[PATCH v4 10/10] vfio/migration: Allow live migration with vIOMMU without VFs using device dirty tracking

[Zhenzhong Duan <zhenzhong.duan@intel.com>]

Commit e46883204c38 ("vfio/migration: Block migration with vIOMMU")
introduces a migration blocker when vIOMMU is enabled, because we need
to calculate the IOVA ranges for device dirty tracking. But this is
unnecessary for iommu dirty tracking.

Limit the vfio_viommu_preset() check to those devices which use device
dirty tracking. This allows live migration with VFIO devices which use
iommu dirty tracking.

Suggested-by: Jason Zeng <jason.zeng@intel.com>
Co-developed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Tested-by: Xudong Hao <xudong.hao@intel.com>
Tested-by: Giovannio Cabiddu <giovanni.cabiddu@intel.com>
Tested-by: Rohith S R <rohith.s.r@intel.com>
---
 hw/vfio/migration.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 0a1d8cac2c..40f337b798 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -1230,7 +1230,8 @@ bool vfio_migration_realize(VFIODevice *vbasedev, Error **errp)
         goto out_deinit;
     }
 
-    if (vfio_viommu_preset(vbasedev)) {
+    if (!vfio_device_dirty_pages_disabled(vbasedev) &&
+        vfio_viommu_preset(vbasedev)) {
         error_setg(&err, "%s: Migration is currently not supported "
                    "with vIOMMU enabled", vbasedev->name);
         goto add_blocker;
-- 
2.47.1