Messages in this thread | | | Date | Fri, 7 Sep 2018 07:10:51 -0700 | From | Andi Kleen <> | Subject | Re: [PATCH v2 6/8] perf/x86/intel/lbr: guest requesting KVM for lbr stack save/restore |
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> This could achieve the above #1, but how would it solve #2 above? That is, > after the guest uses the lbr feature for a while, the lbr stack has been > passed through, then the guest doesn't use lbr any more, but the vCPU will > still save/restore on switching?
If nothing accesses the MSR LBRs after a context switch in the guest nothing gets saved/restored due to:
> > Also when the LBRs haven't been set to direct access the state doesn't > > need to be saved.
-Andi
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