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.h"
  26 #include "net.h"
  27 #include "monitor.h"
  28 #include "console.h"
  29
  30 #include "hw/hw.h"
  31
  32 #include <unistd.h>
  33 #include <fcntl.h>
  34 #include <time.h>
  35 #include <errno.h>
  36 #include <sys/time.h>
  37 #include <signal.h>
  38 #ifdef __FreeBSD__
  39 #include <sys/param.h>
  40 #endif
  41
  42 #ifdef _WIN32
  43 #include <windows.h>
  44 #include <mmsystem.h>
  45 #endif
  46
  47 #include "qemu-timer.h"
  48
  49 /***********************************************************/
  50 /* timers */
  51
  52 #define QEMU_CLOCK_REALTIME 0
  53 #define QEMU_CLOCK_VIRTUAL  1
  54 #define QEMU_CLOCK_HOST     2
  55
  56 struct QEMUClock {
  57     int type;
  58     int enabled;
  59
  60     QEMUTimer *active_timers;
  61
  62     NotifierList reset_notifiers;
  63     int64_t last;
  64 };
  65
  66 struct QEMUTimer {
  67     QEMUClock *clock;
  68     int64_t expire_time;        /* in nanoseconds */
  69     int scale;
  70     QEMUTimerCB *cb;
  71     void *opaque;
  72     struct QEMUTimer *next;
  73 };
  74
  75 struct qemu_alarm_timer {
  76     char const *name;
  77     int (*start)(struct qemu_alarm_timer *t);
  78     void (*stop)(struct qemu_alarm_timer *t);
  79     void (*rearm)(struct qemu_alarm_timer *t, int64_t nearest_delta_ns);
  80 #if defined(__linux__)
  81     int fd;
  82     timer_t timer;
  83 #elif defined(_WIN32)
  84     HANDLE timer;
  85 #endif
  86     char expired;
  87     char pending;
  88 };
  89
  90 static struct qemu_alarm_timer *alarm_timer;
  91
  92 static bool qemu_timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
  93 {
  94     return timer_head && (timer_head->expire_time <= current_time);
  95 }
  96
  97 int qemu_alarm_pending(void)
  98 {
  99     return alarm_timer->pending;
 100 }
 101
 102 static inline int alarm_has_dynticks(struct qemu_alarm_timer *t)
 103 {
 104     return !!t->rearm;
 105 }
 106
 107 static int64_t qemu_next_alarm_deadline(void)
 108 {
 109     int64_t delta;
 110     int64_t rtdelta;
 111
 112     if (!use_icount && vm_clock->active_timers) {
 113         delta = vm_clock->active_timers->expire_time -
 114                      qemu_get_clock_ns(vm_clock);
 115     } else {
 116         delta = INT32_MAX;
 117     }
 118     if (host_clock->active_timers) {
 119         int64_t hdelta = host_clock->active_timers->expire_time -
 120                  qemu_get_clock_ns(host_clock);
 121         if (hdelta < delta) {
 122             delta = hdelta;
 123         }
 124     }
 125     if (rt_clock->active_timers) {
 126         rtdelta = (rt_clock->active_timers->expire_time -
 127                  qemu_get_clock_ns(rt_clock));
 128         if (rtdelta < delta) {
 129             delta = rtdelta;
 130         }
 131     }
 132
 133     return delta;
 134 }
 135
 136 static void qemu_rearm_alarm_timer(struct qemu_alarm_timer *t)
 137 {
 138     int64_t nearest_delta_ns;
 139     assert(alarm_has_dynticks(t));
 140     if (!rt_clock->active_timers &&
 141         !vm_clock->active_timers &&
 142         !host_clock->active_timers) {
 143         return;
 144     }
 145     nearest_delta_ns = qemu_next_alarm_deadline();
 146     t->rearm(t, nearest_delta_ns);
 147 }
 148
 149 /* TODO: MIN_TIMER_REARM_NS should be optimized */
 150 #define MIN_TIMER_REARM_NS 250000
 151
 152 #ifdef _WIN32
 153
 154 static int mm_start_timer(struct qemu_alarm_timer *t);
 155 static void mm_stop_timer(struct qemu_alarm_timer *t);
 156 static void mm_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 157
