On Fri, Apr 09, 2021 at 03:50:42PM +0200, David Hildenbrand wrote: > > > 3. Allow selected users to still grab the pages (esp. KVM to fault them into > > > the page tables). > > > > As long as fault leads to non-present PTEs we are fine. Usespace still may > > want to mlock() some of guest memory. There's no reason to prevent this. > > I'm curious, even get_user_pages() will lead to a present PTE as is, no? So > that will need modifications I assume. (although I think it fundamentally > differs to the way get_user_pages() works - trigger a fault first, then > lookup the PTE in the page tables). For now, the patch has two step poisoning: first fault in, on the add to shadow PTE -- poison. By the time VM has chance to use the page it's poisoned and unmapped from the host userspace. -- Kirill A. Shutemov
