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 __linux__
  43 #include <sys/ioctl.h>
  44 #include <linux/rtc.h>
  45 /* For the benefit of older linux systems which don't supply it,
  46    we use a local copy of hpet.h. */
  47 /* #include <linux/hpet.h> */
  48 #include "hpet.h"
  49 #endif
  50
  51 #ifdef _WIN32
  52 #include <windows.h>
  53 #include <mmsystem.h>
  54 #endif
  55
  56 #include "qemu-timer.h"
  57
  58 /* Conversion factor from emulated instructions to virtual clock ticks.  */
  59 int icount_time_shift;
  60 /* Arbitrarily pick 1MIPS as the minimum allowable speed.  */
  61 #define MAX_ICOUNT_SHIFT 10
  62 /* Compensate for varying guest execution speed.  */
  63 int64_t qemu_icount_bias;
  64 static QEMUTimer *icount_rt_timer;
  65 static QEMUTimer *icount_vm_timer;
  66
  67 /***********************************************************/
  68 /* guest cycle counter */
  69
  70 typedef struct TimersState {
  71     int64_t cpu_ticks_prev;
  72     int64_t cpu_ticks_offset;
  73     int64_t cpu_clock_offset;
  74     int32_t cpu_ticks_enabled;
  75     int64_t dummy;
  76 } TimersState;
  77
  78 TimersState timers_state;
  79
  80 /* return the host CPU cycle counter and handle stop/restart */
  81 int64_t cpu_get_ticks(void)
  82 {
  83     if (use_icount) {
  84         return cpu_get_icount();
  85     }
  86     if (!timers_state.cpu_ticks_enabled) {
  87         return timers_state.cpu_ticks_offset;
  88     } else {
  89         int64_t ticks;
  90         ticks = cpu_get_real_ticks();
  91         if (timers_state.cpu_ticks_prev > ticks) {
  92             /* Note: non increasing ticks may happen if the host uses
  93                software suspend */
  94             timers_state.cpu_ticks_offset += timers_state.cpu_ticks_prev - ticks;
  95         }
  96         timers_state.cpu_ticks_prev = ticks;
  97         return ticks + timers_state.cpu_ticks_offset;
  98     }
  99 }
 100
 101 /* return the host CPU monotonic timer and handle stop/restart */
 102 static int64_t cpu_get_clock(void)
 103 {
 104     int64_t ti;
 105     if (!timers_state.cpu_ticks_enabled) {
 106         return timers_state.cpu_clock_offset;
 107     } else {
 108         ti = get_clock();
 109         return ti + timers_state.cpu_clock_offset;
 110     }
 111 }
 112
 113 static int64_t qemu_icount_delta(void)
 114 {
 115     if (!use_icount) {
 116         return 5000 * (int64_t) 1000000;
 117     } else if (use_icount == 1) {
 118         /* When not using an adaptive execution frequency
 119            we tend to get badly out of sync with real time,
 120            so just delay for a reasonable amount of time.  */
 121         return 0;
 122     } else {
 123         return cpu_get_icount() - cpu_get_clock();
 124     }
 125 }
 126
 127 /* enable cpu_get_ticks() */
 128 void cpu_enable_ticks(void)
 129 {
 130     if (!timers_state.cpu_ticks_enabled) {
 131         timers_state.cpu_ticks_offset -= cpu_get_real_ticks();
 132         timers_state.cpu_clock_offset -= get_clock();
 133         timers_state.cpu_ticks_enabled = 1;
 134     }
 135 }
 136
 137 /* disable cpu_get_ticks() : the clock is stopped. You must not call
 138    cpu_get_ticks() after that.  */
 139 void cpu_disable_ticks(void)
 140 {
 141     if (timers_state.cpu_ticks_enabled) {
 142         timers_state.cpu_ticks_offset = cpu_get_ticks();
 143         timers_state.cpu_clock_offset = cpu_get_clock();
 144         timers_state.cpu_ticks_enabled = 0;
 145     }
 146 }
 147
 148 /***********************************************************/
 149 /* timers */
 150
 151 #define QEMU_CLOCK_REALTIME 0
 152 #define QEMU_CLOCK_VIRTUAL  1
 153 #define QEMU_CLOCK_HOST     2
 154
 155 struct QEMUClock {
 156     int type;
 157     int enabled;
 158     /* XXX: add frequency */
 159 };
 160
 161 struct QEMUTimer {
 162     QEMUClock *clock;
 163     int64_t expire_time;
 164     QEMUTimerCB *cb;
 165     void *opaque;
 166     struct QEMUTimer *next;
 167 };
 168
 169 struct qemu_alarm_timer {
 170     char const *name;
 171     int (*start)(struct qemu_alarm_timer *t);
