On 2025/08/30 5:01, Arun Menon wrote:
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() must report an error
in errp, in case of failure.
When postcopy live migration runs, the device states are loaded by
both the qemu coroutine process_incoming_migration_co() and the
postcopy_ram_listen_thread(). Therefore, it is important that the
coroutine also reports the error in case of failure, with
error_report_err(). Otherwise, the source qemu will not display
any errors before going into the postcopy pause state.
Reviewed-by: Marc-André Lureau <[email protected]>
Reviewed-by: Fabiano Rosas <[email protected]>
Signed-off-by: Arun Menon <[email protected]>
---
migration/migration.c | 9 +++++----
migration/savevm.c | 30 ++++++++++++++++++------------
migration/savevm.h | 2 +-
3 files changed, 24 insertions(+), 17 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index
10c216d25dec01f206eacad2edd24d21f00e614c..c6768d88f45c870c7fad9b9957300766ff69effc
100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -881,7 +881,7 @@ process_incoming_migration_co(void *opaque)
MIGRATION_STATUS_ACTIVE);
mis->loadvm_co = qemu_coroutine_self();
- ret = qemu_loadvm_state(mis->from_src_file);
+ ret = qemu_loadvm_state(mis->from_src_file, &local_err);
mis->loadvm_co = NULL;
trace_vmstate_downtime_checkpoint("dst-precopy-loadvm-completed");
@@ -908,7 +908,8 @@ process_incoming_migration_co(void *opaque)
}
if (ret < 0) {
- error_setg(&local_err, "load of migration failed: %s", strerror(-ret));
+ error_prepend(&local_err, "load of migration failed: %s: ",
+ strerror(-ret));
goto fail;
}
@@ -924,13 +925,13 @@ fail:
migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
MIGRATION_STATUS_FAILED);
migrate_set_error(s, local_err);
- error_free(local_err);
+ error_report_err(local_err);
This is problematic because it results in duplicate error reports when
!mis->exit_on_error; in that case the query-migrate QMP command reports
the error and this error reporting is redundant.
migration_incoming_state_destroy();
if (mis->exit_on_error) {
WITH_QEMU_LOCK_GUARD(&s->error_mutex) {
- error_report_err(s->error);
+ error_free(s->error);
This change is problematic because s->error set somewhere else here will
be ignored.
I think the two changes I commented can be simply removed without
causing other problems.
s->error = NULL;
}
diff --git a/migration/savevm.c b/migration/savevm.c
index
de5671ffd1cd06e728227a3056c3f895d3a6e6f3..0087fca15ce108685667d3808350d80d37b807b1
100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -3159,28 +3159,24 @@ out:
return ret;
}
-int qemu_loadvm_state(QEMUFile *f)
+int qemu_loadvm_state(QEMUFile *f, Error **errp)
{
MigrationState *s = migrate_get_current();
MigrationIncomingState *mis = migration_incoming_get_current();
- Error *local_err = NULL;
int ret;
- if (qemu_savevm_state_blocked(&local_err)) {
- error_report_err(local_err);
+ if (qemu_savevm_state_blocked(errp)) {
return -EINVAL;
}
qemu_loadvm_thread_pool_create(mis);
- ret = qemu_loadvm_state_header(f, &local_err);
+ ret = qemu_loadvm_state_header(f, errp);
if (ret) {
- error_report_err(local_err);
return ret;
}
- if (qemu_loadvm_state_setup(f, &local_err) != 0) {
- error_report_err(local_err);
+ if (qemu_loadvm_state_setup(f, errp) != 0) {
return -EINVAL;
}
@@ -3191,6 +3187,9 @@ int qemu_loadvm_state(QEMUFile *f)
cpu_synchronize_all_pre_loadvm();
ret = qemu_loadvm_state_main(f, mis);
+ if (ret < 0) {
+ error_setg(errp, "Load VM state failed: %d", ret);
+ }
qemu_event_set(&mis->main_thread_load_event);
trace_qemu_loadvm_state_post_main(ret);
@@ -3208,8 +3207,15 @@ int qemu_loadvm_state(QEMUFile *f)
if (migrate_has_error(migrate_get_current()) ||
!qemu_loadvm_thread_pool_wait(s, mis)) {
ret = -EINVAL;
+ error_setg(errp,
+ "Error while loading vmstate");
} else {
ret = qemu_file_get_error(f);
+ if (ret < 0) {
+ error_setg(errp,
+ "Error while loading vmstate: stream error: %d",
+ ret);
+ }
}
}
/*
@@ -3474,6 +3480,7 @@ void qmp_xen_save_devices_state(const char *filename,
bool has_live, bool live,
void qmp_xen_load_devices_state(const char *filename, Error **errp)
{
+ ERRP_GUARD();
QEMUFile *f;
QIOChannelFile *ioc;
int ret;
@@ -3495,10 +3502,10 @@ void qmp_xen_load_devices_state(const char *filename,
Error **errp)
f = qemu_file_new_input(QIO_CHANNEL(ioc));
object_unref(OBJECT(ioc));
- ret = qemu_loadvm_state(f);
+ ret = qemu_loadvm_state(f, errp);
qemu_fclose(f);
if (ret < 0) {
- error_setg(errp, "loading Xen device state failed");
+ error_prepend(errp, "loading Xen device state failed: ");
}
migration_incoming_state_destroy();
}
@@ -3569,13 +3576,12 @@ bool load_snapshot(const char *name, const char
*vmstate,
ret = -EINVAL;
goto err_drain;
}
- ret = qemu_loadvm_state(f);
+ ret = qemu_loadvm_state(f, errp);
migration_incoming_state_destroy();
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
2d5e9c716686f06720325e82fe90c75335ced1de..b80770b7461a60e2ad6ba5e24a7baeae73d90955
100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -64,7 +64,7 @@ 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(MigrationIncomingState *mis);
int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis);
int qemu_load_device_state(QEMUFile *f);
