On Thu, Jul 17, 2025 at 06:07:44AM +0530, 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.
> postcopy_ram_listen_thread() calls qemu_loadvm_state_main()
> to load the vm, and in case of a failure, it should set the error
> in the migration object.
>
> 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.
>
> Signed-off-by: Arun Menon <arme...@redhat.com>
> ---
> migration/migration.c | 2 +-
> migration/savevm.c | 10 ++++++++--
> 2 files changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/migration/savevm.c b/migration/savevm.c
> index
> 0fff65c96344c65191353311e72730cd6e3bfb23..4f67eebe5321c175d51e8029e36ceb336c98ad1f
> 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -2086,6 +2086,7 @@ static void *postcopy_ram_listen_thread(void *opaque)
> QEMUFile *f = mis->from_src_file;
> int load_res;
> MigrationState *migr = migrate_get_current();
> + Error *local_err = NULL;
>
> object_ref(OBJECT(migr));
>
> @@ -2102,7 +2103,7 @@ 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, NULL);
> + load_res = qemu_loadvm_state_main(f, mis, &local_err);
>
> /*
> * This is tricky, but, mis->from_src_file can change after it
> @@ -2128,7 +2129,12 @@ static void *postcopy_ram_listen_thread(void *opaque)
> __func__, load_res);
> load_res = 0; /* prevent further exit() */
> } else {
> - error_report("%s: loadvm failed: %d", __func__, load_res);
> + if (local_err != NULL) {
> + error_prepend(&local_err, "%s: loadvm failed: %d", __func__,
> + load_res);
IMHO __func__ is redundant if you change the message
to be 'loadvm failed during postcopy' like the earlier part
fo the "if { " does.
> + migrate_set_error(migr, local_err);
> + error_report_err(local_err);
> + }
> migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
> MIGRATION_STATUS_FAILED);
With regards,
Daniel
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