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From: Sean Christopherson <seanjc@google.com>
To: Like Xu <like.xu.linux@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Jim Mattson <jmattson@google.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Joerg Roedel <joro@8bytes.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Like Xu <likexu@tencent.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v11 01/17] perf/x86/intel: Add EPT-Friendly PEBS for Ice Lake Server
Date: Tue, 4 Jan 2022 17:25:37 +0000	[thread overview]
Message-ID: <YdSDEUJQgJQfZjWD@google.com> (raw)
In-Reply-To: <69ad949e-4788-0f93-46cb-6af6f79a9f24@gmail.com>

On Fri, Dec 31, 2021, Like Xu wrote:
> On 31/12/2021 2:13 am, Sean Christopherson wrote:
> > On Fri, Dec 10, 2021, Like Xu wrote:
> > > The new hardware facility supporting guest PEBS is only available on
> > > Intel Ice Lake Server platforms for now. KVM will check this field
> > > through perf_get_x86_pmu_capability() instead of hard coding the cpu
> > > models in the KVM code. If it is supported, the guest PEBS capability
> > > will be exposed to the guest.
> > 
> > So what exactly is this new feature?  I've speed read the cover letter and a few
> > changelogs and didn't find anything that actually explained when this feature does.
> > 
> 
> Please check Intel SDM Vol3 18.9.5 for this "EPT-Friendly PEBS" feature.
> 
> I assume when an unfamiliar feature appears in the patch SUBJECT,
> the reviewer may search for the exact name in the specification.

C'mon, seriously?  How the blazes am I supposed to know that the feature name
is EPT-Friendly PEBS?  Or that it's even in the SDM (it's not in the year-old
version of the SDM I currently have open) versus one of the many ISE docs?

This is not hard.  Please spend the 30 seconds it takes to write a small blurb
so that reviewers don't have to spend 5+ minutes wondering WTF this does.

  Add support for EPT-Friendly PEBS, a new CPU feature that enlightens PEBS to
  translate guest linear address through EPT, and facilitates handling VM-Exits
  that occur when accessing PEBS records.  More information can be found in the
  <date> release of Intel's SDM, Volume 3, 18.9.5 "EPT-Friendly PEBS".

  reply	other threads:[~2022-01-04 17:25 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-10 13:35 [PATCH v11 00/17] KVM: x86/pmu: Add *basic* support to enable guest PEBS via DS Like Xu
2021-12-10 13:35 ` [PATCH v11 01/17] perf/x86/intel: Add EPT-Friendly PEBS for Ice Lake Server Like Xu
2021-12-30 18:13   ` Sean Christopherson
2021-12-31  4:00     ` Like Xu
2022-01-04 17:25       ` Sean Christopherson [this message]
2022-01-05  1:49         ` Like Xu
2021-12-10 13:35 ` [PATCH v11 02/17] perf/x86/intel: Handle guest PEBS overflow PMI for KVM guest Like Xu
2021-12-10 13:35 ` [PATCH v11 03/17] perf/x86/core: Pass "struct kvm_pmu *" to determine the guest values Like Xu
2021-12-10 13:35 ` [PATCH v11 04/17] KVM: x86/pmu: Set MSR_IA32_MISC_ENABLE_EMON bit when vPMU is enabled Like Xu
2021-12-10 13:35 ` [PATCH v11 05/17] KVM: x86/pmu: Introduce the ctrl_mask value for fixed counter Like Xu
2021-12-10 13:35 ` [PATCH v11 06/17] x86/perf/core: Add pebs_capable to store valid PEBS_COUNTER_MASK value Like Xu
2021-12-10 13:35 ` [PATCH v11 07/17] KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS Like Xu
2021-12-10 13:35 ` [PATCH v11 08/17] KVM: x86/pmu: Reprogram PEBS event to emulate guest PEBS counter Like Xu
2021-12-10 13:35 ` [PATCH v11 09/17] KVM: x86/pmu: Adjust precise_ip to emulate Ice Lake guest PDIR counter Like Xu
2021-12-10 13:35 ` [PATCH v11 10/17] KVM: x86/pmu: Add IA32_DS_AREA MSR emulation to support guest DS Like Xu
2021-12-10 13:35 ` [PATCH v11 11/17] KVM: x86/pmu: Add PEBS_DATA_CFG MSR emulation to support adaptive PEBS Like Xu
2021-12-10 13:35 ` [PATCH v11 12/17] KVM: x86: Set PEBS_UNAVAIL in IA32_MISC_ENABLE when PEBS is enabled Like Xu
2021-12-10 13:35 ` [PATCH v11 13/17] KVM: x86/pmu: Move pmc_speculative_in_use() to arch/x86/kvm/pmu.h Like Xu
2021-12-10 13:35 ` [PATCH v11 14/17] KVM: x86/pmu: Disable guest PEBS temporarily in two rare situations Like Xu
2021-12-10 13:35 ` [PATCH v11 15/17] KVM: x86/pmu: Add kvm_pmu_cap to optimize perf_get_x86_pmu_capability Like Xu
2021-12-10 13:35 ` [PATCH v11 16/17] KVM: x86/cpuid: Refactor host/guest CPU model consistency check Like Xu
2021-12-10 13:35 ` [PATCH v11 17/17] KVM: x86/pmu: Expose CPUIDs feature bits PDCM, DS, DTES64 Like Xu

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