 172     void (*stop)(struct qemu_alarm_timer *t);
 173     void (*rearm)(struct qemu_alarm_timer *t);
 174     void *priv;
 175
 176     char expired;
 177     char pending;
 178 };
 179
 180 static struct qemu_alarm_timer *alarm_timer;
 181
 182 int qemu_alarm_pending(void)
 183 {
 184     return alarm_timer->pending;
 185 }
 186
 187 static inline int alarm_has_dynticks(struct qemu_alarm_timer *t)
 188 {
 189     return !!t->rearm;
 190 }
 191
 192 static void qemu_rearm_alarm_timer(struct qemu_alarm_timer *t)
 193 {
 194     if (!alarm_has_dynticks(t))
 195         return;
 196
 197     t->rearm(t);
 198 }
 199
 200 /* TODO: MIN_TIMER_REARM_NS should be optimized */
 201 #define MIN_TIMER_REARM_NS 250000
 202
 203 #ifdef _WIN32
 204
 205 struct qemu_alarm_win32 {
 206     MMRESULT timerId;
 207     unsigned int period;
 208 } alarm_win32_data = {0, 0};
 209
 210 static int win32_start_timer(struct qemu_alarm_timer *t);
 211 static void win32_stop_timer(struct qemu_alarm_timer *t);
 212 static void win32_rearm_timer(struct qemu_alarm_timer *t);
 213
 214 #else
 215
 216 static int unix_start_timer(struct qemu_alarm_timer *t);
 217 static void unix_stop_timer(struct qemu_alarm_timer *t);
 218
 219 #ifdef __linux__
 220
 221 static int dynticks_start_timer(struct qemu_alarm_timer *t);
 222 static void dynticks_stop_timer(struct qemu_alarm_timer *t);
 223 static void dynticks_rearm_timer(struct qemu_alarm_timer *t);
 224
 225 static int hpet_start_timer(struct qemu_alarm_timer *t);
 226 static void hpet_stop_timer(struct qemu_alarm_timer *t);
 227
 228 static int rtc_start_timer(struct qemu_alarm_timer *t);
 229 static void rtc_stop_timer(struct qemu_alarm_timer *t);
 230
 231 #endif /* __linux__ */
 232
 233 #endif /* _WIN32 */
 234
 235 /* Correlation between real and virtual time is always going to be
 236    fairly approximate, so ignore small variation.
 237    When the guest is idle real and virtual time will be aligned in
 238    the IO wait loop.  */
 239 #define ICOUNT_WOBBLE (get_ticks_per_sec() / 10)
 240
 241 static void icount_adjust(void)
 242 {
 243     int64_t cur_time;
 244     int64_t cur_icount;
 245     int64_t delta;
 246     static int64_t last_delta;
 247     /* If the VM is not running, then do nothing.  */
 248     if (!vm_running)
 249         return;
 250
 251     cur_time = cpu_get_clock();
 252     cur_icount = qemu_get_clock(vm_clock);
 253     delta = cur_icount - cur_time;
 254     /* FIXME: This is a very crude algorithm, somewhat prone to oscillation.  */
 255     if (delta > 0
 256         && last_delta + ICOUNT_WOBBLE < delta * 2
 257         && icount_time_shift > 0) {
 258         /* The guest is getting too far ahead.  Slow time down.  */
 259         icount_time_shift--;
 260     }
 261     if (delta < 0
 262         && last_delta - ICOUNT_WOBBLE > delta * 2
 263         && icount_time_shift < MAX_ICOUNT_SHIFT) {
 264         /* The guest is getting too far behind.  Speed time up.  */
 265         icount_time_shift++;
 266     }
 267     last_delta = delta;
 268     qemu_icount_bias = cur_icount - (qemu_icount << icount_time_shift);
 269 }
 270
 271 static void icount_adjust_rt(void * opaque)
 272 {
 273     qemu_mod_timer(icount_rt_timer,
 274                    qemu_get_clock(rt_clock) + 1000);
 275     icount_adjust();
 276 }
 277
 278 static void icount_adjust_vm(void * opaque)
 279 {
 280     qemu_mod_timer(icount_vm_timer,
 281                    qemu_get_clock(vm_clock) + get_ticks_per_sec() / 10);
 282     icount_adjust();
 283 }
 284
 285 int64_t qemu_icount_round(int64_t count)
 286 {
 287     return (count + (1 << icount_time_shift) - 1) >> icount_time_shift;
 288 }
 289
 290 static struct qemu_alarm_timer alarm_timers[] = {
 291 #ifndef _WIN32
 292 #ifdef __linux__
 293     {"dynticks", dynticks_start_timer,
 294      dynticks_stop_timer, dynticks_rearm_timer, NULL},
 295     /* HPET - if available - is preferred */
 296     {"hpet", hpet_start_timer, hpet_stop_timer, NULL, NULL},
 297     /* ...otherwise try RTC */
 298     {"rtc", rtc_start_timer, rtc_stop_timer, NULL, NULL},
 299 #endif
 300     {"unix", unix_start_timer, unix_stop_timer, NULL, NULL},
