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* QEMU live migration
* Copyright IBM, Corp. 2008
* Authors:
* Anthony Liguori <>
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
#include "qapi/qmp/qdict.h"
#include "qemu-common.h"
#include "qemu/thread.h"
#include "qemu/notify.h"
#include "migration/vmstate.h"
#include "qapi-types.h"
#include "exec/cpu-common.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_END 0x03
#define QEMU_VM_COMMAND 0x08
struct MigrationParams {
bool blk;
bool shared;
/* Messages sent on the return path from destination to source */
enum mig_rp_message_type {
MIG_RP_MSG_INVALID = 0, /* Must be 0 */
MIG_RP_MSG_SHUT, /* sibling will not send any more RP messages */
MIG_RP_MSG_PONG, /* Response to a PING; data (seq: be32 ) */
MIG_RP_MSG_REQ_PAGES_ID, /* data (start: be64, len: be32, id: string) */
MIG_RP_MSG_REQ_PAGES, /* data (start: be64, len: be32) */
typedef QLIST_HEAD(, LoadStateEntry) LoadStateEntry_Head;
/* The current postcopy state is read/set by postcopy_state_get/set
* which update it atomically.
* The state is updated as postcopy messages are received, and
* in general only one thread should be writing to the state at any one
* time, initially the main thread and then the listen thread;
* Corner cases are where either thread finishes early and/or errors.
* The state is checked as messages are received to ensure that
* the source is sending us messages in the correct order.
* The state is also used by the RAM reception code to know if it
* has to place pages atomically, and the cleanup code at the end of
* the main thread to know if it has to delay cleanup until the end
* of postcopy.
typedef enum {
POSTCOPY_INCOMING_NONE = 0, /* Initial state - no postcopy */
} PostcopyState;
/* State for the incoming migration */
struct MigrationIncomingState {
QEMUFile *from_src_file;
* Free at the start of the main state load, set as the main thread finishes
* loading state.
QemuEvent main_thread_load_event;
bool have_fault_thread;
QemuThread fault_thread;
QemuSemaphore fault_thread_sem;
bool have_listen_thread;
QemuThread listen_thread;
QemuSemaphore listen_thread_sem;
/* For the kernel to send us notifications */
int userfault_fd;
/* To tell the fault_thread to quit */
int userfault_quit_fd;
QEMUFile *to_src_file;
QemuMutex rp_mutex; /* We send replies from multiple threads */
void *postcopy_tmp_page;
int state;
/* See savevm.c */
LoadStateEntry_Head loadvm_handlers;
MigrationIncomingState *migration_incoming_get_current(void);
MigrationIncomingState *migration_incoming_state_new(QEMUFile *f);
void migration_incoming_state_destroy(void);
* An outstanding page request, on the source, having been received
* and queued
struct MigrationSrcPageRequest {
RAMBlock *rb;
hwaddr offset;
hwaddr len;
QSIMPLEQ_ENTRY(MigrationSrcPageRequest) next_req;
struct MigrationState
int64_t bandwidth_limit;
size_t bytes_xfer;
size_t xfer_limit;
QemuThread thread;
QEMUBH *cleanup_bh;
QEMUFile *to_dst_file;
/* New style params from 'migrate-set-parameters' */
MigrationParameters parameters;
int state;
/* Old style params from 'migrate' command */
MigrationParams params;
/* State related to return path */
struct {
QEMUFile *from_dst_file;
QemuThread rp_thread;
bool error;
} rp_state;
double mbps;
int64_t total_time;
int64_t downtime;
int64_t expected_downtime;
int64_t dirty_pages_rate;
int64_t dirty_bytes_rate;
bool enabled_capabilities[MIGRATION_CAPABILITY__MAX];
int64_t xbzrle_cache_size;
int64_t setup_time;
int64_t dirty_sync_count;
/* Count of requests incoming from destination */
int64_t postcopy_requests;
/* Flag set once the migration has been asked to enter postcopy */
bool start_postcopy;
/* Flag set after postcopy has sent the device state */
bool postcopy_after_devices;
/* Flag set once the migration thread is running (and needs joining) */
bool migration_thread_running;
/* Queue of outstanding page requests from the destination */
QemuMutex src_page_req_mutex;
QSIMPLEQ_HEAD(src_page_requests, MigrationSrcPageRequest) src_page_requests;
/* The RAMBlock used in the last src_page_request */
RAMBlock *last_req_rb;
/* The last error that occurred */
Error *error;
void migrate_set_state(int *state, int old_state, int new_state);
void migration_fd_process_incoming(QEMUFile *f);
void qemu_start_incoming_migration(const char *uri, Error **errp);
void migration_channel_process_incoming(MigrationState *s,
QIOChannel *ioc);
void migration_tls_channel_process_incoming(MigrationState *s,
QIOChannel *ioc,
Error **errp);
void migration_channel_connect(MigrationState *s,
QIOChannel *ioc,
const char *hostname);
void migration_tls_channel_connect(MigrationState *s,
QIOChannel *ioc,
const char *hostname,
Error **errp);
uint64_t migrate_max_downtime(void);
void exec_start_incoming_migration(const char *host_port, Error **errp);
void exec_start_outgoing_migration(MigrationState *s, const char *host_port, Error **errp);
void tcp_start_incoming_migration(const char *host_port, Error **errp);
