On Tue, 2024-10-15 at 12:03 +1300, Huang, Kai wrote: > > "Is going to", as in "will be changed to"? Or "does today"? > > Will be changed to (today's behaviour is to go back to guest to let the > fault happen again to retry). > > AFAICT this is what Sean suggested: > > https://lore.kernel.org/all/ZuR09EqzU1WbQYGd@xxxxxxxxxx/ > > The whole point is to let KVM loop internally but not go back to guest > when the fault handler sees a frozen PTE. And in this proposal this > applies to both leaf and non-leaf PTEs IIUC, so it should handle the > case where try_cmpxchg64() fails as mentioned by Yan. > > > > > > retry internally for > > > step 4 (retries N times) because it sees the frozen PTE, but will never go > > > back > > > to guest after the fault is resolved? How can step 4 triggers zero-step? > > > > Step 3-4 is saying it will go back to the guest and fault again. > > As said above, the whole point is to make KVM loop internally when it > sees a frozen PTE, but not go back to guest. Yea, I was saying on that idea that I thought looping forever without checking for a signal would be problematic. Then userspace could re-enter the TD. I don't know if it's a show stopper. In any case the discussion between these threads and LPC/KVM forum hallway chatter has gotten a bit fragmented. I don't think there is any concrete consensus solution at this point.
