linux-kernel - Re: [PATCH 07/11] KVM: selftests: Drop manual CR4.OSXSAVE enabling from CR4/CPUID sync test

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Message-ID: <87ldz4i6gf.fsf@redhat.com>
Date: Fri, 04 Oct 2024 11:05:20 +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 07/11] KVM: selftests: Drop manual CR4.OSXSAVE enabling
 from CR4/CPUID sync test

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

> Now that CR4.OSXSAVE is enabled by default, drop the manual enabling from
> CR4/CPUID sync test and instead assert that CR4.OSXSAVE is enabled.
>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c b/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c
> index da818afb7031..28cc66454601 100644
> --- a/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c
> @@ -27,12 +27,9 @@ static void guest_code(void)
>  		[KVM_CPUID_EAX] = X86_FEATURE_OSXSAVE.function,
>  		[KVM_CPUID_ECX] = X86_FEATURE_OSXSAVE.index,
>  	};
> -	uint64_t cr4;
>  
> -	/* turn on CR4.OSXSAVE */
> -	cr4 = get_cr4();
> -	cr4 |= X86_CR4_OSXSAVE;
> -	set_cr4(cr4);
> +	/* CR4.OSXSAVE should be enabled by default (for selftests vCPUs). */
> +	GUEST_ASSERT(get_cr4() & X86_CR4_OSXSAVE);
>  
>  	/* verify CR4.OSXSAVE == CPUID.OSXSAVE */
>  	GUEST_ASSERT(this_cpu_has(X86_FEATURE_OSXSAVE));

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

-- 
Vitaly