linux-kernel - Re: [RFC PATCH 23/41] KVM: x86/pmu: Implement the save/restore of PMU state for Intel CPU

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Date: Tue, 23 Apr 2024 09:50:47 -0700
From: Mingwei Zhang <mizhang@...gle.com>
To: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
Cc: maobibo <maobibo@...ngson.cn>, Sean Christopherson <seanjc@...gle.com>, 
	Xiong Zhang <xiong.y.zhang@...ux.intel.com>, pbonzini@...hat.com, peterz@...radead.org, 
	kan.liang@...el.com, zhenyuw@...ux.intel.com, jmattson@...gle.com, 
	kvm@...r.kernel.org, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, zhiyuan.lv@...el.com, eranian@...gle.com, 
	irogers@...gle.com, samantha.alt@...el.com, like.xu.linux@...il.com, 
	chao.gao@...el.com
Subject: Re: [RFC PATCH 23/41] KVM: x86/pmu: Implement the save/restore of PMU
 state for Intel CPU

> > Is there any event in the host still having PERF_EVENT_STATE_ACTIVE?
> > If so, hmm, it will reach perf_pmu_disable(event->pmu), which will
> > access the global ctrl MSR.
>
> I don't think there is any event with PERF_EVENT_STATE_ACTIVE state on
> host when guest owns the PMU HW resource.
>
> In current solution, VM would fail to create if there is any system-wide
> event without exclude_guest attribute. If VM is created successfully and
> when vm-entry happens, the helper perf_guest_enter() would put all host
> events with exclude_guest attribute into PERF_EVENT_STATE_INACTIVE state
> and block host to create system-wide events without exclude_guest attribute.
>

Yeah, that's perfect.

Thanks.
-Mingwei