On Thu, Apr 11, 2024 at 06:55:44PM +0200, Paolo Bonzini wrote: > On Mon, Apr 8, 2024 at 3:56 PM Peter Xu <peterx@xxxxxxxxxx> wrote: > > Paolo, > > > > I may miss a bunch of details here (as I still remember some change_pte > > patches previously on the list..), however not sure whether we considered > > enable it? Asked because I remember Andrea used to have a custom tree > > maintaining that part: > > > > https://github.com/aagit/aa/commit/c761078df7a77d13ddfaeebe56a0f4bc128b1968 > > The patch enables it only for KSM, so it would still require a bunch > of cleanups, for example I also would still use set_pte_at() in all > the places that are not KSM. This would at least fix the issue with > the poor documentation of where to use set_pte_at_notify() vs > set_pte_at(). > > With regard to the implementation, I like the idea of disabling the > invalidation on the MMU notifier side, but I would rather have > MMU_NOTIFIER_CHANGE_PTE as a separate field in the range instead of > overloading the event field. > > > Maybe it can't be enabled for some reason that I overlooked in the current > > tree, or we just decided to not to? > > I have just learnt about the patch, nobody had ever mentioned it even > though it's almost 2 years old... It's a lot of code though and no one > has ever reported an issue for over 10 years, so I think it's easiest > to just rip the code out. Right, it was pretty old and I have no idea if that was discussed or published before.. It would be better to have discussed this earlier. As long as we have a decision with that being aware and in mind, then it looks fine to me to take either way to go, and I also agree either way is better than keep the status quo. I also have Andrea copied anyway when I replied, so I guess he should be aware of this and he can chim in anytime. Thanks! -- Peter Xu
