1 /* 2 * QEMU live migration 3 * 4 * Copyright IBM, Corp. 2008 5 * 6 * Authors: 7 * Anthony Liguori <aliguori@us.ibm.com> 8 * 9 * This work is licensed under the terms of the GNU GPL, version 2. See 10 * the COPYING file in the top-level directory. 11 * 12 */ 13 14 #ifndef QEMU_MIGRATION_H 15 #define QEMU_MIGRATION_H 16 17 #include "exec/cpu-common.h" 18 #include "hw/qdev-core.h" 19 #include "qapi/qapi-types-migration.h" 20 #include "qapi/qmp/json-writer.h" 21 #include "qemu/thread.h" 22 #include "qemu/coroutine_int.h" 23 #include "io/channel.h" 24 #include "io/channel-buffer.h" 25 #include "net/announce.h" 26 #include "qom/object.h" 27 #include "postcopy-ram.h" 28 #include "sysemu/runstate.h" 29 30 struct PostcopyBlocktimeContext; 31 32 #define MIGRATION_RESUME_ACK_VALUE (1) 33 34 /* 35 * 1<<6=64 pages -> 256K chunk when page size is 4K. This gives us 36 * the benefit that all the chunks are 64 pages aligned then the 37 * bitmaps are always aligned to LONG. 38 */ 39 #define CLEAR_BITMAP_SHIFT_MIN 6 40 /* 41 * 1<<18=256K pages -> 1G chunk when page size is 4K. This is the 42 * default value to use if no one specified. 43 */ 44 #define CLEAR_BITMAP_SHIFT_DEFAULT 18 45 /* 46 * 1<<31=2G pages -> 8T chunk when page size is 4K. This should be 47 * big enough and make sure we won't overflow easily. 48 */ 49 #define CLEAR_BITMAP_SHIFT_MAX 31 50 51 /* This is an abstraction of a "temp huge page" for postcopy's purpose */ 52 typedef struct { 53 /* 54 * This points to a temporary huge page as a buffer for UFFDIO_COPY. It's 55 * mmap()ed and needs to be freed when cleanup. 56 */ 57 void *tmp_huge_page; 58 /* 59 * This points to the host page we're going to install for this temp page. 60 * It tells us after we've received the whole page, where we should put it. 61 */ 62 void *host_addr; 63 /* Number of small pages copied (in size of TARGET_PAGE_SIZE) */ 64 unsigned int target_pages; 65 /* Whether this page contains all zeros */ 66 bool all_zero; 67 } PostcopyTmpPage; 68 69 typedef enum { 70 PREEMPT_THREAD_NONE = 0, 71 PREEMPT_THREAD_CREATED, 72 PREEMPT_THREAD_QUIT, 73 } PreemptThreadStatus; 74 75 /* State for the incoming migration */ 76 struct MigrationIncomingState { 77 QEMUFile *from_src_file; 78 /* Previously received RAM's RAMBlock pointer */ 79 RAMBlock *last_recv_block[RAM_CHANNEL_MAX]; 80 /* A hook to allow cleanup at the end of incoming migration */ 81 void *transport_data; 82 void (*transport_cleanup)(void *data); 83 /* 84 * Used to sync thread creations. Note that we can't create threads in 85 * parallel with this sem. 86 */ 87 QemuSemaphore thread_sync_sem; 88 /* 89 * Free at the start of the main state load, set as the main thread finishes 90 * loading state. 91 */ 92 QemuEvent main_thread_load_event; 93 94 /* For network announces */ 95 AnnounceTimer announce_timer; 96 97 size_t largest_page_size; 98 bool have_fault_thread; 99 QemuThread fault_thread; 100 /* Set this when we want the fault thread to quit */ 101 bool fault_thread_quit; 102 103 bool have_listen_thread; 104 QemuThread listen_thread; 105 106 /* For the kernel to send us notifications */ 107 int userfault_fd; 108 /* To notify the fault_thread to wake, e.g., when need to quit */ 109 int userfault_event_fd; 110 QEMUFile *to_src_file; 111 QemuMutex rp_mutex; /* We send replies from multiple threads */ 112 /* RAMBlock of last request sent to source */ 113 RAMBlock *last_rb; 114 /* 115 * Number of postcopy channels including the default precopy channel, so 116 * vanilla postcopy will only contain one channel which contain both 117 * precopy and postcopy streams. 118 * 119 * This is calculated when the src requests to enable postcopy but before 120 * it starts. Its value can depend on e.g. whether postcopy preemption is 121 * enabled. 