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.
