qemu-e2k/include/migration/snapshot.h
Steve Sistare 58b105703e 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>
2024-01-04 09:52:42 +08:00

72 lines
2.1 KiB
C

/*
* QEMU snapshots
*
* Copyright (c) 2004-2008 Fabrice Bellard
* Copyright (c) 2009-2015 Red Hat Inc
*
* Authors:
* Juan Quintela <quintela@redhat.com>
*
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef QEMU_MIGRATION_SNAPSHOT_H
#define QEMU_MIGRATION_SNAPSHOT_H
#include "qapi/qapi-builtin-types.h"
#include "qapi/qapi-types-run-state.h"
/**
* save_snapshot: Save an internal snapshot.
* @name: name of internal snapshot
* @overwrite: replace existing snapshot with @name
* @vmstate: blockdev node name to store VM state in
* @has_devices: whether to use explicit device list
* @devices: explicit device list to snapshot
* @errp: pointer to error object
* On success, return %true.
* On failure, store an error through @errp and return %false.
*/
bool save_snapshot(const char *name, bool overwrite,
const char *vmstate,
bool has_devices, strList *devices,
Error **errp);
/**
* load_snapshot: Load an internal snapshot.
* @name: name of internal snapshot
* @vmstate: blockdev node name to load VM state from
* @has_devices: whether to use explicit device list
* @devices: explicit device list to snapshot
* @errp: pointer to error object
* On success, return %true.
* On failure, store an error through @errp and return %false.
*/
bool load_snapshot(const char *name,
const char *vmstate,
bool has_devices, strList *devices,
Error **errp);
/**
* delete_snapshot: Delete a snapshot.
* @name: path to snapshot
* @has_devices: whether to use explicit device list
* @devices: explicit device list to snapshot
* @errp: pointer to error object
* On success, return %true.
* On failure, store an error through @errp and return %false.
*/
bool delete_snapshot(const char *name,
bool has_devices, strList *devices,
Error **errp);
/**
* load_snapshot_resume: Restore runstate after loading snapshot.
* @state: state to restore
*/
void load_snapshot_resume(RunState state);
#endif