migration: Modify ram_init_bitmaps() to report dirty tracking errors

The .save_setup() handler has now an Error** argument that we can use
to propagate errors reported by the .log_global_start() handler. Do
that for the RAM. The caller qemu_savevm_state_setup() will store the
error under the migration stream for later detection in the migration
sequence.

Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240320064911.545001-15-clg@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

migration/ram.c

@@ -2857,9 +2857,8 @@ static void migration_bitmap_clear_discarded_pages(RAMState *rs)
     }
 }
 
-static void ram_init_bitmaps(RAMState *rs)
+static bool ram_init_bitmaps(RAMState *rs, Error **errp)
 {
-    Error *local_err = NULL;
     bool ret = true;
 
     qemu_mutex_lock_ramlist();
@@ -2868,10 +2867,8 @@ static void ram_init_bitmaps(RAMState *rs)
         ram_list_init_bitmaps();
         /* We don't use dirty log with background snapshots */
         if (!migrate_background_snapshot()) {
-            ret = memory_global_dirty_log_start(GLOBAL_DIRTY_MIGRATION,
-                                                &local_err);
+            ret = memory_global_dirty_log_start(GLOBAL_DIRTY_MIGRATION, errp);
             if (!ret) {
-                error_report_err(local_err);
                 goto out_unlock;
             }
             migration_bitmap_sync_precopy(rs, false);
@@ -2882,32 +2879,31 @@ static void ram_init_bitmaps(RAMState *rs)
 
     if (!ret) {
         ram_bitmaps_destroy();
-        return;
+        return false;
     }
 
     /*
      * After an eventual first bitmap sync, fixup the initial bitmap
      * containing all 1s to exclude any discarded pages from migration.
      */
     migration_bitmap_clear_discarded_pages(rs);
+    return true;
 }
 
-static int ram_init_all(RAMState **rsp)
+static int ram_init_all(RAMState **rsp, Error **errp)
 {
-    Error *local_err = NULL;
-
-    if (!ram_state_init(rsp, &local_err)) {
-        error_report_err(local_err);
+    if (!ram_state_init(rsp, errp)) {
         return -1;
     }
 
-    if (!xbzrle_init(&local_err)) {
-        error_report_err(local_err);
+    if (!xbzrle_init(errp)) {
         ram_state_cleanup(rsp);
         return -1;
     }
 
-    ram_init_bitmaps(*rsp);
+    if (!ram_init_bitmaps(*rsp, errp)) {
+        return -1;
+    }
 
     return 0;
 }
@@ -3104,8 +3100,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque, Error **errp)
 
     /* migration has already setup the bitmap, reuse it. */
     if (!migration_in_colo_state()) {
-        if (ram_init_all(rsp) != 0) {
-            error_setg(errp, "%s: failed to setup RAM for migration", __func__);
+        if (ram_init_all(rsp, errp) != 0) {
             compress_threads_save_cleanup();
             return -1;
         }