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

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Message-ID: <20210406124746.ji5iqladdlh73mok@two.firstfloor.org>
Date:   Tue, 6 Apr 2021 05:47:46 -0700
From:   Andi Kleen <andi@...stfloor.org>
To:     "Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.)" 
        <liuxiangdong5@...wei.com>
Cc:     like.xu@...ux.intel.com, andi@...stfloor.org,
        "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

> 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.

> Besides, we have tried this patches set in Icelake.  We can use pebs(eg:
> "perf record -e cycles:pp")
> when guest is kernel-5.11, but can't when kernel-4.18.  Is there a minimum
> guest kernel version requirement?

You would need a guest kernel that supports Icelake server PEBS. 4.18
would need backports for tht.


-Andi