On Fri, Jan 26, 2024, Mingwei Zhang wrote: > +Frederick Mayle +Steven Moreland > > On Fri, Jan 26, 2024 at 10:33 AM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > > > On Thu, Jan 25, 2024, Mingwei Zhang wrote: > > > On Wed, Jan 24, 2024, Sean Christopherson wrote: > > > > On Wed, Jan 24, 2024, Mingwei Zhang wrote: > > > > > I think this makes a lot of confusions on migration where VMM on the source > > > > > believes that a non-zero value from KVM_GET_MSRS is valid and the VMM on the > > > > > target will find it not true. > > > > > > > > Yes, but seeing a non-zero value is a KVM bug that should be fixed. > > > > > > > How about adding an entry in vmx_get_msr() for > > > MSR_IA32_PERF_CAPABILITIES and check pmu_version? This basically pairs > > > with the implementation in vmx_set_msr() for MSR_IA32_PERF_CAPABILITIES. > > > Doing so allows KVM_GET_MSRS return 0 for the MSR instead of returning > > > the initial permitted value. > > > > Hrm, I don't hate it as a stopgap. But if we are the only people that are affected, > > because again I'm pretty sure QEMU is fine, I would rather we just fix things in > > our VMM and/or internal kernel. > > It is not just QEMU. crossvm is another open source VMM that suffers > from this one. Does CrosVM support migration or some other form of save/restore (RR?)? And if so, does CrosVM do that in conjunction with hiding the vPMU from the guest? Because if not, then I think we can squeak by.
