From: Peter Zijlstra <peterz@infradead.org>
To: Andi Kleen <ak@linux.intel.com>
Cc: Wei Wang <wei.w.wang@intel.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
pbonzini@redhat.com, kan.liang@intel.com, mingo@redhat.com,
rkrcmar@redhat.com, like.xu@intel.com, jannh@google.com,
arei.gonglei@huawei.com
Subject: Re: [PATCH v3 4/5] KVM/x86/vPMU: Add APIs to support host save/restore the guest lbr stack
Date: Thu, 20 Sep 2018 18:24:07 +0200 [thread overview]
Message-ID: <20180920162407.GA24124@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180920153035.GB10360@tassilo.jf.intel.com>
On Thu, Sep 20, 2018 at 08:30:35AM -0700, Andi Kleen wrote:
> > +int intel_pmu_enable_save_guest_lbr(struct kvm_vcpu *vcpu)
> > +{
> > + struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
> > + struct perf_event *event;
> > + struct perf_event_attr attr = {
> > + .type = PERF_TYPE_RAW,
> > + .size = sizeof(attr),
> > + .pinned = true,
> > + .exclude_host = true,
> > + .sample_type = PERF_SAMPLE_BRANCH_STACK,
> > + .branch_sample_type = PERF_SAMPLE_BRANCH_CALL_STACK |
> > + PERF_SAMPLE_BRANCH_USER |
> > + PERF_SAMPLE_BRANCH_KERNEL,
>
> I think that will allocate an extra perfmon counter, right?
I throught the same too, but I think the exclude_host/guest, whichever
is the right one makes that work for regular counters too.
That code is a wee bit magical and I didn't take the time to reverse
engineer that. It most certainly needs a comment.
next prev parent reply other threads:[~2018-09-20 16:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-20 10:05 [PATCH v3 0/5] Guest LBR Enabling Wei Wang
2018-09-20 10:05 ` [PATCH v3 1/5] perf/x86: add a function to get the lbr stack Wei Wang
2018-09-20 12:05 ` Peter Zijlstra
2018-09-20 12:07 ` Peter Zijlstra
2018-09-20 10:05 ` [PATCH v3 2/5] KVM/x86: KVM_CAP_X86_GUEST_LBR Wei Wang
2018-09-20 10:05 ` [PATCH v3 3/5] KVM/x86: expose MSR_IA32_PERF_CAPABILITIES to the guest Wei Wang
2018-09-20 12:38 ` Wei Wang
2018-09-20 10:05 ` [PATCH v3 4/5] KVM/x86/vPMU: Add APIs to support host save/restore the guest lbr stack Wei Wang
2018-09-20 12:17 ` Peter Zijlstra
2018-09-20 12:32 ` Peter Zijlstra
2018-09-27 13:45 ` Wang, Wei W
2018-09-20 15:30 ` Andi Kleen
2018-09-20 16:24 ` Peter Zijlstra [this message]
2018-09-27 10:10 ` Wang, Wei W
2018-09-27 10:05 ` Wang, Wei W
2018-09-20 10:05 ` [PATCH v3 5/5] KVM/x86/lbr: lazy save " Wei Wang
2018-09-20 12:07 ` Gonglei (Arei)
2018-09-27 14:11 ` Wang, Wei W
2018-09-20 12:37 ` Peter Zijlstra
2018-09-20 12:58 ` Wei Wang
2018-09-20 12:57 ` Peter Zijlstra
2018-09-20 11:34 ` [PATCH v3 0/5] Guest LBR Enabling Gonglei (Arei)
2018-09-20 12:36 ` Wei Wang
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