migration: MigrationEvent for notifiers

Passing MigrationState to notifiers is unsound because they could access
unstable migration state internals or even modify the state.  Instead, pass
the minimal info needed in a new MigrationEvent struct, which could be
extended in the future if needed.

Suggested-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/1708622920-68779-5-git-send-email-steven.sistare@oracle.com
Signed-off-by: Peter Xu <peterx@redhat.com>

3 files changed, 10 insertions, 13 deletions

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 75f4e86..e803f98 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -3504,7 +3504,7 @@ out:
     return !err;
 }
 
-static void virtio_net_handle_migration_primary(VirtIONet *n, MigrationState *s)
+static void virtio_net_handle_migration_primary(VirtIONet *n, MigrationEvent *e)
 {
     bool should_be_hidden;
     Error *err = NULL;
@@ -3516,7 +3516,7 @@ static void virtio_net_handle_migration_primary(VirtIONet *n, MigrationState *s)
 
     should_be_hidden = qatomic_read(&n->failover_primary_hidden);
 
-    if (migration_in_setup(s) && !should_be_hidden) {
+    if (e->type == MIG_EVENT_PRECOPY_SETUP && !should_be_hidden) {
         if (failover_unplug_primary(n, dev)) {
             vmstate_unregister(VMSTATE_IF(dev), qdev_get_vmsd(dev), dev);
             qapi_event_send_unplug_primary(dev->id);
@@ -3524,7 +3524,7 @@ static void virtio_net_handle_migration_primary(VirtIONet *n, MigrationState *s)
         } else {
             warn_report("couldn't unplug primary device");
         }
-    } else if (migration_has_failed(s)) {
+    } else if (e->type == MIG_EVENT_PRECOPY_FAILED) {
         /* We already unplugged the device let's plug it back */
         if (!failover_replug_primary(n, dev, &err)) {
             if (err) {
@@ -3537,9 +3537,10 @@ static void virtio_net_handle_migration_primary(VirtIONet *n, MigrationState *s)
 static int virtio_net_migration_state_notifier(NotifierWithReturn *notifier,
                                                void *data, Error **errp)
 {
-    MigrationState *s = data;
+    MigrationEvent *e = data;
+
     VirtIONet *n = container_of(notifier, VirtIONet, migration_state);
-    virtio_net_handle_migration_primary(n, s);
+    virtio_net_handle_migration_primary(n, e);
     return 0;
 }
 
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 6b6acc4..869d841 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -757,18 +757,14 @@ static void vfio_vmstate_change(void *opaque, bool running, RunState state)
 static int vfio_migration_state_notifier(NotifierWithReturn *notifier,
                                          void *data, Error **errp)
 {
-    MigrationState *s = data;
+    MigrationEvent *e = data;
     VFIOMigration *migration = container_of(notifier, VFIOMigration,
                                             migration_state);
     VFIODevice *vbasedev = migration->vbasedev;
 
-    trace_vfio_migration_state_notifier(vbasedev->name,
-                                        MigrationStatus_str(s->state));
+    trace_vfio_migration_state_notifier(vbasedev->name, e->type);
 
-    switch (s->state) {
-    case MIGRATION_STATUS_CANCELLING:
-    case MIGRATION_STATUS_CANCELLED:
-    case MIGRATION_STATUS_FAILED:
+    if (e->type == MIG_EVENT_PRECOPY_FAILED) {
         vfio_migration_set_state_or_reset(vbasedev, VFIO_DEVICE_STATE_RUNNING);
     }
     return 0;
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index 8fdde54..f0474b2 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -153,7 +153,7 @@ vfio_load_state(const char *name, uint64_t data) " (%s) data 0x%"PRIx64
 vfio_load_state_device_data(const char *name, uint64_t data_size, int ret) " (%s) size 0x%"PRIx64" ret %d"
 vfio_migration_realize(const char *name) " (%s)"
 vfio_migration_set_state(const char *name, const char *state) " (%s) state %s"
-vfio_migration_state_notifier(const char *name, const char *state) " (%s) state %s"
+vfio_migration_state_notifier(const char *name, int state) " (%s) state %d"
 vfio_save_block(const char *name, int data_size) " (%s) data_size %d"
 vfio_save_cleanup(const char *name) " (%s)"
 vfio_save_complete_precopy(const char *name, int ret) " (%s) ret %d"