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 _WIN32
  37 #include <mmsystem.h>
  38 #endif
  39
  40 /***********************************************************/
  41 /* timers */
  42
  43 struct QEMUClock {
  44     QEMUTimer *active_timers;
  45
  46     NotifierList reset_notifiers;
  47     int64_t last;
  48
  49     int type;
  50     bool enabled;
  51 };
  52
  53 struct QEMUTimer {
  54     int64_t expire_time;        /* in nanoseconds */
  55     QEMUClock *clock;
  56     QEMUTimerCB *cb;
  57     void *opaque;
  58     QEMUTimer *next;
  59     int scale;
  60 };
  61
  62 struct qemu_alarm_timer {
  63     char const *name;
  64     int (*start)(struct qemu_alarm_timer *t);
  65     void (*stop)(struct qemu_alarm_timer *t);
  66     void (*rearm)(struct qemu_alarm_timer *t, int64_t nearest_delta_ns);
  67 #if defined(__linux__)
  68     timer_t timer;
  69     int fd;
  70 #elif defined(_WIN32)
  71     HANDLE timer;
  72 #endif
  73     bool expired;
  74     bool pending;
  75 };
  76
  77 static struct qemu_alarm_timer *alarm_timer;
  78
  79 static bool timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
  80 {
  81     return timer_head && (timer_head->expire_time <= current_time);
  82 }
  83
  84 static int64_t qemu_next_alarm_deadline(void)
  85 {
  86     int64_t delta = INT64_MAX;
  87     int64_t rtdelta;
  88
  89     if (!use_icount && vm_clock->enabled && vm_clock->active_timers) {
  90         delta = vm_clock->active_timers->expire_time -
  91                      qemu_get_clock_ns(vm_clock);
  92     }
  93     if (host_clock->enabled && host_clock->active_timers) {
  94         int64_t hdelta = host_clock->active_timers->expire_time -
  95                  qemu_get_clock_ns(host_clock);
  96         if (hdelta < delta) {
  97             delta = hdelta;
  98         }
  99     }
 100     if (rt_clock->enabled && rt_clock->active_timers) {
 101         rtdelta = (rt_clock->active_timers->expire_time -
 102                  qemu_get_clock_ns(rt_clock));
 103         if (rtdelta < delta) {
 104             delta = rtdelta;
 105         }
 106     }
 107
 108     return delta;
 109 }
 110
 111 static void qemu_rearm_alarm_timer(struct qemu_alarm_timer *t)
 112 {
 113     int64_t nearest_delta_ns = qemu_next_alarm_deadline();
 114     if (nearest_delta_ns < INT64_MAX) {
 115         t->rearm(t, nearest_delta_ns);
 116     }
 117 }
 118
 119 /* TODO: MIN_TIMER_REARM_NS should be optimized */
 120 #define MIN_TIMER_REARM_NS 250000
 121
 122 #ifdef _WIN32
 123
 124 static int mm_start_timer(struct qemu_alarm_timer *t);
 125 static void mm_stop_timer(struct qemu_alarm_timer *t);
 126 static void mm_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 127
 128 static int win32_start_timer(struct qemu_alarm_timer *t);
 129 static void win32_stop_timer(struct qemu_alarm_timer *t);
 130 static void win32_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 131
 132 #else
 133
 134 static int unix_start_timer(struct qemu_alarm_timer *t);
 135 static void unix_stop_timer(struct qemu_alarm_timer *t);
 136 static void unix_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 137
 138 #ifdef __linux__
 139
 140 static int dynticks_start_timer(struct qemu_alarm_timer *t);
 141 static void dynticks_stop_timer(struct qemu_alarm_timer *t);
 142 static void dynticks_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 143
 144 #endif /* __linux__ */
 145
 146 #endif /* _WIN32 */
 147
 148 static struct qemu_alarm_timer alarm_timers[] = {