 158 static int win32_start_timer(struct qemu_alarm_timer *t);
 159 static void win32_stop_timer(struct qemu_alarm_timer *t);
 160 static void win32_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 161
 162 #else
 163
 164 static int unix_start_timer(struct qemu_alarm_timer *t);
 165 static void unix_stop_timer(struct qemu_alarm_timer *t);
 166 static void unix_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 167
 168 #ifdef __linux__
 169
 170 static int dynticks_start_timer(struct qemu_alarm_timer *t);
 171 static void dynticks_stop_timer(struct qemu_alarm_timer *t);
 172 static void dynticks_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 173
 174 #endif /* __linux__ */
 175
 176 #endif /* _WIN32 */
 177
 178 static struct qemu_alarm_timer alarm_timers[] = {
 179 #ifndef _WIN32
 180 #ifdef __linux__
 181     {"dynticks", dynticks_start_timer,
 182      dynticks_stop_timer, dynticks_rearm_timer},
 183 #endif
 184     {"unix", unix_start_timer, unix_stop_timer, unix_rearm_timer},
 185 #else
 186     {"mmtimer", mm_start_timer, mm_stop_timer, NULL},
 187     {"mmtimer2", mm_start_timer, mm_stop_timer, mm_rearm_timer},
 188     {"dynticks", win32_start_timer, win32_stop_timer, win32_rearm_timer},
 189     {"win32", win32_start_timer, win32_stop_timer, NULL},
 190 #endif
 191     {NULL, }
 192 };
 193
 194 static void show_available_alarms(void)
 195 {
 196     int i;
 197
 198     printf("Available alarm timers, in order of precedence:\n");
 199     for (i = 0; alarm_timers[i].name; i++)
 200         printf("%s\n", alarm_timers[i].name);
 201 }
 202
 203 void configure_alarms(char const *opt)
 204 {
 205     int i;
 206     int cur = 0;
 207     int count = ARRAY_SIZE(alarm_timers) - 1;
 208     char *arg;
 209     char *name;
 210     struct qemu_alarm_timer tmp;
 211
 212     if (!strcmp(opt, "?")) {
 213         show_available_alarms();
 214         exit(0);
 215     }
 216
 217     arg = g_strdup(opt);
 218
 219     /* Reorder the array */
 220     name = strtok(arg, ",");
 221     while (name) {
 222         for (i = 0; i < count && alarm_timers[i].name; i++) {
 223             if (!strcmp(alarm_timers[i].name, name))
 224                 break;
 225         }
 226
 227         if (i == count) {
 228             fprintf(stderr, "Unknown clock %s\n", name);
 229             goto next;
 230         }
 231
 232         if (i < cur)
 233             /* Ignore */
 234             goto next;
 235
 236         /* Swap */
 237         tmp = alarm_timers[i];
 238         alarm_timers[i] = alarm_timers[cur];
 239         alarm_timers[cur] = tmp;
 240
 241         cur++;
 242 next:
 243         name = strtok(NULL, ",");
 244     }
 245
 246     g_free(arg);
 247
 248     if (cur) {
 249         /* Disable remaining timers */
 250         for (i = cur; i < count; i++)
 251             alarm_timers[i].name = NULL;
 252     } else {
 253         show_available_alarms();
 254         exit(1);
 255     }
 256 }
 257
 258 QEMUClock *rt_clock;
 259 QEMUClock *vm_clock;
 260 QEMUClock *host_clock;
 261
 262 static QEMUClock *qemu_new_clock(int type)
 263 {
 264     QEMUClock *clock;
 265
 266     clock = g_malloc0(sizeof(QEMUClock));
 267     clock->type = type;
 268     clock->enabled = 1;
 269     notifier_list_init(&clock->reset_notifiers);
 270     /* required to detect & report backward jumps */
 271     if (type == QEMU_CLOCK_HOST) {
 272         clock->last = get_clock_realtime();
 273     }
 274     return clock;
 275 }
 276
 277 void qemu_clock_enable(QEMUClock *clock, int enabled)
 278 {
 279     clock->enabled = enabled;
