linux-kernel - Re: [PATCH v5 0/5] perf/x86: Some minor changes to support guest Arch LBR

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Date:   Fri, 9 Apr 2021 16:51:02 +0800
From:   Like Xu <like.xu@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     pbonzini@...hat.com, Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Kan Liang <kan.liang@...ux.intel.com>, wei.w.wang@...el.com,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH v5 0/5] perf/x86: Some minor changes to support guest Arch
 LBR

Em, does anyone want to review these minor changes？

I believe some of them solve the real problem.

On 2021/4/6 11:20, Like Xu wrote:
> Hi all, do we have any comments on this patch set?
> 
> On 2021/3/26 9:19, Like Xu wrote:
>> Hi Peter,
>>
>> Please help review these minor perf/x86 changes in this patch set,
>> and we need some of them to support Guest Architectural LBR in KVM.
>>
>> This version keeps reserve_lbr_buffers() as is because the LBR xsave
>> buffer is a per-CPU buffer, not a per-event buffer. We only need to
>> allocate the buffer once when initializing the first event.
>>
>> If you are interested in the KVM emulation, please check
>> https://lore.kernel.org/kvm/20210314155225.206661-1-like.xu@linux.intel.com/
>>
>> Please check more details in each commit and feel free to comment.
>>
>> Previous:
>> https://lore.kernel.org/lkml/20210322060635.821531-1-like.xu@linux.intel.com/ 
>>
>>
>> v4->v5 Changelog:
>> - Add "Tested-by: Kan Liang"
>> - Make the commit message simpler
>> - Make check_msr() to ignore msr==0
>> - Use kmem_cache_alloc_node() [Namhyung]
>>
>> Like Xu (5):
>>    perf/x86/intel: Fix the comment about guest LBR support on KVM
>>    perf/x86/lbr: Simplify the exposure check for the LBR_INFO registers
>>    perf/x86: Skip checking MSR for MSR 0x000
>>    perf/x86/lbr: Move cpuc->lbr_xsave allocation out of sleeping region
>>    perf/x86: Move ARCH_LBR_CTL_MASK definition to include/asm/msr-index.h
>>
>>   arch/x86/events/core.c           |  8 +++++---
>>   arch/x86/events/intel/bts.c      |  2 +-
>>   arch/x86/events/intel/core.c     |  7 +++----
>>   arch/x86/events/intel/lbr.c      | 29 ++++++++++++++++++-----------
>>   arch/x86/events/perf_event.h     |  8 +++++++-
>>   arch/x86/include/asm/msr-index.h |  1 +
>>   6 files changed, 35 insertions(+), 20 deletions(-)
>>
>