On 05.02.20 10:35, Wang, Wei W wrote: > On Wednesday, February 5, 2020 5:23 PM, David Hildenbrand wrote: >> So, if you run a TCG guest and use it with free page reporting, the race is >> possible? So the correctness depends on two dirty bitmaps in the hypervisor >> and how they interact. wow this is fragile. >> > > Not sure how TCG tracks the dirty bits. But In whatever implementation, the hypervisor should have There is only a single bitmap for that purpose. (well, the one where KVM syncs to) > already dealt with the race between he current round and the previous round dirty recording. > (the race isn't brought by this feature essentially) It is guaranteed to work reliably without this feature as you only clear what *has been migrated*, not what your guest thinks should not been migrated at one point and decides differently at another point. The race is bought forwards by this feature. -- Thanks, David / dhildenb