 280 }
 281
 282 int64_t qemu_clock_has_timers(QEMUClock *clock)
 283 {
 284     return !!clock->active_timers;
 285 }
 286
 287 int64_t qemu_clock_expired(QEMUClock *clock)
 288 {
 289     return (clock->active_timers &&
 290             clock->active_timers->expire_time < qemu_get_clock_ns(clock));
 291 }
 292
 293 int64_t qemu_clock_deadline(QEMUClock *clock)
 294 {
 295     /* To avoid problems with overflow limit this to 2^32.  */
 296     int64_t delta = INT32_MAX;
 297
 298     if (clock->active_timers) {
 299         delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock);
 300     }
 301     if (delta < 0) {
 302         delta = 0;
 303     }
 304     return delta;
 305 }
 306
 307 QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
 308                           QEMUTimerCB *cb, void *opaque)
 309 {
 310     QEMUTimer *ts;
 311
 312     ts = g_malloc0(sizeof(QEMUTimer));
 313     ts->clock = clock;
 314     ts->cb = cb;
 315     ts->opaque = opaque;
 316     ts->scale = scale;
 317     return ts;
 318 }
 319
 320 void qemu_free_timer(QEMUTimer *ts)
 321 {
 322     g_free(ts);
 323 }
 324
 325 /* stop a timer, but do not dealloc it */
 326 void qemu_del_timer(QEMUTimer *ts)
 327 {
 328     QEMUTimer **pt, *t;
 329
 330     /* NOTE: this code must be signal safe because
 331        qemu_timer_expired() can be called from a signal. */
 332     pt = &ts->clock->active_timers;
 333     for(;;) {
 334         t = *pt;
 335         if (!t)
 336             break;
 337         if (t == ts) {
 338             *pt = t->next;
 339             break;
 340         }
 341         pt = &t->next;
 342     }
 343 }
 344
 345 /* modify the current timer so that it will be fired when current_time
 346    >= expire_time. The corresponding callback will be called. */
 347 static void qemu_mod_timer_ns(QEMUTimer *ts, int64_t expire_time)
 348 {
 349     QEMUTimer **pt, *t;
 350
 351     qemu_del_timer(ts);
 352
 353     /* add the timer in the sorted list */
 354     /* NOTE: this code must be signal safe because
 355        qemu_timer_expired() can be called from a signal. */
 356     pt = &ts->clock->active_timers;
 357     for(;;) {
 358         t = *pt;
 359         if (!qemu_timer_expired_ns(t, expire_time)) {
 360             break;
 361         }
 362         pt = &t->next;
 363     }
 364     ts->expire_time = expire_time;
 365     ts->next = *pt;
 366     *pt = ts;
 367
 368     /* Rearm if necessary  */
 369     if (pt == &ts->clock->active_timers) {
 370         if (!alarm_timer->pending) {
 371             qemu_rearm_alarm_timer(alarm_timer);
 372         }
 373         /* Interrupt execution to force deadline recalculation.  */
 374         qemu_clock_warp(ts->clock);
 375         if (use_icount) {
 376             qemu_notify_event();
 377         }
 378     }
 379 }
 380
 381 /* modify the current timer so that it will be fired when current_time
 382    >= expire_time. The corresponding callback will be called. */
 383 void qemu_mod_timer(QEMUTimer *ts, int64_t expire_time)
 384 {
 385     qemu_mod_timer_ns(ts, expire_time * ts->scale);
 386 }
 387
 388 int qemu_timer_pending(QEMUTimer *ts)
 389 {
 390     QEMUTimer *t;
 391     for (t = ts->clock->active_timers; t != NULL; t = t->next) {
 392         if (t == ts)
 393             return 1;
 394     }
 395     return 0;
 396 }
 397
 398 int qemu_timer_expired(QEMUTimer *timer_head, int64_t current_time)
 399 {
 400     return qemu_timer_expired_ns(timer_head, current_time * timer_head->scale);
 401 }
 402
 403 static void qemu_run_timers(QEMUClock *clock)
 404 {
