diff mbox series

[v3,1/4] KVM: SVM: Inject #GP on guest MSR_TSC_AUX accesses if RDTSCP unsupported

Message ID 20210423223404.3860547-2-seanjc@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: x86: MSR_TSC_AUX fixes and improvements | expand

Commit Message

Sean Christopherson April 23, 2021, 10:34 p.m. UTC
Inject #GP on guest accesses to MSR_TSC_AUX if RDTSCP is unsupported in
the guest's CPUID model.

Fixes: 46896c73c1a4 ("KVM: svm: add support for RDTSCP")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/svm/svm.c | 7 +++++++
 1 file changed, 7 insertions(+)

Comments

Vitaly Kuznetsov April 26, 2021, 8:49 a.m. UTC | #1
Sean Christopherson <seanjc@google.com> writes:

> Inject #GP on guest accesses to MSR_TSC_AUX if RDTSCP is unsupported in
> the guest's CPUID model.
>
> Fixes: 46896c73c1a4 ("KVM: svm: add support for RDTSCP")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  arch/x86/kvm/svm/svm.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index cd8c333ed2dc..9ed9c7bd7cfd 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -2674,6 +2674,9 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>  	case MSR_TSC_AUX:
>  		if (!boot_cpu_has(X86_FEATURE_RDTSCP))
>  			return 1;
> +		if (!msr_info->host_initiated &&
> +		    !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
> +			return 1;

Super-nit: a blank like before and after the condition would make this
consistent with the hunk you add to svm_set_msr() below.

>  		msr_info->data = svm->tsc_aux;
>  		break;
>  	/*
> @@ -2892,6 +2895,10 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
>  		if (!boot_cpu_has(X86_FEATURE_RDTSCP))
>  			return 1;
>  
> +		if (!msr->host_initiated &&
> +		    !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
> +			return 1;
> +
>  		/*
>  		 * This is rare, so we update the MSR here instead of using
>  		 * direct_access_msrs.  Doing that would require a rdmsr in

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
diff mbox series

Patch

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index cd8c333ed2dc..9ed9c7bd7cfd 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2674,6 +2674,9 @@  static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	case MSR_TSC_AUX:
 		if (!boot_cpu_has(X86_FEATURE_RDTSCP))
 			return 1;
+		if (!msr_info->host_initiated &&
+		    !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
+			return 1;
 		msr_info->data = svm->tsc_aux;
 		break;
 	/*
@@ -2892,6 +2895,10 @@  static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 		if (!boot_cpu_has(X86_FEATURE_RDTSCP))
 			return 1;
 
+		if (!msr->host_initiated &&
+		    !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
+			return 1;
+
 		/*
 		 * This is rare, so we update the MSR here instead of using
 		 * direct_access_msrs.  Doing that would require a rdmsr in