PM / Hibernate: Include storage keys in hibernation image on s390

For s390 there is one additional byte associated with each page,
the storage key. This byte contains the referenced and changed
bits and needs to be included into the hibernation image.
If the storage keys are not restored to their previous state all
original pages would appear to be dirty. This can cause
inconsistencies e.g. with read-only filesystems.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

2 files changed, 21 insertions, 0 deletions

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 3744c594b19b..e01e6899592c 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -65,6 +65,9 @@ config HIBERNATION
 
           For more information take a look at <file:Documentation/power/swsusp.txt>.
 
+config ARCH_SAVE_PAGE_KEYS
+        bool
+
 config PM_STD_PARTITION
         string "Default resume partition"
         depends on HIBERNATION
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 06efa54f93d6..cbe2c1441392 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -1339,6 +1339,9 @@ int hibernate_preallocate_memory(void)
         count += highmem;
         count -= totalreserve_pages;
 
+        /* Add number of pages required for page keys (s390 only). */
+        size += page_key_additional_pages(saveable);
+
         /* Compute the maximum number of saveable pages to leave in memory. */
         max_size = (count - (size + PAGES_FOR_IO)) / 2
                         - 2 * DIV_ROUND_UP(reserved_size, PAGE_SIZE);
@@ -1662,6 +1665,8 @@ pack_pfns(unsigned long *buf, struct memory_bitmap *bm)
                 buf[j] = memory_bm_next_pfn(bm);
                 if (unlikely(buf[j] == BM_END_OF_MAP))
                         break;
+                /* Save page key for data page (s390 only). */
+                page_key_read(buf + j);
         }
 }
 
@@ -1821,6 +1826,9 @@ static int unpack_orig_pfns(unsigned long *buf, struct memory_bitmap *bm)
                 if (unlikely(buf[j] == BM_END_OF_MAP))
                         break;
 
+                /* Extract and buffer page key for data page (s390 only). */
+                page_key_memorize(buf + j);
+
                 if (memory_bm_pfn_present(bm, buf[j]))
                         memory_bm_set_bit(bm, buf[j]);
                 else
@@ -2223,6 +2231,11 @@ int snapshot_write_next(struct snapshot_handle *handle)
                 if (error)
                         return error;
 
+                /* Allocate buffer for page keys. */
+                error = page_key_alloc(nr_copy_pages);
+                if (error)
+                        return error;
+
         } else if (handle->cur <= nr_meta_pages + 1) {
                 error = unpack_orig_pfns(buffer, &copy_bm);
                 if (error)
@@ -2243,6 +2256,8 @@ int snapshot_write_next(struct snapshot_handle *handle)
                 }
         } else {
                 copy_last_highmem_page();
+                /* Restore page key for data page (s390 only). */
+                page_key_write(handle->buffer);
                 handle->buffer = get_buffer(&orig_bm, &ca);
                 if (IS_ERR(handle->buffer))
                         return PTR_ERR(handle->buffer);
@@ -2264,6 +2279,9 @@ int snapshot_write_next(struct snapshot_handle *handle)
 void snapshot_write_finalize(struct snapshot_handle *handle)
 {
         copy_last_highmem_page();
+        /* Restore page key for data page (s390 only). */
+        page_key_write(handle->buffer);
+        page_key_free();
         /* Free only if we have loaded the image entirely */
         if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages) {
                 memory_bm_free(&orig_bm, PG_UNSAFE_CLEAR);