cpuid.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Kernel-based Virtual Machine driver for Linux
 * cpuid support routines
 *
 * derived from arch/x86/kvm/x86.c
 *
 * Copyright 2011 Red Hat, Inc. and/or its affiliates.
 * Copyright IBM Corporation, 2008
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kvm_host.h>
#include "linux/lockdep.h"
#include <linux/export.h>
#include <linux/vmalloc.h>
#include <linux/uaccess.h>
#include <linux/sched/stat.h>

#include <asm/processor.h>
#include <asm/user.h>
#include <asm/fpu/xstate.h>
#include <asm/sgx.h>
#include <asm/cpuid/api.h>
#include "cpuid.h"
#include "lapic.h"
#include "mmu.h"
#include "trace.h"
#include "pmu.h"
#include "xen.h"

/*
 * Unlike "struct cpuinfo_x86.x86_capability", kvm_cpu_caps doesn't need to be
 * aligned to sizeof(unsigned long) because it's not accessed via bitops.
 */
u32 kvm_cpu_caps[NR_KVM_CPU_CAPS] __read_mostly;
EXPORT_SYMBOL_GPL(kvm_cpu_caps);

struct cpuid_xstate_sizes {
	u32 eax;
	u32 ebx;
	u32 ecx;
};

static struct cpuid_xstate_sizes xstate_sizes[XFEATURE_MAX] __ro_after_init;

void __init kvm_init_xstate_sizes(void)
{
	u32 ign;
	int i;

	for (i = XFEATURE_YMM; i < ARRAY_SIZE(xstate_sizes); i++) {
		struct cpuid_xstate_sizes *xs = &xstate_sizes[i];

		cpuid_count(0xD, i, &xs->eax, &xs->ebx, &xs->ecx, &ign);
	}
}

u32 xstate_required_size(u64 xstate_bv, bool compacted)
{
	u32 ret = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;
	int i;

	xstate_bv &= XFEATURE_MASK_EXTEND;
	for (i = XFEATURE_YMM; i < ARRAY_SIZE(xstate_sizes) && xstate_bv; i++) {
		struct cpuid_xstate_sizes *xs = &xstate_sizes[i];
		u32 offset;

		if (!(xstate_bv & BIT_ULL(i)))
			continue;

		/* ECX[1]: 64B alignment in compacted form */
		if (compacted)
			offset = (xs->ecx & 0x2) ? ALIGN(ret, 64) : ret;
		else
			offset = xs->ebx;
		ret = max(ret, offset + xs->eax);
		xstate_bv &= ~BIT_ULL(i);
	}

	return ret;
}

struct kvm_cpuid_entry2 *kvm_find_cpuid_entry2(
	struct kvm_cpuid_entry2 *entries, int nent, u32 function, u64 index)
{
	struct kvm_cpuid_entry2 *e;
	int i;

	/*
	 * KVM has a semi-arbitrary rule that querying the guest's CPUID model
	 * with IRQs disabled is disallowed.  The CPUID model can legitimately
	 * have over one hundred entries, i.e. the lookup is slow, and IRQs are
	 * typically disabled in KVM only when KVM is in a performance critical
	 * path, e.g. the core VM-Enter/VM-Exit run loop.  Nothing will break
	 * if this rule is violated, this assertion is purely to flag potential
	 * performance issues.  If this fires, consider moving the lookup out
	 * of the hotpath, e.g. by caching information during CPUID updates.
	 */
	lockdep_assert_irqs_enabled();

	for (i = 0; i < nent; i++) {
		e = &entries[i];

		if (e->function != function)
			continue;

		/*
		 * If the index isn't significant, use the first entry with a
		 * matching function.  It's userspace's responsibility to not
		 * provide "duplicate" entries in all cases.
		 */
		if (!(e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX) || e->index == index)
			return e;


		/*
		 * Similarly, use the first matching entry if KVM is doing a
		 * lookup (as opposed to emulating CPUID) for a function that's
		 * architecturally defined as not having a significant index.
		 */
		if (index == KVM_CPUID_INDEX_NOT_SIGNIFICANT) {
			/*
			 * Direct lookups from KVM should not diverge from what
			 * KVM defines internally (the architectural behavior).
			 */
			WARN_ON_ONCE(cpuid_function_is_indexed(function));
			return e;
		}
	}

	return NULL;
}
EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry2);

static int kvm_check_cpuid(struct kvm_vcpu *vcpu)
{
	struct kvm_cpuid_entry2 *best;
	u64 xfeatures;

	/*
	 * The existing code assumes virtual address is 48-bit or 57-bit in the
	 * canonical address checks; exit if it is ever changed.
	 */
	best = kvm_find_cpuid_entry(vcpu, 0x80000008);
	if (best) {
		int vaddr_bits = (best->eax & 0xff00) >> 8;

		if (vaddr_bits != 48 && vaddr_bits != 57 && vaddr_bits != 0)
			return -EINVAL;
	}

	/*
	 * Exposing dynamic xfeatures to the guest requires additional
	 * enabling in the FPU, e.g. to expand the guest XSAVE state size.
	 */
	best = kvm_find_cpuid_entry_index(vcpu, 0xd, 0);
	if (!best)
		return 0;

	xfeatures = best->eax | ((u64)best->edx << 32);
	xfeatures &= XFEATURE_MASK_USER_DYNAMIC;
	if (!xfeatures)
		return 0;

	return fpu_enable_guest_xfd_features(&vcpu->arch.guest_fpu, xfeatures);
}

static u32 kvm_apply_cpuid_pv_features_quirk(struct kvm_vcpu *vcpu);
static void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu);

/* Check whether the supplied CPUID data is equal to what is already set for the vCPU. */
static int kvm_cpuid_check_equal(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
				 int nent)
{
	struct kvm_cpuid_entry2 *orig;
	int i;

	/*
	 * Apply runtime CPUID updates to the incoming CPUID entries to avoid
	 * false positives due mismatches on KVM-owned feature flags.
	 *
	 * Note!  @e2 and @nent track the _old_ CPUID entries!
	 */
	kvm_update_cpuid_runtime(vcpu);
	kvm_apply_cpuid_pv_features_quirk(vcpu);

	if (nent != vcpu->arch.cpuid_nent)
		return -EINVAL;

	for (i = 0; i < nent; i++) {
		orig = &vcpu->arch.cpuid_entries[i];
		if (e2[i].function != orig->function ||
		    e2[i].index != orig->index ||
		    e2[i].flags != orig->flags ||
		    e2[i].eax != orig->eax || e2[i].ebx != orig->ebx ||
		    e2[i].ecx != orig->ecx || e2[i].edx != orig->edx)
			return -EINVAL;
	}

	return 0;
}

static struct kvm_hypervisor_cpuid kvm_get_hypervisor_cpuid(struct kvm_vcpu *vcpu,
							    const char *sig)
{
	struct kvm_hypervisor_cpuid cpuid = {};
	struct kvm_cpuid_entry2 *entry;
	u32 base;

	for_each_possible_cpuid_base_hypervisor(base) {
		entry = kvm_find_cpuid_entry(vcpu, base);

		if (entry) {
			u32 signature[3];

			signature[0] = entry->ebx;
			signature[1] = entry->ecx;
			signature[2] = entry->edx;

			if (!memcmp(signature, sig, sizeof(signature))) {
				cpuid.base = base;
				cpuid.limit = entry->eax;
				break;
			}
		}
	}

	return cpuid;
}

static u32 kvm_apply_cpuid_pv_features_quirk(struct kvm_vcpu *vcpu)
{
	struct kvm_hypervisor_cpuid kvm_cpuid;
	struct kvm_cpuid_entry2 *best;

	kvm_cpuid = kvm_get_hypervisor_cpuid(vcpu, KVM_SIGNATURE);
	if (!kvm_cpuid.base)
		return 0;

	best = kvm_find_cpuid_entry(vcpu, kvm_cpuid.base | KVM_CPUID_FEATURES);
	if (!best)
		return 0;

	if (kvm_hlt_in_guest(vcpu->kvm))
		best->eax &= ~(1 << KVM_FEATURE_PV_UNHALT);

	return best->eax;
}

/*
 * Calculate guest's supported XCR0 taking into account guest CPUID data and
 * KVM's supported XCR0 (comprised of host's XCR0 and KVM_SUPPORTED_XCR0).
 */
static u64 cpuid_get_supported_xcr0(struct kvm_vcpu *vcpu)
{
	struct kvm_cpuid_entry2 *best;

	best = kvm_find_cpuid_entry_index(vcpu, 0xd, 0);
	if (!best)
		return 0;

	return (best->eax | ((u64)best->edx << 32)) & kvm_caps.supported_xcr0;
}

static __always_inline void kvm_update_feature_runtime(struct kvm_vcpu *vcpu,
						       struct kvm_cpuid_entry2 *entry,
						       unsigned int x86_feature,
						       bool has_feature)
{
	cpuid_entry_change(entry, x86_feature, has_feature);
	guest_cpu_cap_change(vcpu, x86_feature, has_feature);
}

static void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
{
	struct kvm_cpuid_entry2 *best;

	vcpu->arch.cpuid_dynamic_bits_dirty = false;

	best = kvm_find_cpuid_entry(vcpu, 1);
	if (best) {
		kvm_update_feature_runtime(vcpu, best, X86_FEATURE_OSXSAVE,
					   kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE));

		kvm_update_feature_runtime(vcpu, best, X86_FEATURE_APIC,
					   vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);

		if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT))
			kvm_update_feature_runtime(vcpu, best, X86_FEATURE_MWAIT,
						   vcpu->arch.ia32_misc_enable_msr &
						   MSR_IA32_MISC_ENABLE_MWAIT);
	}

	best = kvm_find_cpuid_entry_index(vcpu, 7, 0);
	if (best)
		kvm_update_feature_runtime(vcpu, best, X86_FEATURE_OSPKE,
					   kvm_is_cr4_bit_set(vcpu, X86_CR4_PKE));


	best = kvm_find_cpuid_entry_index(vcpu, 0xD, 0);
	if (best)
		best->ebx = xstate_required_size(vcpu->arch.xcr0, false);

	best = kvm_find_cpuid_entry_index(vcpu, 0xD, 1);
	if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||
		     cpuid_entry_has(best, X86_FEATURE_XSAVEC)))
		best->ebx = xstate_required_size(vcpu->arch.xcr0, true);
}

static bool kvm_cpuid_has_hyperv(struct kvm_vcpu *vcpu)
{
#ifdef CONFIG_KVM_HYPERV
	struct kvm_cpuid_entry2 *entry;