 405     QEMUTimer **ptimer_head, *ts;
 406     int64_t current_time;
 407
 408     if (!clock->enabled)
 409         return;
 410
 411     current_time = qemu_get_clock_ns(clock);
 412     ptimer_head = &clock->active_timers;
 413     for(;;) {
 414         ts = *ptimer_head;
 415         if (!qemu_timer_expired_ns(ts, current_time)) {
 416             break;
 417         }
 418         /* remove timer from the list before calling the callback */
 419         *ptimer_head = ts->next;
 420         ts->next = NULL;
 421
 422         /* run the callback (the timer list can be modified) */
 423         ts->cb(ts->opaque);
 424     }
 425 }
 426
 427 int64_t qemu_get_clock_ns(QEMUClock *clock)
 428 {
 429     int64_t now, last;
 430
 431     switch(clock->type) {
 432     case QEMU_CLOCK_REALTIME:
 433         return get_clock();
 434     default:
 435     case QEMU_CLOCK_VIRTUAL:
 436         if (use_icount) {
 437             return cpu_get_icount();
 438         } else {
 439             return cpu_get_clock();
 440         }
 441     case QEMU_CLOCK_HOST:
 442         now = get_clock_realtime();
 443         last = clock->last;
 444         clock->last = now;
 445         if (now < last) {
 446             notifier_list_notify(&clock->reset_notifiers, &now);
 447         }
 448         return now;
 449     }
 450 }
 451
 452 void qemu_register_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
 453 {
 454     notifier_list_add(&clock->reset_notifiers, notifier);
 455 }
 456
 457 void qemu_unregister_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
 458 {
 459     notifier_list_remove(&clock->reset_notifiers, notifier);
 460 }
 461
 462 void init_clocks(void)
 463 {
 464     rt_clock = qemu_new_clock(QEMU_CLOCK_REALTIME);
 465     vm_clock = qemu_new_clock(QEMU_CLOCK_VIRTUAL);
 466     host_clock = qemu_new_clock(QEMU_CLOCK_HOST);
 467
 468     rtc_clock = host_clock;
 469 }
 470
 471 /* save a timer */
 472 void qemu_put_timer(QEMUFile *f, QEMUTimer *ts)
 473 {
 474     uint64_t expire_time;
 475
 476     if (qemu_timer_pending(ts)) {
 477         expire_time = ts->expire_time;
 478     } else {
 479         expire_time = -1;
 480     }
 481     qemu_put_be64(f, expire_time);
 482 }
 483
 484 void qemu_get_timer(QEMUFile *f, QEMUTimer *ts)
 485 {
 486     uint64_t expire_time;
 487
 488     expire_time = qemu_get_be64(f);
 489     if (expire_time != -1) {
 490         qemu_mod_timer_ns(ts, expire_time);
 491     } else {
 492         qemu_del_timer(ts);
 493     }
 494 }
 495
 496 void qemu_run_all_timers(void)
 497 {
 498     alarm_timer->pending = 0;
 499
 500     /* rearm timer, if not periodic */
 501     if (alarm_timer->expired) {
 502         alarm_timer->expired = 0;
 503         qemu_rearm_alarm_timer(alarm_timer);
 504     }
 505
 506     /* vm time timers */
 507     qemu_run_timers(vm_clock);
 508     qemu_run_timers(rt_clock);
 509     qemu_run_timers(host_clock);
 510 }
 511
 512 #ifdef _WIN32
 513 static void CALLBACK host_alarm_handler(PVOID lpParam, BOOLEAN unused)
 514 #else
 515 static void host_alarm_handler(int host_signum)
 516 #endif
 517 {
 518     struct qemu_alarm_timer *t = alarm_timer;
 519     if (!t)
 520         return;
 521
 522 #if 0
 523 #define DISP_FREQ 1000
 524     {
 525         static int64_t delta_min = INT64_MAX;
 526         static int64_t delta_max, delta_cum, last_clock, delta, ti;
 527         static int count;
 528         ti = qemu_get_clock_ns(vm_clock);
 529         if (last_clock != 0) {
 530             delta = ti - last_clock;
 531             if (delta < delta_min)
