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linux/arch/x86/kvm/cpuid.c
Paolo Bonzini ee3a66f431 kvm: x86: SRSO_USER_KERNEL_NO is not synthesized 
SYNTHESIZED_F() generally is used together with setup_force_cpu_cap(),
i.e. when it makes sense to present the feature even if cpuid does not
have it *and* the VM is not able to see the difference.  For example,
it can be used when mitigations on the host automatically protect
the guest as well.

The "SYNTHESIZED_F(SRSO_USER_KERNEL_NO)" line came in as a conflict
resolution between the CPUID overhaul from the KVM tree and support
for the feature in the x86 tree.  Using it right now does not hurt,
or make a difference for that matter, because there is no
setup_force_cpu_cap(X86_FEATURE_SRSO_USER_KERNEL_NO).  However, it
is a little less future proof in case such a setup_force_cpu_cap()
appears later, for a case where the kernel somehow is not vulnerable
but the guest would have to apply the mitigation.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-02-04 11:13:24 -05:00

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// 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.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)
{
int feature_bit = 0;
u32 ret = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;
xstate_bv &= XFEATURE_MASK_EXTEND;
while (xstate_bv) {
if (xstate_bv & 0x1) {
struct cpuid_xstate_sizes *xs = &xstate_sizes[feature_bit];
u32 offset;
/* 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 >>= 1;
feature_bit++;
}
return ret;
}
/*
* Magic value used by KVM when querying userspace-provided CPUID entries and
* doesn't care about the CPIUD index because the index of the function in
* question is not significant. Note, this magic value must have at least one
* bit set in bits[63:32] and must be consumed as a u64 by cpuid_entry2_find()
* to avoid false positives when processing guest CPUID input.
*/
#define KVM_CPUID_INDEX_NOT_SIGNIFICANT -1ull
static struct kvm_cpuid_entry2 *cpuid_entry2_find(struct kvm_vcpu *vcpu,
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 < vcpu->arch.cpuid_nent; i++) {
e = &vcpu->arch.cpuid_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;
}
struct kvm_cpuid_entry2 *kvm_find_cpuid_entry_index(struct kvm_vcpu *vcpu,
u32 function, u32 index)
{
return cpuid_entry2_find(vcpu, function, index);
}
EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry_index);
struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
u32 function)
{
return cpuid_entry2_find(vcpu, function, KVM_CPUID_INDEX_NOT_SIGNIFICANT);
}
EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
/*
* cpuid_entry2_find() and KVM_CPUID_INDEX_NOT_SIGNIFICANT should never be used
* directly outside of kvm_find_cpuid_entry() and kvm_find_cpuid_entry_index().
*/
#undef KVM_CPUID_INDEX_NOT_SIGNIFICANT
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);
/* 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_hypervisor_cpuid_base(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);
}
void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
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);
}
EXPORT_SYMBOL_GPL(kvm_update_cpuid_runtime);
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;
}
/*
* 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 (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(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_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),
/*
* 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 */
F(NULL_SEL_CLR_BASE),
F(AUTOIBRS),
EMULATED_F(NO_SMM_CTL_MSR),
/* PrefetchCtlMsr */
F(WRMSR_XX_BASE_NS),
SYNTHESIZED_F(SBPB),
SYNTHESIZED_F(IBPB_BRTYPE),
SYNTHESIZED_F(SRSO_NO),
F(SRSO_USER_KERNEL_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;
edx.split.reserved1 = 0;
edx.split.reserved2 = 0;
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, 48);
}
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->ecx = entry->edx = 0;
cpuid_entry_override(entry, CPUID_8000_0021_EAX);
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;
break;
}
cpuid_entry_override(entry, CPUID_8000_0022_EAX);
if (kvm_cpu_cap_has(X86_FEATURE_PERFMON_V2))
ebx.split.num_core_pmc = kvm_pmu_cap.num_counters_gp;
else if (kvm_cpu_cap_has(X86_FEATURE_PERFCTR_CORE))
ebx.split.num_core_pmc = AMD64_NUM_COUNTERS_CORE;
else
ebx.split.num_core_pmc = AMD64_NUM_COUNTERS;
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;
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 (!__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 {
*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);
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