122 */ 123 unsigned int postcopy_channels; 124 /* QEMUFile for postcopy only; it'll be handled by a separate thread */ 125 QEMUFile *postcopy_qemufile_dst; 126 /* 127 * When postcopy_qemufile_dst is properly setup, this sem is posted. 128 * One can wait on this semaphore to wait until the preempt channel is 129 * properly setup. 130 */ 131 QemuSemaphore postcopy_qemufile_dst_done; 132 /* Postcopy priority thread is used to receive postcopy requested pages */ 133 QemuThread postcopy_prio_thread; 134 /* 135 * Always set by the main vm load thread only, but can be read by the 136 * postcopy preempt thread. "volatile" makes sure all reads will be 137 * up-to-date across cores. 138 */ 139 volatile PreemptThreadStatus preempt_thread_status; 140 /* 141 * Used to sync between the ram load main thread and the fast ram load 142 * thread. It protects postcopy_qemufile_dst, which is the postcopy 143 * fast channel. 144 * 145 * The ram fast load thread will take it mostly for the whole lifecycle 146 * because it needs to continuously read data from the channel, and 147 * it'll only release this mutex if postcopy is interrupted, so that 148 * the ram load main thread will take this mutex over and properly 149 * release the broken channel. 150 */ 151 QemuMutex postcopy_prio_thread_mutex; 152 /* 153 * An array of temp host huge pages to be used, one for each postcopy 154 * channel. 155 */ 156 PostcopyTmpPage *postcopy_tmp_pages; 157 /* This is shared for all postcopy channels */ 158 void *postcopy_tmp_zero_page; 159 /* PostCopyFD's for external userfaultfds & handlers of shared memory */ 160 GArray *postcopy_remote_fds; 161 162 int state; 163 164 /* 165 * The incoming migration coroutine, non-NULL during qemu_loadvm_state(). 166 * Used to wake the migration incoming coroutine from rdma code. How much is 167 * it safe - it's a question. 168 */ 169 Coroutine *loadvm_co; 170 171 /* The coroutine we should enter (back) after failover */ 172 Coroutine *colo_incoming_co; 173 QemuSemaphore colo_incoming_sem; 174 175 /* 176 * PostcopyBlocktimeContext to keep information for postcopy 177 * live migration, to calculate vCPU block time 178 * */ 179 struct PostcopyBlocktimeContext *blocktime_ctx; 180 181 /* notify PAUSED postcopy incoming migrations to try to continue */ 182 QemuSemaphore postcopy_pause_sem_dst; 183 QemuSemaphore postcopy_pause_sem_fault; 184 /* 185 * This semaphore is used to allow the ram fast load thread (only when 186 * postcopy preempt is enabled) fall into sleep when there's network 187 * interruption detected. When the recovery is done, the main load 188 * thread will kick the fast ram load thread using this semaphore. 189 */ 190 QemuSemaphore postcopy_pause_sem_fast_load; 191 192 /* List of listening socket addresses */ 193 SocketAddressList *socket_address_list; 194 195 /* A tree of pages that we requested to the source VM */ 196 GTree *page_requested; 197 /* 198 * For postcopy only, count the number of requested page faults that 199 * still haven't been resolved. 200 */ 201 int page_requested_count; 202 /* 203 * The mutex helps to maintain the requested pages that we sent to the 204 * source, IOW, to guarantee coherent between the page_requests tree and 205 * the per-ramblock receivedmap. Note! This does not guarantee consistency 206 * of the real page copy procedures (using UFFDIO_[ZERO]COPY). E.g., even 207 * if one bit in receivedmap is cleared, UFFDIO_COPY could have happened 208 * for that page already. This is intended so that the mutex won't 209 * serialize and blocked by slow operations like UFFDIO_* ioctls. However 210 * this should be enough to make sure the page_requested tree always 211 * contains valid information. 212 */ 213 QemuMutex page_request_mutex; 214 /* 215 * If postcopy preempt is enabled, there is a chance that the main 216 * thread finished loading its data before the preempt channel has 217 * finished loading the urgent pages. If that happens, the two threads 218 * will use this condvar to synchronize, so the main thread will always 219 * wait until all pages received. 