* Paolo Bonzini (pbonz...@redhat.com) wrote:
> The HMP loadvm code is calling load_snapshot rather than
> qmp_snapshot_load, in order to bypass the job infrastructure. The code
> around it is almost the same, with one difference: hmp_loadvm is
> restarting the VM if load_snapshot fails, qmp_snapshot_load is doing so
> if load_snapshot succeeds.
>
> Fix the bug in QMP by moving the common code to load_snapshot.
So I agree it's nice to have them consistent, but hmm.
> Cc: qemu-sta...@nongnu.org
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> migration/savevm.c | 16 ++++++++--------
> monitor/hmp-cmds.c | 7 +------
> 2 files changed, 9 insertions(+), 14 deletions(-)
>
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 52e2d72e4b..a899191cbf 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -2992,6 +2992,7 @@ bool load_snapshot(const char *name, const char
> *vmstate,
> int ret;
> AioContext *aio_context;
> MigrationIncomingState *mis = migration_incoming_get_current();
> + int saved_vm_running = runstate_is_running();
>
> if (!bdrv_all_can_snapshot(has_devices, devices, errp)) {
> return false;
> @@ -3024,6 +3025,8 @@ bool load_snapshot(const char *name, const char
> *vmstate,
> return false;
> }
>
> + vm_stop(RUN_STATE_RESTORE_VM);
> +
> /*
> * Flush the record/replay queue. Now the VM state is going
> * to change. Therefore we don't need to preserve its consistency
> @@ -3061,13 +3064,17 @@ bool load_snapshot(const char *name, const char
> *vmstate,
>
> if (ret < 0) {
> error_setg(errp, "Error %d while loading VM state", ret);
> - return false;
> + goto err_restart;
> }
I don't think this is safe.
If qemu_loadvm_state(f) fails, depending on the point that it fails,
the state of the VM is in a part loaded, indeterminate state - it
doesn't seem right to auto-restart it.
Note, that's a destinct failure from the earlier failures, e.g. trying
to find the snapshot and noticing it doesn't exist - that's OK to
restart the VM.
Then there's the question of what to do if the load_snapshot succeeds;
qmp's behaviour of running the loaded-VM doesn't seem wrong to me;
although you'd think that would be based on the loaded state not the
original; but that's probably a different question.
Dave
> return true;
>
> err_drain:
> bdrv_drain_all_end();
> +err_restart:
> + if (saved_vm_running) {
> + vm_start();
> + }
> return false;
> }
>
> @@ -3135,17 +3142,10 @@ static void snapshot_load_job_bh(void *opaque)
> {
> Job *job = opaque;
> SnapshotJob *s = container_of(job, SnapshotJob, common);
> - int orig_vm_running;
>
> job_progress_set_remaining(&s->common, 1);
>
> - orig_vm_running = runstate_is_running();
> - vm_stop(RUN_STATE_RESTORE_VM);
> -
> s->ret = load_snapshot(s->tag, s->vmstate, true, s->devices, s->errp);
> - if (s->ret && orig_vm_running) {
> - vm_start();
> - }
>
> job_progress_update(&s->common, 1);
>
> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
> index 0ad5b77477..a39436c8cb 100644
> --- a/monitor/hmp-cmds.c
> +++ b/monitor/hmp-cmds.c
> @@ -1127,15 +1127,10 @@ void hmp_balloon(Monitor *mon, const QDict *qdict)
>
> void hmp_loadvm(Monitor *mon, const QDict *qdict)
> {
> - int saved_vm_running = runstate_is_running();
> const char *name = qdict_get_str(qdict, "name");
> Error *err = NULL;
>
> - vm_stop(RUN_STATE_RESTORE_VM);
> -
> - if (!load_snapshot(name, NULL, false, NULL, &err) && saved_vm_running) {
> - vm_start();
> - }
> + load_snapshot(name, NULL, false, NULL, &err);
> hmp_handle_error(mon, err);
> }
>
> --
> 2.26.2
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
