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 "sysemu/sysemu.h"
  26 #include "monitor/monitor.h"
  27 #include "ui/console.h"
  28
  29 #include "hw/hw.h"
  30
  31 #include "qemu/timer.h"
  32 #ifdef CONFIG_POSIX
  33 #include <pthread.h>
  34 #endif
  35
  36 #ifdef CONFIG_PPOLL
  37 #include <poll.h>
  38 #endif
  39
  40 #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
  41 #include <sys/prctl.h>
  42 #endif
  43
  44 /***********************************************************/
  45 /* timers */
  46
  47 typedef struct QEMUClock {
  48     /* We rely on BQL to protect the timerlists */
  49     QLIST_HEAD(, QEMUTimerList) timerlists;
  50
  51     NotifierList reset_notifiers;
  52     int64_t last;
  53
  54     QEMUClockType type;
  55     bool enabled;
  56 } QEMUClock;
  57
  58 QEMUTimerListGroup main_loop_tlg;
  59 QEMUClock qemu_clocks[QEMU_CLOCK_MAX];
  60
  61 /* A QEMUTimerList is a list of timers attached to a clock. More
  62  * than one QEMUTimerList can be attached to each clock, for instance
  63  * used by different AioContexts / threads. Each clock also has
  64  * a list of the QEMUTimerLists associated with it, in order that
  65  * reenabling the clock can call all the notifiers.
  66  */
  67
  68 struct QEMUTimerList {
  69     QEMUClock *clock;
  70     QemuMutex active_timers_lock;
  71     QEMUTimer *active_timers;
  72     QLIST_ENTRY(QEMUTimerList) list;
  73     QEMUTimerListNotifyCB *notify_cb;
  74     void *notify_opaque;
  75
  76     /* lightweight method to mark the end of timerlist's running */
  77     QemuEvent timers_done_ev;
  78 };
  79
  80 /**
  81  * qemu_clock_ptr:
  82  * @type: type of clock
  83  *
  84  * Translate a clock type into a pointer to QEMUClock object.
  85  *
  86  * Returns: a pointer to the QEMUClock object
  87  */
  88 static inline QEMUClock *qemu_clock_ptr(QEMUClockType type)
  89 {
  90     return &qemu_clocks[type];
  91 }
  92
  93 static bool timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
  94 {
  95     return timer_head && (timer_head->expire_time <= current_time);
  96 }
  97
  98 QEMUTimerList *timerlist_new(QEMUClockType type,
  99                              QEMUTimerListNotifyCB *cb,
 100                              void *opaque)
 101 {
 102     QEMUTimerList *timer_list;
 103     QEMUClock *clock = qemu_clock_ptr(type);
 104
 105     timer_list = g_malloc0(sizeof(QEMUTimerList));
 106     qemu_event_init(&timer_list->timers_done_ev, false);
 107     timer_list->clock = clock;
 108     timer_list->notify_cb = cb;
 109     timer_list->notify_opaque = opaque;
 110     qemu_mutex_init(&timer_list->active_timers_lock);
 111     QLIST_INSERT_HEAD(&clock->timerlists, timer_list, list);
 112     return timer_list;
 113 }
 114
 115 void timerlist_free(QEMUTimerList *timer_list)
 116 {
 117     assert(!timerlist_has_timers(timer_list));
 118     if (timer_list->clock) {
 119         QLIST_REMOVE(timer_list, list);
 120     }
 121     qemu_mutex_destroy(&timer_list->active_timers_lock);
 122     g_free(timer_list);
 123 }
 124
 125 static void qemu_clock_init(QEMUClockType type)
 126 {
 127     QEMUClock *clock = qemu_clock_ptr(type);
 128
 129     clock->type = type;
 130     clock->enabled = true;
 131     clock->last = INT64_MIN;
 132     QLIST_INIT(&clock->timerlists);
 133     notifier_list_init(&clock->reset_notifiers);
 134     main_loop_tlg.tl[type] = timerlist_new(type, NULL, NULL);
 135 }
 136
 137 bool qemu_clock_use_for_deadline(QEMUClockType type)
 138 {
 139     return !(use_icount && (type == QEMU_CLOCK_VIRTUAL));
 140 }
 141
 142 void qemu_clock_notify(QEMUClockType type)
 143 {
 144     QEMUTimerList *timer_list;
 145     QEMUClock *clock = qemu_clock_ptr(type);
 146     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
 147         timerlist_notify(timer_list);
 148     }
 149 }
 150
 151 /* Disabling the clock will wait for related timerlists to stop
 152  * executing qemu_run_timers.  Thus, this functions should not
 153  * be used from the callback of a timer that is based on @clock.
