On Tue, Apr 26, 2022, Mingwei Zhang wrote: > > I completely agree that lookup_address() and friends are unnecessarily fragile, > > but I think that attempting to harden them to fix this KVM bug will open a can > > of worms and end up delaying getting KVM fixed. > > So basically, we need to: > - choose perf_get_page_size() instead of using any of the > lookup_address*() in mm. > - add a wrapper layer to adapt: 1) irq disabling/enabling and 2) size > -> level translation. > > Agree? Drat, I didn't see that it returns the page size, not the level. That's a bit unfortunate. It definitely makes me less averse to fixing lookup_address_in_pgd() Hrm. I guess since we know there's at least one broken user, and in theory fixing lookup_address_in_pgd() should do no harm to users that don't need protection, it makes sense to just fix lookup_address_in_pgd() and see if the x86 maintainers push back.