220 */ 221 QemuCond page_request_cond; 222 223 /* 224 * Number of devices that have yet to approve switchover. When this reaches 225 * zero an ACK that it's OK to do switchover is sent to the source. No lock 226 * is needed as this field is updated serially. 227 */ 228 unsigned int switchover_ack_pending_num; 229 }; 230 231 MigrationIncomingState *migration_incoming_get_current(void); 232 void migration_incoming_state_destroy(void); 233 void migration_incoming_transport_cleanup(MigrationIncomingState *mis); 234 /* 235 * Functions to work with blocktime context 236 */ 237 void fill_destination_postcopy_migration_info(MigrationInfo *info); 238 239 #define TYPE_MIGRATION "migration" 240 241 typedef struct MigrationClass MigrationClass; 242 DECLARE_OBJ_CHECKERS(MigrationState, MigrationClass, 243 MIGRATION_OBJ, TYPE_MIGRATION) 244 245 struct MigrationClass { 246 /*< private >*/ 247 DeviceClass parent_class; 248 }; 249 250 struct MigrationState { 251 /*< private >*/ 252 DeviceState parent_obj; 253 254 /*< public >*/ 255 QemuThread thread; 256 /* Protected by qemu_file_lock */ 257 QEMUFile *to_dst_file; 258 /* Postcopy specific transfer channel */ 259 QEMUFile *postcopy_qemufile_src; 260 /* 261 * It is posted when the preempt channel is established. Note: this is 262 * used for both the start or recover of a postcopy migration. We'll 263 * post to this sem every time a new preempt channel is created in the 264 * main thread, and we keep post() and wait() in pair. 265 */ 266 QemuSemaphore postcopy_qemufile_src_sem; 267 QIOChannelBuffer *bioc; 268 /* 269 * Protects to_dst_file/from_dst_file pointers. We need to make sure we 270 * won't yield or hang during the critical section, since this lock will be 271 * used in OOB command handler. 272 */ 273 QemuMutex qemu_file_lock; 274 275 /* 276 * Used to allow urgent requests to override rate limiting. 277 */ 278 QemuSemaphore rate_limit_sem; 279 280 /* pages already send at the beginning of current iteration */ 281 uint64_t iteration_initial_pages; 282 283 /* pages transferred per second */ 284 double pages_per_second; 285 286 /* bytes already send at the beginning of current iteration */ 287 uint64_t iteration_initial_bytes; 288 /* time at the start of current iteration */ 289 int64_t iteration_start_time; 290 /* 291 * The final stage happens when the remaining data is smaller than 292 * this threshold; it's calculated from the requested downtime and 293 * measured bandwidth, or avail-switchover-bandwidth if specified. 294 */ 295 uint64_t threshold_size; 296 297 /* params from 'migrate-set-parameters' */ 298 MigrationParameters parameters; 299 300 int state; 301 302 /* State related to return path */ 303 struct { 304 /* Protected by qemu_file_lock */ 305 QEMUFile *from_dst_file; 306 QemuThread rp_thread; 307 /* 308 * We can also check non-zero of rp_thread, but there's no "official" 309 * way to do this, so this bool makes it slightly more elegant. 310 * Checking from_dst_file for this is racy because from_dst_file will 311 * be cleared in the rp_thread! 312 */ 313 bool rp_thread_created; 314 /* 315 * Used to synchronize between migration main thread and return 316 * path thread. The migration thread can wait() on this sem, while 317 * other threads (e.g., return path thread) can kick it using a 318 * post(). 319 */ 320 QemuSemaphore rp_sem; 321 /* 322 * We post to this when we got one PONG from dest. So far it's an 323 * easy way to know the main channel has successfully established 324 * on dest QEMU. 325 */ 326 QemuSemaphore rp_pong_acks; 327 } rp_state; 328 329 double mbps; 330 /* Timestamp when recent migration starts (ms) */ 331 int64_t start_time; 332 /* Total time used by latest migration (ms) */ 333 int64_t total_time; 334 /* Timestamp when VM is down (ms) to migrate the last stuff */ 335 int64_t downtime_start; 336 int64_t downtime; 337 int64_t expected_downtime; 338 bool capabilities[MIGRATION_CAPABILITY__MAX]; 339 int64_t setup_time; 340 341 /* 342 * State before stopping the vm by vm_stop_force_state(). 