linux-kernel - Re: [PATCH] KVM: x86/pmu: Add '.exclude_hv = 1' for guest perf

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Message-ID: <8bdc60d5-c9ef-4e8f-6b73-b7bd012d9d30@redhat.com>
Date:   Wed, 12 Aug 2020 15:04:44 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     like.xu@...el.com, peterz@...radead.org
Cc:     Like Xu <like.xu@...ux.intel.com>, Yao <yao.jin@...ux.intel.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH] KVM: x86/pmu: Add '.exclude_hv = 1' for guest perf_event

On 12/08/20 14:56, Xu, Like wrote:
> 
> My proposal is to define:
> the "hypervisor privilege levels" events in the KVM/x86 context as
> all the host kernel events plus /dev/kvm user space events.

What are "/dev/kvm user space events"?  In any case, this patch should
be included only in the series that adds exclude_hv support in arch/x86.

Paolo

> If we add ".exclude_hv = 1" in the pmc_reprogram_counter(),
> do you see any side effect to cover the above usages?
> 
> The fact that exclude_hv has never been used in x86 does help
> the generic perf code to handle permission checks in a more concise way.