[PATCH v3 11/13] vfio/migration: Block migration with vIOMMU

[Joao Martins]

Migrating with vIOMMU will require either tracking maximum
IOMMU supported address space (e.g. 39/48 address width on Intel)
or range-track current mappings and dirty track the new ones
post starting dirty tracking. This will be done as a separate
series, so add a live migration blocker until that is fixed.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
 hw/vfio/common.c              | 51 +++++++++++++++++++++++++++++++++++
 hw/vfio/migration.c           |  6 +++++
 include/hw/vfio/vfio-common.h |  2 ++
 3 files changed, 59 insertions(+)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 5b8456975e97..9b909f856722 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -365,6 +365,7 @@ bool vfio_mig_active(void)
 }
 
 static Error *multiple_devices_migration_blocker;
+static Error *giommu_migration_blocker;
 
 static unsigned int vfio_migratable_device_num(void)
 {
@@ -416,6 +417,56 @@ void vfio_unblock_multiple_devices_migration(void)
     multiple_devices_migration_blocker = NULL;
 }
 
+static unsigned int vfio_use_iommu_device_num(void)
+{
+    VFIOGroup *group;
+    VFIODevice *vbasedev;
+    unsigned int device_num = 0;
+
+    QLIST_FOREACH(group, &vfio_group_list, next) {
+        QLIST_FOREACH(vbasedev, &group->device_list, next) {
+            if (vbasedev->group->container->space->as !=
+                                    &address_space_memory) {
+                device_num++;
+            }
+        }
+    }
+
+    return device_num;
+}
+
+int vfio_block_giommu_migration(Error **errp)
+{
+    int ret;
+
+    if (giommu_migration_blocker ||
+        !vfio_use_iommu_device_num()) {
+        return 0;
+    }
+
+    error_setg(&giommu_migration_blocker,
+               "Migration is currently not supported with vIOMMU enabled");
+    ret = migrate_add_blocker(giommu_migration_blocker, errp);
+    if (ret < 0) {
+        error_free(giommu_migration_blocker);
+        giommu_migration_blocker = NULL;
+    }
+
+    return ret;
+}
+
+void vfio_unblock_giommu_migration(void)
+{
+    if (!giommu_migration_blocker ||
+        vfio_use_iommu_device_num()) {
+        return;
+    }
+
+    migrate_del_blocker(giommu_migration_blocker);
+    error_free(giommu_migration_blocker);
+    giommu_migration_blocker = NULL;
+}
+
 static void vfio_set_migration_error(int err)
 {
     MigrationState *ms = migrate_get_current();
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index a2c3d9bade7f..3e75868ae7a9 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -634,6 +634,11 @@ int vfio_migration_probe(VFIODevice *vbasedev, Error 
**errp)
         return ret;
     }
 
+    ret = vfio_block_giommu_migration(errp);
+    if (ret) {
+        return ret;
+    }
+
     trace_vfio_migration_probe(vbasedev->name);
     return 0;
 
@@ -659,6 +664,7 @@ void vfio_migration_finalize(VFIODevice *vbasedev)
         unregister_savevm(VMSTATE_IF(vbasedev->dev), "vfio", vbasedev);
         vfio_migration_exit(vbasedev);
         vfio_unblock_multiple_devices_migration();
+        vfio_unblock_giommu_migration();
     }
 
     if (vbasedev->migration_blocker) {
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 1cbbccd91e11..38e44258925b 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -233,6 +233,8 @@ extern VFIOGroupList vfio_group_list;
 bool vfio_mig_active(void);
 int vfio_block_multiple_devices_migration(Error **errp);
 void vfio_unblock_multiple_devices_migration(void);
+int vfio_block_giommu_migration(Error **errp);
+void vfio_unblock_giommu_migration(void);
 int64_t vfio_mig_bytes_transferred(void);
 
 #ifdef CONFIG_LINUX
-- 
2.17.2