linux-kernel - Re: [PATCH 11/11] KVM: selftests: Ensure KVM supports AVX for SEV-ES VMSA FPU test

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Message-ID: <87cykgi60q.fsf@redhat.com>
Date: Fri, 04 Oct 2024 11:14:45 +0200
From: Vitaly Kuznetsov <vkuznets@...hat.com>
To: Sean Christopherson <seanjc@...gle.com>, Sean Christopherson
 <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/11] KVM: selftests: Ensure KVM supports AVX for
 SEV-ES VMSA FPU test

Sean Christopherson <seanjc@...gle.com> writes:

> Verify that KVM's supported XCR0 includes AVX (and earlier features) when
> running the SEV-ES VMSA XSAVE test.  In practice, the issue will likely
> never pop up, since KVM support for AVX predates KVM support for SEV-ES,
> but checking for KVM support makes the requirement more obvious.
>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  tools/testing/selftests/kvm/x86_64/sev_smoke_test.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c
> index 965fc362dee3..ae77698e6e97 100644
> --- a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c
> @@ -181,6 +181,8 @@ static void test_sev_es_shutdown(void)
>  
>  int main(int argc, char *argv[])
>  {
> +	const u64 xf_mask = XFEATURE_MASK_X87_AVX;
> +
>  	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SEV));
>  
>  	test_sev(guest_sev_code, SEV_POLICY_NO_DBG);
> @@ -193,7 +195,7 @@ int main(int argc, char *argv[])
>  		test_sev_es_shutdown();
>  
>  		if (kvm_has_cap(KVM_CAP_XCRS) &&
> -		    (xgetbv(0) & XFEATURE_MASK_X87_AVX) == XFEATURE_MASK_X87_AVX) {
> +		    (xgetbv(0) & kvm_cpu_supported_xcr0() & xf_mask) == xf_mask) {
>  			test_sync_vmsa(0);
>  			test_sync_vmsa(SEV_POLICY_NO_DBG);
>  		}

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>

-- 
Vitaly