linux-kernel - Re: [PATCH v2 3/3] KVM: x86/cpuid: Add AMD CPUID ExtPerfMonAndDbg leaf 0x80000022

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Date:   Tue, 20 Sep 2022 17:02:46 -0700
From:   Jim Mattson <jmattson@...gle.com>
To:     Like Xu <like.xu.linux@...il.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Sandipan Das <sandipan.das@....com>
Subject: Re: [PATCH v2 3/3] KVM: x86/cpuid: Add AMD CPUID ExtPerfMonAndDbg
 leaf 0x80000022

On Mon, Sep 19, 2022 at 2:35 AM Like Xu <like.xu.linux@...il.com> wrote:
>
> From: Sandipan Das <sandipan.das@....com>
>
> From: Sandipan Das <sandipan.das@....com>
>
> CPUID leaf 0x80000022 i.e. ExtPerfMonAndDbg advertises some
> new performance monitoring features for AMD processors.
>
> Bit 0 of EAX indicates support for Performance Monitoring
> Version 2 (PerfMonV2) features. If found to be set during
> PMU initialization, the EBX bits of the same CPUID function
> can be used to determine the number of available PMCs for
> different PMU types.
>
> Expose the relevant bits via KVM_GET_SUPPORTED_CPUID so
> that guests can make use of the PerfMonV2 features.
>
> Co-developed-by: Like Xu <likexu@...cent.com>
> Signed-off-by: Like Xu <likexu@...cent.com>
> Signed-off-by: Sandipan Das <sandipan.das@....com>
Reviewed-by: Jim Mattson <jmattson@...gle.com>