main-loop.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu-common.h"
  26 #include "qemu-timer.h"
  27 #include "slirp/slirp.h"
  28 #include "main-loop.h"
  29
  30 #ifndef _WIN32
  31
  32 #include "compatfd.h"
  33
  34 static int io_thread_fd = -1;
  35
  36 void qemu_notify_event(void)
  37 {
  38     /* Write 8 bytes to be compatible with eventfd.  */
  39     static const uint64_t val = 1;
  40     ssize_t ret;
  41
  42     if (io_thread_fd == -1) {
  43         return;
  44     }
  45     do {
  46         ret = write(io_thread_fd, &val, sizeof(val));
  47     } while (ret < 0 && errno == EINTR);
  48
  49     /* EAGAIN is fine, a read must be pending.  */
  50     if (ret < 0 && errno != EAGAIN) {
  51         fprintf(stderr, "qemu_notify_event: write() failed: %s\n",
  52                 strerror(errno));
  53         exit(1);
  54     }
  55 }
  56
  57 static void qemu_event_read(void *opaque)
  58 {
  59     int fd = (intptr_t)opaque;
  60     ssize_t len;
  61     char buffer[512];
  62
  63     /* Drain the notify pipe.  For eventfd, only 8 bytes will be read.  */
  64     do {
  65         len = read(fd, buffer, sizeof(buffer));
  66     } while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
  67 }
  68
  69 static int qemu_event_init(void)
  70 {
  71     int err;
  72     int fds[2];
  73
  74     err = qemu_eventfd(fds);
  75     if (err == -1) {
  76         return -errno;
  77     }
  78     err = fcntl_setfl(fds[0], O_NONBLOCK);
  79     if (err < 0) {
  80         goto fail;
  81     }
  82     err = fcntl_setfl(fds[1], O_NONBLOCK);
  83     if (err < 0) {
  84         goto fail;
  85     }
  86     qemu_set_fd_handler2(fds[0], NULL, qemu_event_read, NULL,
  87                          (void *)(intptr_t)fds[0]);
  88
  89     io_thread_fd = fds[1];
  90     return 0;
  91
  92 fail:
  93     close(fds[0]);
  94     close(fds[1]);
  95     return err;
  96 }
  97
  98 /* If we have signalfd, we mask out the signals we want to handle and then
  99  * use signalfd to listen for them.  We rely on whatever the current signal
 100  * handler is to dispatch the signals when we receive them.
 101  */
 102 static void sigfd_handler(void *opaque)
 103 {
 104     int fd = (intptr_t)opaque;
 105     struct qemu_signalfd_siginfo info;
 106     struct sigaction action;
 107     ssize_t len;
 108
 109     while (1) {
 110         do {
 111             len = read(fd, &info, sizeof(info));
 112         } while (len == -1 && errno == EINTR);
 113
 114         if (len == -1 && errno == EAGAIN) {
 115             break;
 116         }
 117
 118         if (len != sizeof(info)) {
 119             printf("read from sigfd returned %zd: %m\n", len);
 120             return;
 121         }
 122
 123         sigaction(info.ssi_signo, NULL, &action);
 124         if ((action.sa_flags & SA_SIGINFO) && action.sa_sigaction) {
 125             action.sa_sigaction(info.ssi_signo,
 126                                 (siginfo_t *)&info, NULL);
 127         } else if (action.sa_handler) {
 128             action.sa_handler(info.ssi_signo);
 129         }
 130     }
 131 }
 132
 133 static int qemu_signal_init(void)
 134 {
 135     int sigfd;
 136     sigset_t set;
 137
 138     /*
 139      * SIG_IPI must be blocked in the main thread and must not be caught
 140      * by sigwait() in the signal thread. Otherwise, the cpu thread will
 141      * not catch it reliably.