void tcp_start_outgoing_migration(MigrationState *s, const char *host_port, Error **errp);
void unix_start_incoming_migration(const char *path, Error **errp);
void unix_start_outgoing_migration(MigrationState *s, const char *path, Error **errp);
void fd_start_incoming_migration(const char *path, Error **errp);
void fd_start_outgoing_migration(MigrationState *s, const char *fdname, Error **errp);
void rdma_start_outgoing_migration(void *opaque, const char *host_port, Error **errp);
void rdma_start_incoming_migration(const char *host_port, Error **errp);
void migrate_fd_error(MigrationState *s, const Error *error);
void migrate_fd_connect(MigrationState *s);
int migrate_fd_close(MigrationState *s);
void add_migration_state_change_notifier(Notifier *notify);
void remove_migration_state_change_notifier(Notifier *notify);
MigrationState *migrate_init(const MigrationParams *params);
bool migration_is_blocked(Error **errp);
bool migration_in_setup(MigrationState *);
bool migration_has_finished(MigrationState *);
bool migration_has_failed(MigrationState *);
/* True if outgoing migration has entered postcopy phase */
bool migration_in_postcopy(MigrationState *);
/* ...and after the device transmission */
bool migration_in_postcopy_after_devices(MigrationState *);
MigrationState *migrate_get_current(void);
void migrate_compress_threads_create(void);
void migrate_compress_threads_join(void);
void migrate_decompress_threads_create(void);
void migrate_decompress_threads_join(void);
uint64_t ram_bytes_remaining(void);
uint64_t ram_bytes_transferred(void);
uint64_t ram_bytes_total(void);
void free_xbzrle_decoded_buf(void);
void acct_update_position(QEMUFile *f, size_t size, bool zero);
uint64_t dup_mig_bytes_transferred(void);
uint64_t dup_mig_pages_transferred(void);
uint64_t skipped_mig_bytes_transferred(void);
uint64_t skipped_mig_pages_transferred(void);
uint64_t norm_mig_bytes_transferred(void);
uint64_t norm_mig_pages_transferred(void);
uint64_t xbzrle_mig_bytes_transferred(void);
uint64_t xbzrle_mig_pages_transferred(void);
uint64_t xbzrle_mig_pages_overflow(void);
uint64_t xbzrle_mig_pages_cache_miss(void);
double xbzrle_mig_cache_miss_rate(void);
void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
void ram_debug_dump_bitmap(unsigned long *todump, bool expected);
/* For outgoing discard bitmap */
int ram_postcopy_send_discard_bitmap(MigrationState *ms);
/* For incoming postcopy discard */
int ram_discard_range(MigrationIncomingState *mis, const char *block_name,
uint64_t start, size_t length);
int ram_postcopy_incoming_init(MigrationIncomingState *mis);
* @migrate_add_blocker - prevent migration from proceeding
* @reason - an error to be returned whenever migration is attempted
void migrate_add_blocker(Error *reason);
* @migrate_del_blocker - remove a blocking error from migration
* @reason - the error blocking migration
void migrate_del_blocker(Error *reason);
bool migrate_postcopy_ram(void);
bool migrate_zero_blocks(void);
bool migrate_auto_converge(void);
int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen,
uint8_t *dst, int dlen);
int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen);
int migrate_use_xbzrle(void);
int64_t migrate_xbzrle_cache_size(void);
int64_t xbzrle_cache_resize(int64_t new_size);
bool migrate_use_compression(void);
int migrate_compress_level(void);
int migrate_compress_threads(void);
int migrate_decompress_threads(void);
bool migrate_use_events(void);
/* Sending on the return path - generic and then for each message type */
void migrate_send_rp_message(MigrationIncomingState *mis,
enum mig_rp_message_type message_type,
uint16_t len, void *data);
void migrate_send_rp_shut(MigrationIncomingState *mis,
uint32_t value);
void migrate_send_rp_pong(MigrationIncomingState *mis,
uint32_t value);
void migrate_send_rp_req_pages(MigrationIncomingState *mis, const char* rbname,
ram_addr_t start, size_t len);
void ram_control_before_iterate(QEMUFile *f, uint64_t flags);
void ram_control_after_iterate(QEMUFile *f, uint64_t flags);
void ram_control_load_hook(QEMUFile *f, uint64_t flags, void *data);
/* Whenever this is found in the data stream, the flags
* will be passed to ram_control_load_hook in the incoming-migration
* side. This lets before_ram_iterate/after_ram_iterate add
* transport-specific sections to the RAM migration data.
#define RAM_SAVE_FLAG_HOOK 0x80
size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
ram_addr_t offset, size_t size,
uint64_t *bytes_sent);
void ram_mig_init(void);
void savevm_skip_section_footers(void);
void register_global_state(void);
void global_state_set_optional(void);
void savevm_skip_configuration(void);
int global_state_store(void);
void global_state_store_running(void);
void flush_page_queue(MigrationState *ms);
int ram_save_queue_pages(MigrationState *ms, const char *rbname,
ram_addr_t start, ram_addr_t len);
PostcopyState postcopy_state_get(void);
/* Set the state and return the old state */
PostcopyState postcopy_state_set(PostcopyState new_state);