qemu-timer.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include "qemu/main-loop.h"
  27 #include "qemu/timer.h"
  28 #include "sysemu/replay.h"
  29 #include "sysemu/sysemu.h"
  30
  31 #ifdef CONFIG_POSIX
  32 #include <pthread.h>
  33 #endif
  34
  35 #ifdef CONFIG_PPOLL
  36 #include <poll.h>
  37 #endif
  38
  39 #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
  40 #include <sys/prctl.h>
  41 #endif
  42
  43 /***********************************************************/
  44 /* timers */
  45
  46 typedef struct QEMUClock {
  47     /* We rely on BQL to protect the timerlists */
  48     QLIST_HEAD(, QEMUTimerList) timerlists;
  49
  50     NotifierList reset_notifiers;
  51     int64_t last;
  52
  53     QEMUClockType type;
  54     bool enabled;
  55 } QEMUClock;
  56
  57 QEMUTimerListGroup main_loop_tlg;
  58 static QEMUClock qemu_clocks[QEMU_CLOCK_MAX];
  59
  60 /* A QEMUTimerList is a list of timers attached to a clock. More
  61  * than one QEMUTimerList can be attached to each clock, for instance
  62  * used by different AioContexts / threads. Each clock also has
  63  * a list of the QEMUTimerLists associated with it, in order that
  64  * reenabling the clock can call all the notifiers.
  65  */
  66
  67 struct QEMUTimerList {
  68     QEMUClock *clock;
  69     QemuMutex active_timers_lock;
  70     QEMUTimer *active_timers;
  71     QLIST_ENTRY(QEMUTimerList) list;
  72     QEMUTimerListNotifyCB *notify_cb;
  73     void *notify_opaque;
  74
  75     /* lightweight method to mark the end of timerlist's running */
  76     QemuEvent timers_done_ev;
  77 };
  78
  79 /**
  80  * qemu_clock_ptr:
  81  * @type: type of clock
  82  *
  83  * Translate a clock type into a pointer to QEMUClock object.
  84  *
  85  * Returns: a pointer to the QEMUClock object
  86  */
  87 static inline QEMUClock *qemu_clock_ptr(QEMUClockType type)
  88 {
  89     return &qemu_clocks[type];
  90 }
  91
  92 static bool timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
  93 {
  94     return timer_head && (timer_head->expire_time <= current_time);
  95 }
  96
  97 QEMUTimerList *timerlist_new(QEMUClockType type,
  98                              QEMUTimerListNotifyCB *cb,
  99                              void *opaque)
 100 {
 101     QEMUTimerList *timer_list;
 102     QEMUClock *clock = qemu_clock_ptr(type);
 103
 104     timer_list = g_malloc0(sizeof(QEMUTimerList));
 105     qemu_event_init(&timer_list->timers_done_ev, true);
 106     timer_list->clock = clock;
 107     timer_list->notify_cb = cb;
 108     timer_list->notify_opaque = opaque;
 109     qemu_mutex_init(&timer_list->active_timers_lock);
 110     QLIST_INSERT_HEAD(&clock->timerlists, timer_list, list);
 111     return timer_list;
 112 }
 113
 114 void timerlist_free(QEMUTimerList *timer_list)
 115 {
 116     assert(!timerlist_has_timers(timer_list));
 117     if (timer_list->clock) {
 118         QLIST_REMOVE(timer_list, list);
 119     }
 120     qemu_mutex_destroy(&timer_list->active_timers_lock);
 121     g_free(timer_list);
 122 }
 123
 124 static void qemu_clock_init(QEMUClockType type)
 125 {
 126     QEMUClock *clock = qemu_clock_ptr(type);
 127
 128     /* Assert that the clock of type TYPE has not been initialized yet. */
 129     assert(main_loop_tlg.tl[type] == NULL);
 130
 131     clock->type = type;
 132     clock->enabled = (type == QEMU_CLOCK_VIRTUAL ? false : true);
 133     clock->last = INT64_MIN;
 134     QLIST_INIT(&clock->timerlists);
 135     notifier_list_init(&clock->reset_notifiers);
 136     main_loop_tlg.tl[type] = timerlist_new(type, NULL, NULL);
 137 }
 138
 139 bool qemu_clock_use_for_deadline(QEMUClockType type)
 140 {
 141     return !(use_icount && (type == QEMU_CLOCK_VIRTUAL));
 142 }
 143
 144 void qemu_clock_notify(QEMUClockType type)
 145 {
 146     QEMUTimerList *timer_list;
 147     QEMUClock *clock = qemu_clock_ptr(type);
 148     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
 149         timerlist_notify(timer_list);
 150     }
 151 }
 152
 153 /* Disabling the clock will wait for related timerlists to stop
 154  * executing qemu_run_timers.  Thus, this functions should not
 155  * be used from the callback of a timer that is based on @clock.