 532                 delta_min = delta;
 533             if (delta > delta_max)
 534                 delta_max = delta;
 535             delta_cum += delta;
 536             if (++count == DISP_FREQ) {
 537                 printf("timer: min=%" PRId64 " us max=%" PRId64 " us avg=%" PRId64 " us avg_freq=%0.3f Hz\n",
 538                        muldiv64(delta_min, 1000000, get_ticks_per_sec()),
 539                        muldiv64(delta_max, 1000000, get_ticks_per_sec()),
 540                        muldiv64(delta_cum, 1000000 / DISP_FREQ, get_ticks_per_sec()),
 541                        (double)get_ticks_per_sec() / ((double)delta_cum / DISP_FREQ));
 542                 count = 0;
 543                 delta_min = INT64_MAX;
 544                 delta_max = 0;
 545                 delta_cum = 0;
 546             }
 547         }
 548         last_clock = ti;
 549     }
 550 #endif
 551     if (alarm_has_dynticks(t) ||
 552         qemu_next_alarm_deadline () <= 0) {
 553         t->expired = alarm_has_dynticks(t);
 554         t->pending = 1;
 555         qemu_notify_event();
 556     }
 557 }
 558
 559 #if defined(__linux__)
 560
 561 #include "compatfd.h"
 562
 563 static int dynticks_start_timer(struct qemu_alarm_timer *t)
 564 {
 565     struct sigevent ev;
 566     timer_t host_timer;
 567     struct sigaction act;
 568
 569     sigfillset(&act.sa_mask);
 570     act.sa_flags = 0;
 571     act.sa_handler = host_alarm_handler;
 572
 573     sigaction(SIGALRM, &act, NULL);
 574
 575     /*
 576      * Initialize ev struct to 0 to avoid valgrind complaining
 577      * about uninitialized data in timer_create call
 578      */
 579     memset(&ev, 0, sizeof(ev));
 580     ev.sigev_value.sival_int = 0;
 581     ev.sigev_notify = SIGEV_SIGNAL;
 582 #ifdef SIGEV_THREAD_ID
 583     if (qemu_signalfd_available()) {
 584         ev.sigev_notify = SIGEV_THREAD_ID;
 585         ev._sigev_un._tid = qemu_get_thread_id();
 586     }
 587 #endif /* SIGEV_THREAD_ID */
 588     ev.sigev_signo = SIGALRM;
 589
 590     if (timer_create(CLOCK_REALTIME, &ev, &host_timer)) {
 591         perror("timer_create");
 592
 593         /* disable dynticks */
 594         fprintf(stderr, "Dynamic Ticks disabled\n");
 595
 596         return -1;
 597     }
 598
 599     t->timer = host_timer;
 600
 601     return 0;
 602 }
 603
 604 static void dynticks_stop_timer(struct qemu_alarm_timer *t)
 605 {
 606     timer_t host_timer = t->timer;
 607
 608     timer_delete(host_timer);
 609 }
 610
 611 static void dynticks_rearm_timer(struct qemu_alarm_timer *t,
 612                                  int64_t nearest_delta_ns)
 613 {
 614     timer_t host_timer = t->timer;
 615     struct itimerspec timeout;
 616     int64_t current_ns;
 617
 618     if (nearest_delta_ns < MIN_TIMER_REARM_NS)
 619         nearest_delta_ns = MIN_TIMER_REARM_NS;
 620
 621     /* check whether a timer is already running */
 622     if (timer_gettime(host_timer, &timeout)) {
 623         perror("gettime");
 624         fprintf(stderr, "Internal timer error: aborting\n");
 625         exit(1);
 626     }
 627     current_ns = timeout.it_value.tv_sec * 1000000000LL + timeout.it_value.tv_nsec;
 628     if (current_ns && current_ns <= nearest_delta_ns)
 629         return;
 630
 631     timeout.it_interval.tv_sec = 0;
 632     timeout.it_interval.tv_nsec = 0; /* 0 for one-shot timer */
 633     timeout.it_value.tv_sec =  nearest_delta_ns / 1000000000;
 634     timeout.it_value.tv_nsec = nearest_delta_ns % 1000000000;
 635     if (timer_settime(host_timer, 0 /* RELATIVE */, &timeout, NULL)) {