	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_INTERFACE);
	return entry && entry->eax == HYPERV_CPUID_SIGNATURE_EAX;
#else
	return false;
#endif
}

static bool guest_cpuid_is_amd_or_hygon(struct kvm_vcpu *vcpu)
{
	struct kvm_cpuid_entry2 *entry;

	entry = kvm_find_cpuid_entry(vcpu, 0);
	if (!entry)
		return false;

	return is_guest_vendor_amd(entry->ebx, entry->ecx, entry->edx) ||
	       is_guest_vendor_hygon(entry->ebx, entry->ecx, entry->edx);
}

/*
 * This isn't truly "unsafe", but except for the cpu_caps initialization code,
 * all register lookups should use __cpuid_entry_get_reg(), which provides
 * compile-time validation of the input.
 */
static u32 cpuid_get_reg_unsafe(struct kvm_cpuid_entry2 *entry, u32 reg)
{
	switch (reg) {
	case CPUID_EAX:
		return entry->eax;
	case CPUID_EBX:
		return entry->ebx;
	case CPUID_ECX:
		return entry->ecx;
	case CPUID_EDX:
		return entry->edx;
	default:
		WARN_ON_ONCE(1);
		return 0;
	}
}

static int cpuid_func_emulated(struct kvm_cpuid_entry2 *entry, u32 func,
			       bool include_partially_emulated);

void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
{
	struct kvm_lapic *apic = vcpu->arch.apic;
	struct kvm_cpuid_entry2 *best;
	struct kvm_cpuid_entry2 *entry;
	bool allow_gbpages;
	int i;

	memset(vcpu->arch.cpu_caps, 0, sizeof(vcpu->arch.cpu_caps));
	BUILD_BUG_ON(ARRAY_SIZE(reverse_cpuid) != NR_KVM_CPU_CAPS);

	/*
	 * Reset guest capabilities to userspace's guest CPUID definition, i.e.
	 * honor userspace's definition for features that don't require KVM or
	 * hardware management/support (or that KVM simply doesn't care about).
	 */
	for (i = 0; i < NR_KVM_CPU_CAPS; i++) {
		const struct cpuid_reg cpuid = reverse_cpuid[i];
		struct kvm_cpuid_entry2 emulated;

		if (!cpuid.function)
			continue;

		entry = kvm_find_cpuid_entry_index(vcpu, cpuid.function, cpuid.index);
		if (!entry)
			continue;

		cpuid_func_emulated(&emulated, cpuid.function, true);

		/*
		 * A vCPU has a feature if it's supported by KVM and is enabled
		 * in guest CPUID.  Note, this includes features that are
		 * supported by KVM but aren't advertised to userspace!
		 */
		vcpu->arch.cpu_caps[i] = kvm_cpu_caps[i] |
					 cpuid_get_reg_unsafe(&emulated, cpuid.reg);
		vcpu->arch.cpu_caps[i] &= cpuid_get_reg_unsafe(entry, cpuid.reg);
	}

	kvm_update_cpuid_runtime(vcpu);

	/*
	 * If TDP is enabled, let the guest use GBPAGES if they're supported in
	 * hardware.  The hardware page walker doesn't let KVM disable GBPAGES,
	 * i.e. won't treat them as reserved, and KVM doesn't redo the GVA->GPA
	 * walk for performance and complexity reasons.  Not to mention KVM
	 * _can't_ solve the problem because GVA->GPA walks aren't visible to
	 * KVM once a TDP translation is installed.  Mimic hardware behavior so
	 * that KVM's is at least consistent, i.e. doesn't randomly inject #PF.
	 * If TDP is disabled, honor *only* guest CPUID as KVM has full control
	 * and can install smaller shadow pages if the host lacks 1GiB support.
	 */
	allow_gbpages = tdp_enabled ? boot_cpu_has(X86_FEATURE_GBPAGES) :
				      guest_cpu_cap_has(vcpu, X86_FEATURE_GBPAGES);
	guest_cpu_cap_change(vcpu, X86_FEATURE_GBPAGES, allow_gbpages);

	best = kvm_find_cpuid_entry(vcpu, 1);
	if (best && apic) {
		if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
			apic->lapic_timer.timer_mode_mask = 3 << 17;
		else
			apic->lapic_timer.timer_mode_mask = 1 << 17;

		kvm_apic_set_version(vcpu);
	}

	vcpu->arch.guest_supported_xcr0 = cpuid_get_supported_xcr0(vcpu);

	vcpu->arch.pv_cpuid.features = kvm_apply_cpuid_pv_features_quirk(vcpu);

	vcpu->arch.is_amd_compatible = guest_cpuid_is_amd_or_hygon(vcpu);
	vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);
	vcpu->arch.reserved_gpa_bits = kvm_vcpu_reserved_gpa_bits_raw(vcpu);

	kvm_pmu_refresh(vcpu);

#define __kvm_cpu_cap_has(UNUSED_, f) kvm_cpu_cap_has(f)
	vcpu->arch.cr4_guest_rsvd_bits = __cr4_reserved_bits(__kvm_cpu_cap_has, UNUSED_) |
					 __cr4_reserved_bits(guest_cpu_cap_has, vcpu);
#undef __kvm_cpu_cap_has

	kvm_hv_set_cpuid(vcpu, kvm_cpuid_has_hyperv(vcpu));

	/* Invoke the vendor callback only after the above state is updated. */
	kvm_x86_call(vcpu_after_set_cpuid)(vcpu);

	/*
	 * Except for the MMU, which needs to do its thing any vendor specific
	 * adjustments to the reserved GPA bits.
	 */
	kvm_mmu_after_set_cpuid(vcpu);
}

int cpuid_query_maxphyaddr(struct kvm_vcpu *vcpu)
{
	struct kvm_cpuid_entry2 *best;

	best = kvm_find_cpuid_entry(vcpu, 0x80000000);
	if (!best || best->eax < 0x80000008)
		goto not_found;
	best = kvm_find_cpuid_entry(vcpu, 0x80000008);
	if (best)
		return best->eax & 0xff;
not_found:
	return 36;
}

int cpuid_query_maxguestphyaddr(struct kvm_vcpu *vcpu)
{
	struct kvm_cpuid_entry2 *best;

	best = kvm_find_cpuid_entry(vcpu, 0x80000000);
	if (!best || best->eax < 0x80000008)
		goto not_found;
	best = kvm_find_cpuid_entry(vcpu, 0x80000008);
	if (best)
		return (best->eax >> 16) & 0xff;
not_found:
	return 0;
}

/*
 * This "raw" version returns the reserved GPA bits without any adjustments for
 * encryption technologies that usurp bits.  The raw mask should be used if and
 * only if hardware does _not_ strip the usurped bits, e.g. in virtual MTRRs.
 */
u64 kvm_vcpu_reserved_gpa_bits_raw(struct kvm_vcpu *vcpu)
{
	return rsvd_bits(cpuid_maxphyaddr(vcpu), 63);
}

static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
                        int nent)
{
	u32 vcpu_caps[NR_KVM_CPU_CAPS];
	int r;

	/*
	 * Swap the existing (old) entries with the incoming (new) entries in
	 * order to massage the new entries, e.g. to account for dynamic bits
	 * that KVM controls, without clobbering the current guest CPUID, which
	 * KVM needs to preserve in order to unwind on failure.
	 *
	 * Similarly, save the vCPU's current cpu_caps so that the capabilities
	 * can be updated alongside the CPUID entries when performing runtime
	 * updates.  Full initialization is done if and only if the vCPU hasn't
	 * run, i.e. only if userspace is potentially changing CPUID features.
	 */
	swap(vcpu->arch.cpuid_entries, e2);
	swap(vcpu->arch.cpuid_nent, nent);

	memcpy(vcpu_caps, vcpu->arch.cpu_caps, sizeof(vcpu_caps));
	BUILD_BUG_ON(sizeof(vcpu_caps) != sizeof(vcpu->arch.cpu_caps));