 156  * Doing so would cause a deadlock.
 157  *
 158  * Caller should hold BQL.
 159  */
 160 void qemu_clock_enable(QEMUClockType type, bool enabled)
 161 {
 162     QEMUClock *clock = qemu_clock_ptr(type);
 163     QEMUTimerList *tl;
 164     bool old = clock->enabled;
 165     clock->enabled = enabled;
 166     if (enabled && !old) {
 167         qemu_clock_notify(type);
 168     } else if (!enabled && old) {
 169         QLIST_FOREACH(tl, &clock->timerlists, list) {
 170             qemu_event_wait(&tl->timers_done_ev);
 171         }
 172     }
 173 }
 174
 175 bool timerlist_has_timers(QEMUTimerList *timer_list)
 176 {
 177     return !!atomic_read(&timer_list->active_timers);
 178 }
 179
 180 bool qemu_clock_has_timers(QEMUClockType type)
 181 {
 182     return timerlist_has_timers(
 183         main_loop_tlg.tl[type]);
 184 }
 185
 186 bool timerlist_expired(QEMUTimerList *timer_list)
 187 {
 188     int64_t expire_time;
 189
 190     if (!atomic_read(&timer_list->active_timers)) {
 191         return false;
 192     }
 193
 194     qemu_mutex_lock(&timer_list->active_timers_lock);
 195     if (!timer_list->active_timers) {
 196         qemu_mutex_unlock(&timer_list->active_timers_lock);
 197         return false;
 198     }
 199     expire_time = timer_list->active_timers->expire_time;
 200     qemu_mutex_unlock(&timer_list->active_timers_lock);
 201
 202     return expire_time < qemu_clock_get_ns(timer_list->clock->type);
 203 }
 204
 205 bool qemu_clock_expired(QEMUClockType type)
 206 {
 207     return timerlist_expired(
 208         main_loop_tlg.tl[type]);
 209 }
 210
 211 /*
 212  * As above, but return -1 for no deadline, and do not cap to 2^32
 213  * as we know the result is always positive.
 214  */
 215
 216 int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
 217 {
 218     int64_t delta;
 219     int64_t expire_time;
 220
 221     if (!atomic_read(&timer_list->active_timers)) {
 222         return -1;
 223     }
 224
 225     if (!timer_list->clock->enabled) {
 226         return -1;
 227     }
 228
 229     /* The active timers list may be modified before the caller uses our return
 230      * value but ->notify_cb() is called when the deadline changes.  Therefore
 231      * the caller should notice the change and there is no race condition.
 232      */
 233     qemu_mutex_lock(&timer_list->active_timers_lock);
 234     if (!timer_list->active_timers) {
 235         qemu_mutex_unlock(&timer_list->active_timers_lock);
 236         return -1;
 237     }
 238     expire_time = timer_list->active_timers->expire_time;
 239     qemu_mutex_unlock(&timer_list->active_timers_lock);
 240
 241     delta = expire_time - qemu_clock_get_ns(timer_list->clock->type);
 242
 243     if (delta <= 0) {
 244         return 0;
 245     }
 246
 247     return delta;
 248 }
 249
 250 /* Calculate the soonest deadline across all timerlists attached
 251  * to the clock. This is used for the icount timeout so we
 252  * ignore whether or not the clock should be used in deadline
 253  * calculations.