 301 #else
 302     {"dynticks", win32_start_timer,
 303      win32_stop_timer, win32_rearm_timer, &alarm_win32_data},
 304     {"win32", win32_start_timer,
 305      win32_stop_timer, NULL, &alarm_win32_data},
 306 #endif
 307     {NULL, }
 308 };
 309
 310 static void show_available_alarms(void)
 311 {
 312     int i;
 313
 314     printf("Available alarm timers, in order of precedence:\n");
 315     for (i = 0; alarm_timers[i].name; i++)
 316         printf("%s\n", alarm_timers[i].name);
 317 }
 318
 319 void configure_alarms(char const *opt)
 320 {
 321     int i;
 322     int cur = 0;
 323     int count = ARRAY_SIZE(alarm_timers) - 1;
 324     char *arg;
 325     char *name;
 326     struct qemu_alarm_timer tmp;
 327
 328     if (!strcmp(opt, "?")) {
 329         show_available_alarms();
 330         exit(0);
 331     }
 332
 333     arg = qemu_strdup(opt);
 334
 335     /* Reorder the array */
 336     name = strtok(arg, ",");
 337     while (name) {
 338         for (i = 0; i < count && alarm_timers[i].name; i++) {
 339             if (!strcmp(alarm_timers[i].name, name))
 340                 break;
 341         }
 342
 343         if (i == count) {
 344             fprintf(stderr, "Unknown clock %s\n", name);
 345             goto next;
 346         }
 347
 348         if (i < cur)
 349             /* Ignore */
 350             goto next;
 351
 352         /* Swap */
 353         tmp = alarm_timers[i];
 354         alarm_timers[i] = alarm_timers[cur];
 355         alarm_timers[cur] = tmp;
 356
 357         cur++;
 358 next:
 359         name = strtok(NULL, ",");
 360     }
 361
 362     qemu_free(arg);
 363
 364     if (cur) {
 365         /* Disable remaining timers */
 366         for (i = cur; i < count; i++)
 367             alarm_timers[i].name = NULL;
 368     } else {
 369         show_available_alarms();
 370         exit(1);
 371     }
 372 }
 373
 374 #define QEMU_NUM_CLOCKS 3
 375
 376 QEMUClock *rt_clock;
 377 QEMUClock *vm_clock;
 378 QEMUClock *host_clock;
 379
 380 static QEMUTimer *active_timers[QEMU_NUM_CLOCKS];
 381
 382 static QEMUClock *qemu_new_clock(int type)
 383 {
 384     QEMUClock *clock;
 385     clock = qemu_mallocz(sizeof(QEMUClock));
 386     clock->type = type;
 387     clock->enabled = 1;
 388     return clock;
 389 }
 390
 391 void qemu_clock_enable(QEMUClock *clock, int enabled)
 392 {
 393     clock->enabled = enabled;
 394 }
 395
 396 QEMUTimer *qemu_new_timer(QEMUClock *clock, QEMUTimerCB *cb, void *opaque)
 397 {
 398     QEMUTimer *ts;
 399
 400     ts = qemu_mallocz(sizeof(QEMUTimer));
 401     ts->clock = clock;
 402     ts->cb = cb;
 403     ts->opaque = opaque;
 404     return ts;
 405 }
 406
 407 void qemu_free_timer(QEMUTimer *ts)
 408 {
 409     qemu_free(ts);
 410 }
 411
 412 /* stop a timer, but do not dealloc it */
 413 void qemu_del_timer(QEMUTimer *ts)
 414 {
 415     QEMUTimer **pt, *t;
 416
 417     /* NOTE: this code must be signal safe because
 418        qemu_timer_expired() can be called from a signal. */
 419     pt = &active_timers[ts->clock->type];
 420     for(;;) {
 421         t = *pt;
 422         if (!t)
 423             break;
 424         if (t == ts) {
 425             *pt = t->next;
 426             break;
 427         }
 428         pt = &t->next;
 429     }
 430 }
 431
 432 /* modify the current timer so that it will be fired when current_time
 433    >= expire_time. The corresponding callback will be called. */
 434 void qemu_mod_timer(QEMUTimer *ts, int64_t expire_time)
 435 {
 436     QEMUTimer **pt, *t;
 437
 438     qemu_del_timer(ts);
 439
 440     /* add the timer in the sorted list */
 441     /* NOTE: this code must be signal safe because
 442        qemu_timer_expired() can be called from a signal. */
 443     pt = &active_timers[ts->clock->type];
 444     for(;;) {
 445         t = *pt;
 446         if (!t)
 447             break;
 448         if (t->expire_time > expire_time)
 449             break;
 450         pt = &t->next;
 451     }
 452     ts->expire_time = expire_time;
 453     ts->next = *pt;
 454     *pt = ts;
 455
 456     /* Rearm if necessary  */