	/*
	 * KVM does not correctly handle changing guest CPUID after KVM_RUN, as
	 * MAXPHYADDR, GBPAGES support, AMD reserved bit behavior, etc.. aren't
	 * tracked in kvm_mmu_page_role.  As a result, KVM may miss guest page
	 * faults due to reusing SPs/SPTEs. In practice no sane VMM mucks with
	 * the core vCPU model on the fly. It would've been better to forbid any
	 * KVM_SET_CPUID{,2} calls after KVM_RUN altogether but unfortunately
	 * some VMMs (e.g. QEMU) reuse vCPU fds for CPU hotplug/unplug and do
	 * KVM_SET_CPUID{,2} again. To support this legacy behavior, check
	 * whether the supplied CPUID data is equal to what's already set.
	 */
	if (kvm_vcpu_has_run(vcpu)) {
		r = kvm_cpuid_check_equal(vcpu, e2, nent);
		if (r)
			goto err;
		goto success;
	}

#ifdef CONFIG_KVM_HYPERV
	if (kvm_cpuid_has_hyperv(vcpu)) {
		r = kvm_hv_vcpu_init(vcpu);
		if (r)
			goto err;
	}
#endif

	r = kvm_check_cpuid(vcpu);
	if (r)
		goto err;

#ifdef CONFIG_KVM_XEN
	vcpu->arch.xen.cpuid = kvm_get_hypervisor_cpuid(vcpu, XEN_SIGNATURE);
#endif
	kvm_vcpu_after_set_cpuid(vcpu);

success:
	kvfree(e2);
	return 0;

err:
	memcpy(vcpu->arch.cpu_caps, vcpu_caps, sizeof(vcpu_caps));
	swap(vcpu->arch.cpuid_entries, e2);
	swap(vcpu->arch.cpuid_nent, nent);
	return r;
}

/* when an old userspace process fills a new kernel module */
int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
			     struct kvm_cpuid *cpuid,
			     struct kvm_cpuid_entry __user *entries)
{
	int r, i;
	struct kvm_cpuid_entry *e = NULL;
	struct kvm_cpuid_entry2 *e2 = NULL;

	if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
		return -E2BIG;

	if (cpuid->nent) {
		e = vmemdup_array_user(entries, cpuid->nent, sizeof(*e));
		if (IS_ERR(e))
			return PTR_ERR(e);

		e2 = kvmalloc_array(cpuid->nent, sizeof(*e2), GFP_KERNEL_ACCOUNT);
		if (!e2) {
			r = -ENOMEM;
			goto out_free_cpuid;
		}
	}
	for (i = 0; i < cpuid->nent; i++) {
		e2[i].function = e[i].function;
		e2[i].eax = e[i].eax;
		e2[i].ebx = e[i].ebx;
		e2[i].ecx = e[i].ecx;
		e2[i].edx = e[i].edx;
		e2[i].index = 0;
		e2[i].flags = 0;
		e2[i].padding[0] = 0;
		e2[i].padding[1] = 0;
		e2[i].padding[2] = 0;
	}

	r = kvm_set_cpuid(vcpu, e2, cpuid->nent);
	if (r)
		kvfree(e2);

out_free_cpuid:
	kvfree(e);

	return r;
}

int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
			      struct kvm_cpuid2 *cpuid,
			      struct kvm_cpuid_entry2 __user *entries)
{
	struct kvm_cpuid_entry2 *e2 = NULL;
	int r;

	if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
		return -E2BIG;

	if (cpuid->nent) {
		e2 = vmemdup_array_user(entries, cpuid->nent, sizeof(*e2));
		if (IS_ERR(e2))
			return PTR_ERR(e2);
	}

	r = kvm_set_cpuid(vcpu, e2, cpuid->nent);
	if (r)
		kvfree(e2);

	return r;
}

int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
			      struct kvm_cpuid2 *cpuid,
			      struct kvm_cpuid_entry2 __user *entries)
{
	if (cpuid->nent < vcpu->arch.cpuid_nent)
		return -E2BIG;

	if (vcpu->arch.cpuid_dynamic_bits_dirty)
		kvm_update_cpuid_runtime(vcpu);

	if (copy_to_user(entries, vcpu->arch.cpuid_entries,
			 vcpu->arch.cpuid_nent * sizeof(struct kvm_cpuid_entry2)))
		return -EFAULT;

	cpuid->nent = vcpu->arch.cpuid_nent;
	return 0;
}

static __always_inline u32 raw_cpuid_get(struct cpuid_reg cpuid)
{
	struct kvm_cpuid_entry2 entry;
	u32 base;

	/*
	 * KVM only supports features defined by Intel (0x0), AMD (0x80000000),
	 * and Centaur (0xc0000000).  WARN if a feature for new vendor base is
	 * defined, as this and other code would need to be updated.
	 */
	base = cpuid.function & 0xffff0000;
	if (WARN_ON_ONCE(base && base != 0x80000000 && base != 0xc0000000))
		return 0;

	if (cpuid_eax(base) < cpuid.function)
		return 0;

	cpuid_count(cpuid.function, cpuid.index,
		    &entry.eax, &entry.ebx, &entry.ecx, &entry.edx);

	return *__cpuid_entry_get_reg(&entry, cpuid.reg);
}

/*
 * For kernel-defined leafs, mask KVM's supported feature set with the kernel's
 * capabilities as well as raw CPUID.  For KVM-defined leafs, consult only raw
 * CPUID, as KVM is the one and only authority (in the kernel).
 */
#define kvm_cpu_cap_init(leaf, feature_initializers...)			\
do {									\
	const struct cpuid_reg cpuid = x86_feature_cpuid(leaf * 32);	\
	const u32 __maybe_unused kvm_cpu_cap_init_in_progress = leaf;	\
	const u32 *kernel_cpu_caps = boot_cpu_data.x86_capability;	\
	u32 kvm_cpu_cap_passthrough = 0;				\
	u32 kvm_cpu_cap_synthesized = 0;				\
	u32 kvm_cpu_cap_emulated = 0;					\
	u32 kvm_cpu_cap_features = 0;					\
									\
	feature_initializers						\
									\
	kvm_cpu_caps[leaf] = kvm_cpu_cap_features;			\
									\
	if (leaf < NCAPINTS)						\
		kvm_cpu_caps[leaf] &= kernel_cpu_caps[leaf];		\
									\
	kvm_cpu_caps[leaf] |= kvm_cpu_cap_passthrough;			\
	kvm_cpu_caps[leaf] &= (raw_cpuid_get(cpuid) |			\
			       kvm_cpu_cap_synthesized);		\
	kvm_cpu_caps[leaf] |= kvm_cpu_cap_emulated;			\
} while (0)

/*
 * Assert that the feature bit being declared, e.g. via F(), is in the CPUID
 * word that's being initialized.  Exempt 0x8000_0001.EDX usage of 0x1.EDX
 * features, as AMD duplicated many 0x1.EDX features into 0x8000_0001.EDX.
 */
#define KVM_VALIDATE_CPU_CAP_USAGE(name)				\
do {									\
	u32 __leaf = __feature_leaf(X86_FEATURE_##name);		\
									\
	BUILD_BUG_ON(__leaf != kvm_cpu_cap_init_in_progress);		\
} while (0)

#define F(name)							\
({								\
	KVM_VALIDATE_CPU_CAP_USAGE(name);			\
	kvm_cpu_cap_features |= feature_bit(name);		\
})

/* Scattered Flag - For features that are scattered by cpufeatures.h. */
#define SCATTERED_F(name)					\
({								\
	BUILD_BUG_ON(X86_FEATURE_##name >= MAX_CPU_FEATURES);	\
	KVM_VALIDATE_CPU_CAP_USAGE(name);			\
	if (boot_cpu_has(X86_FEATURE_##name))			\
		F(name);					\
})

/* Features that KVM supports only on 64-bit kernels. */
#define X86_64_F(name)						\
({								\
	KVM_VALIDATE_CPU_CAP_USAGE(name);			\
	if (IS_ENABLED(CONFIG_X86_64))				\
		F(name);					\
})

/*
 * Emulated Feature - For features that KVM emulates in software irrespective
 * of host CPU/kernel support.
 */
#define EMULATED_F(name)					\
({								\
	kvm_cpu_cap_emulated |= feature_bit(name);		\
	F(name);						\
})

/*
 * Synthesized Feature - For features that are synthesized into boot_cpu_data,
 * i.e. may not be present in the raw CPUID, but can still be advertised to
 * userspace.  Primarily used for mitigation related feature flags.
 */
#define SYNTHESIZED_F(name)					\
({								\
	kvm_cpu_cap_synthesized |= feature_bit(name);		\
	F(name);						\
})

/*
 * Passthrough Feature - For features that KVM supports based purely on raw
 * hardware CPUID, i.e. that KVM virtualizes even if the host kernel doesn't
 * use the feature.  Simply force set the feature in KVM's capabilities, raw
 * CPUID support will be factored in by kvm_cpu_cap_mask().
 */
#define PASSTHROUGH_F(name)					\
({								\
	kvm_cpu_cap_passthrough |= feature_bit(name);		\
	F(name);						\
})