 254  */
 255 int64_t qemu_clock_deadline_ns_all(QEMUClockType type)
 256 {
 257     int64_t deadline = -1;
 258     QEMUTimerList *timer_list;
 259     QEMUClock *clock = qemu_clock_ptr(type);
 260     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
 261         deadline = qemu_soonest_timeout(deadline,
 262                                         timerlist_deadline_ns(timer_list));
 263     }
 264     return deadline;
 265 }
 266
 267 QEMUClockType timerlist_get_clock(QEMUTimerList *timer_list)
 268 {
 269     return timer_list->clock->type;
 270 }
 271
 272 QEMUTimerList *qemu_clock_get_main_loop_timerlist(QEMUClockType type)
 273 {
 274     return main_loop_tlg.tl[type];
 275 }
 276
 277 void timerlist_notify(QEMUTimerList *timer_list)
 278 {
 279     if (timer_list->notify_cb) {
 280         timer_list->notify_cb(timer_list->notify_opaque);
 281     } else {
 282         qemu_notify_event();
 283     }
 284 }
 285
 286 /* Transition function to convert a nanosecond timeout to ms
 287  * This is used where a system does not support ppoll
 288  */
 289 int qemu_timeout_ns_to_ms(int64_t ns)
 290 {
 291     int64_t ms;
 292     if (ns < 0) {
 293         return -1;
 294     }
 295
 296     if (!ns) {
 297         return 0;
 298     }
 299
 300     /* Always round up, because it's better to wait too long than to wait too
 301      * little and effectively busy-wait
 302      */
 303     ms = DIV_ROUND_UP(ns, SCALE_MS);
 304
 305     /* To avoid overflow problems, limit this to 2^31, i.e. approx 25 days */
 306     if (ms > (int64_t) INT32_MAX) {
 307         ms = INT32_MAX;
 308     }
 309
 310     return (int) ms;
 311 }
 312
 313
 314 /* qemu implementation of g_poll which uses a nanosecond timeout but is
 315  * otherwise identical to g_poll
 316  */
 317 int qemu_poll_ns(GPollFD *fds, guint nfds, int64_t timeout)
 318 {
 319 #ifdef CONFIG_PPOLL
 320     if (timeout < 0) {
 321         return ppoll((struct pollfd *)fds, nfds, NULL, NULL);
 322     } else {
 323         struct timespec ts;
 324         int64_t tvsec = timeout / 1000000000LL;
 325         /* Avoid possibly overflowing and specifying a negative number of
 326          * seconds, which would turn a very long timeout into a busy-wait.
 327          */
 328         if (tvsec > (int64_t)INT32_MAX) {
 329             tvsec = INT32_MAX;
 330         }
 331         ts.tv_sec = tvsec;
 332         ts.tv_nsec = timeout % 1000000000LL;
 333         return ppoll((struct pollfd *)fds, nfds, &ts, NULL);
 334     }
 335 #else
 336     return g_poll(fds, nfds, qemu_timeout_ns_to_ms(timeout));
 337 #endif
 338 }
 339
 340
 341 void timer_init_tl(QEMUTimer *ts,
 342                    QEMUTimerList *timer_list, int scale,
 343                    QEMUTimerCB *cb, void *opaque)
 344 {
 345     ts->timer_list = timer_list;
 346     ts->cb = cb;
 347     ts->opaque = opaque;
 348     ts->scale = scale;
 349     ts->expire_time = -1;
 350 }
 351
 352 void timer_deinit(QEMUTimer *ts)
 353 {
 354     assert(ts->expire_time == -1);
 355     ts->timer_list = NULL;
 356 }
 357
 358 void timer_free(QEMUTimer *ts)
 359 {
 360     g_free(ts);
 361 }
 362
 363 static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
 364 {
 365     QEMUTimer **pt, *t;
 366
 367     ts->expire_time = -1;
 368     pt = &timer_list->active_timers;
 369     for(;;) {
 370         t = *pt;
 371         if (!t)
 372             break;
 373         if (t == ts) {
 374             atomic_set(pt, t->next);
 375             break;
 376         }
 377         pt = &t->next;
 378     }
 379 }
 380
 381 static bool timer_mod_ns_locked(QEMUTimerList *timer_list,
 382                                 QEMUTimer *ts, int64_t expire_time)
 383 {
 384     QEMUTimer **pt, *t;
 385
 386     /* add the timer in the sorted list */
 387     pt = &timer_list->active_timers;
 388     for (;;) {
 389         t = *pt;
 390         if (!timer_expired_ns(t, expire_time)) {
 391             break;
 392         }
 393         pt = &t->next;
 394     }
 395     ts->expire_time = MAX(expire_time, 0);
 396     ts->next = *pt;
 397     atomic_set(pt, ts);
 398
 399     return pt == &timer_list->active_timers;
 400 }
 401
 402 static void timerlist_rearm(QEMUTimerList *timer_list)
 403 {
 404     /* Interrupt execution to force deadline recalculation.  */
 405     if (timer_list->clock->type == QEMU_CLOCK_VIRTUAL) {
 406         qemu_start_warp_timer();
 407     }
 408     timerlist_notify(timer_list);
 409 }
 410
 411 /* stop a timer, but do not dealloc it */
 412 void timer_del(QEMUTimer *ts)
 413 {
 414     QEMUTimerList *timer_list = ts->timer_list;
 415
 416     if (timer_list) {
 417         qemu_mutex_lock(&timer_list->active_timers_lock);
 418         timer_del_locked(timer_list, ts);
 419         qemu_mutex_unlock(&timer_list->active_timers_lock);
 420     }
 421 }
 422
 423 /* modify the current timer so that it will be fired when current_time
 424    >= expire_time. The corresponding callback will be called. */
 425 void timer_mod_ns(QEMUTimer *ts, int64_t expire_time)
 426 {
 427     QEMUTimerList *timer_list = ts->timer_list;
 428     bool rearm;
 429
 430     qemu_mutex_lock(&timer_list->active_timers_lock);
 431     timer_del_locked(timer_list, ts);
 432     rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
 433     qemu_mutex_unlock(&timer_list->active_timers_lock);
 434
 435     if (rearm) {
 436         timerlist_rearm(timer_list);
 437     }
 438 }
 439
 440 /* modify the current timer so that it will be fired when current_time
 441    >= expire_time or the current deadline, whichever comes earlier.