 154  * Doing so would cause a deadlock.
 155  *
 156  * Caller should hold BQL.
 157  */
 158 void qemu_clock_enable(QEMUClockType type, bool enabled)
 159 {
 160     QEMUClock *clock = qemu_clock_ptr(type);
 161     QEMUTimerList *tl;
 162     bool old = clock->enabled;
 163     clock->enabled = enabled;
 164     if (enabled && !old) {
 165         qemu_clock_notify(type);
 166     } else if (!enabled && old) {
 167         QLIST_FOREACH(tl, &clock->timerlists, list) {
 168             qemu_event_wait(&tl->timers_done_ev);
 169         }
 170     }
 171 }
 172
 173 bool timerlist_has_timers(QEMUTimerList *timer_list)
 174 {
 175     return !!timer_list->active_timers;
 176 }
 177
 178 bool qemu_clock_has_timers(QEMUClockType type)
 179 {
 180     return timerlist_has_timers(
 181         main_loop_tlg.tl[type]);
 182 }
 183
 184 bool timerlist_expired(QEMUTimerList *timer_list)
 185 {
 186     int64_t expire_time;
 187
 188     qemu_mutex_lock(&timer_list->active_timers_lock);
 189     if (!timer_list->active_timers) {
 190         qemu_mutex_unlock(&timer_list->active_timers_lock);
 191         return false;
 192     }
 193     expire_time = timer_list->active_timers->expire_time;
 194     qemu_mutex_unlock(&timer_list->active_timers_lock);
 195
 196     return expire_time < qemu_clock_get_ns(timer_list->clock->type);
 197 }
 198
 199 bool qemu_clock_expired(QEMUClockType type)
 200 {
 201     return timerlist_expired(
 202         main_loop_tlg.tl[type]);
 203 }
 204
 205 /*
 206  * As above, but return -1 for no deadline, and do not cap to 2^32
 207  * as we know the result is always positive.
 208  */
 209
 210 int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
 211 {
 212     int64_t delta;
 213     int64_t expire_time;
 214
 215     if (!timer_list->clock->enabled) {
 216         return -1;
 217     }
 218
 219     /* The active timers list may be modified before the caller uses our return
 220      * value but ->notify_cb() is called when the deadline changes.  Therefore
 221      * the caller should notice the change and there is no race condition.
 222      */
 223     qemu_mutex_lock(&timer_list->active_timers_lock);
 224     if (!timer_list->active_timers) {
 225         qemu_mutex_unlock(&timer_list->active_timers_lock);
 226         return -1;
 227     }
 228     expire_time = timer_list->active_timers->expire_time;
 229     qemu_mutex_unlock(&timer_list->active_timers_lock);
 230
 231     delta = expire_time - qemu_clock_get_ns(timer_list->clock->type);
 232
 233     if (delta <= 0) {
 234         return 0;
 235     }
 236
 237     return delta;
 238 }
 239
 240 /* Calculate the soonest deadline across all timerlists attached
 241  * to the clock. This is used for the icount timeout so we
 242  * ignore whether or not the clock should be used in deadline
 243  * calculations.
 244  */
 245 int64_t qemu_clock_deadline_ns_all(QEMUClockType type)
 246 {
 247     int64_t deadline = -1;
 248     QEMUTimerList *timer_list;
 249     QEMUClock *clock = qemu_clock_ptr(type);
 250     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
 251         deadline = qemu_soonest_timeout(deadline,
 252                                         timerlist_deadline_ns(timer_list));
 253     }
 254     return deadline;
 255 }
 256
 257 QEMUClockType timerlist_get_clock(QEMUTimerList *timer_list)
 258 {
 259     return timer_list->clock->type;
 260 }
 261
 262 QEMUTimerList *qemu_clock_get_main_loop_timerlist(QEMUClockType type)
 263 {
 264     return main_loop_tlg.tl[type];
 265 }
 266
 267 void timerlist_notify(QEMUTimerList *timer_list)
 268 {
 269     if (timer_list->notify_cb) {
 270         timer_list->notify_cb(timer_list->notify_opaque);
 271     } else {
 272         qemu_notify_event();
 273     }
 274 }
 275
 276 /* Transition function to convert a nanosecond timeout to ms
 277  * This is used where a system does not support ppoll
 278  */
 279 int qemu_timeout_ns_to_ms(int64_t ns)
 280 {
 281     int64_t ms;
 282     if (ns < 0) {
 283         return -1;
 284     }
 285
 286     if (!ns) {
 287         return 0;
 288     }
 289
 290     /* Always round up, because it's better to wait too long than to wait too
