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Date:   Fri, 15 Jan 2021 12:33:46 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Like Xu <like.xu@linux.intel.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>, eranian@google.com,
        kvm@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Andi Kleen <andi@firstfloor.org>,
        Kan Liang <kan.liang@linux.intel.com>, wei.w.wang@intel.com,
        luwei.kang@intel.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 05/17] KVM: x86/pmu: Reprogram guest PEBS event to
 emulate guest PEBS counter
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References: <20210104131542.495413-1-like.xu@linux.intel.com>
 <20210104131542.495413-6-like.xu@linux.intel.com>
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On Mon, Jan 04, 2021 at 09:15:30PM +0800, Like Xu wrote:
> When a guest counter is configured as a PEBS counter through
> IA32_PEBS_ENABLE, a guest PEBS event will be reprogrammed by
> configuring a non-zero precision level in the perf_event_attr.
> 
> The guest PEBS overflow PMI bit would be set in the guest
> GLOBAL_STATUS MSR when PEBS facility generates a PEBS
> overflow PMI based on guest IA32_DS_AREA MSR.
> 
> The attr.precise_ip would be adjusted to a special precision
> level when the new PEBS-PDIR feature is supported later which
> would affect the host counters scheduling.

This seems like a random collection of changes, all required, but
loosely related.

> The guest PEBS event would not be reused for non-PEBS
> guest event even with the same guest counter index.

/me rolls eyes at the whole destroy+create nonsense...