Re: [PATCH 2/3] KVM: arm64: Clear the whole hugetlb folio when storing MTE tags

[Fuad Tabba]

Hi Lorenzo,

On Tue, 20 Oct 2026 12:58:13 +0100, Lorenzo Stoakes (ARM)
<ljs@xxxxxxxxxx> wrote:
[...]
> > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
[...]
> > @@ -1042,12 +1043,14 @@ int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm,
[...]
> > -                        if (folio_test_hugetlb(folio))
> > -                                folio_try_hugetlb_mte_tagging(folio);
> > -                        else
> > +                        if (!folio_test_hugetlb(folio))
> >                                  try_page_mte_tagging(page);
> > +                        else if (folio_try_hugetlb_mte_tagging(folio))
>
> Slightly awkward logic, testing a negative then the negative of the negative
> (i.e. else) plus folio_try_hugetlb_mte_tagging(), makes it a little harder to
> understand.
>
> With mte_clear_folio_tags() you can make life simpler:
>
>         if (folio_test_hugetlb(folio)) {
>                 if (folio_try_hugetlb_mte_tagging(folio))
>                         mte_clear_folio_tags(folio);
>         } else {
>                 try_page_mte_tagging(page);
>         }

Without the helper, the extra level of nesting takes the loop body
past 100 columns, so I'll switch to your version in the separate patch
that adds mte_clear_folio_tags() (see 1/3).

Thanks,
/fuad