linux-kernel - Re: [PATCH] KVM: x86/pmu: Clear anythread deprecated bit when 0xa leaf is unsupported on the SVM

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Message-ID: <7f5d7af0-a48e-5bca-34e2-2a6f2bdab448@redhat.com>
Date:   Thu, 8 Jul 2021 18:44:11 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Like Xu <like.xu.linux@...il.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Stephane Eranian <eranian@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: x86/pmu: Clear anythread deprecated bit when 0xa
 leaf is unsupported on the SVM

On 28/06/21 09:43, Like Xu wrote:
> The AMD platform does not support the functions Ah CPUID leaf. The returned
> results for this entry should all remain zero just like the native does:
> 
> AMD host:
>     0x0000000a 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 edx=0x00000000
> (uncanny) AMD guest:
>     0x0000000a 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 edx=0x00008000
> 
> Fixes: cadbaa039b99 ("perf/x86/intel: Make anythread filter support conditional")
> Signed-off-by: Like Xu <likexu@...cent.com>
> ---
>   arch/x86/kvm/cpuid.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 0edda1fc4fe7..b1808e4fc7d5 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -765,7 +765,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
>   
>   		edx.split.num_counters_fixed = min(cap.num_counters_fixed, MAX_FIXED_COUNTERS);
>   		edx.split.bit_width_fixed = cap.bit_width_fixed;
> -		edx.split.anythread_deprecated = 1;
> +		if (cap.version)
> +			edx.split.anythread_deprecated = 1;
>   		edx.split.reserved1 = 0;
>   		edx.split.reserved2 = 0;
>   
> 

Queued, thanks.

Paolo