On Sat, Nov 12, 2022 at 08:17:04AM +0000, Ricardo Koller wrote:
> The page table walker does not visit block PTEs in post-order. But there
> are some cases where doing so would be beneficial, for example: breaking a
> 1G block PTE into a full tree in post-order avoids visiting the new tree.
>
> Allow post order visits of block PTEs. This will be used in a subsequent
> commit for eagerly breaking huge pages.
>
> Signed-off-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/kvm_pgtable.h | 4 ++--
> arch/arm64/kvm/hyp/nvhe/setup.c | 2 +-
> arch/arm64/kvm/hyp/pgtable.c | 25 ++++++++++++-------------
> 3 files changed, 15 insertions(+), 16 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> index e2edeed462e8..d2e4a5032146 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -255,7 +255,7 @@ struct kvm_pgtable {
> * entries.
> * @KVM_PGTABLE_WALK_TABLE_PRE: Visit table entries before their
> * children.
> - * @KVM_PGTABLE_WALK_TABLE_POST: Visit table entries after their
> + * @KVM_PGTABLE_WALK_POST: Visit leaf or table entries after their
> * children.
It is not immediately obvious from this change alone that promoting the
post-order traversal of every walker to cover leaf + table PTEs is safe.
Have you considered using a flag for just leaf post-order visits?
--
Thanks,
Oliver