/*
 * Aliased Features - For features in 0x8000_0001.EDX that are duplicates of
 * identical 0x1.EDX features, and thus are aliased from 0x1 to 0x8000_0001.
 */
#define ALIASED_1_EDX_F(name)							\
({										\
	BUILD_BUG_ON(__feature_leaf(X86_FEATURE_##name) != CPUID_1_EDX);	\
	BUILD_BUG_ON(kvm_cpu_cap_init_in_progress != CPUID_8000_0001_EDX);	\
	kvm_cpu_cap_features |= feature_bit(name);				\
})

/*
 * Vendor Features - For features that KVM supports, but are added in later
 * because they require additional vendor enabling.
 */
#define VENDOR_F(name)						\
({								\
	KVM_VALIDATE_CPU_CAP_USAGE(name);			\
})

/*
 * Runtime Features - For features that KVM dynamically sets/clears at runtime,
 * e.g. when CR4 changes, but which are never advertised to userspace.
 */
#define RUNTIME_F(name)						\
({								\
	KVM_VALIDATE_CPU_CAP_USAGE(name);			\
})

/*
 * Undefine the MSR bit macro to avoid token concatenation issues when
 * processing X86_FEATURE_SPEC_CTRL_SSBD.
 */
#undef SPEC_CTRL_SSBD

/* DS is defined by ptrace-abi.h on 32-bit builds. */
#undef DS

void kvm_set_cpu_caps(void)
{
	memset(kvm_cpu_caps, 0, sizeof(kvm_cpu_caps));

	BUILD_BUG_ON(sizeof(kvm_cpu_caps) - (NKVMCAPINTS * sizeof(*kvm_cpu_caps)) >
		     sizeof(boot_cpu_data.x86_capability));

	kvm_cpu_cap_init(CPUID_1_ECX,
		F(XMM3),
		F(PCLMULQDQ),
		VENDOR_F(DTES64),
		/*
		 * NOTE: MONITOR (and MWAIT) are emulated as NOP, but *not*
		 * advertised to guests via CPUID!  MWAIT is also technically a
		 * runtime flag thanks to IA32_MISC_ENABLES; mark it as such so
		 * that KVM is aware that it's a known, unadvertised flag.
		 */
		RUNTIME_F(MWAIT),
		/* DS-CPL */
		VENDOR_F(VMX),
		/* SMX, EST */
		/* TM2 */
		F(SSSE3),
		/* CNXT-ID */
		/* Reserved */
		F(FMA),
		F(CX16),
		/* xTPR Update */
		F(PDCM),
		F(PCID),
		/* Reserved, DCA */
		F(XMM4_1),
		F(XMM4_2),
		EMULATED_F(X2APIC),
		F(MOVBE),
		F(POPCNT),
		EMULATED_F(TSC_DEADLINE_TIMER),
		F(AES),
		F(XSAVE),
		RUNTIME_F(OSXSAVE),
		F(AVX),
		F(F16C),
		F(RDRAND),
		EMULATED_F(HYPERVISOR),
	);

	kvm_cpu_cap_init(CPUID_1_EDX,
		F(FPU),
		F(VME),
		F(DE),
		F(PSE),
		F(TSC),
		F(MSR),
		F(PAE),
		F(MCE),
		F(CX8),
		F(APIC),
		/* Reserved */
		F(SEP),
		F(MTRR),
		F(PGE),
		F(MCA),
		F(CMOV),
		F(PAT),
		F(PSE36),
		/* PSN */
		F(CLFLUSH),
		/* Reserved */
		VENDOR_F(DS),
		/* ACPI */
		F(MMX),
		F(FXSR),
		F(XMM),
		F(XMM2),
		F(SELFSNOOP),
		/* HTT, TM, Reserved, PBE */
	);

	kvm_cpu_cap_init(CPUID_7_0_EBX,
		F(FSGSBASE),
		EMULATED_F(TSC_ADJUST),
		F(SGX),
		F(BMI1),
		F(HLE),
		F(AVX2),
		F(FDP_EXCPTN_ONLY),
		F(SMEP),
		F(BMI2),
		F(ERMS),
		F(INVPCID),
		F(RTM),
		F(ZERO_FCS_FDS),
		VENDOR_F(MPX),
		F(AVX512F),
		F(AVX512DQ),
		F(RDSEED),
		F(ADX),
		F(SMAP),
		F(AVX512IFMA),
		F(CLFLUSHOPT),
		F(CLWB),
		VENDOR_F(INTEL_PT),
		F(AVX512PF),
		F(AVX512ER),
		F(AVX512CD),
		F(SHA_NI),
		F(AVX512BW),
		F(AVX512VL),
	);

	kvm_cpu_cap_init(CPUID_7_ECX,
		F(AVX512VBMI),
		PASSTHROUGH_F(LA57),
		F(PKU),
		RUNTIME_F(OSPKE),
		F(RDPID),
		F(AVX512_VPOPCNTDQ),
		F(UMIP),
		F(AVX512_VBMI2),
		F(GFNI),
		F(VAES),
		F(VPCLMULQDQ),
		F(AVX512_VNNI),
		F(AVX512_BITALG),
		F(CLDEMOTE),
		F(MOVDIRI),
		F(MOVDIR64B),
		VENDOR_F(WAITPKG),
		F(SGX_LC),
		F(BUS_LOCK_DETECT),
	);

	/*
	 * PKU not yet implemented for shadow paging and requires OSPKE
	 * to be set on the host. Clear it if that is not the case
	 */
	if (!tdp_enabled || !boot_cpu_has(X86_FEATURE_OSPKE))
		kvm_cpu_cap_clear(X86_FEATURE_PKU);

	kvm_cpu_cap_init(CPUID_7_EDX,
		F(AVX512_4VNNIW),
		F(AVX512_4FMAPS),
		F(SPEC_CTRL),
		F(SPEC_CTRL_SSBD),
		EMULATED_F(ARCH_CAPABILITIES),
		F(INTEL_STIBP),
		F(MD_CLEAR),
		F(AVX512_VP2INTERSECT),
		F(FSRM),
		F(SERIALIZE),
		F(TSXLDTRK),
		F(AVX512_FP16),
		F(AMX_TILE),
		F(AMX_INT8),
		F(AMX_BF16),
		F(FLUSH_L1D),
	);

	if (boot_cpu_has(X86_FEATURE_AMD_IBPB_RET) &&
	    boot_cpu_has(X86_FEATURE_AMD_IBPB) &&
	    boot_cpu_has(X86_FEATURE_AMD_IBRS))
		kvm_cpu_cap_set(X86_FEATURE_SPEC_CTRL);
	if (boot_cpu_has(X86_FEATURE_STIBP))
		kvm_cpu_cap_set(X86_FEATURE_INTEL_STIBP);
	if (boot_cpu_has(X86_FEATURE_AMD_SSBD))
		kvm_cpu_cap_set(X86_FEATURE_SPEC_CTRL_SSBD);

	kvm_cpu_cap_init(CPUID_7_1_EAX,
		F(SHA512),
		F(SM3),
		F(SM4),
		F(AVX_VNNI),
		F(AVX512_BF16),
		F(CMPCCXADD),
		F(FZRM),
		F(FSRS),
		F(FSRC),
		F(WRMSRNS),
		X86_64_F(LKGS),
		F(AMX_FP16),
		F(AVX_IFMA),
		F(LAM),
	);

	kvm_cpu_cap_init(CPUID_7_1_EDX,
		F(AVX_VNNI_INT8),
		F(AVX_NE_CONVERT),
		F(AMX_COMPLEX),
		F(AVX_VNNI_INT16),
		F(PREFETCHITI),
		F(AVX10),
	);

	kvm_cpu_cap_init(CPUID_7_2_EDX,
		F(INTEL_PSFD),
		F(IPRED_CTRL),
		F(RRSBA_CTRL),
		F(DDPD_U),
		F(BHI_CTRL),
		F(MCDT_NO),
	);

	kvm_cpu_cap_init(CPUID_D_1_EAX,
		F(XSAVEOPT),
		F(XSAVEC),
		F(XGETBV1),
		F(XSAVES),
		X86_64_F(XFD),
	);

	kvm_cpu_cap_init(CPUID_12_EAX,
		SCATTERED_F(SGX1),
		SCATTERED_F(SGX2),
		SCATTERED_F(SGX_EDECCSSA),
	);

	kvm_cpu_cap_init(CPUID_24_0_EBX,
		F(AVX10_128),
		F(AVX10_256),
		F(AVX10_512),
	);

	kvm_cpu_cap_init(CPUID_8000_0001_ECX,
		F(LAHF_LM),
		F(CMP_LEGACY),
		VENDOR_F(SVM),
		/* ExtApicSpace */
		F(CR8_LEGACY),
		F(ABM),
		F(SSE4A),
		F(MISALIGNSSE),
		F(3DNOWPREFETCH),
		F(OSVW),
		/* IBS */
		F(XOP),
		/* SKINIT, WDT, LWP */
		F(FMA4),
		F(TBM),
		F(TOPOEXT),
		VENDOR_F(PERFCTR_CORE),
	);