 149 #ifndef _WIN32
 150 #ifdef __linux__
 151     {"dynticks", dynticks_start_timer,
 152      dynticks_stop_timer, dynticks_rearm_timer},
 153 #endif
 154     {"unix", unix_start_timer, unix_stop_timer, unix_rearm_timer},
 155 #else
 156     {"mmtimer", mm_start_timer, mm_stop_timer, mm_rearm_timer},
 157     {"dynticks", win32_start_timer, win32_stop_timer, win32_rearm_timer},
 158 #endif
 159     {NULL, }
 160 };
 161
 162 static void show_available_alarms(void)
 163 {
 164     int i;
 165
 166     printf("Available alarm timers, in order of precedence:\n");
 167     for (i = 0; alarm_timers[i].name; i++)
 168         printf("%s\n", alarm_timers[i].name);
 169 }
 170
 171 void configure_alarms(char const *opt)
 172 {
 173     int i;
 174     int cur = 0;
 175     int count = ARRAY_SIZE(alarm_timers) - 1;
 176     char *arg;
 177     char *name;
 178     struct qemu_alarm_timer tmp;
 179
 180     if (is_help_option(opt)) {
 181         show_available_alarms();
 182         exit(0);
 183     }
 184
 185     arg = g_strdup(opt);
 186
 187     /* Reorder the array */
 188     name = strtok(arg, ",");
 189     while (name) {
 190         for (i = 0; i < count && alarm_timers[i].name; i++) {
 191             if (!strcmp(alarm_timers[i].name, name))
 192                 break;
 193         }
 194
 195         if (i == count) {
 196             fprintf(stderr, "Unknown clock %s\n", name);
 197             goto next;
 198         }
 199
 200         if (i < cur)
 201             /* Ignore */
 202             goto next;
 203
 204         /* Swap */
 205         tmp = alarm_timers[i];
 206         alarm_timers[i] = alarm_timers[cur];
 207         alarm_timers[cur] = tmp;
 208
 209         cur++;
 210 next:
 211         name = strtok(NULL, ",");
 212     }
 213
 214     g_free(arg);
 215
 216     if (cur) {
 217         /* Disable remaining timers */
 218         for (i = cur; i < count; i++)
 219             alarm_timers[i].name = NULL;
 220     } else {
 221         show_available_alarms();
 222         exit(1);
 223     }
 224 }
 225
 226 QEMUClock *rt_clock;
 227 QEMUClock *vm_clock;
 228 QEMUClock *host_clock;
 229
 230 static QEMUClock *qemu_clock_new(int type)
 231 {
 232     QEMUClock *clock;
 233
 234     clock = g_malloc0(sizeof(QEMUClock));
 235     clock->type = type;
 236     clock->enabled = true;
 237     clock->last = INT64_MIN;
 238     notifier_list_init(&clock->reset_notifiers);
 239     return clock;
 240 }
 241
 242 void qemu_clock_enable(QEMUClock *clock, bool enabled)
 243 {
 244     bool old = clock->enabled;
 245     clock->enabled = enabled;
 246     if (enabled && !old) {
 247         qemu_rearm_alarm_timer(alarm_timer);
 248     }
 249 }
 250
 251 int64_t qemu_clock_has_timers(QEMUClock *clock)
 252 {
 253     return !!clock->active_timers;
 254 }
 255
 256 int64_t qemu_clock_expired(QEMUClock *clock)
 257 {
 258     return (clock->active_timers &&
 259             clock->active_timers->expire_time < qemu_get_clock_ns(clock));
 260 }
 261
 262 int64_t qemu_clock_deadline(QEMUClock *clock)
 263 {
 264     /* To avoid problems with overflow limit this to 2^32.  */
 265     int64_t delta = INT32_MAX;
 266
 267     if (clock->enabled && clock->active_timers) {
 268         delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock);
 269     }
 270     if (delta < 0) {
 271         delta = 0;
 272     }
 273     return delta;
 274 }
 275
 276 /*
 277  * As above, but return -1 for no deadline, and do not cap to 2^32
 278  * as we know the result is always positive.
