[XEN PATCH v2] xen/page_alloc: scrub each page in unprepare_staticmem_pages

[peter kang <peter.kang@xxxxxxxxxx>]

From: Peter Kang <peter.kang@xxxxxxxxxx>

unprepare_staticmem_pages() can unprepare multiple pages in a static
memory range. When need_scrub is true, each page must be scrubbed
before it is marked static.

The loop currently passes the base pointer pg to scrub_one_page() on
every iteration. For a multi-page range, this repeatedly scrubs page 0
and leaves the remaining pages unscrubbed, so a guest can later read
stale data from pages 1..nr_mfns-1 of a static or static-shared bank.

Pass &pg[i] to scrub_one_page() so each iteration scrubs the page it
is processing. This ensures every page in the range is scrubbed before
it is marked static.

Fixes: 4a9e73e6e53e ("xen/arm: static memory initialization")
Signed-off-by: Peter Kang <peter.kang@xxxxxxxxxx>

---
Changes:
v1 -> v2
 - Use Peter Kang's Signed-off-by.
 - no code change
---
 xen/common/page_alloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 2682fff9cc..426bd11c2e 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -2941,7 +2941,7 @@ void unprepare_staticmem_pages(struct page_info *pg, 
unsigned long nr_mfns,
         if ( need_scrub )
         {
             /* TODO: asynchronous scrubbing for pages of static memory. */
-            scrub_one_page(pg);
+            scrub_one_page(&pg[i]);
         }
 
         pg[i].count_info |= PGC_static;
-- 
2.43.0