Sean Christopherson <seanjc@xxxxxxxxxx> writes: > On Mon, Aug 22, 2022, Vitaly Kuznetsov wrote: >> So I reached out to Microsoft and their answer was that for all these new >> eVMCS fields (including *PerfGlobalCtrl) observing architectural VMX >> MSRs should be enough. *PerfGlobalCtrl case is special because of Win11 >> bug (if we expose the feature in VMX feature MSRs but don't set >> CPUID.0x4000000A.EBX BIT(0) it just doesn't boot). > > Does this mean that KVM-on-HyperV needs to avoid using the PERF_GLOBAL_CTRL fields > when the bit is not set? It doesn't have to, based on the reply I got from Microsoft, if PERF_GLOBAL_CTRL is exposed in architectural VMX feature MSRs than eVMCS fields are guaranteed to be present. The PV bit is 'extra'. -- Vitaly