	kvm_cpu_cap_init(CPUID_8000_0001_EDX,
		ALIASED_1_EDX_F(FPU),
		ALIASED_1_EDX_F(VME),
		ALIASED_1_EDX_F(DE),
		ALIASED_1_EDX_F(PSE),
		ALIASED_1_EDX_F(TSC),
		ALIASED_1_EDX_F(MSR),
		ALIASED_1_EDX_F(PAE),
		ALIASED_1_EDX_F(MCE),
		ALIASED_1_EDX_F(CX8),
		ALIASED_1_EDX_F(APIC),
		/* Reserved */
		F(SYSCALL),
		ALIASED_1_EDX_F(MTRR),
		ALIASED_1_EDX_F(PGE),
		ALIASED_1_EDX_F(MCA),
		ALIASED_1_EDX_F(CMOV),
		ALIASED_1_EDX_F(PAT),
		ALIASED_1_EDX_F(PSE36),
		/* Reserved */
		F(NX),
		/* Reserved */
		F(MMXEXT),
		ALIASED_1_EDX_F(MMX),
		ALIASED_1_EDX_F(FXSR),
		F(FXSR_OPT),
		X86_64_F(GBPAGES),
		F(RDTSCP),
		/* Reserved */
		X86_64_F(LM),
		F(3DNOWEXT),
		F(3DNOW),
	);

	if (!tdp_enabled && IS_ENABLED(CONFIG_X86_64))
		kvm_cpu_cap_set(X86_FEATURE_GBPAGES);

	kvm_cpu_cap_init(CPUID_8000_0007_EDX,
		SCATTERED_F(CONSTANT_TSC),
	);

	kvm_cpu_cap_init(CPUID_8000_0008_EBX,
		F(CLZERO),
		F(XSAVEERPTR),
		F(WBNOINVD),
		F(AMD_IBPB),
		F(AMD_IBRS),
		F(AMD_SSBD),
		F(VIRT_SSBD),
		F(AMD_SSB_NO),
		F(AMD_STIBP),
		F(AMD_STIBP_ALWAYS_ON),
		F(AMD_IBRS_SAME_MODE),
		F(AMD_PSFD),
		F(AMD_IBPB_RET),
	);

	/*
	 * AMD has separate bits for each SPEC_CTRL bit.
	 * arch/x86/kernel/cpu/bugs.c is kind enough to
	 * record that in cpufeatures so use them.
	 */
	if (boot_cpu_has(X86_FEATURE_IBPB)) {
		kvm_cpu_cap_set(X86_FEATURE_AMD_IBPB);
		if (boot_cpu_has(X86_FEATURE_SPEC_CTRL) &&
		    !boot_cpu_has_bug(X86_BUG_EIBRS_PBRSB))
			kvm_cpu_cap_set(X86_FEATURE_AMD_IBPB_RET);
	}
	if (boot_cpu_has(X86_FEATURE_IBRS))
		kvm_cpu_cap_set(X86_FEATURE_AMD_IBRS);
	if (boot_cpu_has(X86_FEATURE_STIBP))
		kvm_cpu_cap_set(X86_FEATURE_AMD_STIBP);
	if (boot_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD))
		kvm_cpu_cap_set(X86_FEATURE_AMD_SSBD);
	if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
		kvm_cpu_cap_set(X86_FEATURE_AMD_SSB_NO);
	/*
	 * The preference is to use SPEC CTRL MSR instead of the
	 * VIRT_SPEC MSR.
	 */
	if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
	    !boot_cpu_has(X86_FEATURE_AMD_SSBD))
		kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD);

	/* All SVM features required additional vendor module enabling. */
	kvm_cpu_cap_init(CPUID_8000_000A_EDX,
		VENDOR_F(NPT),
		VENDOR_F(VMCBCLEAN),
		VENDOR_F(FLUSHBYASID),
		VENDOR_F(NRIPS),
		VENDOR_F(TSCRATEMSR),
		VENDOR_F(V_VMSAVE_VMLOAD),
		VENDOR_F(LBRV),
		VENDOR_F(PAUSEFILTER),
		VENDOR_F(PFTHRESHOLD),
		VENDOR_F(VGIF),
		VENDOR_F(VNMI),
		VENDOR_F(SVME_ADDR_CHK),
	);

	kvm_cpu_cap_init(CPUID_8000_001F_EAX,
		VENDOR_F(SME),
		VENDOR_F(SEV),
		/* VM_PAGE_FLUSH */
		VENDOR_F(SEV_ES),
		F(SME_COHERENT),
	);

	kvm_cpu_cap_init(CPUID_8000_0021_EAX,
		F(NO_NESTED_DATA_BP),
		F(WRMSR_XX_BASE_NS),
		/*
		 * Synthesize "LFENCE is serializing" into the AMD-defined entry
		 * in KVM's supported CPUID, i.e. if the feature is reported as
		 * supported by the kernel.  LFENCE_RDTSC was a Linux-defined
		 * synthetic feature long before AMD joined the bandwagon, e.g.
		 * LFENCE is serializing on most CPUs that support SSE2.  On
		 * CPUs that don't support AMD's leaf, ANDing with the raw host
		 * CPUID will drop the flags, and reporting support in AMD's
		 * leaf can make it easier for userspace to detect the feature.
		 */
		SYNTHESIZED_F(LFENCE_RDTSC),
		/* SmmPgCfgLock */
		/* 4: Resv */
		SYNTHESIZED_F(VERW_CLEAR),
		F(NULL_SEL_CLR_BASE),
		/* UpperAddressIgnore */
		F(AUTOIBRS),
		F(PREFETCHI),
		EMULATED_F(NO_SMM_CTL_MSR),
		/* PrefetchCtlMsr */
		/* GpOnUserCpuid */
		/* EPSF */
		SYNTHESIZED_F(SBPB),
		SYNTHESIZED_F(IBPB_BRTYPE),
		SYNTHESIZED_F(SRSO_NO),
		F(SRSO_USER_KERNEL_NO),
	);

	kvm_cpu_cap_init(CPUID_8000_0021_ECX,
		SYNTHESIZED_F(TSA_SQ_NO),
		SYNTHESIZED_F(TSA_L1_NO),
	);

	kvm_cpu_cap_init(CPUID_8000_0022_EAX,
		F(PERFMON_V2),
	);

	if (!static_cpu_has_bug(X86_BUG_NULL_SEG))
		kvm_cpu_cap_set(X86_FEATURE_NULL_SEL_CLR_BASE);

	kvm_cpu_cap_init(CPUID_C000_0001_EDX,
		F(XSTORE),
		F(XSTORE_EN),
		F(XCRYPT),
		F(XCRYPT_EN),
		F(ACE2),
		F(ACE2_EN),
		F(PHE),
		F(PHE_EN),
		F(PMM),
		F(PMM_EN),
	);

	/*
	 * Hide RDTSCP and RDPID if either feature is reported as supported but
	 * probing MSR_TSC_AUX failed.  This is purely a sanity check and
	 * should never happen, but the guest will likely crash if RDTSCP or
	 * RDPID is misreported, and KVM has botched MSR_TSC_AUX emulation in
	 * the past.  For example, the sanity check may fire if this instance of
	 * KVM is running as L1 on top of an older, broken KVM.
	 */
	if (WARN_ON((kvm_cpu_cap_has(X86_FEATURE_RDTSCP) ||
		     kvm_cpu_cap_has(X86_FEATURE_RDPID)) &&
		     !kvm_is_supported_user_return_msr(MSR_TSC_AUX))) {
		kvm_cpu_cap_clear(X86_FEATURE_RDTSCP);
		kvm_cpu_cap_clear(X86_FEATURE_RDPID);
	}
}
EXPORT_SYMBOL_GPL(kvm_set_cpu_caps);

#undef F
#undef SCATTERED_F
#undef X86_64_F
#undef EMULATED_F
#undef SYNTHESIZED_F
#undef PASSTHROUGH_F
#undef ALIASED_1_EDX_F
#undef VENDOR_F
#undef RUNTIME_F

struct kvm_cpuid_array {
	struct kvm_cpuid_entry2 *entries;
	int maxnent;
	int nent;
};

static struct kvm_cpuid_entry2 *get_next_cpuid(struct kvm_cpuid_array *array)
{
	if (array->nent >= array->maxnent)
		return NULL;

	return &array->entries[array->nent++];
}

static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array,
					      u32 function, u32 index)
{
	struct kvm_cpuid_entry2 *entry = get_next_cpuid(array);

	if (!entry)
		return NULL;

	memset(entry, 0, sizeof(*entry));
	entry->function = function;
	entry->index = index;
	switch (function & 0xC0000000) {
	case 0x40000000:
		/* Hypervisor leaves are always synthesized by __do_cpuid_func.  */
		return entry;

	case 0x80000000:
		/*
		 * 0x80000021 is sometimes synthesized by __do_cpuid_func, which
		 * would result in out-of-bounds calls to do_host_cpuid.
		 */
		{
			static int max_cpuid_80000000;
			if (!READ_ONCE(max_cpuid_80000000))
				WRITE_ONCE(max_cpuid_80000000, cpuid_eax(0x80000000));
			if (function > READ_ONCE(max_cpuid_80000000))
				return entry;
		}
		break;

	default:
		break;
	}

	cpuid_count(entry->function, entry->index,
		    &entry->eax, &entry->ebx, &entry->ecx, &entry->edx);

	if (cpuid_function_is_indexed(function))
		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;

