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KVM: x86: Do runtime CPUID update before updating vcpu->arch.cpuid_entries

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kvm_update_cpuid_runtime() mangles CPUID data coming from userspace
VMM after updating 'vcpu->arch.cpuid_entries', this makes it
impossible to compare an update with what was previously
supplied. Introduce __kvm_update_cpuid_runtime() version which can be
used to tweak the input before it goes to 'vcpu->arch.cpuid_entries'
so the upcoming update check can compare tweaked data.

No functional change intended.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220117150542.2176196-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2022-01-17 16:05:39 +01:00 committed by Paolo Bonzini
parent a21864486f
commit ee3a5f9e3d
1 changed files with 24 additions and 10 deletions
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34
arch/x86/kvm/cpuid.c
View file

@ -145,14 +145,21 @@ static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu)
}
}
static struct kvm_cpuid_entry2 *kvm_find_kvm_cpuid_features(struct kvm_vcpu *vcpu)
static struct kvm_cpuid_entry2 *__kvm_find_kvm_cpuid_features(struct kvm_vcpu *vcpu,
struct kvm_cpuid_entry2 *entries, int nent)
{
u32 base = vcpu->arch.kvm_cpuid_base;
if (!base)
return NULL;
return kvm_find_cpuid_entry(vcpu, base | KVM_CPUID_FEATURES, 0);
return cpuid_entry2_find(entries, nent, base | KVM_CPUID_FEATURES, 0);
}
static struct kvm_cpuid_entry2 *kvm_find_kvm_cpuid_features(struct kvm_vcpu *vcpu)
{
return __kvm_find_kvm_cpuid_features(vcpu, vcpu->arch.cpuid_entries,
vcpu->arch.cpuid_nent);
}
void kvm_update_pv_runtime(struct kvm_vcpu *vcpu)
@ -167,11 +174,12 @@ void kvm_update_pv_runtime(struct kvm_vcpu *vcpu)
vcpu->arch.pv_cpuid.features = best->eax;
}
void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
static void __kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *entries,
int nent)
{
struct kvm_cpuid_entry2 *best;
best = kvm_find_cpuid_entry(vcpu, 1, 0);
best = cpuid_entry2_find(entries, nent, 1, 0);
if (best) {
/* Update OSXSAVE bit */
if (boot_cpu_has(X86_FEATURE_XSAVE))
@ -182,33 +190,38 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
}
best = kvm_find_cpuid_entry(vcpu, 7, 0);
best = cpuid_entry2_find(entries, nent, 7, 0);
if (best && boot_cpu_has(X86_FEATURE_PKU) && best->function == 0x7)
cpuid_entry_change(best, X86_FEATURE_OSPKE,
kvm_read_cr4_bits(vcpu, X86_CR4_PKE));
best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
best = cpuid_entry2_find(entries, nent, 0xD, 0);
if (best)
best->ebx = xstate_required_size(vcpu->arch.xcr0, false);
best = kvm_find_cpuid_entry(vcpu, 0xD, 1);
best = cpuid_entry2_find(entries, nent, 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);
best = kvm_find_kvm_cpuid_features(vcpu);
best = __kvm_find_kvm_cpuid_features(vcpu, entries, nent);
if (kvm_hlt_in_guest(vcpu->kvm) && best &&
(best->eax & (1 << KVM_FEATURE_PV_UNHALT)))
best->eax &= ~(1 << KVM_FEATURE_PV_UNHALT);
if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT)) {
best = kvm_find_cpuid_entry(vcpu, 0x1, 0);
best = cpuid_entry2_find(entries, nent, 0x1, 0);
if (best)
cpuid_entry_change(best, X86_FEATURE_MWAIT,
vcpu->arch.ia32_misc_enable_msr &
MSR_IA32_MISC_ENABLE_MWAIT);
}
}
void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
{
__kvm_update_cpuid_runtime(vcpu, vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent);
}
EXPORT_SYMBOL_GPL(kvm_update_cpuid_runtime);
static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
@ -298,6 +311,8 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
{
int r;
__kvm_update_cpuid_runtime(vcpu, e2, nent);
r = kvm_check_cpuid(vcpu, e2, nent);
if (r)
return r;
@ -307,7 +322,6 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
vcpu->arch.cpuid_nent = nent;
kvm_update_kvm_cpuid_base(vcpu);
kvm_update_cpuid_runtime(vcpu);
kvm_vcpu_after_set_cpuid(vcpu);
return 0;