[PATCH 01/33] migration: push Error **errp into qemu_loadvm_state()

["Daniel P. Berrangé" <berrange@redhat.com>]

This is an incremental step in converting vmstate loading code to report
via Error objects instead of printing directly to the console/monitor.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 migration/migration.c |  4 ++--
 migration/savevm.c    | 36 ++++++++++++++++++++----------------
 migration/savevm.h    |  2 +-
 3 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 1986cb8573..287a18d269 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -519,7 +519,7 @@ static void process_incoming_migration_co(void *opaque)
     postcopy_state_set(POSTCOPY_INCOMING_NONE);
     migrate_set_state(&mis->state, MIGRATION_STATUS_NONE,
                       MIGRATION_STATUS_ACTIVE);
-    ret = qemu_loadvm_state(mis->from_src_file);
+    ret = qemu_loadvm_state(mis->from_src_file, &local_err);
 
     ps = postcopy_state_get();
     trace_process_incoming_migration_co_end(ret, ps);
@@ -563,7 +563,7 @@ static void process_incoming_migration_co(void *opaque)
     }
 
     if (ret < 0) {
-        error_report("load of migration failed: %s", strerror(-ret));
+        error_report_err(local_err);
         goto fail;
     }
     mis->bh = qemu_bh_new(process_incoming_migration_bh, mis);
diff --git a/migration/savevm.c b/migration/savevm.c
index 6b320423c7..c8d93eee1e 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2638,40 +2638,49 @@ out:
     return ret;
 }
 
-int qemu_loadvm_state(QEMUFile *f)
+int qemu_loadvm_state(QEMUFile *f, Error **errp)
 {
     MigrationIncomingState *mis = migration_incoming_get_current();
-    Error *local_err = NULL;
     int ret;
 
-    if (qemu_savevm_state_blocked(&local_err)) {
-        error_report_err(local_err);
-        return -EINVAL;
+    if (qemu_savevm_state_blocked(errp)) {
+        return -1;
     }
 
     ret = qemu_loadvm_state_header(f);
     if (ret) {
-        return ret;
+        error_setg(errp, "Error %d while loading VM state", ret);
+        return -1;
     }
 
     if (qemu_loadvm_state_setup(f) != 0) {
-        return -EINVAL;
+        error_setg(errp, "Error %d while loading VM state", -EINVAL);
+        return -1;
     }
 
     cpu_synchronize_all_pre_loadvm();
 
     ret = qemu_loadvm_state_main(f, mis);
+    if (ret < 0) {
+        error_setg(errp, "Error %d while loading VM state", ret);
+        ret = -1;
+    }
     qemu_event_set(&mis->main_thread_load_event);
 
     trace_qemu_loadvm_state_post_main(ret);
 
     if (mis->have_listen_thread) {
+        error_setg(errp, "Error %d while loading VM state", ret);
         /* Listen thread still going, can't clean up yet */
         return ret;
     }
 
     if (ret == 0) {
         ret = qemu_file_get_error(f);
+        if (ret < 0) {
+            error_setg(errp, "Error %d while loading VM state", ret);
+            ret = -1;
+        }
     }
 
     /*
@@ -2690,8 +2699,8 @@ int qemu_loadvm_state(QEMUFile *f)
         uint8_t  section_type = qemu_get_byte(f);
 
         if (section_type != QEMU_VM_VMDESCRIPTION) {
-            error_report("Expected vmdescription section, but got %d",
-                         section_type);
+            error_setg(errp, "Expected vmdescription section, but got %d",
+                       section_type);
             /*
              * It doesn't seem worth failing at this point since
              * we apparently have an otherwise valid VM state
@@ -2921,7 +2930,6 @@ void qmp_xen_load_devices_state(const char *filename, Error **errp)
 {
     QEMUFile *f;
     QIOChannelFile *ioc;
-    int ret;
 
     /* Guest must be paused before loading the device state; the RAM state
      * will already have been loaded by xc
@@ -2940,11 +2948,8 @@ void qmp_xen_load_devices_state(const char *filename, Error **errp)
     f = qemu_fopen_channel_input(QIO_CHANNEL(ioc));
     object_unref(OBJECT(ioc));
 
-    ret = qemu_loadvm_state(f);
+    qemu_loadvm_state(f, errp);
     qemu_fclose(f);
-    if (ret < 0) {
-        error_setg(errp, QERR_IO_ERROR);
-    }
     migration_incoming_state_destroy();
 }
 
@@ -3018,14 +3023,13 @@ bool load_snapshot(const char *name, const char *vmstate,
         goto err_drain;
     }
     aio_context_acquire(aio_context);
-    ret = qemu_loadvm_state(f);
+    ret = qemu_loadvm_state(f, errp);
     migration_incoming_state_destroy();
     aio_context_release(aio_context);
 
     bdrv_drain_all_end();
 
     if (ret < 0) {
-        error_setg(errp, "Error %d while loading VM state", ret);
         return false;
     }
 
diff --git a/migration/savevm.h b/migration/savevm.h
index ba64a7e271..1069e2dd4f 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -60,7 +60,7 @@ void qemu_savevm_send_colo_enable(QEMUFile *f);
 void qemu_savevm_live_state(QEMUFile *f);
 int qemu_save_device_state(QEMUFile *f);
 
-int qemu_loadvm_state(QEMUFile *f);
+int qemu_loadvm_state(QEMUFile *f, Error **errp);
 void qemu_loadvm_state_cleanup(void);
 int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis);
 int qemu_load_device_state(QEMUFile *f);
-- 
2.29.2