 291      * little and effectively busy-wait
 292      */
 293     ms = (ns + SCALE_MS - 1) / SCALE_MS;
 294
 295     /* To avoid overflow problems, limit this to 2^31, i.e. approx 25 days */
 296     if (ms > (int64_t) INT32_MAX) {
 297         ms = INT32_MAX;
 298     }
 299
 300     return (int) ms;
 301 }
 302
 303
 304 /* qemu implementation of g_poll which uses a nanosecond timeout but is
 305  * otherwise identical to g_poll
 306  */
 307 int qemu_poll_ns(GPollFD *fds, guint nfds, int64_t timeout)
 308 {
 309 #ifdef CONFIG_PPOLL
 310     if (timeout < 0) {
 311         return ppoll((struct pollfd *)fds, nfds, NULL, NULL);
 312     } else {
 313         struct timespec ts;
 314         ts.tv_sec = timeout / 1000000000LL;
 315         ts.tv_nsec = timeout % 1000000000LL;
 316         return ppoll((struct pollfd *)fds, nfds, &ts, NULL);
 317     }
 318 #else
 319     return g_poll(fds, nfds, qemu_timeout_ns_to_ms(timeout));
 320 #endif
 321 }
 322
 323
 324 void timer_init(QEMUTimer *ts,
 325                 QEMUTimerList *timer_list, int scale,
 326                 QEMUTimerCB *cb, void *opaque)
 327 {
 328     ts->timer_list = timer_list;
 329     ts->cb = cb;
 330     ts->opaque = opaque;
 331     ts->scale = scale;
 332     ts->expire_time = -1;
 333 }
 334
 335 void timer_free(QEMUTimer *ts)
 336 {
 337     g_free(ts);
 338 }
 339
 340 static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
 341 {
 342     QEMUTimer **pt, *t;
 343
 344     ts->expire_time = -1;
 345     pt = &timer_list->active_timers;
 346     for(;;) {
 347         t = *pt;
 348         if (!t)
 349             break;
 350         if (t == ts) {
 351             *pt = t->next;
 352             break;
 353         }
 354         pt = &t->next;
 355     }
 356 }
 357
 358 /* stop a timer, but do not dealloc it */
 359 void timer_del(QEMUTimer *ts)
 360 {
 361     QEMUTimerList *timer_list = ts->timer_list;
 362
 363     qemu_mutex_lock(&timer_list->active_timers_lock);
 364     timer_del_locked(timer_list, ts);
 365     qemu_mutex_unlock(&timer_list->active_timers_lock);
 366 }
 367
 368 /* modify the current timer so that it will be fired when current_time
 369    >= expire_time. The corresponding callback will be called. */
 370 void timer_mod_ns(QEMUTimer *ts, int64_t expire_time)
 371 {
 372     QEMUTimerList *timer_list = ts->timer_list;
 373     QEMUTimer **pt, *t;
 374
 375     qemu_mutex_lock(&timer_list->active_timers_lock);
 376     timer_del_locked(timer_list, ts);
 377
 378     /* add the timer in the sorted list */
 379     pt = &timer_list->active_timers;
 380     for(;;) {
 381         t = *pt;
 382         if (!timer_expired_ns(t, expire_time)) {
 383             break;
 384         }
 385         pt = &t->next;
 386     }
 387     ts->expire_time = MAX(expire_time, 0);
 388     ts->next = *pt;
 389     *pt = ts;
 390     qemu_mutex_unlock(&timer_list->active_timers_lock);
 391
 392     /* Rearm if necessary  */
 393     if (pt == &timer_list->active_timers) {
 394         /* Interrupt execution to force deadline recalculation.  */
 395         qemu_clock_warp(timer_list->clock->type);
 396         timerlist_notify(timer_list);
 397     }
 398 }
 399
 400 void timer_mod(QEMUTimer *ts, int64_t expire_time)
 401 {
 402     timer_mod_ns(ts, expire_time * ts->scale);
 403 }
 404
 405 bool timer_pending(QEMUTimer *ts)
 406 {
 407     return ts->expire_time >= 0;
 408 }
 409
 410 bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
 411 {
 412     return timer_expired_ns(timer_head, current_time * timer_head->scale);
 413 }
 414
 415 bool timerlist_run_timers(QEMUTimerList *timer_list)
 416 {
 417     QEMUTimer *ts;
 418     int64_t current_time;
 419     bool progress = false;
 420     QEMUTimerCB *cb;
 421     void *opaque;
 422
 423     qemu_event_reset(&timer_list->timers_done_ev);
 424     if (!timer_list->clock->enabled) {
 425         goto out;
 426     }
 427
 428     current_time = qemu_clock_get_ns(timer_list->clock->type);
 429     for(;;) {
 430         qemu_mutex_lock(&timer_list->active_timers_lock);
 431         ts = timer_list->active_timers;