 142      */
 143     sigemptyset(&set);
 144     sigaddset(&set, SIG_IPI);
 145     pthread_sigmask(SIG_BLOCK, &set, NULL);
 146
 147     sigemptyset(&set);
 148     sigaddset(&set, SIGIO);
 149     sigaddset(&set, SIGALRM);
 150     sigaddset(&set, SIGBUS);
 151     pthread_sigmask(SIG_BLOCK, &set, NULL);
 152
 153     sigfd = qemu_signalfd(&set);
 154     if (sigfd == -1) {
 155         fprintf(stderr, "failed to create signalfd\n");
 156         return -errno;
 157     }
 158
 159     fcntl_setfl(sigfd, O_NONBLOCK);
 160
 161     qemu_set_fd_handler2(sigfd, NULL, sigfd_handler, NULL,
 162                          (void *)(intptr_t)sigfd);
 163
 164     return 0;
 165 }
 166
 167 #else /* _WIN32 */
 168
 169 HANDLE qemu_event_handle;
 170
 171 static void dummy_event_handler(void *opaque)
 172 {
 173 }
 174
 175 static int qemu_event_init(void)
 176 {
 177     qemu_event_handle = CreateEvent(NULL, FALSE, FALSE, NULL);
 178     if (!qemu_event_handle) {
 179         fprintf(stderr, "Failed CreateEvent: %ld\n", GetLastError());
 180         return -1;
 181     }
 182     qemu_add_wait_object(qemu_event_handle, dummy_event_handler, NULL);
 183     return 0;
 184 }
 185
 186 void qemu_notify_event(void)
 187 {
 188     if (!SetEvent(qemu_event_handle)) {
 189         fprintf(stderr, "qemu_notify_event: SetEvent failed: %ld\n",
 190                 GetLastError());
 191         exit(1);
 192     }
 193 }
 194
 195 static int qemu_signal_init(void)
 196 {
 197     return 0;
 198 }
 199 #endif
 200
 201 int qemu_init_main_loop(void)
 202 {
 203     int ret;
 204
 205     qemu_mutex_lock_iothread();
 206     ret = qemu_signal_init();
 207     if (ret) {
 208         return ret;
 209     }
 210
 211     /* Note eventfd must be drained before signalfd handlers run */
 212     ret = qemu_event_init();
 213     if (ret) {
 214         return ret;
 215     }
 216
 217     return 0;
 218 }
 219
 220
 221 static GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
 222 static int n_poll_fds;
 223 static int max_priority;
 224
 225 static void glib_select_fill(int *max_fd, fd_set *rfds, fd_set *wfds,
 226                              fd_set *xfds, struct timeval *tv)
 227 {
 228     GMainContext *context = g_main_context_default();
 229     int i;
 230     int timeout = 0, cur_timeout;
 231
 232     g_main_context_prepare(context, &max_priority);
 233
 234     n_poll_fds = g_main_context_query(context, max_priority, &timeout,
 235                                       poll_fds, ARRAY_SIZE(poll_fds));
 236     g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds));
 237
 238     for (i = 0; i < n_poll_fds; i++) {
 239         GPollFD *p = &poll_fds[i];
 240
 241         if ((p->events & G_IO_IN)) {
 242             FD_SET(p->fd, rfds);
 243             *max_fd = MAX(*max_fd, p->fd);
 244         }
 245         if ((p->events & G_IO_OUT)) {
 246             FD_SET(p->fd, wfds);
 247             *max_fd = MAX(*max_fd, p->fd);
 248         }
 249         if ((p->events & G_IO_ERR)) {
 250             FD_SET(p->fd, xfds);
 251             *max_fd = MAX(*max_fd, p->fd);
 252         }
 253     }
 254
 255     cur_timeout = (tv->tv_sec * 1000) + ((tv->tv_usec + 500) / 1000);
 256     if (timeout >= 0 && timeout < cur_timeout) {
 257         tv->tv_sec = timeout / 1000;
 258         tv->tv_usec = (timeout % 1000) * 1000;
 259     }
 260 }
 261
 262 static void glib_select_poll(fd_set *rfds, fd_set *wfds, fd_set *xfds,
 263                              bool err)
 264 {
 265     GMainContext *context = g_main_context_default();
 266
 267     if (!err) {
 268         int i;
 269
 270         for (i = 0; i < n_poll_fds; i++) {
 271             GPollFD *p = &poll_fds[i];
 272
 273             if ((p->events & G_IO_IN) && FD_ISSET(p->fd, rfds)) {
 274                 p->revents |= G_IO_IN;
 275             }
 276             if ((p->events & G_IO_OUT) && FD_ISSET(p->fd, wfds)) {
 277                 p->revents |= G_IO_OUT;
 278             }
 279             if ((p->events & G_IO_ERR) && FD_ISSET(p->fd, xfds)) {
 280                 p->revents |= G_IO_ERR;
 281             }
 282         }
 283     }
 284
 285     if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
 286         g_main_context_dispatch(context);
 287     }
 288 }
 289
 290 #ifdef _WIN32
 291 /***********************************************************/
 292 /* Polling handling */
 293
 294 typedef struct PollingEntry {
 295     PollingFunc *func;
 296     void *opaque;
 297     struct PollingEntry *next;
 298 } PollingEntry;
 299
 300 static PollingEntry *first_polling_entry;
 301
 302 int qemu_add_polling_cb(PollingFunc *func, void *opaque)
 303 {
 304     PollingEntry **ppe, *pe;
 305     pe = g_malloc0(sizeof(PollingEntry));
 306     pe->func = func;
 307     pe->opaque = opaque;
 308     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next);
 309     *ppe = pe;
 310     return 0;
 311 }
 312
 313 void qemu_del_polling_cb(PollingFunc *func, void *opaque)
