In paravirtualized guests, the struct page* for mappings is only a
placeholder, and cannot be used to access the granted memory. Use the
userspace mapping that we have set up in order to implement
UNMAP_NOTIFY_CLEAR_BYTE.
Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 06de2c0..2b67f15 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -287,7 +287,12 @@ static int unmap_grant_pages(struct grant_map *map, int
offset, int pages)
if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
int pgno = (map->notify.addr >> PAGE_SHIFT);
- if (pgno >= offset && pgno < offset + pages) {
+ if (pgno >= offset && pgno < offset + pages && use_ptemod) {
+ void __user *tmp;
+ tmp = map->vma->vm_start + map->notify.addr;
+ copy_to_user(tmp, &err, 1);
+ map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
+ } else if (pgno >= offset && pgno < offset + pages) {
uint8_t *tmp = kmap(map->pages[pgno]);
tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
kunmap(map->pages[pgno]);
@@ -296,7 +301,7 @@ static int unmap_grant_pages(struct grant_map *map, int
offset, int pages)
}
pr_debug("map %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
- err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages, pages);
+ err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset,
pages);
if (err)
return err;
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