On Fri, Jul 22, 2022, Paolo Bonzini wrote: > On 7/22/22 17:27, Sean Christopherson wrote: > > > So revert it, at the potential cost > > > of breaking L1s with a 6 year old kernel. > > I would further qualify this with "breaking L1s with an_unpatched_ 6 year old > > kernel". That fix was tagged for stable and made it way to at least the 4.9 and > > 4.4 LTS releases. > > > > Well, there _are_ people that use very old kernels and keep them up-to-date > with fixes for only critical CVEs (for example by, ehm, paying my employer > to do so). Heh, I'm sure that's a winning strategy. > But still it's way way unlikely for them to be used as L1 in a nested setup, > whether on their own hardware or in the cloud. > > I pushed everything to kvm/queue, but depending on what you post it may be > deferred to 5.21. Can you drop the PERF_GLOBAL_CTRL revert? I figured out how to achieve what you intended, but in a more robust (and IMO more logical) manner. If you don't drop it before I concoct the series, I'll just include a throwaway patch to revert it.
