Hi Marc, > > BTW, if we have no intention of supporting a mix of vCPUs with and > > without PMU, I think it would be nice if we have a clear comment on > > that in the code. Or I'm hoping to disallow it if possible though. > > I'm not sure we're in a position to do this right now. The current API > has always (for good or bad reasons) been per-vcpu as it is tied to > the vcpu initialisation. Thank you for your comments! Then, when a guest that has a mix of vCPUs with and without PMU, userspace can set kvm->arch.dfr0_pmuver to zero or IMPDEF, and the PMUVER for vCPUs with PMU will become 0 or IMPDEF as I mentioned. For instance, on the host whose PMUVER==1, if vCPU#0 has no PMU(PMUVER==0), vCPU#1 has PMU(PMUVER==1), if the guest is migrated to another host with same CPU features (PMUVER==1), if SET_ONE_REG of ID_AA64DFR0_EL1 for vCPU#0 is done after for vCPU#1, kvm->arch.dfr0_pmuver will be set to 0, and the guest will see PMUVER==0 even for vCPU1. Should we be concerned about this case? Thank you, Reiji _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
