linux-kernel - Re: [PATCH v3 09/11] KVM: selftests: Add x86 feature and properties for AMD PMU in processor.h

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Date:   Thu, 17 Aug 2023 16:26:26 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Jinrong Liang <ljr.kernel@...il.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, Like Xu <likexu@...cent.com>,
        David Matlack <dmatlack@...gle.com>,
        Aaron Lewis <aaronlewis@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jinrong Liang <cloudliang@...cent.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 09/11] KVM: selftests: Add x86 feature and properties
 for AMD PMU in processor.h

On Mon, Aug 14, 2023, Jinrong Liang wrote:
> From: Jinrong Liang <cloudliang@...cent.com>
> 
> Add x86 feature and properties for AMD PMU so that tests don't have
> to manually retrieve the correct CPUID leaf+register, and so that the
> resulting code is self-documenting.
> 
> Signed-off-by: Jinrong Liang <cloudliang@...cent.com>
> ---
>  tools/testing/selftests/kvm/include/x86_64/processor.h | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
> index 6b146e1c6736..07b980b8bec2 100644
> --- a/tools/testing/selftests/kvm/include/x86_64/processor.h
> +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
> @@ -167,6 +167,7 @@ struct kvm_x86_cpu_feature {
>   */
>  #define	X86_FEATURE_SVM			KVM_X86_CPU_FEATURE(0x80000001, 0, ECX, 2)
>  #define	X86_FEATURE_NX			KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 20)
> +#define	X86_FEATURE_AMD_PMU_EXT_CORE	KVM_X86_CPU_FEATURE(0x80000001, 0, ECX, 23)

I think it makes sense to follow the kernel, even though I find the kernel name
a bit funky in this case.  I.e. X86_FEATURE_PERFCTR_CORE

>  #define	X86_FEATURE_GBPAGES		KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 26)
>  #define	X86_FEATURE_RDTSCP		KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 27)
>  #define	X86_FEATURE_LM			KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 29)
> @@ -182,6 +183,9 @@ struct kvm_x86_cpu_feature {
>  #define	X86_FEATURE_VGIF		KVM_X86_CPU_FEATURE(0x8000000A, 0, EDX, 16)
>  #define X86_FEATURE_SEV			KVM_X86_CPU_FEATURE(0x8000001F, 0, EAX, 1)
>  #define X86_FEATURE_SEV_ES		KVM_X86_CPU_FEATURE(0x8000001F, 0, EAX, 3)
> +#define X86_FEATURE_AMD_PERFMON_V2	KVM_X86_CPU_FEATURE(0x80000022, 0, EAX, 0)

X86_FEATURE_PERFMON_V2

> +#define X86_FEATURE_AMD_LBR_STACK	KVM_X86_CPU_FEATURE(0x80000022, 0, EAX, 1)

Eh, I'd drop the "AMD".

> +#define X86_FEATURE_AMD_LBR_PMC_FREEZE	KVM_X86_CPU_FEATURE(0x80000022, 0, EAX, 2)

Same here.

>  /*
>   * KVM defined paravirt features.
> @@ -267,6 +271,9 @@ struct kvm_x86_cpu_property {
>  #define X86_PROPERTY_MAX_VIRT_ADDR		KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 8, 15)
>  #define X86_PROPERTY_PHYS_ADDR_REDUCTION	KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 6, 11)
>  
> +#define X86_PROPERTY_AMD_PMU_NR_CORE_COUNTERS	KVM_X86_CPU_PROPERTY(0x80000022, 0, EBX, 0, 3)
> +#define X86_PROPERTY_AMD_PMU_LBR_STACK_SIZE	KVM_X86_CPU_PROPERTY(0x80000022, 0, EBX, 4, 9)

And here.  I think we can get away with "GP and fixed counters means Intel, core
counters means AMD", at least as far as X86_FEATURES go.  LBRs might be a different
story, but so long as there's no conflict....

Splattering AMD everywhere but not Intel everywhere bugs me :-)

> +
>  #define X86_PROPERTY_MAX_CENTAUR_LEAF		KVM_X86_CPU_PROPERTY(0xC0000000, 0, EAX, 0, 31)
>  
>  /*
> -- 
> 2.39.3
>