diff options
| author | David Hildenbrand <david@redhat.com> | 2024-08-02 17:55:21 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-09-01 20:26:01 -0700 |
| commit | 85a7e5432dba4c750129797feb399a7bff8b241f (patch) | |
| tree | 0193ce5298414855ca160a116f86498c264c72b0 /arch/s390/kernel/uv.c | |
| parent | 8710f6ed34e7bcf98971d65acfb5eaed5fc469b0 (diff) | |
s390/uv: convert gmap_destroy_page() from follow_page() to folio_walk
Let's get rid of another follow_page() user and perform the UV calls under
PTL -- which likely should be fine.
No need for an additional reference while holding the PTL:
uv_destroy_folio() and uv_convert_from_secure_folio() raise the refcount,
so any concurrent make_folio_secure() would see an unexpted reference and
cannot set PG_arch_1 concurrently.
Do we really need a writable PTE? Likely yes, because the "destroy" part
is, in comparison to the export, a destructive operation. So we'll keep
the writability check for now.
We'll lose the secretmem check from follow_page(). Likely we don't care
about that here.
Link: https://lkml.kernel.org/r/20240802155524.517137-9-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'arch/s390/kernel/uv.c')
| -rw-r--r-- | arch/s390/kernel/uv.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c index 35ed2aea8891..9646f773208a 100644 --- a/arch/s390/kernel/uv.c +++ b/arch/s390/kernel/uv.c @@ -14,6 +14,7 @@ #include <linux/memblock.h> #include <linux/pagemap.h> #include <linux/swap.h> +#include <linux/pagewalk.h> #include <asm/facility.h> #include <asm/sections.h> #include <asm/uv.h> @@ -462,9 +463,9 @@ EXPORT_SYMBOL_GPL(gmap_convert_to_secure); int gmap_destroy_page(struct gmap *gmap, unsigned long gaddr) { struct vm_area_struct *vma; + struct folio_walk fw; unsigned long uaddr; struct folio *folio; - struct page *page; int rc; rc = -EFAULT; @@ -483,11 +484,15 @@ int gmap_destroy_page(struct gmap *gmap, unsigned long gaddr) goto out; rc = 0; - /* we take an extra reference here */ - page = follow_page(vma, uaddr, FOLL_WRITE | FOLL_GET); - if (IS_ERR_OR_NULL(page)) + folio = folio_walk_start(&fw, vma, uaddr, 0); + if (!folio) goto out; - folio = page_folio(page); + /* + * See gmap_make_secure(): large folios cannot be secure. Small + * folio implies FW_LEVEL_PTE. + */ + if (folio_test_large(folio) || !pte_write(fw.pte)) + goto out_walk_end; rc = uv_destroy_folio(folio); /* * Fault handlers can race; it is possible that two CPUs will fault @@ -500,7 +505,8 @@ int gmap_destroy_page(struct gmap *gmap, unsigned long gaddr) */ if (rc) rc = uv_convert_from_secure_folio(folio); - folio_put(folio); +out_walk_end: + folio_walk_end(&fw, vma); out: mmap_read_unlock(gmap->mm); return rc; |