343 * If migration is interrupted by any reason, we need to continue 344 * running the guest on source if it was running or restore its stopped 345 * state. 346 */ 347 RunState vm_old_state; 348 349 /* Flag set once the migration has been asked to enter postcopy */ 350 bool start_postcopy; 351 352 /* Flag set once the migration thread is running (and needs joining) */ 353 bool migration_thread_running; 354 355 /* Flag set once the migration thread called bdrv_inactivate_all */ 356 bool block_inactive; 357 358 /* Migration is waiting for guest to unplug device */ 359 QemuSemaphore wait_unplug_sem; 360 361 /* Migration is paused due to pause-before-switchover */ 362 QemuSemaphore pause_sem; 363 364 /* The semaphore is used to notify COLO thread that failover is finished */ 365 QemuSemaphore colo_exit_sem; 366 367 /* The event is used to notify COLO thread to do checkpoint */ 368 QemuEvent colo_checkpoint_event; 369 int64_t colo_checkpoint_time; 370 QEMUTimer *colo_delay_timer; 371 372 /* The first error that has occurred. 373 We used the mutex to be able to return the 1st error message */ 374 Error *error; 375 /* mutex to protect errp */ 376 QemuMutex error_mutex; 377 378 /* Do we have to clean up -b/-i from old migrate parameters */ 379 /* This feature is deprecated and will be removed */ 380 bool must_remove_block_options; 381 382 /* 383 * Global switch on whether we need to store the global state 384 * during migration. 385 */ 386 bool store_global_state; 387 388 /* Whether we send QEMU_VM_CONFIGURATION during migration */ 389 bool send_configuration; 390 /* Whether we send section footer during migration */ 391 bool send_section_footer; 392 393 /* Needed by postcopy-pause state */ 394 QemuSemaphore postcopy_pause_sem; 395 /* 396 * Whether we abort the migration if decompression errors are 397 * detected at the destination. It is left at false for qemu 398 * older than 3.0, since only newer qemu sends streams that 399 * do not trigger spurious decompression errors. 400 */ 401 bool decompress_error_check; 402 /* 403 * This variable only affects behavior when postcopy preempt mode is 404 * enabled. 405 * 406 * When set: 407 * 408 * - postcopy preempt src QEMU instance will generate an EOS message at 409 * the end of migration to shut the preempt channel on dest side. 410 * 411 * - postcopy preempt channel will be created at the setup phase on src 412 QEMU. 413 * 414 * When clear: 415 * 416 * - postcopy preempt src QEMU instance will _not_ generate an EOS 417 * message at the end of migration, the dest qemu will shutdown the 418 * channel itself. 419 * 420 * - postcopy preempt channel will be created at the switching phase 421 * from precopy -> postcopy (to avoid race condition of misordered 422 * creation of channels). 423 * 424 * NOTE: See message-id <ZBoShWArKDPpX/D7@work-vm> on qemu-devel 425 * mailing list for more information on the possible race. Everyone 426 * should probably just keep this value untouched after set by the 427 * machine type (or the default). 428 */ 429 bool preempt_pre_7_2; 430 431 /* 432 * flush every channel after each section sent. 433 * 434 * This assures that we can't mix pages from one iteration through 435 * ram pages with pages for the following iteration. We really 436 * only need to do this flush after we have go through all the 437 * dirty pages. For historical reasons, we do that after each 438 * section. This is suboptimal (we flush too many times). 