 279  */
 280
 281 int64_t qemu_clock_deadline_ns(QEMUClock *clock)
 282 {
 283     int64_t delta;
 284
 285     if (!clock->enabled || !clock->active_timers) {
 286         return -1;
 287     }
 288
 289     delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock);
 290
 291     if (delta <= 0) {
 292         return 0;
 293     }
 294
 295     return delta;
 296 }
 297
 298 /* Transition function to convert a nanosecond timeout to ms
 299  * This is used where a system does not support ppoll
 300  */
 301 int qemu_timeout_ns_to_ms(int64_t ns)
 302 {
 303     int64_t ms;
 304     if (ns < 0) {
 305         return -1;
 306     }
 307
 308     if (!ns) {
 309         return 0;
 310     }
 311
 312     /* Always round up, because it's better to wait too long than to wait too
 313      * little and effectively busy-wait
 314      */
 315     ms = (ns + SCALE_MS - 1) / SCALE_MS;
 316
 317     /* To avoid overflow problems, limit this to 2^31, i.e. approx 25 days */
 318     if (ms > (int64_t) INT32_MAX) {
 319         ms = INT32_MAX;
 320     }
 321
 322     return (int) ms;
 323 }
 324
 325
 326 QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
 327                           QEMUTimerCB *cb, void *opaque)
 328 {
 329     QEMUTimer *ts;
 330
 331     ts = g_malloc0(sizeof(QEMUTimer));
 332     ts->clock = clock;
 333     ts->cb = cb;
 334     ts->opaque = opaque;
 335     ts->scale = scale;
 336     return ts;
 337 }
 338
 339 void qemu_free_timer(QEMUTimer *ts)
 340 {
 341     g_free(ts);
 342 }
 343
 344 /* stop a timer, but do not dealloc it */
 345 void qemu_del_timer(QEMUTimer *ts)
 346 {
 347     QEMUTimer **pt, *t;
 348
 349     /* NOTE: this code must be signal safe because
 350        timer_expired() can be called from a signal. */
 351     pt = &ts->clock->active_timers;
 352     for(;;) {
 353         t = *pt;
 354         if (!t)
 355             break;
 356         if (t == ts) {
 357             *pt = t->next;
 358             break;
 359         }
 360         pt = &t->next;
 361     }
 362 }
 363
 364 /* modify the current timer so that it will be fired when current_time
 365    >= expire_time. The corresponding callback will be called. */
 366 void qemu_mod_timer_ns(QEMUTimer *ts, int64_t expire_time)
 367 {
 368     QEMUTimer **pt, *t;
 369
 370     qemu_del_timer(ts);
 371
 372     /* add the timer in the sorted list */
 373     /* NOTE: this code must be signal safe because
 374        timer_expired() can be called from a signal. */
 375     pt = &ts->clock->active_timers;
 376     for(;;) {
 377         t = *pt;
 378         if (!timer_expired_ns(t, expire_time)) {
 379             break;
 380         }
 381         pt = &t->next;
 382     }
 383     ts->expire_time = expire_time;
 384     ts->next = *pt;
 385     *pt = ts;
 386
 387     /* Rearm if necessary  */
 388     if (pt == &ts->clock->active_timers) {
 389         if (!alarm_timer->pending) {
 390             qemu_rearm_alarm_timer(alarm_timer);
 391         }
 392         /* Interrupt execution to force deadline recalculation.  */
 393         qemu_clock_warp(ts->clock);
 394         if (use_icount) {
 395             qemu_notify_event();
 396         }
 397     }
 398 }
 399
 400 void qemu_mod_timer(QEMUTimer *ts, int64_t expire_time)
 401 {
 402     qemu_mod_timer_ns(ts, expire_time * ts->scale);
 403 }
 404
 405 bool timer_pending(QEMUTimer *ts)
 406 {
 407     QEMUTimer *t;
 408     for (t = ts->clock->active_timers; t != NULL; t = t->next) {
 409         if (t == ts) {
 410             return true;
 411         }
 412     }
 413     return false;
 414 }
 415
 416 bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
 417 {
 418     return timer_expired_ns(timer_head, current_time * timer_head->scale);
 419 }
 420
 421 void qemu_run_timers(QEMUClock *clock)
 422 {
 423     QEMUTimer *ts;
 424     int64_t current_time;
