> It would be a bigger concern if we expected virtual PMU migration to
> work, but I think it would be nice to update kvm_pmu_cpuid_update() to
> notice the presence/absence of the new CPUID bits, and then store that
> into per-VM kvm_pmu->pebs_allowed rather than relying only on the
> per-host perf_pebs_virtualization().
I hope at some point it can work. There shouldn't be any problems
with migrating to the same CPU model, in many cases (same event
and same PEBS format) it'll likely even work between models or
gracefully degrade.