kvm_cpuid_check_equal() checks for the (full) equality of the supplied
CPUID data so .flags need to be checked too.

Reported-by: Sean Christopherson <seanjc@google.com>
Fixes: c6617c61e8fe ("KVM: x86: Partially allow KVM_SET_CPUID{,2} after KVM_RUN")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/kvm/cpuid.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 89d7822a8f5b..ddfd97f62ba8 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -133,6 +133,7 @@ static int kvm_cpuid_check_equal(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2
 		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;
-- 
2.34.1

On 1/26/22 14:18, Vitaly Kuznetsov wrote:
> kvm_cpuid_check_equal() checks for the (full) equality of the supplied
> CPUID data so .flags need to be checked too.
> 
> Reported-by: Sean Christopherson <seanjc@google.com>
> Fixes: c6617c61e8fe ("KVM: x86: Partially allow KVM_SET_CPUID{,2} after KVM_RUN")
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
>   arch/x86/kvm/cpuid.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 89d7822a8f5b..ddfd97f62ba8 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -133,6 +133,7 @@ static int kvm_cpuid_check_equal(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2
>   		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;

Queued, with Cc to stable.

Paolo