms_hyperv.paravisor_present) {
				/* To be supported: more work is required.  */
				ms_hyperv.features &= ~HV_MSR_REFERENCE_TSC_AVAILABLE;

				/* HV_MSR_CRASH_CTL is unsupported. */
				ms_hyperv.misc_features &= ~HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;

				/* Don't trust Hyper-V's TLB-flushing hypercalls. */
				ms_hyperv.hints &= ~HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED;

				x86_init.acpi.reduced_hw_early_init = reduced_hw_init;
			}
		}
	}

	if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
		ms_hyperv.nested_features =
			cpuid_eax(HYPERV_CPUID_NESTED_FEATURES);
		pr_info("Hyper-V: Nested features: 0x%x\n",
			ms_hyperv.nested_features);
	}

#ifdef CONFIG_X86_LOCAL_APIC
	if (ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
	    ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
		/*
		 * Get the APIC frequency.
		 */
		u64	hv_lapic_frequency;

		rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
		hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
		lapic_timer_period = hv_lapic_frequency;
		pr_info("Hyper-V: LAPIC Timer Frequency: %#x\n",
			lapic_timer_period);
	}

	register_nmi_handler(NMI_UNKNOWN, hv_nmi_unknown, NMI_FLAG_FIRST,
			     "hv_nmi_unknown");
#endif

#ifdef CONFIG_X86_IO_APIC
	no_timer_check = 1;
#endif

#if IS_ENABLED(CONFIG_HYPERV)
#if defined(CONFIG_KEXEC_CORE)
	machine_ops.shutdown = hv_machine_shutdown;
#endif
#if defined(CONFIG_CRASH_DUMP)
	machine_ops.crash_shutdown = hv_machine_crash_shutdown;
#endif
#endif
	if (ms_hyperv.features & HV_ACCESS_TSC_INVARIANT) {
		/*
		 * Writing to synthetic MSR 0x40000118 updates/changes the
		 * guest visible CPUIDs. Setting bit 0 of this MSR  enables
		 * guests to report invariant TSC feature through CPUID
		 * instruction, CPUID 0x800000007/EDX, bit 8. See code in
		 * early_init_intel() where this bit is examined. The
		 * setting of this MSR bit should happen before init_intel()
		 * is called.
		 */
		wrmsrl(HV_X64_MSR_TSC_INVARIANT_CONTROL, HV_EXPOSE_INVARIANT_TSC);
		setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
	}

	/*
	 * Generation 2 instances don't support reading the NMI status from
	 * 0x61 port.
	 */
	if (efi_enabled(EFI_BOOT))
		x86_platform.get_nmi_reason = hv_get_nmi_reason;

	/*
	 * Hyper-V VMs have a PIT emulation quirk such that zeroing the
	 * counter register during PIT shutdown restarts the PIT. So it
	 * continues to interrupt @18.2 HZ. Setting i8253_clear_counter
	 * to false tells pit_shutdown() not to zero the counter so that
	 * the PIT really is shutdown. Generation 2 VMs don't have a PIT,
	 * and setting this value has no effect.
	 */
	i8253_clear_counter_on_shutdown = false;

#if IS_ENABLED(CONFIG_HYPERV)
	if ((hv_get_isolation_type() == HV_ISOLATION_TYPE_VBS) ||
	    ms_hyperv.paravisor_present)
		hv_vtom_init();
	/*
	 * Setup the hook to get control post apic initialization.
	 */
	x86_platform.apic_post_init = hyperv_init;
	hyperv_setup_mmu_ops();

	/* Install system interrupt handler for hypervisor callback */
	sysvec_install(HYPERVISOR_CALLBACK_VECTOR, sysvec_hyperv_callback);

	/* Install system interrupt handler for reenlightenment notifications */
	if (ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT) {
		sysvec_install(HYPERV_REENLIGHTENMENT_VECTOR, sysvec_hyperv_reenlightenment);
	}