 457     if (pt == &active_timers[ts->clock->type]) {
 458         if (!alarm_timer->pending) {
 459             qemu_rearm_alarm_timer(alarm_timer);
 460         }
 461         /* Interrupt execution to force deadline recalculation.  */
 462         if (use_icount)
 463             qemu_notify_event();
 464     }
 465 }
 466
 467 int qemu_timer_pending(QEMUTimer *ts)
 468 {
 469     QEMUTimer *t;
 470     for(t = active_timers[ts->clock->type]; t != NULL; t = t->next) {
 471         if (t == ts)
 472             return 1;
 473     }
 474     return 0;
 475 }
 476
 477 int qemu_timer_expired(QEMUTimer *timer_head, int64_t current_time)
 478 {
 479     if (!timer_head)
 480         return 0;
 481     return (timer_head->expire_time <= current_time);
 482 }
 483
 484 static void qemu_run_timers(QEMUClock *clock)
 485 {
 486     QEMUTimer **ptimer_head, *ts;
 487     int64_t current_time;
 488
 489     if (!clock->enabled)
 490         return;
 491
 492     current_time = qemu_get_clock (clock);
 493     ptimer_head = &active_timers[clock->type];
 494     for(;;) {
 495         ts = *ptimer_head;
 496         if (!ts || ts->expire_time > current_time)
 497             break;
 498         /* remove timer from the list before calling the callback */
 499         *ptimer_head = ts->next;
 500         ts->next = NULL;
 501
 502         /* run the callback (the timer list can be modified) */
 503         ts->cb(ts->opaque);
 504     }
 505 }
 506
 507 int64_t qemu_get_clock(QEMUClock *clock)
 508 {
 509     switch(clock->type) {
 510     case QEMU_CLOCK_REALTIME:
 511         return get_clock() / 1000000;
 512     default:
 513     case QEMU_CLOCK_VIRTUAL:
 514         if (use_icount) {
 515             return cpu_get_icount();
 516         } else {
 517             return cpu_get_clock();
 518         }
 519     case QEMU_CLOCK_HOST:
 520         return get_clock_realtime();
 521     }
 522 }
 523
 524 int64_t qemu_get_clock_ns(QEMUClock *clock)
 525 {
 526     switch(clock->type) {
 527     case QEMU_CLOCK_REALTIME:
 528         return get_clock();
 529     default:
 530     case QEMU_CLOCK_VIRTUAL:
 531         if (use_icount) {
 532             return cpu_get_icount();
 533         } else {
 534             return cpu_get_clock();
 535         }
 536     case QEMU_CLOCK_HOST:
 537         return get_clock_realtime();
 538     }
 539 }
 540
 541 void init_clocks(void)
 542 {
 543     rt_clock = qemu_new_clock(QEMU_CLOCK_REALTIME);
 544     vm_clock = qemu_new_clock(QEMU_CLOCK_VIRTUAL);
 545     host_clock = qemu_new_clock(QEMU_CLOCK_HOST);
 546
 547     rtc_clock = host_clock;
 548 }
 549
 550 /* save a timer */
 551 void qemu_put_timer(QEMUFile *f, QEMUTimer *ts)
 552 {
 553     uint64_t expire_time;
 554
 555     if (qemu_timer_pending(ts)) {
 556         expire_time = ts->expire_time;
 557     } else {
 558         expire_time = -1;
 559     }
 560     qemu_put_be64(f, expire_time);
 561 }
 562
 563 void qemu_get_timer(QEMUFile *f, QEMUTimer *ts)
 564 {
 565     uint64_t expire_time;
 566
 567     expire_time = qemu_get_be64(f);
 568     if (expire_time != -1) {
 569         qemu_mod_timer(ts, expire_time);
 570     } else {
 571         qemu_del_timer(ts);
 572     }
 573 }
 574
 575 static const VMStateDescription vmstate_timers = {
 576     .name = "timer",
 577     .version_id = 2,
 578     .minimum_version_id = 1,
 579     .minimum_version_id_old = 1,
 580     .fields      = (VMStateField []) {
 581         VMSTATE_INT64(cpu_ticks_offset, TimersState),
 582         VMSTATE_INT64(dummy, TimersState),
 583         VMSTATE_INT64_V(cpu_clock_offset, TimersState, 2),
 584         VMSTATE_END_OF_LIST()
 585     }
 586 };
 587
 588 void configure_icount(const char *option)
 589 {
 590     vmstate_register(NULL, 0, &vmstate_timers, &timers_state);
 591     if (!option)
 592         return;
 593
 594     if (strcmp(option, "auto") != 0) {
 595         icount_time_shift = strtol(option, NULL, 0);
 596         use_icount = 1;
 597         return;
 598     }
 599
 600     use_icount = 2;
 601
 602     /* 125MIPS seems a reasonable initial guess at the guest speed.