	return entry;
}

static int cpuid_func_emulated(struct kvm_cpuid_entry2 *entry, u32 func,
			       bool include_partially_emulated)
{
	memset(entry, 0, sizeof(*entry));

	entry->function = func;
	entry->index = 0;
	entry->flags = 0;

	switch (func) {
	case 0:
		entry->eax = 7;
		return 1;
	case 1:
		entry->ecx = feature_bit(MOVBE);
		/*
		 * KVM allows userspace to enumerate MONITOR+MWAIT support to
		 * the guest, but the MWAIT feature flag is never advertised
		 * to userspace because MONITOR+MWAIT aren't virtualized by
		 * hardware, can't be faithfully emulated in software (KVM
		 * emulates them as NOPs), and allowing the guest to execute
		 * them natively requires enabling a per-VM capability.
		 */
		if (include_partially_emulated)
			entry->ecx |= feature_bit(MWAIT);
		return 1;
	case 7:
		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
		entry->eax = 0;
		if (kvm_cpu_cap_has(X86_FEATURE_RDTSCP))
			entry->ecx = feature_bit(RDPID);
		return 1;
	default:
		return 0;
	}
}

static int __do_cpuid_func_emulated(struct kvm_cpuid_array *array, u32 func)
{
	if (array->nent >= array->maxnent)
		return -E2BIG;

	array->nent += cpuid_func_emulated(&array->entries[array->nent], func, false);
	return 0;
}

static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
{
	struct kvm_cpuid_entry2 *entry;
	int r, i, max_idx;

	/* all calls to cpuid_count() should be made on the same cpu */
	get_cpu();

	r = -E2BIG;

	entry = do_host_cpuid(array, function, 0);
	if (!entry)
		goto out;

	switch (function) {
	case 0:
		/* Limited to the highest leaf implemented in KVM. */
		entry->eax = min(entry->eax, 0x24U);
		break;
	case 1:
		cpuid_entry_override(entry, CPUID_1_EDX);
		cpuid_entry_override(entry, CPUID_1_ECX);
		break;
	case 2:
		/*
		 * On ancient CPUs, function 2 entries are STATEFUL.  That is,
		 * CPUID(function=2, index=0) may return different results each
		 * time, with the least-significant byte in EAX enumerating the
		 * number of times software should do CPUID(2, 0).
		 *
		 * Modern CPUs, i.e. every CPU KVM has *ever* run on are less
		 * idiotic.  Intel's SDM states that EAX & 0xff "will always
		 * return 01H. Software should ignore this value and not
		 * interpret it as an informational descriptor", while AMD's
		 * APM states that CPUID(2) is reserved.
		 *
		 * WARN if a frankenstein CPU that supports virtualization and
		 * a stateful CPUID.0x2 is encountered.
		 */
		WARN_ON_ONCE((entry->eax & 0xff) > 1);
		break;
	/* functions 4 and 0x8000001d have additional index. */
	case 4:
	case 0x8000001d:
		/*
		 * Read entries until the cache type in the previous entry is
		 * zero, i.e. indicates an invalid entry.
		 */
		for (i = 1; entry->eax & 0x1f; ++i) {
			entry = do_host_cpuid(array, function, i);
			if (!entry)
				goto out;
		}
		break;
	case 6: /* Thermal management */
		entry->eax = 0x4; /* allow ARAT */
		entry->ebx = 0;
		entry->ecx = 0;
		entry->edx = 0;
		break;
	/* function 7 has additional index. */
	case 7:
		max_idx = entry->eax = min(entry->eax, 2u);
		cpuid_entry_override(entry, CPUID_7_0_EBX);
		cpuid_entry_override(entry, CPUID_7_ECX);
		cpuid_entry_override(entry, CPUID_7_EDX);

		/* KVM only supports up to 0x7.2, capped above via min(). */
		if (max_idx >= 1) {
			entry = do_host_cpuid(array, function, 1);
			if (!entry)
				goto out;

			cpuid_entry_override(entry, CPUID_7_1_EAX);
			cpuid_entry_override(entry, CPUID_7_1_EDX);
			entry->ebx = 0;
			entry->ecx = 0;
		}
		if (max_idx >= 2) {
			entry = do_host_cpuid(array, function, 2);
			if (!entry)
				goto out;

			cpuid_entry_override(entry, CPUID_7_2_EDX);
			entry->ecx = 0;
			entry->ebx = 0;
			entry->eax = 0;
		}
		break;
	case 0xa: { /* Architectural Performance Monitoring */
		union cpuid10_eax eax = { };
		union cpuid10_edx edx = { };

		if (!enable_pmu || !static_cpu_has(X86_FEATURE_ARCH_PERFMON)) {
			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
			break;
		}

		eax.split.version_id = kvm_pmu_cap.version;
		eax.split.num_counters = kvm_pmu_cap.num_counters_gp;
		eax.split.bit_width = kvm_pmu_cap.bit_width_gp;
		eax.split.mask_length = kvm_pmu_cap.events_mask_len;
		edx.split.num_counters_fixed = kvm_pmu_cap.num_counters_fixed;
		edx.split.bit_width_fixed = kvm_pmu_cap.bit_width_fixed;

		if (kvm_pmu_cap.version)
			edx.split.anythread_deprecated = 1;

		entry->eax = eax.full;
		entry->ebx = kvm_pmu_cap.events_mask;
		entry->ecx = 0;
		entry->edx = edx.full;
		break;
	}
	case 0x1f:
	case 0xb:
		/*
		 * No topology; a valid topology is indicated by the presence
		 * of subleaf 1.
		 */
		entry->eax = entry->ebx = entry->ecx = 0;
		break;
	case 0xd: {
		u64 permitted_xcr0 = kvm_get_filtered_xcr0();
		u64 permitted_xss = kvm_caps.supported_xss;

		entry->eax &= permitted_xcr0;
		entry->ebx = xstate_required_size(permitted_xcr0, false);
		entry->ecx = entry->ebx;
		entry->edx &= permitted_xcr0 >> 32;
		if (!permitted_xcr0)
			break;

		entry = do_host_cpuid(array, function, 1);
		if (!entry)
			goto out;

		cpuid_entry_override(entry, CPUID_D_1_EAX);
		if (entry->eax & (feature_bit(XSAVES) | feature_bit(XSAVEC)))
			entry->ebx = xstate_required_size(permitted_xcr0 | permitted_xss,
							  true);
		else {
			WARN_ON_ONCE(permitted_xss != 0);
			entry->ebx = 0;
		}
		entry->ecx &= permitted_xss;
		entry->edx &= permitted_xss >> 32;

		for (i = 2; i < 64; ++i) {
			bool s_state;
			if (permitted_xcr0 & BIT_ULL(i))
				s_state = false;
			else if (permitted_xss & BIT_ULL(i))
				s_state = true;
			else
				continue;

			entry = do_host_cpuid(array, function, i);
			if (!entry)
				goto out;

			/*
			 * The supported check above should have filtered out
			 * invalid sub-leafs.  Only valid sub-leafs should
			 * reach this point, and they should have a non-zero
			 * save state size.  Furthermore, check whether the
			 * processor agrees with permitted_xcr0/permitted_xss
			 * on whether this is an XCR0- or IA32_XSS-managed area.
			 */
			if (WARN_ON_ONCE(!entry->eax || (entry->ecx & 0x1) != s_state)) {
				--array->nent;
				continue;
			}

			if (!kvm_cpu_cap_has(X86_FEATURE_XFD))
				entry->ecx &= ~BIT_ULL(2);
			entry->edx = 0;
		}
		break;
	}
	case 0x12:
		/* Intel SGX */
		if (!kvm_cpu_cap_has(X86_FEATURE_SGX)) {
			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
			break;
		}

		/*
		 * Index 0: Sub-features, MISCSELECT (a.k.a extended features)
		 * and max enclave sizes.   The SGX sub-features and MISCSELECT
		 * are restricted by kernel and KVM capabilities (like most
		 * feature flags), while enclave size is unrestricted.
		 */
		cpuid_entry_override(entry, CPUID_12_EAX);
		entry->ebx &= SGX_MISC_EXINFO;

		entry = do_host_cpuid(array, function, 1);
		if (!entry)
			goto out;

		/*
		 * Index 1: SECS.ATTRIBUTES.  ATTRIBUTES are restricted a la
		 * feature flags.  Advertise all supported flags, including
		 * privileged attributes that require explicit opt-in from
		 * userspace.  ATTRIBUTES.XFRM is not adjusted as userspace is
		 * expected to derive it from supported XCR0.
		 */
		entry->eax &= SGX_ATTR_PRIV_MASK | SGX_ATTR_UNPRIV_MASK;
		entry->ebx &= 0;
		break;
	/* Intel PT */
	case 0x14:
		if (!kvm_cpu_cap_has(X86_FEATURE_INTEL_PT)) {
			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
			break;
		}

		for (i = 1, max_idx = entry->eax; i <= max_idx; ++i) {
			if (!do_host_cpuid(array, function, i))
				goto out;
		}
		break;
	/* Intel AMX TILE */
	case 0x1d:
		if (!kvm_cpu_cap_has(X86_FEATURE_AMX_TILE)) {
			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
			break;
		}

		for (i = 1, max_idx = entry->eax; i <= max_idx; ++i) {
			if (!do_host_cpuid(array, function, i))
				goto out;
		}
		break;
	case 0x1e: /* TMUL information */
		if (!kvm_cpu_cap_has(X86_FEATURE_AMX_TILE)) {
			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
			break;
		}
		break;
	case 0x24: {
		u8 avx10_version;

		if (!kvm_cpu_cap_has(X86_FEATURE_AVX10)) {
			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
			break;
		}

