3 files changed, 80 insertions, 1 deletions

diff --git a/include/migration/client-options.h b/include/migration/client-options.h
index 59f4b55cf4..289c9d7762 100644
--- a/include/migration/client-options.h
+++ b/include/migration/client-options.h
@@ -10,6 +10,10 @@
 #ifndef QEMU_MIGRATION_CLIENT_OPTIONS_H
 #define QEMU_MIGRATION_CLIENT_OPTIONS_H
 
+
+/* properties */
+bool migrate_send_switchover_start(void);
+
 /* capabilities */
 
 bool migrate_background_snapshot(void);
diff --git a/include/migration/misc.h b/include/migration/misc.h
index c660be8095..8fd36eba1d 100644
--- a/include/migration/misc.h
+++ b/include/migration/misc.h
@@ -45,9 +45,12 @@ bool migrate_ram_is_ignored(RAMBlock *block);
 /* migration/block.c */
 
 AnnounceParameters *migrate_announce_params(void);
+
 /* migration/savevm.c */
 
 void dump_vmstate_json_to_file(FILE *out_fp);
+void qemu_loadvm_start_load_thread(MigrationLoadThread function,
+                                   void *opaque);
 
 /* migration/migration.c */
 void migration_object_init(void);
@@ -115,4 +118,26 @@ bool migrate_is_uri(const char *uri);
 bool migrate_uri_parse(const char *uri, MigrationChannel **channel,
                        Error **errp);
 
+/* migration/multifd-device-state.c */
+typedef struct SaveLiveCompletePrecopyThreadData {
+    SaveLiveCompletePrecopyThreadHandler hdlr;
+    char *idstr;
+    uint32_t instance_id;
+    void *handler_opaque;
+} SaveLiveCompletePrecopyThreadData;
+
+bool multifd_queue_device_state(char *idstr, uint32_t instance_id,
+                                char *data, size_t len);
+bool multifd_device_state_supported(void);
+
+void
+multifd_spawn_device_state_save_thread(SaveLiveCompletePrecopyThreadHandler hdlr,
+                                       char *idstr, uint32_t instance_id,
+                                       void *opaque);
+
+bool multifd_device_state_save_thread_should_exit(void);
+
+void multifd_abort_device_state_save_threads(void);
+bool multifd_join_device_state_save_threads(void);
+
 #endif
diff --git a/include/migration/register.h b/include/migration/register.h
index f60e797894..c041ce32f2 100644
--- a/include/migration/register.h
+++ b/include/migration/register.h
@@ -69,7 +69,9 @@ typedef struct SaveVMHandlers {
     /**
      * @save_cleanup
      *
-     * Uninitializes the data structures on the source
+     * Uninitializes the data structures on the source.
+     * Note that this handler can be called even if save_setup
+     * wasn't called earlier.
      *
      * @opaque: data pointer passed to register_savevm_live()
      */
@@ -103,6 +105,25 @@ typedef struct SaveVMHandlers {
      */
     int (*save_live_complete_precopy)(QEMUFile *f, void *opaque);
 
+    /**
+     * @save_live_complete_precopy_thread (invoked in a separate thread)
+     *
+     * Called at the end of a precopy phase from a separate worker thread
+     * in configurations where multifd device state transfer is supported
+     * in order to perform asynchronous transmission of the remaining data in
+     * parallel with @save_live_complete_precopy handlers.
+     * When postcopy is enabled, devices that support postcopy will skip this
+     * step.
+     *
+     * @d: a #SaveLiveCompletePrecopyThreadData containing parameters that the
+     * handler may need, including this device section idstr and instance_id,
+     * and opaque data pointer passed to register_savevm_live().
+     * @errp: pointer to Error*, to store an error if it happens.
+     *
+     * Returns true to indicate success and false for errors.
+     */
+    SaveLiveCompletePrecopyThreadHandler save_live_complete_precopy_thread;
+
     /* This runs both outside and inside the BQL.  */
 
     /**
@@ -228,6 +249,21 @@ typedef struct SaveVMHandlers {
     int (*load_state)(QEMUFile *f, void *opaque, int version_id);
 
     /**
+     * @load_state_buffer (invoked outside the BQL)
+     *
+     * Load device state buffer provided to qemu_loadvm_load_state_buffer().
+     *
+     * @opaque: data pointer passed to register_savevm_live()
+     * @buf: the data buffer to load
+     * @len: the data length in buffer
+     * @errp: pointer to Error*, to store an error if it happens.
+     *
+     * Returns true to indicate success and false for errors.
+     */
+    bool (*load_state_buffer)(void *opaque, char *buf, size_t len,
+                              Error **errp);
+
+    /**
      * @load_setup
      *
      * Initializes the data structures on the destination.
@@ -244,6 +280,8 @@ typedef struct SaveVMHandlers {
      * @load_cleanup
      *
      * Uninitializes the data structures on the destination.
+     * Note that this handler can be called even if load_setup
+     * wasn't called earlier.
      *
      * @opaque: data pointer passed to register_savevm_live()
      *
@@ -275,6 +313,18 @@ typedef struct SaveVMHandlers {
      * otherwise
      */
     bool (*switchover_ack_needed)(void *opaque);
+
+    /**
+     * @switchover_start
+     *
+     * Notifies that the switchover has started. Called only on
+     * the destination.
+     *
+     * @opaque: data pointer passed to register_savevm_live()
+     *
+     * Returns zero to indicate success and negative for error
+     */
+    int (*switchover_start)(void *opaque);
 } SaveVMHandlers;
 
 /**