migration: Move more initializations to migrate_init()

Initialization of mig_stats, compression_counters and VFIO bytes
transferred is hard-coded in migration code path and snapshot code path.

Make the code cleaner by initializing them in migrate_init().

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>

migration/migration.c

@@ -1425,6 +1425,13 @@ void migrate_init(MigrationState *s)
     s->iteration_initial_bytes = 0;
     s->threshold_size = 0;
     s->switchover_acked = false;
+    /*
+     * set mig_stats compression_counters memory to zero for a
+     * new migration
+     */
+    memset(&mig_stats, 0, sizeof(mig_stats));
+    memset(&compression_counters, 0, sizeof(compression_counters));
+    migration_reset_vfio_bytes_transferred();
 }
 
 int migrate_add_blocker_internal(Error *reason, Error **errp)
@@ -1635,13 +1642,6 @@ static bool migrate_prepare(MigrationState *s, bool blk, bool blk_inc,
     }
 
     migrate_init(s);
-    /*
-     * set mig_stats compression_counters memory to zero for a
-     * new migration
-     */
-    memset(&mig_stats, 0, sizeof(mig_stats));
-    memset(&compression_counters, 0, sizeof(compression_counters));
-    migration_reset_vfio_bytes_transferred();
 
     return true;
 }

migration/savevm.c

@@ -1620,9 +1620,6 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp)
     }
 
     migrate_init(ms);
-    memset(&mig_stats, 0, sizeof(mig_stats));
-    memset(&compression_counters, 0, sizeof(compression_counters));
-    migration_reset_vfio_bytes_transferred();
     ms->to_dst_file = f;
 
     qemu_mutex_unlock_iothread();