vfio/migration: Don't block migration device dirty tracking is unsupported

By default VFIO migration is set to auto, which will support live
migration if the migration capability is set *and* also dirty page
tracking is supported.

For testing purposes one can force enable without dirty page tracking
via enable-migration=on, but that option is generally left for testing
purposes.

So starting with IOMMU dirty tracking it can use to accommodate the lack of
VF dirty page tracking allowing us to minimize the VF requirements for
migration and thus enabling migration by default for those too.

While at it change the error messages to mention IOMMU dirty tracking as
well.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
[ clg: - spelling in commit log ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 34d4be2ce1b13626a8690d4787366ee41a9ebe1e..cbfaef7afffe2c464496f9380a88ac9e229ada64 100644 (file)
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -1036,16 +1036,16 @@ bool vfio_migration_realize(VFIODevice *vbasedev, Error **errp)
         return !vfio_block_migration(vbasedev, err, errp);
     }
 
-    if (!vbasedev->dirty_pages_supported) {
+    if (!vbasedev->dirty_pages_supported && !vbasedev->iommu_dirty_tracking) {
         if (vbasedev->enable_migration == ON_OFF_AUTO_AUTO) {
             error_setg(&err,
-                       "%s: VFIO device doesn't support device dirty tracking",
-                       vbasedev->name);
+                       "%s: VFIO device doesn't support device and "
+                       "IOMMU dirty tracking", vbasedev->name);
             goto add_blocker;
         }
 
-        warn_report("%s: VFIO device doesn't support device dirty tracking",
-                    vbasedev->name);
+        warn_report("%s: VFIO device doesn't support device and "
+                    "IOMMU dirty tracking", vbasedev->name);
     }
 
     ret = vfio_block_multiple_devices_migration(vbasedev, errp);