 425
 426     if (!clock->enabled)
 427         return;
 428
 429     current_time = qemu_get_clock_ns(clock);
 430     for(;;) {
 431         ts = clock->active_timers;
 432         if (!timer_expired_ns(ts, current_time)) {
 433             break;
 434         }
 435         /* remove timer from the list before calling the callback */
 436         clock->active_timers = ts->next;
 437         ts->next = NULL;
 438
 439         /* run the callback (the timer list can be modified) */
 440         ts->cb(ts->opaque);
 441     }
 442 }
 443
 444 int64_t qemu_get_clock_ns(QEMUClock *clock)
 445 {
 446     int64_t now, last;
 447
 448     switch(clock->type) {
 449     case QEMU_CLOCK_REALTIME:
 450         return get_clock();
 451     default:
 452     case QEMU_CLOCK_VIRTUAL:
 453         if (use_icount) {
 454             return cpu_get_icount();
 455         } else {
 456             return cpu_get_clock();
 457         }
 458     case QEMU_CLOCK_HOST:
 459         now = get_clock_realtime();
 460         last = clock->last;
 461         clock->last = now;
 462         if (now < last) {
 463             notifier_list_notify(&clock->reset_notifiers, &now);
 464         }
 465         return now;
 466     }
 467 }
 468
 469 void qemu_register_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
 470 {
 471     notifier_list_add(&clock->reset_notifiers, notifier);
 472 }
 473
 474 void qemu_unregister_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
 475 {
 476     notifier_remove(notifier);
 477 }
 478
 479 void init_clocks(void)
 480 {
 481     if (!rt_clock) {
 482         rt_clock = qemu_clock_new(QEMU_CLOCK_REALTIME);
 483         vm_clock = qemu_clock_new(QEMU_CLOCK_VIRTUAL);
 484         host_clock = qemu_clock_new(QEMU_CLOCK_HOST);
 485     }
 486 }
 487
 488 uint64_t timer_expire_time_ns(QEMUTimer *ts)
 489 {
 490     return timer_pending(ts) ? ts->expire_time : -1;
 491 }
 492
 493 void qemu_run_all_timers(void)
 494 {
 495     alarm_timer->pending = false;
 496
 497     /* vm time timers */
 498     qemu_run_timers(vm_clock);
 499     qemu_run_timers(rt_clock);
 500     qemu_run_timers(host_clock);
 501
 502     /* rearm timer, if not periodic */
 503     if (alarm_timer->expired) {
 504         alarm_timer->expired = false;
 505         qemu_rearm_alarm_timer(alarm_timer);
 506     }
 507 }
 508
 509 #ifdef _WIN32
 510 static void CALLBACK host_alarm_handler(PVOID lpParam, BOOLEAN unused)
 511 #else
 512 static void host_alarm_handler(int host_signum)
 513 #endif
 514 {
 515     struct qemu_alarm_timer *t = alarm_timer;
 516     if (!t)
 517         return;
 518
 519     t->expired = true;
 520     t->pending = true;
 521     qemu_notify_event();
 522 }
 523
 524 #if defined(__linux__)
 525
 526 #include "qemu/compatfd.h"
 527
 528 static int dynticks_start_timer(struct qemu_alarm_timer *t)
 529 {
 530     struct sigevent ev;
 531     timer_t host_timer;
 532     struct sigaction act;
 533
 534     sigfillset(&act.sa_mask);
 535     act.sa_flags = 0;
 536     act.sa_handler = host_alarm_handler;
 537
 538     sigaction(SIGALRM, &act, NULL);
 539
 540     /*
 541      * Initialize ev struct to 0 to avoid valgrind complaining
 542      * about uninitialized data in timer_create call
 543      */
 544     memset(&ev, 0, sizeof(ev));
 545     ev.sigev_value.sival_int = 0;
 546     ev.sigev_notify = SIGEV_SIGNAL;
 547 #ifdef CONFIG_SIGEV_THREAD_ID
 548     if (qemu_signalfd_available()) {
 549         ev.sigev_notify = SIGEV_THREAD_ID;
 550         ev._sigev_un._tid = qemu_get_thread_id();
 551     }
 552 #endif /* CONFIG_SIGEV_THREAD_ID */
 553     ev.sigev_signo = SIGALRM;
 554
 555     if (timer_create(CLOCK_REALTIME, &ev, &host_timer)) {
 556         perror("timer_create");
 557         return -1;
 558     }
 559
 560     t->timer = host_timer;
 561
 562     return 0;
 563 }
 564
