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