 314 {
 315     PollingEntry **ppe, *pe;
 316     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) {
 317         pe = *ppe;
 318         if (pe->func == func && pe->opaque == opaque) {
 319             *ppe = pe->next;
 320             g_free(pe);
 321             break;
 322         }
 323     }
 324 }
 325
 326 /***********************************************************/
 327 /* Wait objects support */
 328 typedef struct WaitObjects {
 329     int num;
 330     HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
 331     WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1];
 332     void *opaque[MAXIMUM_WAIT_OBJECTS + 1];
 333 } WaitObjects;
 334
 335 static WaitObjects wait_objects = {0};
 336
 337 int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 338 {
 339     WaitObjects *w = &wait_objects;
 340     if (w->num >= MAXIMUM_WAIT_OBJECTS) {
 341         return -1;
 342     }
 343     w->events[w->num] = handle;
 344     w->func[w->num] = func;
 345     w->opaque[w->num] = opaque;
 346     w->num++;
 347     return 0;
 348 }
 349
 350 void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 351 {
 352     int i, found;
 353     WaitObjects *w = &wait_objects;
 354
 355     found = 0;
 356     for (i = 0; i < w->num; i++) {
 357         if (w->events[i] == handle) {
 358             found = 1;
 359         }
 360         if (found) {
 361             w->events[i] = w->events[i + 1];
 362             w->func[i] = w->func[i + 1];
 363             w->opaque[i] = w->opaque[i + 1];
 364         }
 365     }
 366     if (found) {
 367         w->num--;
 368     }
 369 }
 370
 371 static void os_host_main_loop_wait(int *timeout)
 372 {
 373     int ret, ret2, i;
 374     PollingEntry *pe;
 375
 376     /* XXX: need to suppress polling by better using win32 events */
 377     ret = 0;
 378     for (pe = first_polling_entry; pe != NULL; pe = pe->next) {
 379         ret |= pe->func(pe->opaque);
 380     }
 381     if (ret == 0) {
 382         int err;
 383         WaitObjects *w = &wait_objects;
 384
 385         qemu_mutex_unlock_iothread();
 386         ret = WaitForMultipleObjects(w->num, w->events, FALSE, *timeout);
 387         qemu_mutex_lock_iothread();
 388         if (WAIT_OBJECT_0 + 0 <= ret && ret <= WAIT_OBJECT_0 + w->num - 1) {
 389             if (w->func[ret - WAIT_OBJECT_0]) {
 390                 w->func[ret - WAIT_OBJECT_0](w->opaque[ret - WAIT_OBJECT_0]);
 391             }
 392
 393             /* Check for additional signaled events */
 394             for (i = (ret - WAIT_OBJECT_0 + 1); i < w->num; i++) {
 395                 /* Check if event is signaled */
 396                 ret2 = WaitForSingleObject(w->events[i], 0);
 397                 if (ret2 == WAIT_OBJECT_0) {
 398                     if (w->func[i]) {
 399                         w->func[i](w->opaque[i]);
 400                     }
 401                 } else if (ret2 != WAIT_TIMEOUT) {
 402                     err = GetLastError();
 403                     fprintf(stderr, "WaitForSingleObject error %d %d\n", i, err);
 404                 }
 405             }
 406         } else if (ret != WAIT_TIMEOUT) {
 407             err = GetLastError();
 408             fprintf(stderr, "WaitForMultipleObjects error %d %d\n", ret, err);
 409         }
 410     }
 411
 412     *timeout = 0;
 413 }
 414 #else
 415 static inline void os_host_main_loop_wait(int *timeout)
 416 {
 417 }
 418 #endif
 419
 420 int main_loop_wait(int nonblocking)
 421 {
 422     fd_set rfds, wfds, xfds;
 423     int ret, nfds;
 424     struct timeval tv;
 425     int timeout;
 426
 427     if (nonblocking) {
 428         timeout = 0;
 429     } else {
 430         timeout = qemu_calculate_timeout();
 431         qemu_bh_update_timeout(&timeout);
 432     }
 433
 434     os_host_main_loop_wait(&timeout);
 435
 436     tv.tv_sec = timeout / 1000;
 437     tv.tv_usec = (timeout % 1000) * 1000;
 438
 439     /* poll any events */
 440     /* XXX: separate device handlers from system ones */
 441     nfds = -1;
 442     FD_ZERO(&rfds);
 443     FD_ZERO(&wfds);
 444     FD_ZERO(&xfds);
 445
 446 #ifdef CONFIG_SLIRP
 447     slirp_select_fill(&nfds, &rfds, &wfds, &xfds);
 448 #endif
 449     qemu_iohandler_fill(&nfds, &rfds, &wfds, &xfds);
 450     glib_select_fill(&nfds, &rfds, &wfds, &xfds, &tv);
 451
 452     if (timeout > 0) {
 453         qemu_mutex_unlock_iothread();
 454     }
 455
 456     ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv);
 457
 458     if (timeout > 0) {
 459         qemu_mutex_lock_iothread();
 460     }
 461
 462     glib_select_poll(&rfds, &wfds, &xfds, (ret < 0));
 463     qemu_iohandler_poll(&rfds, &wfds, &xfds, ret);
 464 #ifdef CONFIG_SLIRP
 465     slirp_select_poll(&rfds, &wfds, &xfds, (ret < 0));
 466 #endif
 467
 468     qemu_run_all_timers();
 469
 470     /* Check bottom-halves last in case any of the earlier events triggered
 471        them.  */
 472     qemu_bh_poll();
 473
 474     return ret;
 475 }