linux-kernel - Re: [PATCH v12 00/11] Guest Last Branch Recording Enabling

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Date:   Thu, 2 Jul 2020 09:40:59 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Like Xu <like.xu@...ux.intel.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, ak@...ux.intel.com,
        wei.w.wang@...el.com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, "Liang, Kan" <kan.liang@...el.com>
Subject: Re: [PATCH v12 00/11] Guest Last Branch Recording Enabling

On Sat, Jun 13, 2020 at 04:09:45PM +0800, Like Xu wrote:
> Like Xu (10):
>   perf/x86/core: Refactor hw->idx checks and cleanup
>   perf/x86/lbr: Add interface to get LBR information
>   perf/x86: Add constraint to create guest LBR event without hw counter
>   perf/x86: Keep LBR records unchanged in host context for guest usage

> Wei Wang (1):
>   perf/x86: Fix variable types for LBR registers

>  arch/x86/events/core.c            |  26 +--
>  arch/x86/events/intel/core.c      | 109 ++++++++-----
>  arch/x86/events/intel/lbr.c       |  51 +++++-
>  arch/x86/events/perf_event.h      |   8 +-
>  arch/x86/include/asm/perf_event.h |  34 +++-

These look good to me; but at the same time Kan is sending me
Architectural LBR patches.

Kan, if I take these perf patches and stick them in a tip/perf/vlbr
topic branch, can you rebase the arch lbr stuff on top, or is there
anything in the arch-lbr series that badly conflicts with this work?

Paolo, would that topic branch work for you too, to then stick these
patches in top?

>   KVM: vmx/pmu: Expose LBR to guest via MSR_IA32_PERF_CAPABILITIES
>   KVM: vmx/pmu: Unmask LBR fields in the MSR_IA32_DEBUGCTLMSR emualtion
>   KVM: vmx/pmu: Pass-through LBR msrs when guest LBR event is scheduled
>   KVM: vmx/pmu: Emulate legacy freezing LBRs on virtual PMI
>   KVM: vmx/pmu: Reduce the overhead of LBR pass-through or cancellation
>   KVM: vmx/pmu: Release guest LBR event via lazy release mechanism

>  arch/x86/kvm/pmu.c                |  12 +-
>  arch/x86/kvm/pmu.h                |   5 +
>  arch/x86/kvm/vmx/capabilities.h   |  23 ++-
>  arch/x86/kvm/vmx/pmu_intel.c      | 253 +++++++++++++++++++++++++++++-
>  arch/x86/kvm/vmx/vmx.c            |  86 +++++++++-
>  arch/x86/kvm/vmx/vmx.h            |  17 ++
>  arch/x86/kvm/x86.c                |  13 --

>  12 files changed, 559 insertions(+), 78 deletions(-)