s390/mm/fault: convert do_secure_storage_access() from follow_page() to folio_walk

Let's get rid of another follow_page() user and perform the conversion
under PTL: Note that this is also what follow_page_pte() ends up doing.

Unfortunately we cannot currently optimize out the additional reference,
because arch_make_folio_accessible() must be called with a raised refcount
to protect against concurrent conversion to secure.  We can just move the
arch_make_folio_accessible() under the PTL, like follow_page_pte() would.

We'll effectively drop the "writable" check implied by FOLL_WRITE:
follow_page_pte() would also not check that when calling
arch_make_folio_accessible(), so there is no good reason for doing that
here.

We'll lose the secretmem check from follow_page() as well, about which we
shouldn't really care.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Reviewed-by: Claudio Imbrenda <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Gerald Schaefer <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Janosch Frank <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions