migration/migration.h

   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     QEMUBH *bh;
 163
 164     int state;
 165
 166     /*
 167      * The incoming migration coroutine, non-NULL during qemu_loadvm_state().
 168      * Used to wake the migration incoming coroutine from rdma code. How much is
 169      * it safe - it's a question.
 170      */
 171     Coroutine *loadvm_co;
 172
 173     /* The coroutine we should enter (back) after failover */
 174     Coroutine *colo_incoming_co;
 175     QemuSemaphore colo_incoming_sem;
 176
 177     /*
 178      * PostcopyBlocktimeContext to keep information for postcopy
 179      * live migration, to calculate vCPU block time
 180      * */
 181     struct PostcopyBlocktimeContext *blocktime_ctx;
 182
 183     /* notify PAUSED postcopy incoming migrations to try to continue */
 184     QemuSemaphore postcopy_pause_sem_dst;
 185     QemuSemaphore postcopy_pause_sem_fault;
 186     /*
 187      * This semaphore is used to allow the ram fast load thread (only when
 188      * postcopy preempt is enabled) fall into sleep when there's network
 189      * interruption detected.  When the recovery is done, the main load
 190      * thread will kick the fast ram load thread using this semaphore.
 191      */
 192     QemuSemaphore postcopy_pause_sem_fast_load;
 193
 194     /* List of listening socket addresses  */
 195     SocketAddressList *socket_address_list;
 196
 197     /* A tree of pages that we requested to the source VM */
 198     GTree *page_requested;
 199     /*
 200      * For postcopy only, count the number of requested page faults that
 201      * still haven't been resolved.
 202      */
 203     int page_requested_count;
 204     /*
 205      * The mutex helps to maintain the requested pages that we sent to the
 206      * source, IOW, to guarantee coherent between the page_requests tree and
 207      * the per-ramblock receivedmap.  Note! This does not guarantee consistency
 208      * of the real page copy procedures (using UFFDIO_[ZERO]COPY).  E.g., even
 209      * if one bit in receivedmap is cleared, UFFDIO_COPY could have happened
 210      * for that page already.  This is intended so that the mutex won't
 211      * serialize and blocked by slow operations like UFFDIO_* ioctls.  However
 212      * this should be enough to make sure the page_requested tree always
 213      * contains valid information.
 214      */
 215     QemuMutex page_request_mutex;
 216     /*
 217      * If postcopy preempt is enabled, there is a chance that the main
 218      * thread finished loading its data before the preempt channel has
 219      * finished loading the urgent pages.  If that happens, the two threads
 220      * will use this condvar to synchronize, so the main thread will always
 221      * wait until all pages received.
 222      */
 223     QemuCond page_request_cond;
 224
 225     /*
 226      * Number of devices that have yet to approve switchover. When this reaches
 227      * zero an ACK that it's OK to do switchover is sent to the source. No lock
 228      * is needed as this field is updated serially.
 229      */
 230     unsigned int switchover_ack_pending_num;
 231 };
 232
 233 MigrationIncomingState *migration_incoming_get_current(void);
 234 void migration_incoming_state_destroy(void);
 235 void migration_incoming_transport_cleanup(MigrationIncomingState *mis);
 236 /*
 237  * Functions to work with blocktime context
 238  */
 239 void fill_destination_postcopy_migration_info(MigrationInfo *info);
 240
 241 #define TYPE_MIGRATION "migration"
 242
 243 typedef struct MigrationClass MigrationClass;
 244 DECLARE_OBJ_CHECKERS(MigrationState, MigrationClass,
 245                      MIGRATION_OBJ, TYPE_MIGRATION)
 246
 247 struct MigrationClass {
 248     /*< private >*/
 249     DeviceClass parent_class;
 250 };
 251
 252 struct MigrationState {
 253     /*< private >*/
 254     DeviceState parent_obj;
 255
 256     /*< public >*/
 257     QemuThread thread;
 258     QEMUBH *vm_start_bh;
 259     QEMUBH *cleanup_bh;
 260     /* Protected by qemu_file_lock */
 261     QEMUFile *to_dst_file;
 262     /* Postcopy specific transfer channel */
 263     QEMUFile *postcopy_qemufile_src;
 264     /*
 265      * It is posted when the preempt channel is established.  Note: this is
 266      * used for both the start or recover of a postcopy migration.  We'll
 267      * post to this sem every time a new preempt channel is created in the
 268      * main thread, and we keep post() and wait() in pair.
 269      */
 270     QemuSemaphore postcopy_qemufile_src_sem;
 271     QIOChannelBuffer *bioc;
 272     /*
 273      * Protects to_dst_file/from_dst_file pointers.  We need to make sure we
 274      * won't yield or hang during the critical section, since this lock will be
 275      * used in OOB command handler.
 276      */
 277     QemuMutex qemu_file_lock;
 278
 279     /*
 280      * Used to allow urgent requests to override rate limiting.
 281      */
 282     QemuSemaphore rate_limit_sem;
 283
 284     /* pages already send at the beginning of current iteration */
 285     uint64_t iteration_initial_pages;
 286
 287     /* pages transferred per second */
 288     double pages_per_second;
 289
 290     /* bytes already send at the beginning of current iteration */
 291     uint64_t iteration_initial_bytes;
 292     /* time at the start of current iteration */
 293     int64_t iteration_start_time;
 294     /*
 295      * The final stage happens when the remaining data is smaller than
 296      * this threshold; it's calculated from the requested downtime and
 297      * measured bandwidth
 298      */
 299     int64_t threshold_size;
 300
 301     /* params from 'migrate-set-parameters' */
 302     MigrationParameters parameters;
 303
 304     int state;
 305
 306     /* State related to return path */
 307     struct {
 308         /* Protected by qemu_file_lock */
 309         QEMUFile     *from_dst_file;
 310         QemuThread    rp_thread;
 311         bool          error;
 312         /*
 313          * We can also check non-zero of rp_thread, but there's no "official"
 314          * way to do this, so this bool makes it slightly more elegant.
 315          * Checking from_dst_file for this is racy because from_dst_file will
 316          * be cleared in the rp_thread!
 317          */
 318         bool          rp_thread_created;
 319         QemuSemaphore rp_sem;
 320         /*
 321          * We post to this when we got one PONG from dest. So far it's an
 322          * easy way to know the main channel has successfully established
 323          * on dest QEMU.
 324          */
 325         QemuSemaphore rp_pong_acks;
 326     } rp_state;
 327
 328     double mbps;
 329     /* Timestamp when recent migration starts (ms) */
 330     int64_t start_time;
 331     /* Total time used by latest migration (ms) */
 332     int64_t total_time;
 333     /* Timestamp when VM is down (ms) to migrate the last stuff */
 334     int64_t downtime_start;
 335     int64_t downtime;
 336     int64_t expected_downtime;
 337     bool capabilities[MIGRATION_CAPABILITY__MAX];
 338     int64_t setup_time;
 339
 340     /*
 341      * State before stopping the vm by vm_stop_force_state().
 342      * If migration is interrupted by any reason, we need to continue
 343      * running the guest on source if it was running or restore its stopped
 344      * state.
 345      */
 346     RunState vm_old_state;
 347
 348     /* Flag set once the migration has been asked to enter postcopy */
 349     bool start_postcopy;
 350     /* Flag set after postcopy has sent the device state */
 351     bool postcopy_after_devices;
 352
 353     /* Flag set once the migration thread is running (and needs joining) */
 354     bool migration_thread_running;
 355
 356     /* Flag set once the migration thread called bdrv_inactivate_all */
 357     bool block_inactive;
 358
 359     /* Migration is waiting for guest to unplug device */
 360     QemuSemaphore wait_unplug_sem;
 361
 362     /* Migration is paused due to pause-before-switchover */
 363     QemuSemaphore pause_sem;
 364
 365     /* The semaphore is used to notify COLO thread that failover is finished */
 366     QemuSemaphore colo_exit_sem;
 367
 368     /* The event is used to notify COLO thread to do checkpoint */
 369     QemuEvent colo_checkpoint_event;
 370     int64_t colo_checkpoint_time;
 371     QEMUTimer *colo_delay_timer;
 372
 373     /* The first error that has occurred.
 374        We used the mutex to be able to return the 1st error message */
 375     Error *error;
 376     /* mutex to protect errp */
 377     QemuMutex error_mutex;
 378
 379     /* Do we have to clean up -b/-i from old migrate parameters */
 380     /* This feature is deprecated and will be removed */
 381     bool must_remove_block_options;
 382
 383     /*
 384      * Global switch on whether we need to store the global state
 385      * during migration.
 386      */
 387     bool store_global_state;
 388
 389     /* Whether we send QEMU_VM_CONFIGURATION during migration */
 390     bool send_configuration;
 391     /* Whether we send section footer during migration */
 392     bool send_section_footer;
 393
 394     /* Needed by postcopy-pause state */
 395     QemuSemaphore postcopy_pause_sem;
 396     /*
 397      * Whether we abort the migration if decompression errors are
 398      * detected at the destination. It is left at false for qemu
 399      * older than 3.0, since only newer qemu sends streams that
 400      * do not trigger spurious decompression errors.
 401      */
 402     bool decompress_error_check;
 403     /*
 404      * This variable only affects behavior when postcopy preempt mode is
 405      * enabled.
 406      *
 407      * When set:
 408      *
 409      * - postcopy preempt src QEMU instance will generate an EOS message at
 410      *   the end of migration to shut the preempt channel on dest side.
 411      *
 412      * - postcopy preempt channel will be created at the setup phase on src
 413          QEMU.
 414      *
 415      * When clear:
 416      *
 417      * - postcopy preempt src QEMU instance will _not_ generate an EOS
 418      *   message at the end of migration, the dest qemu will shutdown the
 419      *   channel itself.
 420      *
 421      * - postcopy preempt channel will be created at the switching phase
 422      *   from precopy -> postcopy (to avoid race condition of misordered
 423      *   creation of channels).
 424      *
 425      * NOTE: See message-id <ZBoShWArKDPpX/D7@work-vm> on qemu-devel
 426      * mailing list for more information on the possible race.  Everyone
 427      * should probably just keep this value untouched after set by the
 428      * machine type (or the default).
 429      */
 430     bool preempt_pre_7_2;
 431
 432     /*
 433      * flush every channel after each section sent.
 434      *
 435      * This assures that we can't mix pages from one iteration through
 436      * ram pages with pages for the following iteration.  We really
 437      * only need to do this flush after we have go through all the
 438      * dirty pages.  For historical reasons, we do that after each
 439      * section.  This is suboptimal (we flush too many times).
 440      * Default value is false. (since 8.1)
 441      */
 442     bool multifd_flush_after_each_section;
 443     /*
 444      * This decides the size of guest memory chunk that will be used
 445      * to track dirty bitmap clearing.  The size of memory chunk will
 446      * be GUEST_PAGE_SIZE << N.  Say, N=0 means we will clear dirty
 447      * bitmap for each page to send (1<<0=1); N=10 means we will clear
 448      * dirty bitmap only once for 1<<10=1K continuous guest pages
 449      * (which is in 4M chunk).
 450      */
 451     uint8_t clear_bitmap_shift;
 452
 453     /*
 454      * This save hostname when out-going migration starts
 455      */
 456     char *hostname;
 457
 458     /* QEMU_VM_VMDESCRIPTION content filled for all non-iterable devices. */
 459     JSONWriter *vmdesc;
 460
 461     /*
 462      * Indicates whether an ACK from the destination that it's OK to do
 463      * switchover has been received.
 464      */
 465     bool switchover_acked;
 466 };
 467
 468 void migrate_set_state(int *state, int old_state, int new_state);
 469
 470 void migration_fd_process_incoming(QEMUFile *f, Error **errp);
 471 void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp);
 472 void migration_incoming_process(void);
 473
 474 bool  migration_has_all_channels(void);
 475
 476 uint64_t migrate_max_downtime(void);
 477
 478 void migrate_set_error(MigrationState *s, const Error *error);
 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 MigrationState *migrate_get_current(void);
 490
 491 uint64_t ram_get_total_transferred_pages(void);
 492
 493 /* Sending on the return path - generic and then for each message type */
 494 void migrate_send_rp_shut(MigrationIncomingState *mis,
 495                           uint32_t value);
 496 void migrate_send_rp_pong(MigrationIncomingState *mis,
 497                           uint32_t value);
 498 int migrate_send_rp_req_pages(MigrationIncomingState *mis, RAMBlock *rb,
 499                               ram_addr_t start, uint64_t haddr);
 500 int migrate_send_rp_message_req_pages(MigrationIncomingState *mis,
 501                                       RAMBlock *rb, ram_addr_t start);
 502 void migrate_send_rp_recv_bitmap(MigrationIncomingState *mis,
 503                                  char *block_name);
 504 void migrate_send_rp_resume_ack(MigrationIncomingState *mis, uint32_t value);
 505 int migrate_send_rp_switchover_ack(MigrationIncomingState *mis);
 506
 507 void dirty_bitmap_mig_before_vm_start(void);
 508 void dirty_bitmap_mig_cancel_outgoing(void);
 509 void dirty_bitmap_mig_cancel_incoming(void);
 510 bool check_dirty_bitmap_mig_alias_map(const BitmapMigrationNodeAliasList *bbm,
 511                                       Error **errp);
 512
 513 void migrate_add_address(SocketAddress *address);
 514
 515 int foreach_not_ignored_block(RAMBlockIterFunc func, void *opaque);
 516
 517 #define qemu_ram_foreach_block \
 518   #warning "Use foreach_not_ignored_block in migration code"
 519
 520 void migration_make_urgent_request(void);
 521 void migration_consume_urgent_request(void);
 522 bool migration_rate_limit(void);
 523 void migration_cancel(const Error *error);
 524
 525 void migration_populate_vfio_info(MigrationInfo *info);
 526 void migration_reset_vfio_bytes_transferred(void);
 527 void postcopy_temp_page_reset(PostcopyTmpPage *tmp_page);
 528
 529 #endif