linux-kernel - Re: [PATCH v4 17/38] KVM: x86/pmu: Add perf_capabilities field in struct kvm_host

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Message-ID: <aCUxc3c6Tt6yVmqi@google.com>
Date: Wed, 14 May 2025 17:12:35 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Mingwei Zhang <mizhang@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Paolo Bonzini <pbonzini@...hat.com>, Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, Liang@...gle.com, 
	Kan <kan.liang@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	kvm@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	Yongwei Ma <yongwei.ma@...el.com>, Xiong Zhang <xiong.y.zhang@...ux.intel.com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>, Jim Mattson <jmattson@...gle.com>, 
	Sandipan Das <sandipan.das@....com>, Zide Chen <zide.chen@...el.com>, 
	Eranian Stephane <eranian@...gle.com>, Shukla Manali <Manali.Shukla@....com>, 
	Nikunj Dadhania <nikunj.dadhania@....com>
Subject: Re: [PATCH v4 17/38] KVM: x86/pmu: Add perf_capabilities field in
 struct kvm_host_values{}

On Mon, Mar 24, 2025, Mingwei Zhang wrote:
> From: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> 
> Add perf_capabilities in kvm_host_values{} structure to record host perf
> capabilities. KVM needs to know if host supports some PMU capabilities
> and then decide if passthrough or intercept some PMU MSRs or instruction
> like rdpmc, e.g. If host supports PERF_METRICES, but guest is configured
> not to support it, then rdpmc instruction needs to be intercepted.

This is wrong (spoiler alert).  This patch can be dropped.