 636         perror("settime");
 637         fprintf(stderr, "Internal timer error: aborting\n");
 638         exit(1);
 639     }
 640 }
 641
 642 #endif /* defined(__linux__) */
 643
 644 #if !defined(_WIN32)
 645
 646 static int unix_start_timer(struct qemu_alarm_timer *t)
 647 {
 648     struct sigaction act;
 649
 650     /* timer signal */
 651     sigfillset(&act.sa_mask);
 652     act.sa_flags = 0;
 653     act.sa_handler = host_alarm_handler;
 654
 655     sigaction(SIGALRM, &act, NULL);
 656     return 0;
 657 }
 658
 659 static void unix_rearm_timer(struct qemu_alarm_timer *t,
 660                              int64_t nearest_delta_ns)
 661 {
 662     struct itimerval itv;
 663     int err;
 664
 665     if (nearest_delta_ns < MIN_TIMER_REARM_NS)
 666         nearest_delta_ns = MIN_TIMER_REARM_NS;
 667
 668     itv.it_interval.tv_sec = 0;
 669     itv.it_interval.tv_usec = 0; /* 0 for one-shot timer */
 670     itv.it_value.tv_sec =  nearest_delta_ns / 1000000000;
 671     itv.it_value.tv_usec = (nearest_delta_ns % 1000000000) / 1000;
 672     err = setitimer(ITIMER_REAL, &itv, NULL);
 673     if (err) {
 674         perror("setitimer");
 675         fprintf(stderr, "Internal timer error: aborting\n");
 676         exit(1);
 677     }
 678 }
 679
 680 static void unix_stop_timer(struct qemu_alarm_timer *t)
 681 {
 682     struct itimerval itv;
 683
 684     memset(&itv, 0, sizeof(itv));
 685     setitimer(ITIMER_REAL, &itv, NULL);
 686 }
 687
 688 #endif /* !defined(_WIN32) */
 689
 690
 691 #ifdef _WIN32
 692
 693 static MMRESULT mm_timer;
 694 static unsigned mm_period;
 695
 696 static void CALLBACK mm_alarm_handler(UINT uTimerID, UINT uMsg,
 697                                       DWORD_PTR dwUser, DWORD_PTR dw1,
 698                                       DWORD_PTR dw2)
 699 {
 700     struct qemu_alarm_timer *t = alarm_timer;
 701     if (!t) {
 702         return;
 703     }
 704     if (alarm_has_dynticks(t) || qemu_next_alarm_deadline() <= 0) {
 705         t->expired = alarm_has_dynticks(t);
 706         t->pending = 1;
 707         qemu_notify_event();
 708     }
 709 }
 710
 711 static int mm_start_timer(struct qemu_alarm_timer *t)
 712 {
 713     TIMECAPS tc;
 714     UINT flags;
 715
 716     memset(&tc, 0, sizeof(tc));
 717     timeGetDevCaps(&tc, sizeof(tc));
 718
 719     mm_period = tc.wPeriodMin;
 720     timeBeginPeriod(mm_period);
 721
 722     flags = TIME_CALLBACK_FUNCTION;
 723     if (alarm_has_dynticks(t)) {
 724         flags |= TIME_ONESHOT;
 725     } else {
 726         flags |= TIME_PERIODIC;
 727     }
 728
 729     mm_timer = timeSetEvent(1,                  /* interval (ms) */
 730                             mm_period,          /* resolution */
 731                             mm_alarm_handler,   /* function */
 732                             (DWORD_PTR)t,       /* parameter */
 733                             flags);
 734
 735     if (!mm_timer) {
 736         fprintf(stderr, "Failed to initialize win32 alarm timer: %ld\n",
 737                 GetLastError());
 738         timeEndPeriod(mm_period);
 739         return -1;
 740     }
 741
 742     return 0;
 743 }
 744
 745 static void mm_stop_timer(struct qemu_alarm_timer *t)
 746 {
 747     timeKillEvent(mm_timer);
 748     timeEndPeriod(mm_period);
 749 }
 750
 751 static void mm_rearm_timer(struct qemu_alarm_timer *t, int64_t delta)
 752 {
 753     int nearest_delta_ms = (delta + 999999) / 1000000;
 754     if (nearest_delta_ms < 1) {
 755         nearest_delta_ms = 1;
 756     }
 757
 758     timeKillEvent(mm_timer);
