Files
qemu/migration/savevm.h
Juraj Marcin 7b842fe354 migration: Introduce POSTCOPY_DEVICE state
Currently, when postcopy starts, the source VM starts switchover and
sends a package containing the state of all non-postcopiable devices.
When the destination loads this package, the switchover is complete and
the destination VM starts. However, if the device state load fails or
the destination side crashes, the source side is already in
POSTCOPY_ACTIVE state and cannot be recovered, even when it has the most
up-to-date machine state as the destination has not yet started.

This patch introduces a new POSTCOPY_DEVICE state which is active while
the destination machine is loading the device state, is not yet running,
and the source side can be resumed in case of a migration failure.
Return-path is required for this state to function, otherwise it will be
skipped in favor of POSTCOPY_ACTIVE.

To transition from POSTCOPY_DEVICE to POSTCOPY_ACTIVE, the source
side uses a PONG message that is a response to a PING message processed
just before the POSTCOPY_RUN command that starts the destination VM.
Thus, this feature is effective even if the destination side does not
yet support this new state.

Signed-off-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20251103183301.3840862-9-jmarcin@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
2025-11-03 16:04:10 -05:00

82 lines
3.4 KiB
C

/*
* QEMU save vm functions
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (c) 2009-2017 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 MIGRATION_SAVEVM_H
#define MIGRATION_SAVEVM_H
#define QEMU_VM_FILE_MAGIC 0x5145564d
#define QEMU_VM_FILE_VERSION_COMPAT 0x00000002
#define QEMU_VM_FILE_VERSION 0x00000003
#define QEMU_VM_EOF 0x00
#define QEMU_VM_SECTION_START 0x01
#define QEMU_VM_SECTION_PART 0x02
#define QEMU_VM_SECTION_END 0x03
#define QEMU_VM_SECTION_FULL 0x04
#define QEMU_VM_SUBSECTION 0x05
#define QEMU_VM_VMDESCRIPTION 0x06
#define QEMU_VM_CONFIGURATION 0x07
#define QEMU_VM_COMMAND 0x08
#define QEMU_VM_SECTION_FOOTER 0x7e
#define QEMU_VM_PING_PACKAGED_LOADED 0x42
bool qemu_savevm_state_blocked(Error **errp);
void qemu_savevm_non_migratable_list(strList **reasons);
int qemu_savevm_state_prepare(Error **errp);
int qemu_savevm_state_setup(QEMUFile *f, Error **errp);
bool qemu_savevm_state_guest_unplug_pending(void);
int qemu_savevm_state_resume_prepare(MigrationState *s);
void qemu_savevm_state_header(QEMUFile *f);
int qemu_savevm_state_iterate(QEMUFile *f, bool postcopy);
void qemu_savevm_state_cleanup(void);
void qemu_savevm_state_complete_postcopy(QEMUFile *f);
int qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only);
void qemu_savevm_state_pending_exact(uint64_t *must_precopy,
uint64_t *can_postcopy);
void qemu_savevm_state_pending_estimate(uint64_t *must_precopy,
uint64_t *can_postcopy);
int qemu_savevm_state_complete_precopy_iterable(QEMUFile *f, bool in_postcopy);
bool qemu_savevm_state_postcopy_prepare(QEMUFile *f, Error **errp);
void qemu_savevm_send_ping(QEMUFile *f, uint32_t value);
void qemu_savevm_send_open_return_path(QEMUFile *f);
int qemu_savevm_send_packaged(QEMUFile *f, const uint8_t *buf, size_t len);
void qemu_savevm_send_postcopy_advise(QEMUFile *f);
void qemu_savevm_send_postcopy_listen(QEMUFile *f);
void qemu_savevm_send_postcopy_run(QEMUFile *f);
void qemu_savevm_send_postcopy_resume(QEMUFile *f);
void qemu_savevm_send_recv_bitmap(QEMUFile *f, char *block_name);
void qemu_savevm_maybe_send_switchover_start(QEMUFile *f);
void qemu_savevm_send_postcopy_ram_discard(QEMUFile *f, const char *name,
uint16_t len,
uint64_t *start_list,
uint64_t *length_list);
void qemu_savevm_send_colo_enable(QEMUFile *f);
void qemu_savevm_live_state(QEMUFile *f);
int qemu_save_device_state(QEMUFile *f);
int qemu_loadvm_state(QEMUFile *f, Error **errp);
void qemu_loadvm_state_cleanup(MigrationIncomingState *mis);
int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis,
Error **errp);
int qemu_load_device_state(QEMUFile *f, Error **errp);
int qemu_loadvm_approve_switchover(void);
int qemu_savevm_state_complete_precopy_non_iterable(QEMUFile *f,
bool in_postcopy);
bool qemu_loadvm_load_state_buffer(const char *idstr, uint32_t instance_id,
char *buf, size_t len, Error **errp);
#endif