From: Andi Kleen <ak@linux.intel.com>
To: "Chen, Zide" <zide.chen@intel.com>
Cc: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, Jim Mattson <jmattson@google.com>,
linux-kernel@vger.kernel.org, Mingwei Zhang <mizhang@google.com>,
Das Sandipan <Sandipan.Das@amd.com>,
Shukla Manali <Manali.Shukla@amd.com>,
Dapeng Mi <dapeng1.mi@linux.intel.com>,
Xudong Hao <xudong.hao@intel.com>
Subject: Re: [PATCH v8 7/8] KVM: x86/pmu: Emulate RDPMC on performance metrics
Date: Tue, 18 Aug 2026 12:24:05 -0700 [thread overview]
Message-ID: <aoSxVRJqjJzQssMJ@tassilo> (raw)
In-Reply-To: <cdd88e7c-abc9-4e49-8947-bb7226f3a385@intel.com>
On Tue, Aug 18, 2026 at 01:30:32PM -0500, Chen, Zide wrote:
>
>
> On 8/18/2026 12:41 PM, Andi Kleen wrote:
> > On Mon, Aug 17, 2026 at 11:31:41AM -0700, Zide Chen wrote:
> >> If the host has the PERF_METRICS capability but it's not present on
> >> the guest, RDPMC interception must be enabled and KVM should inject
> >> an #GP when the guest attempts a PERF_METRICS RDPMC.
> >>
> >> If the guest has PERF_METRICS but RDPMC interception is enabled for
> >> other reasons, KVM needs to emulate RDPMC with type 0x2000.
> >>
> >> For simplicity, Metrics Clear Mode is not supported.
> >
> > But is the bit cleared in PERF_CAPABILITIES? And would
> > the enable bit fault?
>
> Currently KVM doesn't advertise
> IA32_PERF_CAPABILITIES.RDPMC_METRICS_CLEAR[19].
Thanks.
How about the fault for the enable bit?
> > It would be better to just support it, metrics clear is actually useful.
>
> Sure, I'll add it.
I guess it could be a follow-on patch, no need to hold up this one.
-Andi
next prev parent reply other threads:[~2026-08-18 19:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-17 18:31 [PATCH v8 0/8] KVM: x86/pmu: Add hardware Topdown metrics support Zide Chen
2026-08-17 18:31 ` [PATCH v8 1/8] KVM: x86/pmu: Do not map fixed counters >= 3 to generic perf events Zide Chen
2026-08-17 18:31 ` [PATCH v8 2/8] KVM: x86/pmu: Support Intel fixed counter 3 on mediated vPMU Zide Chen
2026-08-17 18:31 ` [PATCH v8 3/8] KVM: x86/pmu: Rename and move vcpu_get_perf_capabilities() to pmu.h Zide Chen
2026-08-17 18:52 ` sashiko-bot
2026-08-17 21:45 ` Chen, Zide
2026-08-17 18:31 ` [PATCH v8 4/8] KVM: x86/pmu: Snapshot host IA32_PERF_CAPABILITIES in kvm_host Zide Chen
2026-08-17 18:31 ` [PATCH v8 5/8] KVM: x86/pmu: Support PERF_METRICS MSR in mediated vPMU Zide Chen
2026-08-17 19:04 ` sashiko-bot
2026-08-17 22:07 ` Chen, Zide
2026-08-20 0:56 ` Mi, Dapeng
2026-08-17 18:31 ` [PATCH v8 6/8] KVM: x86/pmu: Move RDPMC emulation into per-vendor callbacks Zide Chen
2026-08-19 3:14 ` Sandipan Das
2026-08-17 18:31 ` [PATCH v8 7/8] KVM: x86/pmu: Emulate RDPMC on performance metrics Zide Chen
2026-08-17 19:01 ` sashiko-bot
2026-08-17 22:02 ` Chen, Zide
2026-08-18 17:41 ` Andi Kleen
2026-08-18 18:30 ` Chen, Zide
2026-08-18 19:24 ` Andi Kleen [this message]
2026-08-18 19:59 ` Chen, Zide
2026-08-17 18:31 ` [PATCH v8 8/8] KVM: selftests: Add PERF_METRICS and fixed counter 3 tests Zide Chen
2026-08-17 18:57 ` sashiko-bot
2026-08-17 21:44 ` Chen, Zide
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