On Wed, Nov 23, 2022, David Woodhouse wrote: > On Wed, 2022-11-23 at 17:17 +0000, Sean Christopherson wrote: > And with or without that cache, we can *still* end up doing a partial > update if the page goes away. The byte with the XEN_RUNSTATE_UPDATE bit > might still be accessible, but bets are off about what state the rest > of the structure is in — and those runtimes are supposed to add up, or > the guest is going to get unhappy. Ugh. What a terrible ABI. > I'm actually OK with locking two GPCs. It wasn't my first choice, but > it's reasonable enough IMO given that none of the alternatives jump out > as being particularly attractive either. I detest the two GPCs, but since KVM apparently needs to provide "all or nothing" updates, I don't see a better option.
