commit ee3a5f9e3d9bf94159f3cc80da542fbe83502dd8 upstream.
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@xxxxxxxxxx>
Message-Id: <20220117150542.2176196-2-vkuznets@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 54 ++++++++++++++++++++++++++++----------------
1 file changed, 34 insertions(+), 20 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 07e9215e911d..c4d4c350afbe 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -125,14 +125,21 @@ 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)
@@ -147,11 +154,12 @@ 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))
@@ -162,33 +170,38 @@ 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)
@@ -276,21 +289,22 @@ u64 kvm_vcpu_reserved_gpa_bits_raw(struct kvm_vcpu *vcpu)
static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
int nent)
{
- int r;
+ int r;
- r = kvm_check_cpuid(e2, nent);
- if (r)
- return r;
+ __kvm_update_cpuid_runtime(vcpu, e2, nent);
- kvfree(vcpu->arch.cpuid_entries);
- vcpu->arch.cpuid_entries = e2;
- vcpu->arch.cpuid_nent = nent;
+ r = kvm_check_cpuid(e2, nent);
+ if (r)
+ return r;
- kvm_update_kvm_cpuid_base(vcpu);
- kvm_update_cpuid_runtime(vcpu);
- kvm_vcpu_after_set_cpuid(vcpu);
+ kvfree(vcpu->arch.cpuid_entries);
+ vcpu->arch.cpuid_entries = e2;
+ vcpu->arch.cpuid_nent = nent;
- return 0;
+ kvm_update_kvm_cpuid_base(vcpu);
+ kvm_vcpu_after_set_cpuid(vcpu);
+
+ return 0;
}
/* when an old userspace process fills a new kernel module */
--
2.34.1