 442    The corresponding callback will be called. */
 443 void timer_mod_anticipate_ns(QEMUTimer *ts, int64_t expire_time)
 444 {
 445     QEMUTimerList *timer_list = ts->timer_list;
 446     bool rearm;
 447
 448     qemu_mutex_lock(&timer_list->active_timers_lock);
 449     if (ts->expire_time == -1 || ts->expire_time > expire_time) {
 450         if (ts->expire_time != -1) {
 451             timer_del_locked(timer_list, ts);
 452         }
 453         rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
 454     } else {
 455         rearm = false;
 456     }
 457     qemu_mutex_unlock(&timer_list->active_timers_lock);
 458
 459     if (rearm) {
 460         timerlist_rearm(timer_list);
 461     }
 462 }
 463
 464 void timer_mod(QEMUTimer *ts, int64_t expire_time)
 465 {
 466     timer_mod_ns(ts, expire_time * ts->scale);
 467 }
 468
 469 void timer_mod_anticipate(QEMUTimer *ts, int64_t expire_time)
 470 {
 471     timer_mod_anticipate_ns(ts, expire_time * ts->scale);
 472 }
 473
 474 bool timer_pending(QEMUTimer *ts)
 475 {
 476     return ts->expire_time >= 0;
 477 }
 478
 479 bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
 480 {
 481     return timer_expired_ns(timer_head, current_time * timer_head->scale);
 482 }
 483
 484 bool timerlist_run_timers(QEMUTimerList *timer_list)
 485 {
 486     QEMUTimer *ts;
 487     int64_t current_time;
 488     bool progress = false;
 489     QEMUTimerCB *cb;
 490     void *opaque;
 491
 492     if (!atomic_read(&timer_list->active_timers)) {
 493         return false;
 494     }
 495
 496     qemu_event_reset(&timer_list->timers_done_ev);
 497     if (!timer_list->clock->enabled) {
 498         goto out;
 499     }
 500
 501     switch (timer_list->clock->type) {
 502     case QEMU_CLOCK_REALTIME:
 503         break;
 504     default:
 505     case QEMU_CLOCK_VIRTUAL:
 506         if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) {
 507             goto out;
 508         }
 509         break;
 510     case QEMU_CLOCK_HOST:
 511         if (!replay_checkpoint(CHECKPOINT_CLOCK_HOST)) {
 512             goto out;
 513         }
 514         break;
 515     case QEMU_CLOCK_VIRTUAL_RT:
 516         if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL_RT)) {
 517             goto out;
 518         }
 519         break;
 520     }
 521
 522     current_time = qemu_clock_get_ns(timer_list->clock->type);
 523     for(;;) {
 524         qemu_mutex_lock(&timer_list->active_timers_lock);
 525         ts = timer_list->active_timers;
 526         if (!timer_expired_ns(ts, current_time)) {
 527             qemu_mutex_unlock(&timer_list->active_timers_lock);
 528             break;
 529         }
 530
 531         /* remove timer from the list before calling the callback */
 532         timer_list->active_timers = ts->next;
 533         ts->next = NULL;
 534         ts->expire_time = -1;
 535         cb = ts->cb;
 536         opaque = ts->opaque;
 537         qemu_mutex_unlock(&timer_list->active_timers_lock);
 538
 539         /* run the callback (the timer list can be modified) */
 540         cb(opaque);
 541         progress = true;
 542     }
 543
 544 out:
 545     qemu_event_set(&timer_list->timers_done_ev);
 546     return progress;
 547 }
 548
 549 bool qemu_clock_run_timers(QEMUClockType type)
 550 {
 551     return timerlist_run_timers(main_loop_tlg.tl[type]);
 552 }
 553
 554 void timerlistgroup_init(QEMUTimerListGroup *tlg,
 555                          QEMUTimerListNotifyCB *cb, void *opaque)
 556 {
 557     QEMUClockType type;
