On Fri, Apr 18, 2025 at 08:13:17AM -0700, Sean Christopherson wrote:
>
> That all looks good to me. And to ensure we don't go off the rails due to bad
> inputs (which are supposed to be fully validated by common KVM), we could add a
> WARN to detect a non-exclusive range->end.
>
> So this?
>
> if (WARN_ON_ONCE(range->end <= range->start))
> return false;
>
> /*
> * If the head and tail pages of the range currently allow a hugepage,
> * i.e. reside fully in the slot and don't have mixed attributes, then
> * add each corresponding hugepage range to the ongoing invalidation,
> * e.g. to prevent KVM from creating a hugepage in response to a fault
> * for a gfn whose attributes aren't changing. Note, only the range
> * of gfns whose attributes are being modified needs to be explicitly
> * unmapped, as that will unmap any existing hugepages.
> */
> for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) {
> gfn_t start = gfn_round_for_level(range->start, level);
> gfn_t end = gfn_round_for_level(range->end - 1, level);
> gfn_t nr_pages = KVM_PAGES_PER_HPAGE(level);
>
> if ((start != range->start || start + nr_pages > range->end) &&
> start >= slot->base_gfn &&
> start + nr_pages <= slot->base_gfn + slot->npages &&
> !hugepage_test_mixed(slot, start, level))
> kvm_mmu_invalidate_range_add(kvm, start, start + nr_pages);
>
> if (end == start)
> continue;
>
> if ((end + nr_pages) <= (slot->base_gfn + slot->npages) &&
> !hugepage_test_mixed(slot, end, level))
> kvm_mmu_invalidate_range_add(kvm, end, end + nr_pages);
> }
Looks good! Re-tested with this version of the patch and it seems to address
the original issue.
Tested-by: Michael Roth <michael.roth@xxxxxxx>
Thanks,
Mike