 603        It will be corrected fairly quickly anyway.  */
 604     icount_time_shift = 3;
 605
 606     /* Have both realtime and virtual time triggers for speed adjustment.
 607        The realtime trigger catches emulated time passing too slowly,
 608        the virtual time trigger catches emulated time passing too fast.
 609        Realtime triggers occur even when idle, so use them less frequently
 610        than VM triggers.  */
 611     icount_rt_timer = qemu_new_timer(rt_clock, icount_adjust_rt, NULL);
 612     qemu_mod_timer(icount_rt_timer,
 613                    qemu_get_clock(rt_clock) + 1000);
 614     icount_vm_timer = qemu_new_timer(vm_clock, icount_adjust_vm, NULL);
 615     qemu_mod_timer(icount_vm_timer,
 616                    qemu_get_clock(vm_clock) + get_ticks_per_sec() / 10);
 617 }
 618
 619 void qemu_run_all_timers(void)
 620 {
 621     alarm_timer->pending = 0;
 622
 623     /* rearm timer, if not periodic */
 624     if (alarm_timer->expired) {
 625         alarm_timer->expired = 0;
 626         qemu_rearm_alarm_timer(alarm_timer);
 627     }
 628
 629     /* vm time timers */
 630     if (vm_running) {
 631         qemu_run_timers(vm_clock);
 632     }
 633
 634     qemu_run_timers(rt_clock);
 635     qemu_run_timers(host_clock);
 636 }
 637
 638 static int64_t qemu_next_alarm_deadline(void);
 639
 640 #ifdef _WIN32
 641 static void CALLBACK host_alarm_handler(UINT uTimerID, UINT uMsg,
 642                                         DWORD_PTR dwUser, DWORD_PTR dw1,
 643                                         DWORD_PTR dw2)
 644 #else
 645 static void host_alarm_handler(int host_signum)
 646 #endif
 647 {
 648     struct qemu_alarm_timer *t = alarm_timer;
 649     if (!t)
 650         return;
 651
 652 #if 0
 653 #define DISP_FREQ 1000
 654     {
 655         static int64_t delta_min = INT64_MAX;
 656         static int64_t delta_max, delta_cum, last_clock, delta, ti;
 657         static int count;
 658         ti = qemu_get_clock(vm_clock);
 659         if (last_clock != 0) {
 660             delta = ti - last_clock;
 661             if (delta < delta_min)
 662                 delta_min = delta;
 663             if (delta > delta_max)
 664                 delta_max = delta;
 665             delta_cum += delta;
 666             if (++count == DISP_FREQ) {
 667                 printf("timer: min=%" PRId64 " us max=%" PRId64 " us avg=%" PRId64 " us avg_freq=%0.3f Hz\n",
 668                        muldiv64(delta_min, 1000000, get_ticks_per_sec()),
 669                        muldiv64(delta_max, 1000000, get_ticks_per_sec()),
 670                        muldiv64(delta_cum, 1000000 / DISP_FREQ, get_ticks_per_sec()),
 671                        (double)get_ticks_per_sec() / ((double)delta_cum / DISP_FREQ));
 672                 count = 0;
 673                 delta_min = INT64_MAX;
 674                 delta_max = 0;
 675                 delta_cum = 0;
 676             }
 677         }
 678         last_clock = ti;
 679     }
 680 #endif
 681     if (alarm_has_dynticks(t) ||
 682         qemu_next_alarm_deadline () <= 0) {
 683         t->expired = alarm_has_dynticks(t);
 684         t->pending = 1;
 685         qemu_notify_event();
 686     }
 687 }
 688
 689 int64_t qemu_next_deadline(void)
 690 {
 691     /* To avoid problems with overflow limit this to 2^32.  */
 692     int64_t delta = INT32_MAX;
 693
 694     if (active_timers[QEMU_CLOCK_VIRTUAL]) {
 695         delta = active_timers[QEMU_CLOCK_VIRTUAL]->expire_time -
 696                      qemu_get_clock_ns(vm_clock);
 697     }
 698     if (active_timers[QEMU_CLOCK_HOST]) {
 699         int64_t hdelta = active_timers[QEMU_CLOCK_HOST]->expire_time -
 700                  qemu_get_clock_ns(host_clock);
 701         if (hdelta < delta)
 702             delta = hdelta;
 703     }
 704
 705     if (delta < 0)
 706         delta = 0;
 707
 708     return delta;
 709 }
 710
 711 #ifndef _WIN32
 712
 713 static int64_t qemu_next_alarm_deadline(void)
 714 {