 432         if (!timer_expired_ns(ts, current_time)) {
 433             qemu_mutex_unlock(&timer_list->active_timers_lock);
 434             break;
 435         }
 436
 437         /* remove timer from the list before calling the callback */
 438         timer_list->active_timers = ts->next;
 439         ts->next = NULL;
 440         ts->expire_time = -1;
 441         cb = ts->cb;
 442         opaque = ts->opaque;
 443         qemu_mutex_unlock(&timer_list->active_timers_lock);
 444
 445         /* run the callback (the timer list can be modified) */
 446         cb(opaque);
 447         progress = true;
 448     }
 449
 450 out:
 451     qemu_event_set(&timer_list->timers_done_ev);
 452     return progress;
 453 }
 454
 455 bool qemu_clock_run_timers(QEMUClockType type)
 456 {
 457     return timerlist_run_timers(main_loop_tlg.tl[type]);
 458 }
 459
 460 void timerlistgroup_init(QEMUTimerListGroup *tlg,
 461                          QEMUTimerListNotifyCB *cb, void *opaque)
 462 {
 463     QEMUClockType type;
 464     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 465         tlg->tl[type] = timerlist_new(type, cb, opaque);
 466     }
 467 }
 468
 469 void timerlistgroup_deinit(QEMUTimerListGroup *tlg)
 470 {
 471     QEMUClockType type;
 472     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 473         timerlist_free(tlg->tl[type]);
 474     }
 475 }
 476
 477 bool timerlistgroup_run_timers(QEMUTimerListGroup *tlg)
 478 {
 479     QEMUClockType type;
 480     bool progress = false;
 481     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 482         progress |= timerlist_run_timers(tlg->tl[type]);
 483     }
 484     return progress;
 485 }
 486
 487 int64_t timerlistgroup_deadline_ns(QEMUTimerListGroup *tlg)
 488 {
 489     int64_t deadline = -1;
 490     QEMUClockType type;
 491     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 492         if (qemu_clock_use_for_deadline(tlg->tl[type]->clock->type)) {
 493             deadline = qemu_soonest_timeout(deadline,
 494                                             timerlist_deadline_ns(
 495                                                 tlg->tl[type]));
 496         }
 497     }
 498     return deadline;
 499 }
 500
 501 int64_t qemu_clock_get_ns(QEMUClockType type)
 502 {
 503     int64_t now, last;
 504     QEMUClock *clock = qemu_clock_ptr(type);
 505
 506     switch (type) {
 507     case QEMU_CLOCK_REALTIME:
 508         return get_clock();
 509     default:
 510     case QEMU_CLOCK_VIRTUAL:
 511         if (use_icount) {
 512             return cpu_get_icount();
 513         } else {
 514             return cpu_get_clock();
 515         }
 516     case QEMU_CLOCK_HOST:
 517         now = get_clock_realtime();
 518         last = clock->last;
 519         clock->last = now;
 520         if (now < last) {
 521             notifier_list_notify(&clock->reset_notifiers, &now);
 522         }
 523         return now;
 524     }
 525 }
 526
 527 void qemu_clock_register_reset_notifier(QEMUClockType type,
 528                                         Notifier *notifier)
 529 {
 530     QEMUClock *clock = qemu_clock_ptr(type);
 531     notifier_list_add(&clock->reset_notifiers, notifier);
 532 }
 533
 534 void qemu_clock_unregister_reset_notifier(QEMUClockType type,
 535                                           Notifier *notifier)
 536 {
 537     notifier_remove(notifier);
 538 }
 539
 540 void init_clocks(void)
 541 {
 542     QEMUClockType type;
 543     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 544         qemu_clock_init(type);
 545     }
 546
 547 #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
 548     prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
 549 #endif
 550 }
 551
 552 uint64_t timer_expire_time_ns(QEMUTimer *ts)
 553 {
 554     return timer_pending(ts) ? ts->expire_time : -1;
 555 }
 556
 557 bool qemu_clock_run_all_timers(void)
 558 {
 559     bool progress = false;
 560     QEMUClockType type;
 561
 562     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 563         progress |= qemu_clock_run_timers(type);
 564     }
 565
 566     return progress;
 567 }