On Tue, Jun 02, 2026 at 12:26:09PM +0300, Avihai Horon wrote:
> migration_completion_precopy() doesn't propagate errors to migration
> core which leads to error information loss. Fix that.
>
> This prepares for a follow-up where migration_switchover_start() can
> fail on switchover-ack and still report a useful error. Errors from
> qemu_savevm_state_complete_precopy() are not propagated yet as it
> requires more plumbing.
>
> Signed-off-by: Avihai Horon <[email protected]>
> ---
> migration/migration.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 074d3f2c69..7488a94206 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2814,7 +2814,7 @@ static bool migration_switchover_start(MigrationState
> *s, Error **errp)
> return true;
> }
>
> -static int migration_completion_precopy(MigrationState *s)
> +static int migration_completion_precopy(MigrationState *s, Error **errp)
> {
> int ret;
>
> @@ -2823,11 +2823,12 @@ static int
> migration_completion_precopy(MigrationState *s)
> if (!migrate_mode_is_cpr()) {
> ret = migration_stop_vm(s, RUN_STATE_FINISH_MIGRATE);
> if (ret < 0) {
> + error_setg_errno(errp, -ret, "Failed to stop the VM");
> goto out_unlock;
> }
> }
>
> - if (!migration_switchover_start(s, NULL)) {
> + if (!migration_switchover_start(s, errp)) {
> ret = -EFAULT;
> goto out_unlock;
> }
IIUC this patch overlooked the follow up call:
ret = qemu_savevm_state_complete_precopy(s);
We should make sure ret!=0 will always set Error*. Better pass Error**
into qemu_savevm_state_complete_precopy() too.
Thanks,
> @@ -2869,7 +2870,7 @@ static void migration_completion(MigrationState *s)
> Error *local_err = NULL;
>
> if (s->state == MIGRATION_STATUS_ACTIVE) {
> - ret = migration_completion_precopy(s);
> + ret = migration_completion_precopy(s, &local_err);
> } else if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) {
> migration_completion_postcopy(s);
> } else {
> @@ -2900,7 +2901,9 @@ static void migration_completion(MigrationState *s)
> return;
>
> fail:
> - if (qemu_file_get_error_obj(s->to_dst_file, &local_err)) {
> + if (local_err) {
> + migrate_error_propagate(s, local_err);
> + } else if (qemu_file_get_error_obj(s->to_dst_file, &local_err)) {
> migrate_error_propagate(s, local_err);
> } else if (ret) {
> error_setg_errno(&local_err, -ret, "Error in migration completion");
> --
> 2.40.1
>
--
Peter Xu