		/*
		 * The AVX10 version is encoded in EBX[7:0].  Note, the version
		 * is guaranteed to be >=1 if AVX10 is supported.  Note #2, the
		 * version needs to be captured before overriding EBX features!
		 */
		avx10_version = min_t(u8, entry->ebx & 0xff, 1);
		cpuid_entry_override(entry, CPUID_24_0_EBX);
		entry->ebx |= avx10_version;

		entry->eax = 0;
		entry->ecx = 0;
		entry->edx = 0;
		break;
	}
	case KVM_CPUID_SIGNATURE: {
		const u32 *sigptr = (const u32 *)KVM_SIGNATURE;
		entry->eax = KVM_CPUID_FEATURES;
		entry->ebx = sigptr[0];
		entry->ecx = sigptr[1];
		entry->edx = sigptr[2];
		break;
	}
	case KVM_CPUID_FEATURES:
		entry->eax = (1 << KVM_FEATURE_CLOCKSOURCE) |
			     (1 << KVM_FEATURE_NOP_IO_DELAY) |
			     (1 << KVM_FEATURE_CLOCKSOURCE2) |
			     (1 << KVM_FEATURE_ASYNC_PF) |
			     (1 << KVM_FEATURE_PV_EOI) |
			     (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
			     (1 << KVM_FEATURE_PV_UNHALT) |
			     (1 << KVM_FEATURE_PV_TLB_FLUSH) |
			     (1 << KVM_FEATURE_ASYNC_PF_VMEXIT) |
			     (1 << KVM_FEATURE_PV_SEND_IPI) |
			     (1 << KVM_FEATURE_POLL_CONTROL) |
			     (1 << KVM_FEATURE_PV_SCHED_YIELD) |
			     (1 << KVM_FEATURE_ASYNC_PF_INT);

		if (sched_info_on())
			entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);

		entry->ebx = 0;
		entry->ecx = 0;
		entry->edx = 0;
		break;
	case 0x80000000:
		entry->eax = min(entry->eax, 0x80000022);
		/*
		 * Serializing LFENCE is reported in a multitude of ways, and
		 * NullSegClearsBase is not reported in CPUID on Zen2; help
		 * userspace by providing the CPUID leaf ourselves.
		 *
		 * However, only do it if the host has CPUID leaf 0x8000001d.
		 * QEMU thinks that it can query the host blindly for that
		 * CPUID leaf if KVM reports that it supports 0x8000001d or
		 * above.  The processor merrily returns values from the
		 * highest Intel leaf which QEMU tries to use as the guest's
		 * 0x8000001d.  Even worse, this can result in an infinite
		 * loop if said highest leaf has no subleaves indexed by ECX.
		 */
		if (entry->eax >= 0x8000001d &&
		    (static_cpu_has(X86_FEATURE_LFENCE_RDTSC)
		     || !static_cpu_has_bug(X86_BUG_NULL_SEG)))
			entry->eax = max(entry->eax, 0x80000021);
		break;
	case 0x80000001:
		entry->ebx &= ~GENMASK(27, 16);
		cpuid_entry_override(entry, CPUID_8000_0001_EDX);
		cpuid_entry_override(entry, CPUID_8000_0001_ECX);
		break;
	case 0x80000005:
		/*  Pass host L1 cache and TLB info. */
		break;
	case 0x80000006:
		/* Drop reserved bits, pass host L2 cache and TLB info. */
		entry->edx &= ~GENMASK(17, 16);
		break;
	case 0x80000007: /* Advanced power management */
		cpuid_entry_override(entry, CPUID_8000_0007_EDX);

		/* mask against host */
		entry->edx &= boot_cpu_data.x86_power;
		entry->eax = entry->ebx = entry->ecx = 0;
		break;
	case 0x80000008: {
		/*
		 * GuestPhysAddrSize (EAX[23:16]) is intended for software
		 * use.
		 *
		 * KVM's ABI is to report the effective MAXPHYADDR for the
		 * guest in PhysAddrSize (phys_as), and the maximum
		 * *addressable* GPA in GuestPhysAddrSize (g_phys_as).
		 *
		 * GuestPhysAddrSize is valid if and only if TDP is enabled,
		 * in which case the max GPA that can be addressed by KVM may
		 * be less than the max GPA that can be legally generated by
		 * the guest, e.g. if MAXPHYADDR>48 but the CPU doesn't
		 * support 5-level TDP.
		 */
		unsigned int virt_as = max((entry->eax >> 8) & 0xff, 48U);
		unsigned int phys_as, g_phys_as;

		/*
		 * If TDP (NPT) is disabled use the adjusted host MAXPHYADDR as
		 * the guest operates in the same PA space as the host, i.e.
		 * reductions in MAXPHYADDR for memory encryption affect shadow
		 * paging, too.
		 *
		 * If TDP is enabled, use the raw bare metal MAXPHYADDR as
		 * reductions to the HPAs do not affect GPAs.  The max
		 * addressable GPA is the same as the max effective GPA, except
		 * that it's capped at 48 bits if 5-level TDP isn't supported
		 * (hardware processes bits 51:48 only when walking the fifth
		 * level page table).
		 */
		if (!tdp_enabled) {
			phys_as = boot_cpu_data.x86_phys_bits;
			g_phys_as = 0;
		} else {
			phys_as = entry->eax & 0xff;
			g_phys_as = phys_as;
			if (kvm_mmu_get_max_tdp_level() < 5)
				g_phys_as = min(g_phys_as, 48U);
		}

		entry->eax = phys_as | (virt_as << 8) | (g_phys_as << 16);
		entry->ecx &= ~(GENMASK(31, 16) | GENMASK(11, 8));
		entry->edx = 0;
		cpuid_entry_override(entry, CPUID_8000_0008_EBX);
		break;
	}
	case 0x8000000A:
		if (!kvm_cpu_cap_has(X86_FEATURE_SVM)) {
			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
			break;
		}
		entry->eax = 1; /* SVM revision 1 */
		entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper
				   ASID emulation to nested SVM */
		entry->ecx = 0; /* Reserved */
		cpuid_entry_override(entry, CPUID_8000_000A_EDX);
		break;
	case 0x80000019:
		entry->ecx = entry->edx = 0;
		break;
	case 0x8000001a:
		entry->eax &= GENMASK(2, 0);
		entry->ebx = entry->ecx = entry->edx = 0;
		break;
	case 0x8000001e:
		/* Do not return host topology information.  */
		entry->eax = entry->ebx = entry->ecx = 0;
		entry->edx = 0; /* reserved */
		break;
	case 0x8000001F:
		if (!kvm_cpu_cap_has(X86_FEATURE_SEV)) {
			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
		} else {
			cpuid_entry_override(entry, CPUID_8000_001F_EAX);
			/* Clear NumVMPL since KVM does not support VMPL.  */
			entry->ebx &= ~GENMASK(31, 12);
			/*
			 * Enumerate '0' for "PA bits reduction", the adjusted
			 * MAXPHYADDR is enumerated directly (see 0x80000008).
			 */
			entry->ebx &= ~GENMASK(11, 6);
		}
		break;
	case 0x80000020:
		entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
		break;
	case 0x80000021:
		entry->ebx = entry->edx = 0;
		cpuid_entry_override(entry, CPUID_8000_0021_EAX);
		cpuid_entry_override(entry, CPUID_8000_0021_ECX);
		break;
	/* AMD Extended Performance Monitoring and Debug */
	case 0x80000022: {
		union cpuid_0x80000022_ebx ebx = { };

		entry->ecx = entry->edx = 0;
		if (!enable_pmu || !kvm_cpu_cap_has(X86_FEATURE_PERFMON_V2)) {
			entry->eax = entry->ebx = 0;
			break;
		}

		cpuid_entry_override(entry, CPUID_8000_0022_EAX);

		ebx.split.num_core_pmc = kvm_pmu_cap.num_counters_gp;
		entry->ebx = ebx.full;
		break;
	}
	/*Add support for Centaur's CPUID instruction*/
	case 0xC0000000:
		/*Just support up to 0xC0000004 now*/
		entry->eax = min(entry->eax, 0xC0000004);
		break;
	case 0xC0000001:
		cpuid_entry_override(entry, CPUID_C000_0001_EDX);
		break;
	case 3: /* Processor serial number */
	case 5: /* MONITOR/MWAIT */
	case 0xC0000002:
	case 0xC0000003:
	case 0xC0000004:
	default:
		entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
		break;
	}

	r = 0;

out:
	put_cpu();

	return r;
}

static int do_cpuid_func(struct kvm_cpuid_array *array, u32 func,
			 unsigned int type)
{
	if (type == KVM_GET_EMULATED_CPUID)
		return __do_cpuid_func_emulated(array, func);

	return __do_cpuid_func(array, func);
}

#define CENTAUR_CPUID_SIGNATURE 0xC0000000

static int get_cpuid_func(struct kvm_cpuid_array *array, u32 func,
			  unsigned int type)
{
	u32 limit;
	int r;

	if (func == CENTAUR_CPUID_SIGNATURE &&
	    boot_cpu_data.x86_vendor != X86_VENDOR_CENTAUR)
		return 0;

	r = do_cpuid_func(array, func, type);
	if (r)
		return r;

	limit = array->entries[array->nent - 1].eax;
	for (func = func + 1; func <= limit; ++func) {
		r = do_cpuid_func(array, func, type);
		if (r)
			break;
	}

	return r;
}

static bool sanity_check_entries(struct kvm_cpuid_entry2 __user *entries,
				 __u32 num_entries, unsigned int ioctl_type)
{
	int i;
	__u32 pad[3];

	if (ioctl_type != KVM_GET_EMULATED_CPUID)
		return false;

