On Wed, 29 Jan 2025 at 17:35, Brendan Jackman <jackmanb@xxxxxxxxxx> wrote: > > On Wed, 29 Jan 2025 at 13:40, Brendan Jackman <jackmanb@xxxxxxxxxx> wrote: > > - Can we totally avoid the need to allocate pagetables during allocation, by > > keeping ASI’s restricted copy of the physmap in-sync with the unrestricted one, > > different only in _PAGE_PRESENT? Er, doing that specifically (relying on _PAGE_PRESENT) would be a bad idea, I forgot how broken the old CPUs are, this would probably let you exploit L1TF or something. We would have to munge the PFN too. Anyway as long as we only have to do that at the leaf pagetable, I think the idea still works, we can actually just make the entry pmd_none().
