linux-kernel - Re: [PATCH v4 01/16] perf/x86/intel: Add x86_pmu.pebs

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Message-ID: <20210407143227.xoue623sigpx57c3@two.firstfloor.org>
Date:   Wed, 7 Apr 2021 07:32:27 -0700
From:   Andi Kleen <andi@...stfloor.org>
To:     "Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.)" 
        <liuxiangdong5@...wei.com>
Cc:     Andi Kleen <andi@...stfloor.org>, like.xu@...ux.intel.com,
        "Fangyi (Eric)" <eric.fangyi@...wei.com>,
        Xiexiangyou <xiexiangyou@...wei.com>, kan.liang@...ux.intel.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        wei.w.wang@...el.com, x86@...nel.org
Subject: Re: [PATCH v4 01/16] perf/x86/intel: Add x86_pmu.pebs_vmx for Ice
 Lake Servers

On Wed, Apr 07, 2021 at 11:05:20AM +0800, Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.) wrote:
> 
> 
> On 2021/4/6 20:47, Andi Kleen wrote:
> > > AFAIK， Icelake supports adaptive PEBS and extended PEBS which Skylake
> > > doesn't.
> > > But we can still use IA32_PEBS_ENABLE MSR to indicate general-purpose
> > > counter in Skylake.
> > > Is there anything else that only Icelake supports in this patches set?
> > Only Icelake server has the support for recovering from a EPT violation
> > on the PEBS data structures. To use it on Skylake server you would
> > need to pin the whole guest, but that is currently not done.
> Sorry. Some questions about "Pin the whole guest". Do you mean VmPin equals
> VmSize
> in "/proc/$(pidof qemu-kvm)/status"? Or just VmLck equals VmSize? Or
> something else?

Either would be sufficient. All that matters is that the EPT pages don't get
unmapped ever while PEBS is active.

-Andi