 558     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 559         tlg->tl[type] = timerlist_new(type, cb, opaque);
 560     }
 561 }
 562
 563 void timerlistgroup_deinit(QEMUTimerListGroup *tlg)
 564 {
 565     QEMUClockType type;
 566     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 567         timerlist_free(tlg->tl[type]);
 568     }
 569 }
 570
 571 bool timerlistgroup_run_timers(QEMUTimerListGroup *tlg)
 572 {
 573     QEMUClockType type;
 574     bool progress = false;
 575     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 576         progress |= timerlist_run_timers(tlg->tl[type]);
 577     }
 578     return progress;
 579 }
 580
 581 int64_t timerlistgroup_deadline_ns(QEMUTimerListGroup *tlg)
 582 {
 583     int64_t deadline = -1;
 584     QEMUClockType type;
 585     bool play = replay_mode == REPLAY_MODE_PLAY;
 586     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 587         if (qemu_clock_use_for_deadline(type)) {
 588             if (!play || type == QEMU_CLOCK_REALTIME) {
 589                 deadline = qemu_soonest_timeout(deadline,
 590                                                 timerlist_deadline_ns(tlg->tl[type]));
 591             } else {
 592                 /* Read clock from the replay file and
 593                    do not calculate the deadline, based on virtual clock. */
 594                 qemu_clock_get_ns(type);
 595             }
 596         }
 597     }
 598     return deadline;
 599 }
 600
 601 int64_t qemu_clock_get_ns(QEMUClockType type)
 602 {
 603     int64_t now, last;
 604     QEMUClock *clock = qemu_clock_ptr(type);
 605
 606     switch (type) {
 607     case QEMU_CLOCK_REALTIME:
 608         return get_clock();
 609     default:
 610     case QEMU_CLOCK_VIRTUAL:
 611         if (use_icount) {
 612             return cpu_get_icount();
 613         } else {
 614             return cpu_get_clock();
 615         }
 616     case QEMU_CLOCK_HOST:
 617         now = REPLAY_CLOCK(REPLAY_CLOCK_HOST, get_clock_realtime());
 618         last = clock->last;
 619         clock->last = now;
 620         if (now < last || now > (last + get_max_clock_jump())) {
 621             notifier_list_notify(&clock->reset_notifiers, &now);
 622         }
 623         return now;
 624     case QEMU_CLOCK_VIRTUAL_RT:
 625         return REPLAY_CLOCK(REPLAY_CLOCK_VIRTUAL_RT, cpu_get_clock());
 626     }
 627 }
 628
 629 void qemu_clock_register_reset_notifier(QEMUClockType type,
 630                                         Notifier *notifier)
 631 {
 632     QEMUClock *clock = qemu_clock_ptr(type);
 633     notifier_list_add(&clock->reset_notifiers, notifier);
 634 }
 635
 636 void qemu_clock_unregister_reset_notifier(QEMUClockType type,
 637                                           Notifier *notifier)
 638 {
 639     notifier_remove(notifier);
 640 }
 641
 642 void init_clocks(void)
 643 {
 644     QEMUClockType type;
 645     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 646         qemu_clock_init(type);
 647     }
 648
 649 #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
 650     prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
 651 #endif
 652 }
 653
 654 uint64_t timer_expire_time_ns(QEMUTimer *ts)
 655 {
 656     return timer_pending(ts) ? ts->expire_time : -1;
 657 }
 658
 659 bool qemu_clock_run_all_timers(void)
 660 {
 661     bool progress = false;
 662     QEMUClockType type;
 663
 664     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 665         progress |= qemu_clock_run_timers(type);
 666     }
 667
 668     return progress;
 669 }