migration: preserve suspended for snapshot
Restoring a snapshot can break a suspended guest. Snapshots suffer from the same suspended-state issues that affect live migration, plus they must handle an additional problematic scenario, which is that a running vm must remain running if it loads a suspended snapshot. To save, the existing vm_stop call now completely stops the suspended state. Finish with vm_resume to leave the vm in the state it had prior to the save, correctly restoring the suspended state. To load, if the snapshot is not suspended, then vm_stop + vm_resume correctly handles all states, and leaves the vm in the state it had prior to the load. However, if the snapshot is suspended, restoration is trickier. First, call vm_resume to restore the state to suspended so the current state matches the saved state. Then, if the pre-load state is running, call wakeup to resume running. Prior to these changes, the vm_stop to RUN_STATE_SAVE_VM and RUN_STATE_RESTORE_VM did not change runstate if the current state was suspended, but now it does, so allow these transitions. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Peter Xu <peterx@redhat.com> Link: https://lore.kernel.org/r/1704312341-66640-8-git-send-email-steven.sistare@oracle.com Signed-off-by: Peter Xu <peterx@redhat.com>
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@ -16,6 +16,7 @@
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#define QEMU_MIGRATION_SNAPSHOT_H
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#include "qapi/qapi-builtin-types.h"
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#include "qapi/qapi-types-run-state.h"
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/**
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* save_snapshot: Save an internal snapshot.
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@ -61,4 +62,10 @@ bool delete_snapshot(const char *name,
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bool has_devices, strList *devices,
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Error **errp);
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/**
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* load_snapshot_resume: Restore runstate after loading snapshot.
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* @state: state to restore
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*/
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void load_snapshot_resume(RunState state);
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#endif
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@ -399,15 +399,17 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
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void hmp_loadvm(Monitor *mon, const QDict *qdict)
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{
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int saved_vm_running = runstate_is_running();
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RunState saved_state = runstate_get();
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const char *name = qdict_get_str(qdict, "name");
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Error *err = NULL;
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vm_stop(RUN_STATE_RESTORE_VM);
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if (load_snapshot(name, NULL, false, NULL, &err) && saved_vm_running) {
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vm_start();
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if (load_snapshot(name, NULL, false, NULL, &err)) {
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load_snapshot_resume(saved_state);
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}
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hmp_handle_error(mon, err);
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}
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@ -3046,7 +3046,7 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
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QEMUSnapshotInfo sn1, *sn = &sn1;
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int ret = -1, ret2;
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QEMUFile *f;
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int saved_vm_running;
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RunState saved_state = runstate_get();
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uint64_t vm_state_size;
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g_autoptr(GDateTime) now = g_date_time_new_now_local();
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@ -3092,8 +3092,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
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return false;
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}
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saved_vm_running = runstate_is_running();
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global_state_store();
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vm_stop(RUN_STATE_SAVE_VM);
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@ -3147,9 +3145,7 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
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the_end:
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bdrv_drain_all_end();
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if (saved_vm_running) {
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vm_start();
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}
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vm_resume(saved_state);
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return ret == 0;
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}
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@ -3317,6 +3313,14 @@ err_drain:
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return false;
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}
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void load_snapshot_resume(RunState state)
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{
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vm_resume(state);
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if (state == RUN_STATE_RUNNING && runstate_get() == RUN_STATE_SUSPENDED) {
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qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, &error_abort);
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}
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}
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bool delete_snapshot(const char *name, bool has_devices,
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strList *devices, Error **errp)
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{
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@ -3381,16 +3385,15 @@ static void snapshot_load_job_bh(void *opaque)
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{
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Job *job = opaque;
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SnapshotJob *s = container_of(job, SnapshotJob, common);
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int orig_vm_running;
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RunState orig_state = runstate_get();
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job_progress_set_remaining(&s->common, 1);
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orig_vm_running = runstate_is_running();
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vm_stop(RUN_STATE_RESTORE_VM);
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s->ret = load_snapshot(s->tag, s->vmstate, true, s->devices, s->errp);
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if (s->ret && orig_vm_running) {
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vm_start();
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if (s->ret) {
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load_snapshot_resume(orig_state);
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}
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job_progress_update(&s->common, 1);
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@ -77,6 +77,7 @@ typedef struct {
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static const RunStateTransition runstate_transitions_def[] = {
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{ RUN_STATE_PRELAUNCH, RUN_STATE_INMIGRATE },
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{ RUN_STATE_PRELAUNCH, RUN_STATE_SUSPENDED },
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{ RUN_STATE_DEBUG, RUN_STATE_RUNNING },
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{ RUN_STATE_DEBUG, RUN_STATE_FINISH_MIGRATE },
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@ -132,6 +133,7 @@ static const RunStateTransition runstate_transitions_def[] = {
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{ RUN_STATE_RESTORE_VM, RUN_STATE_RUNNING },
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{ RUN_STATE_RESTORE_VM, RUN_STATE_PRELAUNCH },
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{ RUN_STATE_RESTORE_VM, RUN_STATE_SUSPENDED },
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{ RUN_STATE_COLO, RUN_STATE_RUNNING },
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{ RUN_STATE_COLO, RUN_STATE_PRELAUNCH },
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@ -150,6 +152,7 @@ static const RunStateTransition runstate_transitions_def[] = {
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{ RUN_STATE_RUNNING, RUN_STATE_COLO},
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{ RUN_STATE_SAVE_VM, RUN_STATE_RUNNING },
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{ RUN_STATE_SAVE_VM, RUN_STATE_SUSPENDED },
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{ RUN_STATE_SHUTDOWN, RUN_STATE_PAUSED },
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{ RUN_STATE_SHUTDOWN, RUN_STATE_FINISH_MIGRATE },
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@ -163,6 +166,8 @@ static const RunStateTransition runstate_transitions_def[] = {
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{ RUN_STATE_SUSPENDED, RUN_STATE_PRELAUNCH },
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{ RUN_STATE_SUSPENDED, RUN_STATE_COLO},
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{ RUN_STATE_SUSPENDED, RUN_STATE_PAUSED},
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{ RUN_STATE_SUSPENDED, RUN_STATE_SAVE_VM },
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{ RUN_STATE_SUSPENDED, RUN_STATE_RESTORE_VM },
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{ RUN_STATE_WATCHDOG, RUN_STATE_RUNNING },
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{ RUN_STATE_WATCHDOG, RUN_STATE_FINISH_MIGRATE },
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@ -2710,7 +2710,9 @@ void qmp_x_exit_preconfig(Error **errp)
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qemu_machine_creation_done();
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if (loadvm) {
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RunState state = autostart ? RUN_STATE_RUNNING : runstate_get();
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load_snapshot(loadvm, NULL, false, NULL, &error_fatal);
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load_snapshot_resume(state);
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}
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if (replay_mode != REPLAY_MODE_NONE) {
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replay_vmstate_init();
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