[PATCH v4 18/23] migration: push Error **errp into qemu_loadvm_state_main()

[Arun Menon <armenon@redhat.com>]

This is an incremental step in converting vmstate loading
code to report error via Error objects instead of directly
printing it to console/monitor.
It is ensured that qemu_loadvm_state_main() must report an error
in errp, in case of failure.
loadvm_process_command also sets the errp object explicitly.

Signed-off-by: Arun Menon <armenon@redhat.com>
---
 migration/colo.c   |  5 +++--
 migration/savevm.c | 23 +++++++++++++----------
 migration/savevm.h |  3 ++-
 3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/migration/colo.c b/migration/colo.c
index e0f713c837f5da25d67afbd02ceb6c54024ca3af..ddc628cab4194b3cb82388c5e878286c820004b2 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -686,11 +686,12 @@ static void colo_incoming_process_checkpoint(MigrationIncomingState *mis,
 
     bql_lock();
     cpu_synchronize_all_states();
-    ret = qemu_loadvm_state_main(mis->from_src_file, mis);
+    ret = qemu_loadvm_state_main(mis->from_src_file, mis, &local_err);
     bql_unlock();
 
     if (ret < 0) {
-        error_setg(errp, "Load VM's live state (ram) error");
+        error_propagate_prepend(errp, local_err,
+                                "Load VM's live state (ram) error");
         return;
     }
 
diff --git a/migration/savevm.c b/migration/savevm.c
index 2df266129f24d3d0d24ee84c3a8d2f494e50d03f..9752fad6e1aa2d677b68cb6ae9180d1059d54019 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2102,7 +2102,7 @@ static void *postcopy_ram_listen_thread(void *opaque)
     qemu_file_set_blocking(f, true);
 
     /* TODO: sanity check that only postcopiable data will be loaded here */
-    load_res = qemu_loadvm_state_main(f, mis);
+    load_res = qemu_loadvm_state_main(f, mis, NULL);
 
     /*
      * This is tricky, but, mis->from_src_file can change after it
@@ -2453,9 +2453,9 @@ static int loadvm_handle_cmd_packaged(MigrationIncomingState *mis, Error **errp)
         qemu_coroutine_yield();
     } while (1);
 
-    ret = qemu_loadvm_state_main(packf, mis);
+    ret = qemu_loadvm_state_main(packf, mis, errp);
     if (ret < 0) {
-        error_setg(errp, "VM state load failed: %d", ret);
+        error_prepend(errp, "Loading VM state failed: %d ", ret);
     }
     trace_loadvm_handle_cmd_packaged_main(ret);
     qemu_fclose(packf);
@@ -3057,7 +3057,8 @@ static bool postcopy_pause_incoming(MigrationIncomingState *mis)
     return true;
 }
 
-int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis)
+int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis,
+                           Error **errp)
 {
     uint8_t section_type;
     int ret = 0;
@@ -3068,6 +3069,8 @@ retry:
 
         ret = qemu_file_get_error_obj_any(f, mis->postcopy_qemufile_dst, NULL);
         if (ret) {
+            error_setg(errp, "Failed to load device state section ID : %d",
+                       ret);
             break;
         }
 
@@ -3075,20 +3078,20 @@ retry:
         switch (section_type) {
         case QEMU_VM_SECTION_START:
         case QEMU_VM_SECTION_FULL:
-            ret = qemu_loadvm_section_start_full(f, section_type, NULL);
+            ret = qemu_loadvm_section_start_full(f, section_type, errp);
             if (ret < 0) {
                 goto out;
             }
             break;
         case QEMU_VM_SECTION_PART:
         case QEMU_VM_SECTION_END:
-            ret = qemu_loadvm_section_part_end(f, section_type, NULL);
+            ret = qemu_loadvm_section_part_end(f, section_type, errp);
             if (ret < 0) {
                 goto out;
             }
             break;
         case QEMU_VM_COMMAND:
-            ret = loadvm_process_command(f, NULL);
+            ret = loadvm_process_command(f, errp);
             trace_qemu_loadvm_state_section_command(ret);
             if ((ret < 0) || (ret == LOADVM_QUIT)) {
                 goto out;
@@ -3098,7 +3101,7 @@ retry:
             /* This is the end of migration */
             goto out;
         default:
-            error_report("Unknown savevm section type %d", section_type);
+            error_setg(errp, "Unknown savevm section type %d", section_type);
             ret = -EINVAL;
             goto out;
         }
@@ -3162,7 +3165,7 @@ int qemu_loadvm_state(QEMUFile *f)
 
     cpu_synchronize_all_pre_loadvm();
 
-    ret = qemu_loadvm_state_main(f, mis);
+    ret = qemu_loadvm_state_main(f, mis, NULL);
     qemu_event_set(&mis->main_thread_load_event);
 
     trace_qemu_loadvm_state_post_main(ret);
@@ -3236,7 +3239,7 @@ int qemu_load_device_state(QEMUFile *f)
     int ret;
 
     /* Load QEMU_VM_SECTION_FULL section */
-    ret = qemu_loadvm_state_main(f, mis);
+    ret = qemu_loadvm_state_main(f, mis, NULL);
     if (ret < 0) {
         error_report("Failed to load device state: %d", ret);
         return ret;
diff --git a/migration/savevm.h b/migration/savevm.h
index 2d5e9c716686f06720325e82fe90c75335ced1de..fd7419e6ff90062970ed246b3ea71e6d49a6e372 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -66,7 +66,8 @@ int qemu_save_device_state(QEMUFile *f);
 
 int qemu_loadvm_state(QEMUFile *f);
 void qemu_loadvm_state_cleanup(MigrationIncomingState *mis);
-int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis);
+int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis,
+                           Error **errp);
 int qemu_load_device_state(QEMUFile *f);
 int qemu_loadvm_approve_switchover(void);
 int qemu_savevm_state_complete_precopy_non_iterable(QEMUFile *f,

-- 
2.50.0