 565 static void dynticks_stop_timer(struct qemu_alarm_timer *t)
 566 {
 567     timer_t host_timer = t->timer;
 568
 569     timer_delete(host_timer);
 570 }
 571
 572 static void dynticks_rearm_timer(struct qemu_alarm_timer *t,
 573                                  int64_t nearest_delta_ns)
 574 {
 575     timer_t host_timer = t->timer;
 576     struct itimerspec timeout;
 577     int64_t current_ns;
 578
 579     if (nearest_delta_ns < MIN_TIMER_REARM_NS)
 580         nearest_delta_ns = MIN_TIMER_REARM_NS;
 581
 582     /* check whether a timer is already running */
 583     if (timer_gettime(host_timer, &timeout)) {
 584         perror("gettime");
 585         fprintf(stderr, "Internal timer error: aborting\n");
 586         exit(1);
 587     }
 588     current_ns = timeout.it_value.tv_sec * 1000000000LL + timeout.it_value.tv_nsec;
 589     if (current_ns && current_ns <= nearest_delta_ns)
 590         return;
 591
 592     timeout.it_interval.tv_sec = 0;
 593     timeout.it_interval.tv_nsec = 0; /* 0 for one-shot timer */
 594     timeout.it_value.tv_sec =  nearest_delta_ns / 1000000000;
 595     timeout.it_value.tv_nsec = nearest_delta_ns % 1000000000;
 596     if (timer_settime(host_timer, 0 /* RELATIVE */, &timeout, NULL)) {
 597         perror("settime");
 598         fprintf(stderr, "Internal timer error: aborting\n");
 599         exit(1);
 600     }
 601 }
 602
 603 #endif /* defined(__linux__) */
 604
 605 #if !defined(_WIN32)
 606
 607 static int unix_start_timer(struct qemu_alarm_timer *t)
 608 {
 609     struct sigaction act;
 610
 611     /* timer signal */
 612     sigfillset(&act.sa_mask);
 613     act.sa_flags = 0;
 614     act.sa_handler = host_alarm_handler;
 615
 616     sigaction(SIGALRM, &act, NULL);
 617     return 0;
 618 }
 619
 620 static void unix_rearm_timer(struct qemu_alarm_timer *t,
 621                              int64_t nearest_delta_ns)
 622 {
 623     struct itimerval itv;
 624     int err;
 625
 626     if (nearest_delta_ns < MIN_TIMER_REARM_NS)
 627         nearest_delta_ns = MIN_TIMER_REARM_NS;
 628
 629     itv.it_interval.tv_sec = 0;
 630     itv.it_interval.tv_usec = 0; /* 0 for one-shot timer */
 631     itv.it_value.tv_sec =  nearest_delta_ns / 1000000000;
 632     itv.it_value.tv_usec = (nearest_delta_ns % 1000000000) / 1000;
 633     err = setitimer(ITIMER_REAL, &itv, NULL);
 634     if (err) {
 635         perror("setitimer");
 636         fprintf(stderr, "Internal timer error: aborting\n");
 637         exit(1);
 638     }
 639 }
 640
 641 static void unix_stop_timer(struct qemu_alarm_timer *t)
 642 {
 643     struct itimerval itv;
 644
 645     memset(&itv, 0, sizeof(itv));
 646     setitimer(ITIMER_REAL, &itv, NULL);
 647 }
 648
 649 #endif /* !defined(_WIN32) */
 650
 651
 652 #ifdef _WIN32
 653
 654 static MMRESULT mm_timer;
 655 static TIMECAPS mm_tc;
 656
 657 static void CALLBACK mm_alarm_handler(UINT uTimerID, UINT uMsg,
 658                                       DWORD_PTR dwUser, DWORD_PTR dw1,
 659                                       DWORD_PTR dw2)
 660 {
 661     struct qemu_alarm_timer *t = alarm_timer;
 662     if (!t) {
 663         return;
 664     }
 665     t->expired = true;
 666     t->pending = true;
 667     qemu_notify_event();
 668 }
 669
 670 static int mm_start_timer(struct qemu_alarm_timer *t)
 671 {
 672     timeGetDevCaps(&mm_tc, sizeof(mm_tc));
 673     return 0;
 674 }
 675
 676 static void mm_stop_timer(struct qemu_alarm_timer *t)
 677 {
 678     if (mm_timer) {
 679         timeKillEvent(mm_timer);
 680     }
 681 }
 682
 683 static void mm_rearm_timer(struct qemu_alarm_timer *t, int64_t delta)
 684 {
 685     int64_t nearest_delta_ms = delta / 1000000;
 686     if (nearest_delta_ms < mm_tc.wPeriodMin) {
 687         nearest_delta_ms = mm_tc.wPeriodMin;
 688     } else if (nearest_delta_ms > mm_tc.wPeriodMax) {
