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

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Message-ID: <69bac394-f10c-c0ad-a23d-36cbbd479212@intel.com>
Date:   Wed, 12 Aug 2020 21:14:16 +0800
From:   "Xu, Like" <like.xu@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.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 2020/8/12 21:04, Paolo Bonzini wrote:
> 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.
The exclude_kernel events from the QEMU or whoever else has opened /dev/kvm.

Do you see any (patches) gap if we map
the exclude_host events into exclude_hv events naturally ?

Thanks,
Like Xu
> 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.