 715     int64_t delta;
 716     int64_t rtdelta;
 717
 718     if (!use_icount && active_timers[QEMU_CLOCK_VIRTUAL]) {
 719         delta = active_timers[QEMU_CLOCK_VIRTUAL]->expire_time -
 720                      qemu_get_clock(vm_clock);
 721     } else {
 722         delta = INT32_MAX;
 723     }
 724     if (active_timers[QEMU_CLOCK_HOST]) {
 725         int64_t hdelta = active_timers[QEMU_CLOCK_HOST]->expire_time -
 726                  qemu_get_clock_ns(host_clock);
 727         if (hdelta < delta)
 728             delta = hdelta;
 729     }
 730     if (active_timers[QEMU_CLOCK_REALTIME]) {
 731         rtdelta = (active_timers[QEMU_CLOCK_REALTIME]->expire_time * 1000000 -
 732                  qemu_get_clock_ns(rt_clock));
 733         if (rtdelta < delta)
 734             delta = rtdelta;
 735     }
 736
 737     return delta;
 738 }
 739
 740 #if defined(__linux__)
 741
 742 #define RTC_FREQ 1024
 743
 744 static void enable_sigio_timer(int fd)
 745 {
 746     struct sigaction act;
 747
 748     /* timer signal */
 749     sigfillset(&act.sa_mask);
 750     act.sa_flags = 0;
 751     act.sa_handler = host_alarm_handler;
 752
 753     sigaction(SIGIO, &act, NULL);
 754     fcntl_setfl(fd, O_ASYNC);
 755     fcntl(fd, F_SETOWN, getpid());
 756 }
 757
 758 static int hpet_start_timer(struct qemu_alarm_timer *t)
 759 {
 760     struct hpet_info info;
 761     int r, fd;
 762
 763     fd = qemu_open("/dev/hpet", O_RDONLY);
 764     if (fd < 0)
 765         return -1;
 766
 767     /* Set frequency */
 768     r = ioctl(fd, HPET_IRQFREQ, RTC_FREQ);
 769     if (r < 0) {
 770         fprintf(stderr, "Could not configure '/dev/hpet' to have a 1024Hz timer. This is not a fatal\n"
 771                 "error, but for better emulation accuracy type:\n"
 772                 "'echo 1024 > /proc/sys/dev/hpet/max-user-freq' as root.\n");
 773         goto fail;
 774     }
 775
 776     /* Check capabilities */
 777     r = ioctl(fd, HPET_INFO, &info);
 778     if (r < 0)
 779         goto fail;
 780
 781     /* Enable periodic mode */
 782     r = ioctl(fd, HPET_EPI, 0);
 783     if (info.hi_flags && (r < 0))
 784         goto fail;
 785
 786     /* Enable interrupt */
 787     r = ioctl(fd, HPET_IE_ON, 0);
 788     if (r < 0)
 789         goto fail;
 790
 791     enable_sigio_timer(fd);
 792     t->priv = (void *)(long)fd;
 793
 794     return 0;
 795 fail:
 796     close(fd);
 797     return -1;
 798 }
 799
 800 static void hpet_stop_timer(struct qemu_alarm_timer *t)
 801 {
 802     int fd = (long)t->priv;
 803
 804     close(fd);
 805 }
 806
 807 static int rtc_start_timer(struct qemu_alarm_timer *t)
 808 {
 809     int rtc_fd;
 810     unsigned long current_rtc_freq = 0;
 811
 812     TFR(rtc_fd = qemu_open("/dev/rtc", O_RDONLY));
 813     if (rtc_fd < 0)
 814         return -1;
 815     ioctl(rtc_fd, RTC_IRQP_READ, &current_rtc_freq);
 816     if (current_rtc_freq != RTC_FREQ &&
 817         ioctl(rtc_fd, RTC_IRQP_SET, RTC_FREQ) < 0) {
 818         fprintf(stderr, "Could not configure '/dev/rtc' to have a 1024 Hz timer. This is not a fatal\n"
 819                 "error, but for better emulation accuracy either use a 2.6 host Linux kernel or\n"
 820                 "type 'echo 1024 > /proc/sys/dev/rtc/max-user-freq' as root.\n");
 821         goto fail;
 822     }
 823     if (ioctl(rtc_fd, RTC_PIE_ON, 0) < 0) {
 824     fail:
 825         close(rtc_fd);
 826         return -1;
 827     }
 828
 829     enable_sigio_timer(rtc_fd);
 830
 831     t->priv = (void *)(long)rtc_fd;
 832
 833     return 0;
 834 }
 835
 836 static void rtc_stop_timer(struct qemu_alarm_timer *t)
 837 {
 838     int rtc_fd = (long)t->priv;
 839
 840     close(rtc_fd);
 841 }
 842
 843 static int dynticks_start_timer(struct qemu_alarm_timer *t)
 844 {
 845     struct sigevent ev;
 846     timer_t host_timer;
 847     struct sigaction act;
 848
 849     sigfillset(&act.sa_mask);
 850     act.sa_flags = 0;
 851     act.sa_handler = host_alarm_handler;
 852