 689         nearest_delta_ms = mm_tc.wPeriodMax;
 690     }
 691
 692     if (mm_timer) {
 693         timeKillEvent(mm_timer);
 694     }
 695     mm_timer = timeSetEvent((UINT)nearest_delta_ms,
 696                             mm_tc.wPeriodMin,
 697                             mm_alarm_handler,
 698                             (DWORD_PTR)t,
 699                             TIME_ONESHOT | TIME_CALLBACK_FUNCTION);
 700
 701     if (!mm_timer) {
 702         fprintf(stderr, "Failed to re-arm win32 alarm timer\n");
 703         timeEndPeriod(mm_tc.wPeriodMin);
 704         exit(1);
 705     }
 706 }
 707
 708 static int win32_start_timer(struct qemu_alarm_timer *t)
 709 {
 710     HANDLE hTimer;
 711     BOOLEAN success;
 712
 713     /* If you call ChangeTimerQueueTimer on a one-shot timer (its period
 714        is zero) that has already expired, the timer is not updated.  Since
 715        creating a new timer is relatively expensive, set a bogus one-hour
 716        interval in the dynticks case.  */
 717     success = CreateTimerQueueTimer(&hTimer,
 718                           NULL,
 719                           host_alarm_handler,
 720                           t,
 721                           1,
 722                           3600000,
 723                           WT_EXECUTEINTIMERTHREAD);
 724
 725     if (!success) {
 726         fprintf(stderr, "Failed to initialize win32 alarm timer: %ld\n",
 727                 GetLastError());
 728         return -1;
 729     }
 730
 731     t->timer = hTimer;
 732     return 0;
 733 }
 734
 735 static void win32_stop_timer(struct qemu_alarm_timer *t)
 736 {
 737     HANDLE hTimer = t->timer;
 738
 739     if (hTimer) {
 740         DeleteTimerQueueTimer(NULL, hTimer, NULL);
 741     }
 742 }
 743
 744 static void win32_rearm_timer(struct qemu_alarm_timer *t,
 745                               int64_t nearest_delta_ns)
 746 {
 747     HANDLE hTimer = t->timer;
 748     int64_t nearest_delta_ms;
 749     BOOLEAN success;
 750
 751     nearest_delta_ms = nearest_delta_ns / 1000000;
 752     if (nearest_delta_ms < 1) {
 753         nearest_delta_ms = 1;
 754     }
 755     /* ULONG_MAX can be 32 bit */
 756     if (nearest_delta_ms > ULONG_MAX) {
 757         nearest_delta_ms = ULONG_MAX;
 758     }
 759     success = ChangeTimerQueueTimer(NULL,
 760                                     hTimer,
 761                                     (unsigned long) nearest_delta_ms,
 762                                     3600000);
 763
 764     if (!success) {
 765         fprintf(stderr, "Failed to rearm win32 alarm timer: %ld\n",
 766                 GetLastError());
 767         exit(-1);
 768     }
 769
 770 }
 771
 772 #endif /* _WIN32 */
 773
 774 static void quit_timers(void)
 775 {
 776     struct qemu_alarm_timer *t = alarm_timer;
 777     alarm_timer = NULL;
 778     t->stop(t);
 779 }
 780
 781 #ifdef CONFIG_POSIX
 782 static void reinit_timers(void)
 783 {
 784     struct qemu_alarm_timer *t = alarm_timer;
 785     t->stop(t);
 786     if (t->start(t)) {
 787         fprintf(stderr, "Internal timer error: aborting\n");
 788         exit(1);
 789     }
 790     qemu_rearm_alarm_timer(t);
 791 }
 792 #endif /* CONFIG_POSIX */
 793
 794 int init_timer_alarm(void)
 795 {
 796     struct qemu_alarm_timer *t = NULL;
 797     int i, err = -1;
 798
 799     if (alarm_timer) {
 800         return 0;
 801     }
 802
 803     for (i = 0; alarm_timers[i].name; i++) {
 804         t = &alarm_timers[i];
 805
 806         err = t->start(t);
 807         if (!err)
 808             break;
 809     }
 810
 811     if (err) {
 812         err = -ENOENT;
 813         goto fail;
 814     }
 815
 816     atexit(quit_timers);
 817 #ifdef CONFIG_POSIX
 818     pthread_atfork(NULL, NULL, reinit_timers);
 819 #endif
 820     alarm_timer = t;
 821     return 0;
 822
 823 fail:
 824     return err;
 825 }
 826