3 files changed, 38 insertions, 2 deletions
diff --git a/migration/migration.c b/migration/migration.c
index fdadee290e..4698b47442 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -223,13 +223,18 @@ void migration_object_init(void)
     dirty_bitmap_mig_init();
 }
 
+void migration_cancel(void)
+{
+    migrate_fd_cancel(current_migration);
+}
+
 void migration_shutdown(void)
 {
     /*
      * Cancel the current migration - that will (eventually)
      * stop the migration using this structure
      */
-    migrate_fd_cancel(current_migration);
+    migration_cancel();
     object_unref(OBJECT(current_migration));
 
     /*
@@ -2307,7 +2312,7 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
 
 void qmp_migrate_cancel(Error **errp)
 {
-    migrate_fd_cancel(migrate_get_current());
+    migration_cancel();
 }
 
 void qmp_migrate_continue(MigrationStatus state, Error **errp)
diff --git a/migration/migration.h b/migration/migration.h
index db6708326b..f7b388d718 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -375,5 +375,6 @@ int foreach_not_ignored_block(RAMBlockIterFunc func, void *opaque);
 void migration_make_urgent_request(void);
 void migration_consume_urgent_request(void);
 bool migration_rate_limit(void);
+void migration_cancel(void);
 
 #endif
diff --git a/migration/ram.c b/migration/ram.c
index bb52bd97db..77922c445e 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -4096,8 +4096,38 @@ static SaveVMHandlers savevm_ram_handlers = {
     .resume_prepare = ram_resume_prepare,
 };
 
+static void ram_mig_ram_block_resized(RAMBlockNotifier *n, void *host,
+                                      size_t old_size, size_t new_size)
+{
+    ram_addr_t offset;
+    RAMBlock *rb = qemu_ram_block_from_host(host, false, &offset);
+    Error *err = NULL;
+
+    if (ramblock_is_ignored(rb)) {
+        return;
+    }
+
+    if (!migration_is_idle()) {
+        /*
+         * Precopy code on the source cannot deal with the size of RAM blocks
+         * changing at random points in time - especially after sending the
+         * RAM block sizes in the migration stream, they must no longer change.
+         * Abort and indicate a proper reason.
+         */
+        error_setg(&err, "RAM block '%s' resized during precopy.", rb->idstr);
+        migrate_set_error(migrate_get_current(), err);
+        error_free(err);
+        migration_cancel();
+    }
+}
+
+static RAMBlockNotifier ram_mig_ram_notifier = {
+    .ram_block_resized = ram_mig_ram_block_resized,
+};
+
 void ram_mig_init(void)
 {
     qemu_mutex_init(&XBZRLE.lock);
     register_savevm_live("ram", 0, 4, &savevm_ram_handlers, &ram_state);
+    ram_block_notifier_add(&ram_mig_ram_notifier);
 }