> > The destination userspace should simply call KVM_SUBPAGES_SET_ACCESS, > > and KVM will process it just like it would on the source. In other > > words, it shouldn't matter if the ioctl is done as part of migration or > > the first time a VM is setup. And in both cases, lazy setup should be > > fine. > > The problem is in current patch (as in link), it assumes > the target pages are there in EPT, but in migration case, these pages > are not setup in ETP, so KVM_SUBPAGES_SET_ACCESS during migration or > destination bootup will fail, should I modify the patch to setup the > ETP in lazy mode? Yes, definitely. Remember that EPT page tables come and go (pages could be swapped out, or moved from one host physical address to another; there is also a shrinker that will release EPT page tables if memory is low), so SPP support should be ready for that. Migration is just a special case. Paolo