 759     mm_timer = timeSetEvent(nearest_delta_ms,
 760                             mm_period,
 761                             mm_alarm_handler,
 762                             (DWORD_PTR)t,
 763                             TIME_ONESHOT | TIME_CALLBACK_FUNCTION);
 764
 765     if (!mm_timer) {
 766         fprintf(stderr, "Failed to re-arm win32 alarm timer %ld\n",
 767                 GetLastError());
 768
 769         timeEndPeriod(mm_period);
 770         exit(1);
 771     }
 772 }
 773
 774 static int win32_start_timer(struct qemu_alarm_timer *t)
 775 {
 776     HANDLE hTimer;
 777     BOOLEAN success;
 778
 779     /* If you call ChangeTimerQueueTimer on a one-shot timer (its period
 780        is zero) that has already expired, the timer is not updated.  Since
 781        creating a new timer is relatively expensive, set a bogus one-hour
 782        interval in the dynticks case.  */
 783     success = CreateTimerQueueTimer(&hTimer,
 784                           NULL,
 785                           host_alarm_handler,
 786                           t,
 787                           1,
 788                           alarm_has_dynticks(t) ? 3600000 : 1,
 789                           WT_EXECUTEINTIMERTHREAD);
 790
 791     if (!success) {
 792         fprintf(stderr, "Failed to initialize win32 alarm timer: %ld\n",
 793                 GetLastError());
 794         return -1;
 795     }
 796
 797     t->timer = hTimer;
 798     return 0;
 799 }
 800
 801 static void win32_stop_timer(struct qemu_alarm_timer *t)
 802 {
 803     HANDLE hTimer = t->timer;
 804
 805     if (hTimer) {
 806         DeleteTimerQueueTimer(NULL, hTimer, NULL);
 807     }
 808 }
 809
 810 static void win32_rearm_timer(struct qemu_alarm_timer *t,
 811                               int64_t nearest_delta_ns)
 812 {
 813     HANDLE hTimer = t->timer;
 814     int nearest_delta_ms;
 815     BOOLEAN success;
 816
 817     nearest_delta_ms = (nearest_delta_ns + 999999) / 1000000;
 818     if (nearest_delta_ms < 1) {
 819         nearest_delta_ms = 1;
 820     }
 821     success = ChangeTimerQueueTimer(NULL,
 822                                     hTimer,
 823                                     nearest_delta_ms,
 824                                     3600000);
 825
 826     if (!success) {
 827         fprintf(stderr, "Failed to rearm win32 alarm timer: %ld\n",
 828                 GetLastError());
 829         exit(-1);
 830     }
 831
 832 }
 833
 834 #endif /* _WIN32 */
 835
 836 static void alarm_timer_on_change_state_rearm(void *opaque, int running,
 837                                               RunState state)
 838 {
 839     if (running)
 840         qemu_rearm_alarm_timer((struct qemu_alarm_timer *) opaque);
 841 }
 842
 843 int init_timer_alarm(void)
 844 {
 845     struct qemu_alarm_timer *t = NULL;
 846     int i, err = -1;
 847
 848     for (i = 0; alarm_timers[i].name; i++) {
 849         t = &alarm_timers[i];
 850
 851         err = t->start(t);
 852         if (!err)
 853             break;
 854     }
 855
 856     if (err) {
 857         err = -ENOENT;
 858         goto fail;
 859     }
 860
 861     /* first event is at time 0 */
 862     t->pending = 1;
 863     alarm_timer = t;
 864     qemu_add_vm_change_state_handler(alarm_timer_on_change_state_rearm, t);
 865
 866     return 0;
 867
 868 fail:
 869     return err;
 870 }
 871
 872 void quit_timers(void)
 873 {
 874     struct qemu_alarm_timer *t = alarm_timer;
 875     alarm_timer = NULL;
 876     t->stop(t);
 877 }
 878
 879 int qemu_calculate_timeout(void)
 880 {
 881     return 1000;
 882 }
 883