Messages in this thread | | | Date | Fri, 22 Jan 2021 10:56:12 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS |
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On Fri, Jan 15, 2021 at 10:51:38AM -0800, Sean Christopherson wrote: > On Fri, Jan 15, 2021, Andi Kleen wrote: > > > I'm asking about ucode/hardare. Is the "guest pebs buffer write -> PEBS PMI" > > > guaranteed to be atomic? > > > > Of course not. > > So there's still a window where the guest could observe the bad counter index, > correct?
Guest could do a hypercall to fix up the DS area before it tries to read it I suppose. Or the HV could expose the index mapping and have the guest fix up it.
Adding a little virt crud on top shouldn't be too hard.
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