 853     sigaction(SIGALRM, &act, NULL);
 854
 855     /*
 856      * Initialize ev struct to 0 to avoid valgrind complaining
 857      * about uninitialized data in timer_create call
 858      */
 859     memset(&ev, 0, sizeof(ev));
 860     ev.sigev_value.sival_int = 0;
 861     ev.sigev_notify = SIGEV_SIGNAL;
 862     ev.sigev_signo = SIGALRM;
 863
 864     if (timer_create(CLOCK_REALTIME, &ev, &host_timer)) {
 865         perror("timer_create");
 866
 867         /* disable dynticks */
 868         fprintf(stderr, "Dynamic Ticks disabled\n");
 869
 870         return -1;
 871     }
 872
 873     t->priv = (void *)(long)host_timer;
 874
 875     return 0;
 876 }
 877
 878 static void dynticks_stop_timer(struct qemu_alarm_timer *t)
 879 {
 880     timer_t host_timer = (timer_t)(long)t->priv;
 881
 882     timer_delete(host_timer);
 883 }
 884
 885 static void dynticks_rearm_timer(struct qemu_alarm_timer *t)
 886 {
 887     timer_t host_timer = (timer_t)(long)t->priv;
 888     struct itimerspec timeout;
 889     int64_t nearest_delta_ns = INT64_MAX;
 890     int64_t current_ns;
 891
 892     assert(alarm_has_dynticks(t));
 893     if (!active_timers[QEMU_CLOCK_REALTIME] &&
 894         !active_timers[QEMU_CLOCK_VIRTUAL] &&
 895         !active_timers[QEMU_CLOCK_HOST])
 896         return;
 897
 898     nearest_delta_ns = qemu_next_alarm_deadline();
 899     if (nearest_delta_ns < MIN_TIMER_REARM_NS)
 900         nearest_delta_ns = MIN_TIMER_REARM_NS;
 901
 902     /* check whether a timer is already running */
 903     if (timer_gettime(host_timer, &timeout)) {
 904         perror("gettime");
 905         fprintf(stderr, "Internal timer error: aborting\n");
 906         exit(1);
 907     }
 908     current_ns = timeout.it_value.tv_sec * 1000000000LL + timeout.it_value.tv_nsec;
 909     if (current_ns && current_ns <= nearest_delta_ns)
 910         return;
 911
 912     timeout.it_interval.tv_sec = 0;
 913     timeout.it_interval.tv_nsec = 0; /* 0 for one-shot timer */
 914     timeout.it_value.tv_sec =  nearest_delta_ns / 1000000000;
 915     timeout.it_value.tv_nsec = nearest_delta_ns % 1000000000;
 916     if (timer_settime(host_timer, 0 /* RELATIVE */, &timeout, NULL)) {
 917         perror("settime");
 918         fprintf(stderr, "Internal timer error: aborting\n");
 919         exit(1);
 920     }
 921 }
 922
 923 #endif /* defined(__linux__) */
 924
 925 static int unix_start_timer(struct qemu_alarm_timer *t)
 926 {
 927     struct sigaction act;
 928     struct itimerval itv;
 929     int err;
 930
 931     /* timer signal */
 932     sigfillset(&act.sa_mask);
 933     act.sa_flags = 0;
 934     act.sa_handler = host_alarm_handler;
 935
 936     sigaction(SIGALRM, &act, NULL);
 937
 938     itv.it_interval.tv_sec = 0;
 939     /* for i386 kernel 2.6 to get 1 ms */
 940     itv.it_interval.tv_usec = 999;
 941     itv.it_value.tv_sec = 0;
 942     itv.it_value.tv_usec = 10 * 1000;
 943
 944     err = setitimer(ITIMER_REAL, &itv, NULL);
 945     if (err)
 946         return -1;
 947
 948     return 0;
 949 }
 950
 951 static void unix_stop_timer(struct qemu_alarm_timer *t)
 952 {
 953     struct itimerval itv;
 954
 955     memset(&itv, 0, sizeof(itv));
 956     setitimer(ITIMER_REAL, &itv, NULL);
 957 }
 958
 959 #endif /* !defined(_WIN32) */
 960
 961
 962 #ifdef _WIN32
 963
 964 static int win32_start_timer(struct qemu_alarm_timer *t)
 965 {
 966     TIMECAPS tc;
 967     struct qemu_alarm_win32 *data = t->priv;
 968     UINT flags;
 969
 970     memset(&tc, 0, sizeof(tc));
 971     timeGetDevCaps(&tc, sizeof(tc));
 972
 973     data->period = tc.wPeriodMin;
 974     timeBeginPeriod(data->period);
 975
 976     flags = TIME_CALLBACK_FUNCTION;
 977     if (alarm_has_dynticks(t))
 978         flags |= TIME_ONESHOT;
 979     else
 980         flags |= TIME_PERIODIC;
 981
 982     data->timerId = timeSetEvent(1,         // interval (ms)
 983                         data->period,       // resolution
 984                         host_alarm_handler, // function
