From 58b105703e86c1721d1a4cb9f6aaaca49c82145e Mon Sep 17 00:00:00 2001 From: Steve Sistare Date: Wed, 3 Jan 2024 12:05:36 -0800 Subject: 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 Reviewed-by: Peter Xu Link: https://lore.kernel.org/r/1704312341-66640-8-git-send-email-steven.sistare@oracle.com Signed-off-by: Peter Xu --- migration/savevm.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) (limited to 'migration/savevm.c') diff --git a/migration/savevm.c b/migration/savevm.c index 1b9ab7b8ee..74f915f3ac 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -3046,7 +3046,7 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate, QEMUSnapshotInfo sn1, *sn = &sn1; int ret = -1, ret2; QEMUFile *f; - int saved_vm_running; + RunState saved_state = runstate_get(); uint64_t vm_state_size; g_autoptr(GDateTime) now = g_date_time_new_now_local(); @@ -3092,8 +3092,6 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate, return false; } - saved_vm_running = runstate_is_running(); - global_state_store(); vm_stop(RUN_STATE_SAVE_VM); @@ -3147,9 +3145,7 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate, the_end: bdrv_drain_all_end(); - if (saved_vm_running) { - vm_start(); - } + vm_resume(saved_state); return ret == 0; } @@ -3317,6 +3313,14 @@ err_drain: return false; } +void load_snapshot_resume(RunState state) +{ + vm_resume(state); + if (state == RUN_STATE_RUNNING && runstate_get() == RUN_STATE_SUSPENDED) { + qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER, &error_abort); + } +} + bool delete_snapshot(const char *name, bool has_devices, strList *devices, Error **errp) { @@ -3381,16 +3385,15 @@ static void snapshot_load_job_bh(void *opaque) { Job *job = opaque; SnapshotJob *s = container_of(job, SnapshotJob, common); - int orig_vm_running; + RunState orig_state = runstate_get(); 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(); + if (s->ret) { + load_snapshot_resume(orig_state); } job_progress_update(&s->common, 1); -- cgit v1.2.3