linux-kernel - Re: [PATCH v2 2/6] KVM: x86/pmu: Refactoring find_arch_event() to pmc_perf_hw

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Message-ID: <71689d29-caf8-ed7e-2cd7-61cbab0fc7e0@gmail.com>
Date:   Wed, 16 Feb 2022 15:44:04 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Ravi Bangoria <ravi.bangoria@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, David Dunn <daviddunn@...gle.com>,
        Stephane Eranian <eranian@...gle.com>,
        Kim Phillips <kim.phillips@....com>,
        Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH v2 2/6] KVM: x86/pmu: Refactoring find_arch_event() to
 pmc_perf_hw_id()

On 14/2/2022 6:14 pm, Ravi Bangoria wrote:
> 
> 
> On 11-Feb-22 11:46 PM, Jim Mattson wrote:
>> On Fri, Feb 11, 2022 at 1:56 AM Ravi Bangoria <ravi.bangoria@....com> wrote:
>>>
>>>
>>>
>>> On 10-Feb-22 4:58 PM, Like Xu wrote:
>>>> cc Kim and Ravi to help confirm more details about this change.
>>>>
>>>> On 10/2/2022 3:30 am, Jim Mattson wrote:
>>>>> By the way, the following events from amd_event_mapping[] are not
>>>>> listed in the Milan PPR:
>>>>> { 0x7d, 0x07, PERF_COUNT_HW_CACHE_REFERENCES }
>>>>> { 0x7e, 0x07, PERF_COUNT_HW_CACHE_MISSES }
>>>>> { 0xd0, 0x00, PERF_COUNT_HW_STALLED_CYCLES_FRONTEND }
>>>>> { 0xd1, 0x00, PERF_COUNT_HW_STALLED_CYCLES_BACKEND }
>>>>>
>>>>> Perhaps we should build a table based on amd_f17h_perfmon_event_map[]
>>>>> for newer AMD processors?

So do we need another amd_f19h_perfmon_event_map[] in the host perf code ?

>>>
>>> I think Like's other patch series to unify event mapping across kvm
>>> and host will fix it. No?
>>> https://lore.kernel.org/lkml/20220117085307.93030-4-likexu@tencent.com
>>
>> Yes, that should fix it. But why do we even bother? What is the
>> downside of using PERF_TYPE_RAW all of the time?
> 
> There are few places where PERF_TYPE_HARDWARE and PERF_TYPE_RAW are treated
> differently. Ex, x86_pmu_event_init(), perf_init_event(). So I think it makes
> sense to keep using PERF_TYPE_HARDWARE for generalized events?
> 
> Ravi