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Date:   Wed, 7 Apr 2021 07:32:27 -0700
From:   Andi Kleen <andi@firstfloor.org>
To:     "Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.)" 
        <liuxiangdong5@huawei.com>
Cc:     Andi Kleen <andi@firstfloor.org>, like.xu@linux.intel.com,
        "Fangyi (Eric)" <eric.fangyi@huawei.com>,
        Xiexiangyou <xiexiangyou@huawei.com>, kan.liang@linux.intel.com,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        wei.w.wang@intel.com, x86@kernel.org
Subject: Re: [PATCH v4 01/16] perf/x86/intel: Add x86_pmu.pebs_vmx for Ice
 Lake Servers
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 <606BD46F.7050903@huawei.com>
 <20210406124746.ji5iqladdlh73mok@two.firstfloor.org>
 <606D2170.6020203@huawei.com>
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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