 985                         (DWORD)t,           // parameter
 986                         flags);
 987
 988     if (!data->timerId) {
 989         fprintf(stderr, "Failed to initialize win32 alarm timer: %ld\n",
 990                 GetLastError());
 991         timeEndPeriod(data->period);
 992         return -1;
 993     }
 994
 995     return 0;
 996 }
 997
 998 static void win32_stop_timer(struct qemu_alarm_timer *t)
 999 {
1000     struct qemu_alarm_win32 *data = t->priv;
1001
1002     timeKillEvent(data->timerId);
1003     timeEndPeriod(data->period);
1004 }
1005
1006 static void win32_rearm_timer(struct qemu_alarm_timer *t)
1007 {
1008     struct qemu_alarm_win32 *data = t->priv;
1009
1010     assert(alarm_has_dynticks(t));
1011     if (!active_timers[QEMU_CLOCK_REALTIME] &&
1012         !active_timers[QEMU_CLOCK_VIRTUAL] &&
1013         !active_timers[QEMU_CLOCK_HOST])
1014         return;
1015
1016     timeKillEvent(data->timerId);
1017
1018     data->timerId = timeSetEvent(1,
1019                         data->period,
1020                         host_alarm_handler,
1021                         (DWORD)t,
1022                         TIME_ONESHOT | TIME_CALLBACK_FUNCTION);
1023
1024     if (!data->timerId) {
1025         fprintf(stderr, "Failed to re-arm win32 alarm timer %ld\n",
1026                 GetLastError());
1027
1028         timeEndPeriod(data->period);
1029         exit(1);
1030     }
1031 }
1032
1033 #endif /* _WIN32 */
1034
1035 static void alarm_timer_on_change_state_rearm(void *opaque, int running, int reason)
1036 {
1037     if (running)
1038         qemu_rearm_alarm_timer((struct qemu_alarm_timer *) opaque);
1039 }
1040
1041 int init_timer_alarm(void)
1042 {
1043     struct qemu_alarm_timer *t = NULL;
1044     int i, err = -1;
1045
1046     for (i = 0; alarm_timers[i].name; i++) {
1047         t = &alarm_timers[i];
1048
1049         err = t->start(t);
1050         if (!err)
1051             break;
1052     }
1053
1054     if (err) {
1055         err = -ENOENT;
1056         goto fail;
1057     }
1058
1059     /* first event is at time 0 */
1060     t->pending = 1;
1061     alarm_timer = t;
1062     qemu_add_vm_change_state_handler(alarm_timer_on_change_state_rearm, t);
1063
1064     return 0;
1065
1066 fail:
1067     return err;
1068 }
1069
1070 void quit_timers(void)
1071 {
1072     struct qemu_alarm_timer *t = alarm_timer;
1073     alarm_timer = NULL;
1074     t->stop(t);
1075 }
1076
1077 int qemu_calculate_timeout(void)
1078 {
1079     int timeout;
1080
1081 #ifdef CONFIG_IOTHREAD
1082     /* When using icount, making forward progress with qemu_icount when the
1083        guest CPU is idle is critical. We only use the static io-thread timeout
1084        for non icount runs.  */
1085     if (!use_icount) {
1086         return 1000;
1087     }
1088 #endif
1089
1090     if (!vm_running)
1091         timeout = 5000;
1092     else {
1093      /* XXX: use timeout computed from timers */
1094         int64_t add;
1095         int64_t delta;
1096         /* Advance virtual time to the next event.  */
1097         delta = qemu_icount_delta();
1098         if (delta > 0) {
1099             /* If virtual time is ahead of real time then just
1100                wait for IO.  */
1101             timeout = (delta + 999999) / 1000000;
1102         } else {
1103             /* Wait for either IO to occur or the next
1104                timer event.  */
1105             add = qemu_next_deadline();
1106             /* We advance the timer before checking for IO.
1107                Limit the amount we advance so that early IO
1108                activity won't get the guest too far ahead.  */
1109             if (add > 10000000)
1110                 add = 10000000;
1111             delta += add;
1112             qemu_icount += qemu_icount_round (add);
1113             timeout = delta / 1000000;
1114             if (timeout < 0)
1115                 timeout = 0;
1116         }
1117     }
1118
1119     return timeout;
1120 }
1121