439 * Default value is false. (since 8.1) 440 */ 441 bool multifd_flush_after_each_section; 442 /* 443 * This decides the size of guest memory chunk that will be used 444 * to track dirty bitmap clearing. The size of memory chunk will 445 * be GUEST_PAGE_SIZE << N. Say, N=0 means we will clear dirty 446 * bitmap for each page to send (1<<0=1); N=10 means we will clear 447 * dirty bitmap only once for 1<<10=1K continuous guest pages 448 * (which is in 4M chunk). 449 */ 450 uint8_t clear_bitmap_shift; 451 452 /* 453 * This save hostname when out-going migration starts 454 */ 455 char *hostname; 456 457 /* QEMU_VM_VMDESCRIPTION content filled for all non-iterable devices. */ 458 JSONWriter *vmdesc; 459 460 /* 461 * Indicates whether an ACK from the destination that it's OK to do 462 * switchover has been received. 463 */ 464 bool switchover_acked; 465 /* Is this a rdma migration */ 466 bool rdma_migration; 467 }; 468 469 void migrate_set_state(int *state, int old_state, int new_state); 470 471 void migration_fd_process_incoming(QEMUFile *f); 472 void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp); 473 void migration_incoming_process(void); 474 475 bool migration_has_all_channels(void); 476 477 void migrate_set_error(MigrationState *s, const Error *error); 478 bool migrate_has_error(MigrationState *s); 479 480 void migrate_fd_connect(MigrationState *s, Error *error_in); 481 482 bool migration_is_setup_or_active(int state); 483 bool migration_is_running(int state); 484 485 int migrate_init(MigrationState *s, Error **errp); 486 bool migration_is_blocked(Error **errp); 487 /* True if outgoing migration has entered postcopy phase */ 488 bool migration_in_postcopy(void); 489 bool migration_postcopy_is_alive(int state); 490 MigrationState *migrate_get_current(void); 491 492 uint64_t ram_get_total_transferred_pages(void); 493 494 /* Sending on the return path - generic and then for each message type */ 495 void migrate_send_rp_shut(MigrationIncomingState *mis, 496 uint32_t value); 497 void migrate_send_rp_pong(MigrationIncomingState *mis, 498 uint32_t value); 499 int migrate_send_rp_req_pages(MigrationIncomingState *mis, RAMBlock *rb, 500 ram_addr_t start, uint64_t haddr); 501 int migrate_send_rp_message_req_pages(MigrationIncomingState *mis, 502 RAMBlock *rb, ram_addr_t start); 503 void migrate_send_rp_recv_bitmap(MigrationIncomingState *mis, 504 char *block_name); 505 void migrate_send_rp_resume_ack(MigrationIncomingState *mis, uint32_t value); 506 int migrate_send_rp_switchover_ack(MigrationIncomingState *mis); 507 508 void dirty_bitmap_mig_before_vm_start(void); 509 void dirty_bitmap_mig_cancel_outgoing(void); 510 void dirty_bitmap_mig_cancel_incoming(void); 511 bool check_dirty_bitmap_mig_alias_map(const BitmapMigrationNodeAliasList *bbm, 512 Error **errp); 513 514 void migrate_add_address(SocketAddress *address); 515 bool migrate_uri_parse(const char *uri, MigrationChannel **channel, 516 Error **errp); 517 int foreach_not_ignored_block(RAMBlockIterFunc func, void *opaque); 518 519 #define qemu_ram_foreach_block \ 520 #warning "Use foreach_not_ignored_block in migration code" 521 522 void migration_make_urgent_request(void); 523 void migration_consume_urgent_request(void); 524 bool migration_rate_limit(void); 525 void migration_bh_schedule(QEMUBHFunc *cb, void *opaque); 526 void migration_cancel(const Error *error); 527 528 void migration_populate_vfio_info(MigrationInfo *info); 529 void migration_reset_vfio_bytes_transferred(void); 530 void postcopy_temp_page_reset(PostcopyTmpPage *tmp_page); 531 532 /* 533 * Migration thread waiting for return path thread. Return non-zero if an 534 * error is detected. 535 */ 536 int migration_rp_wait(MigrationState *s); 537 /* 538 * Kick the migration thread waiting for return path messages. NOTE: the 539 * name can be slightly confusing (when read as "kick the rp thread"), just 540 * to remember the target is always the migration thread. 541 */ 542 void migration_rp_kick(MigrationState *s); 543 544 #endif 545