iommu/amd: Argument page_size could be uninitialized

Argument "page_size" passing to function "fetch_pte" could be
uninitialized if the function returns NULL

The caller "iommu_unmap_page" checks the return value but the page_size is
used outside the if block.
Signed-off-by: yzhai003@ucr.edu <yzhai003@ucr.edu>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd_iommu.c

@@ -1404,6 +1404,8 @@ static u64 *fetch_pte(struct protection_domain *domain,
 	int level;
 	u64 *pte;
 
+	*page_size = 0;
+
 	if (address > PM_LEVEL_SIZE(domain->mode))
 		return NULL;