linux-kernel - Re: [PATCH v3 0/8] KVM: x86: Add AMD Guest PerfMonV2 PMU support

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Date:   Tue, 6 Dec 2022 16:32:17 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sean Christopherson <seanjc@...gle.com>
Subject: Re: [PATCH v3 0/8] KVM: x86: Add AMD Guest PerfMonV2 PMU support

Any comments to move it forward ?

On 11/11/2022 6:26 pm, Like Xu wrote:
> Starting with Zen4, core PMU on AMD platforms such as Genoa and
> Ryzen-7000 will support PerfMonV2, and it is also compatible with
> legacy PERFCTR_CORE behavior and msr addresses.
> 
> If you don't have access to the hardware specification, the commits
> d6d0c7f681fd..7685665c390d for host perf can also bring a quick
> overview. Its main change is the addition of three msr's equivalent
> to Intel V2, namely global_ctrl, global_status, global_status_clear.
> 
> It is worth noting that this feature is very attractive for reducing the
> overhead of PMU virtualization, since multiple msr accesses to multiple
> counters will be replaced by a single access to the global register,
> plus more accuracy gain when multiple guest counters are used.
> 
> All related testcases are passed on a Genoa box.
> Please feel free to run more tests, add more or share comments.
> 
> Previous:
> https://lore.kernel.org/kvm/20220919093453.71737-1-likexu@tencent.com/
> 
> V2 -> V3 Changelog:
> - Renme pmc_is_enabled(); (Jim)
> - Move the reprogram_counters() changes as a separate patch; (Jim)
> - Refactoring to align with other set_msr() helper; (Sean)
> - Fix the issue if userspace wants to expose v1 for whatever reason; (Sean)
> - Add the feature flag X86_FEATURE_AMD_PMU_V2; (Sean)
> - Check enable_pmu for intel 0xa as well; (Sean)
> - Limit AMD pmu's KVM support to version 2 as well;
> - Other nit changes around C code taste; (Sean)
> 
> Like Xu (7):
>    KVM: x86/pmu: Rename pmc_is_enabled() to pmc_is_globally_enabled()
>    KVM: x86/pmu: Rewrite reprogram_counters() to improve performance
>    KVM: x86/pmu: Make part of the Intel v2 PMU MSRs handling x86 generic
>    KVM: x86/cpuid: Add X86_FEATURE_AMD_PMU_V2 as a KVM-only leaf entry
>    KVM: x86/svm/pmu: Add AMD PerfMonV2 support
>    KVM: x86/cpuid: Add AMD CPUID ExtPerfMonAndDbg leaf 0x80000022
>    KVM: x86/cpuid: Use fast return for cpuid "0xa" leaf when !enable_pmu
> 
> Sean Christopherson (1):
>    KVM: VMX: Refactor intel_pmu_set_msr() to align with other set_msr()
>      helpers
> 
>   arch/x86/include/asm/kvm-x86-pmu-ops.h |   1 -
>   arch/x86/include/asm/kvm_host.h        |   1 +
>   arch/x86/kvm/cpuid.c                   |  32 ++++++-
>   arch/x86/kvm/pmu.c                     |  65 +++++++++++++--
>   arch/x86/kvm/pmu.h                     |  28 ++++++-
>   arch/x86/kvm/reverse_cpuid.h           |  10 +++
>   arch/x86/kvm/svm/pmu.c                 |  73 +++++++++++-----
>   arch/x86/kvm/svm/svm.c                 |  11 ++-
>   arch/x86/kvm/vmx/pmu_intel.c           | 111 +++++++------------------
>   arch/x86/kvm/x86.c                     |  14 +++-
>   10 files changed, 228 insertions(+), 118 deletions(-)
>