	/* Install system interrupt handler for stimer0 */
	if (ms_hyperv.misc_features & HV_STIMER_DIRECT_MODE_AVAILABLE) {
		sysvec_install(HYPERV_STIMER0_VECTOR, sysvec_hyperv_stimer0);
	}

# ifdef CONFIG_SMP
	smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu;
	if (hv_root_partition ||
	    (!ms_hyperv.paravisor_present && hv_isolation_type_snp()))
		smp_ops.smp_prepare_cpus = hv_smp_prepare_cpus;
# endif

	/*
	 * Hyper-V doesn't provide irq remapping for IO-APIC. To enable x2apic,
	 * set x2apic destination mode to physical mode when x2apic is available
	 * and Hyper-V IOMMU driver makes sure cpus assigned with IO-APIC irqs
	 * have 8-bit APIC id.
	 */
# ifdef CONFIG_X86_X2APIC
	if (x2apic_supported())
		x2apic_phys = 1;
# endif

	/* Register Hyper-V specific clocksource */
	hv_init_clocksource();
	hv_vtl_init_platform();
#endif
	/*
	 * TSC should be marked as unstable only after Hyper-V
	 * clocksource has been initialized. This ensures that the
	 * stability of the sched_clock is not altered.
	 */
	if (!(ms_hyperv.features & HV_ACCESS_TSC_INVARIANT))
		mark_tsc_unstable("running on Hyper-V");

	hardlockup_detector_disable();
}

static bool __init ms_hyperv_x2apic_available(void)
{
	return x2apic_supported();
}

/*
 * If ms_hyperv_msi_ext_dest_id() returns true, hyperv_prepare_irq_remapping()
 * returns -ENODEV and the Hyper-V IOMMU driver is not used; instead, the
 * generic support of the 15-bit APIC ID is used: see __irq_msi_compose_msg().
 *
 * Note: for a VM on Hyper-V, the I/O-APIC is the only device which
 * (logically) generates MSIs directly to the system APIC irq domain.
 * There is no HPET, and PCI MSI/MSI-X interrupts are remapped by the
 * pci-hyperv host bridge.
 *
 * Note: for a Hyper-V root partition, this will always return false.
 * The hypervisor doesn't expose these HYPERV_CPUID_VIRT_STACK_* cpuids by
 * default, they are implemented as intercepts by the Windows Hyper-V stack.
 * Even a nested root partition (L2 root) will not get them because the
 * nested (L1) hypervisor filters them out.
 */
static bool __init ms_hyperv_msi_ext_dest_id(void)
{
	u32 eax;

	eax = cpuid_eax(HYPERV_CPUID_VIRT_STACK_INTERFACE);
	if (eax != HYPERV_VS_INTERFACE_EAX_SIGNATURE)
		return false;

	eax = cpuid_eax(HYPERV_CPUID_VIRT_STACK_PROPERTIES);
	return eax & HYPERV_VS_PROPERTIES_EAX_EXTENDED_IOAPIC_RTE;
}

#ifdef CONFIG_AMD_MEM_ENCRYPT
static void hv_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
{
	/* RAX and CPL are already in the GHCB */
	ghcb_set_rcx(ghcb, regs->cx);
	ghcb_set_rdx(ghcb, regs->dx);
	ghcb_set_r8(ghcb, regs->r8);
}

static bool hv_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
{
	/* No checking of the return state needed */
	return true;
}
#endif

const __initconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
	.name			= "Microsoft Hyper-V",
	.detect			= ms_hyperv_platform,
	.type			= X86_HYPER_MS_HYPERV,
	.init.x2apic_available	= ms_hyperv_x2apic_available,
	.init.msi_ext_dest_id	= ms_hyperv_msi_ext_dest_id,
	.init.init_platform	= ms_hyperv_init_platform,
	.init.guest_late_init	= ms_hyperv_late_init,
#ifdef CONFIG_AMD_MEM_ENCRYPT
	.runtime.sev_es_hcall_prepare = hv_sev_es_hcall_prepare,
	.runtime.sev_es_hcall_finish = hv_sev_es_hcall_finish,
#endif
};