	/*
	 * We want to make sure that ->padding is being passed clean from
	 * userspace in case we want to use it for something in the future.
	 *
	 * Sadly, this wasn't enforced for KVM_GET_SUPPORTED_CPUID and so we
	 * have to give ourselves satisfied only with the emulated side. /me
	 * sheds a tear.
	 */
	for (i = 0; i < num_entries; i++) {
		if (copy_from_user(pad, entries[i].padding, sizeof(pad)))
			return true;

		if (pad[0] || pad[1] || pad[2])
			return true;
	}
	return false;
}

int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
			    struct kvm_cpuid_entry2 __user *entries,
			    unsigned int type)
{
	static const u32 funcs[] = {
		0, 0x80000000, CENTAUR_CPUID_SIGNATURE, KVM_CPUID_SIGNATURE,
	};

	struct kvm_cpuid_array array = {
		.nent = 0,
	};
	int r, i;

	if (cpuid->nent < 1)
		return -E2BIG;
	if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
		cpuid->nent = KVM_MAX_CPUID_ENTRIES;

	if (sanity_check_entries(entries, cpuid->nent, type))
		return -EINVAL;

	array.entries = kvcalloc(cpuid->nent, sizeof(struct kvm_cpuid_entry2), GFP_KERNEL);
	if (!array.entries)
		return -ENOMEM;

	array.maxnent = cpuid->nent;

	for (i = 0; i < ARRAY_SIZE(funcs); i++) {
		r = get_cpuid_func(&array, funcs[i], type);
		if (r)
			goto out_free;
	}
	cpuid->nent = array.nent;

	if (copy_to_user(entries, array.entries,
			 array.nent * sizeof(struct kvm_cpuid_entry2)))
		r = -EFAULT;

out_free:
	kvfree(array.entries);
	return r;
}

/*
 * Intel CPUID semantics treats any query for an out-of-range leaf as if the
 * highest basic leaf (i.e. CPUID.0H:EAX) were requested.  AMD CPUID semantics
 * returns all zeroes for any undefined leaf, whether or not the leaf is in
 * range.  Centaur/VIA follows Intel semantics.
 *
 * A leaf is considered out-of-range if its function is higher than the maximum
 * supported leaf of its associated class or if its associated class does not
 * exist.
 *
 * There are three primary classes to be considered, with their respective
 * ranges described as "<base> - <top>[,<base2> - <top2>] inclusive.  A primary
 * class exists if a guest CPUID entry for its <base> leaf exists.  For a given
 * class, CPUID.<base>.EAX contains the max supported leaf for the class.
 *
 *  - Basic:      0x00000000 - 0x3fffffff, 0x50000000 - 0x7fffffff
 *  - Hypervisor: 0x40000000 - 0x4fffffff
 *  - Extended:   0x80000000 - 0xbfffffff
 *  - Centaur:    0xc0000000 - 0xcfffffff
 *
 * The Hypervisor class is further subdivided into sub-classes that each act as
 * their own independent class associated with a 0x100 byte range.  E.g. if Qemu
 * is advertising support for both HyperV and KVM, the resulting Hypervisor
 * CPUID sub-classes are:
 *
 *  - HyperV:     0x40000000 - 0x400000ff
 *  - KVM:        0x40000100 - 0x400001ff
 */
static struct kvm_cpuid_entry2 *
get_out_of_range_cpuid_entry(struct kvm_vcpu *vcpu, u32 *fn_ptr, u32 index)
{
	struct kvm_cpuid_entry2 *basic, *class;
	u32 function = *fn_ptr;

	basic = kvm_find_cpuid_entry(vcpu, 0);
	if (!basic)
		return NULL;

	if (is_guest_vendor_amd(basic->ebx, basic->ecx, basic->edx) ||
	    is_guest_vendor_hygon(basic->ebx, basic->ecx, basic->edx))
		return NULL;

	if (function >= 0x40000000 && function <= 0x4fffffff)
		class = kvm_find_cpuid_entry(vcpu, function & 0xffffff00);
	else if (function >= 0xc0000000)
		class = kvm_find_cpuid_entry(vcpu, 0xc0000000);
	else
		class = kvm_find_cpuid_entry(vcpu, function & 0x80000000);

	if (class && function <= class->eax)
		return NULL;

	/*
	 * Leaf specific adjustments are also applied when redirecting to the
	 * max basic entry, e.g. if the max basic leaf is 0xb but there is no
	 * entry for CPUID.0xb.index (see below), then the output value for EDX
	 * needs to be pulled from CPUID.0xb.1.
	 */
	*fn_ptr = basic->eax;

	/*
	 * The class does not exist or the requested function is out of range;
	 * the effective CPUID entry is the max basic leaf.  Note, the index of
	 * the original requested leaf is observed!
	 */
	return kvm_find_cpuid_entry_index(vcpu, basic->eax, index);
}

bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
	       u32 *ecx, u32 *edx, bool exact_only)
{
	u32 orig_function = *eax, function = *eax, index = *ecx;
	struct kvm_cpuid_entry2 *entry;
	bool exact, used_max_basic = false;

	if (vcpu->arch.cpuid_dynamic_bits_dirty)
		kvm_update_cpuid_runtime(vcpu);

	entry = kvm_find_cpuid_entry_index(vcpu, function, index);
	exact = !!entry;

	if (!entry && !exact_only) {
		entry = get_out_of_range_cpuid_entry(vcpu, &function, index);
		used_max_basic = !!entry;
	}

	if (entry) {
		*eax = entry->eax;
		*ebx = entry->ebx;
		*ecx = entry->ecx;
		*edx = entry->edx;
		if (function == 7 && index == 0) {
			u64 data;
			if ((*ebx & (feature_bit(RTM) | feature_bit(HLE))) &&
			    !__kvm_get_msr(vcpu, MSR_IA32_TSX_CTRL, &data, true) &&
			    (data & TSX_CTRL_CPUID_CLEAR))
				*ebx &= ~(feature_bit(RTM) | feature_bit(HLE));
		} else if (function == 0x80000007) {
			if (kvm_hv_invtsc_suppressed(vcpu))
				*edx &= ~feature_bit(CONSTANT_TSC);
		} else if (IS_ENABLED(CONFIG_KVM_XEN) &&
			   kvm_xen_is_tsc_leaf(vcpu, function)) {
			/*
			 * Update guest TSC frequency information if necessary.
			 * Ignore failures, there is no sane value that can be
			 * provided if KVM can't get the TSC frequency.
			 */
			if (kvm_check_request(KVM_REQ_CLOCK_UPDATE, vcpu))
				kvm_guest_time_update(vcpu);

			if (index == 1) {
				*ecx = vcpu->arch.pvclock_tsc_mul;
				*edx = vcpu->arch.pvclock_tsc_shift;
			} else if (index == 2) {
				*eax = vcpu->arch.hw_tsc_khz;
			}
		}
	} else {
		*eax = *ebx = *ecx = *edx = 0;
		/*
		 * When leaf 0BH or 1FH is defined, CL is pass-through
		 * and EDX is always the x2APIC ID, even for undefined
		 * subleaves. Index 1 will exist iff the leaf is
		 * implemented, so we pass through CL iff leaf 1
		 * exists. EDX can be copied from any existing index.
		 */
		if (function == 0xb || function == 0x1f) {
			entry = kvm_find_cpuid_entry_index(vcpu, function, 1);
			if (entry) {
				*ecx = index & 0xff;
				*edx = entry->edx;
			}
		}
	}
	trace_kvm_cpuid(orig_function, index, *eax, *ebx, *ecx, *edx, exact,
			used_max_basic);
	return exact;
}
EXPORT_SYMBOL_GPL(kvm_cpuid);

int kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
{
	u32 eax, ebx, ecx, edx;

	if (cpuid_fault_enabled(vcpu) && !kvm_require_cpl(vcpu, 0))
		return 1;

	eax = kvm_rax_read(vcpu);
	ecx = kvm_rcx_read(vcpu);
	kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx, false);
	kvm_rax_write(vcpu, eax);
	kvm_rbx_write(vcpu, ebx);
	kvm_rcx_write(vcpu, ecx);
	kvm_rdx_write(vcpu, edx);
	return kvm_skip_emulated_instruction(vcpu);
}
EXPORT_SYMBOL_GPL(kvm_emulate_cpuid);