vfio/migration: Fix page size calculation

Coverity detected an issue of left shifting int by more than 31 bits leading
to undefined behavior.

In practice bcontainer->dirty_pgsizes always have some common page sizes
when dirty tracking is supported.

Resolves: Coverity CID 1644186
Resolves: Coverity CID 1644187
Resolves: Coverity CID 1644188
Fixes: 46c763311419 ("vfio/migration: Add migration blocker if VM memory is too large to cause unmap_bitmap failure").
Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20260116060315.65723-1-zhenzhong.duan@intel.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index f857dc25ed4d0f824bdabc168228a5e925ac7dbe..b4695030c7295f318faf1d12ac48ba951aa943c7 100644 (file)
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -1173,7 +1173,7 @@ static bool vfio_dirty_tracking_exceed_limit(VFIODevice *vbasedev)
      * can also switch to use IOMMUFD backend if there is a need to migrate
      * large VM.
      */
-    page_size = 1 << ctz64(bcontainer->dirty_pgsizes);
+    page_size = 1ULL << ctz64(bcontainer->dirty_pgsizes);
     max_size = bcontainer->max_dirty_bitmap_size * BITS_PER_BYTE * page_size;
 
     return current_machine->ram_size > max_size;