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Date:   Mon, 2 Oct 2023 14:29:09 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Ravi Bangoria <ravi.bangoria@amd.com>
Cc:     Sean Christopherson <seanjc@google.com>,
        Dapeng Mi <dapeng1.mi@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Kan Liang <kan.liang@linux.intel.com>,
        Like Xu <likexu@tencent.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Ian Rogers <irogers@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>, kvm@vger.kernel.org,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
        Zhenyu Wang <zhenyuw@linux.intel.com>,
        Zhang Xiong <xiong.y.zhang@intel.com>,
        Lv Zhiyuan <zhiyuan.lv@intel.com>,
        Yang Weijiang <weijiang.yang@intel.com>,
        Dapeng Mi <dapeng1.mi@intel.com>,
        Jim Mattson <jmattson@google.com>,
        David Dunn <daviddunn@google.com>,
        Mingwei Zhang <mizhang@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        Manali Shukla <manali.shukla@amd.com>
Subject: Re: [Patch v4 07/13] perf/x86: Add constraint for guest perf metrics
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On Fri, Sep 29, 2023 at 08:50:07PM +0530, Ravi Bangoria wrote:
> On 29-Sep-23 5:23 PM, Peter Zijlstra wrote:

> > I don't think you need to go that far, host can use PMU just fine as
> > long as it doesn't overlap with a vCPU. Basically, if you force
> > perf_attr::exclude_guest on everything your vCPU can haz the full thing.

^ this..

> How about keying off based on PMU specific KVM module parameter? Something
> like what Manali has proposed for AMD VIBS? Please see solution 1.1:
> 
> https://lore.kernel.org/r/3a6c693e-1ef4-6542-bc90-d4468773b97d@amd.com

So I hadn't read that, but isn't that more or less what I proposed
above?