xen-gntdev: Fix unmap notify on PV domains
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@tycho.nsa.gov>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 2aa8316..75f8037c9 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -289,7 +289,12 @@
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]);
@@ -298,7 +303,7 @@
}
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;