[v1] SVM guest shadow stack support

[RFC PATCH 7/7] KVM: SVM: Add CET features to supported_xss

Posted by John Allen 3 years, 5 months ago

If the CPU supports CET, add CET XSAVES feature bits to the
supported_xss mask.

Signed-off-by: John Allen <john.allen@amd.com>
---
 arch/x86/kvm/svm/svm.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index b474c7e57139..b815865ad0fb 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -5026,6 +5026,11 @@ static __init void svm_set_cpu_caps(void)
 	    boot_cpu_has(X86_FEATURE_AMD_SSBD))
 		kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD);
 
+	if (kvm_cpu_cap_has(X86_FEATURE_SHSTK)) {
+		kvm_caps.supported_xss |= XFEATURE_MASK_CET_USER |
+					  XFEATURE_MASK_CET_KERNEL;
+	}
+
 	/* AMD PMU PERFCTR_CORE CPUID */
 	if (enable_pmu && boot_cpu_has(X86_FEATURE_PERFCTR_CORE))
 		kvm_cpu_cap_set(X86_FEATURE_PERFCTR_CORE);
-- 
2.34.3

Re: [RFC PATCH 7/7] KVM: SVM: Add CET features to supported_xss

Posted by Sean Christopherson 3 years, 2 months ago

On Wed, Oct 12, 2022, John Allen wrote:
> If the CPU supports CET, add CET XSAVES feature bits to the
> supported_xss mask.
> 
> Signed-off-by: John Allen <john.allen@amd.com>
> ---
>  arch/x86/kvm/svm/svm.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index b474c7e57139..b815865ad0fb 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -5026,6 +5026,11 @@ static __init void svm_set_cpu_caps(void)
>  	    boot_cpu_has(X86_FEATURE_AMD_SSBD))
>  		kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD);
>  
> +	if (kvm_cpu_cap_has(X86_FEATURE_SHSTK)) {

No need for curly braces.

> +		kvm_caps.supported_xss |= XFEATURE_MASK_CET_USER |
> +					  XFEATURE_MASK_CET_KERNEL;
> +	}
> +
>  	/* AMD PMU PERFCTR_CORE CPUID */
>  	if (enable_pmu && boot_cpu_has(X86_FEATURE_PERFCTR_CORE))
>  		kvm_cpu_cap_set(X86_FEATURE_PERFCTR_CORE);
> -- 
> 2.34.3
>