linux-kernel - Re: [PATCH] perf/x86: KVM: Disable vPMU support on hybrid CPUs (host PMUs)

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Message-ID: <8eda340a-8c5d-a801-54eb-501c44a68d89@linux.intel.com>
Date:   Tue, 24 Jan 2023 10:31:00 -0500
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Andi Kleen <ak@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>, linux-perf-users@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Jianfeng Gao <jianfeng.gao@...el.com>,
        Andrew Cooper <Andrew.Cooper3@...rix.com>
Subject: Re: [PATCH] perf/x86: KVM: Disable vPMU support on hybrid CPUs (host
 PMUs)



On 2023-01-23 8:04 p.m., Andi Kleen wrote:
> 
>> If I understand correct, the workaround in KVM is to add a white/black
>> list to filter the events. I think we can do the same thing for the
>> hybrid machine for now.
>> https://lore.kernel.org/lkml/CAOyeoRUUK+T_71J=+zcToyL93LkpARpsuWSfZS7jbJq=wd1rQg@mail.gmail.com/
> 
> 
> This will make everyone who actually wants to use the PMU sad.

Yes, but we still have all the architecture events work. I think it
should be good enough as a short-term solution, when the hybrid is not
completely supported in KVM.
> 
> It's reasonable if the vCPUs are not bound, but if they are bound it
> would be better to expose it with a suitable CPUID for the types.
> 

Yes, and also the CPUID leaf 0x23H support to enumerate the PMU features
of each types.


Thanks,
Kan