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 "qemu/main-loop.h"
  29 #include "block/aio.h"
  30
  31 #ifndef _WIN32
  32
  33 #include "qemu/compatfd.h"
  34
  35 /* If we have signalfd, we mask out the signals we want to handle and then
  36  * use signalfd to listen for them.  We rely on whatever the current signal
  37  * handler is to dispatch the signals when we receive them.
  38  */
  39 static void sigfd_handler(void *opaque)
  40 {
  41     int fd = (intptr_t)opaque;
  42     struct qemu_signalfd_siginfo info;
  43     struct sigaction action;
  44     ssize_t len;
  45
  46     while (1) {
  47         do {
  48             len = read(fd, &info, sizeof(info));
  49         } while (len == -1 && errno == EINTR);
  50
  51         if (len == -1 && errno == EAGAIN) {
  52             break;
  53         }
  54
  55         if (len != sizeof(info)) {
  56             printf("read from sigfd returned %zd: %m\n", len);
  57             return;
  58         }
  59
  60         sigaction(info.ssi_signo, NULL, &action);
  61         if ((action.sa_flags & SA_SIGINFO) && action.sa_sigaction) {
  62             action.sa_sigaction(info.ssi_signo,
  63                                 (siginfo_t *)&info, NULL);
  64         } else if (action.sa_handler) {
  65             action.sa_handler(info.ssi_signo);
  66         }
  67     }
  68 }
  69
  70 static int qemu_signal_init(void)
  71 {
  72     int sigfd;
  73     sigset_t set;
  74
  75     /*
  76      * SIG_IPI must be blocked in the main thread and must not be caught
  77      * by sigwait() in the signal thread. Otherwise, the cpu thread will
  78      * not catch it reliably.
  79      */
  80     sigemptyset(&set);
  81     sigaddset(&set, SIG_IPI);
  82     sigaddset(&set, SIGIO);
  83     sigaddset(&set, SIGALRM);
  84     sigaddset(&set, SIGBUS);
  85     pthread_sigmask(SIG_BLOCK, &set, NULL);
  86
  87     sigdelset(&set, SIG_IPI);
  88     sigfd = qemu_signalfd(&set);
  89     if (sigfd == -1) {
  90         fprintf(stderr, "failed to create signalfd\n");
  91         return -errno;
  92     }
  93
  94     fcntl_setfl(sigfd, O_NONBLOCK);
  95
  96     qemu_set_fd_handler2(sigfd, NULL, sigfd_handler, NULL,
  97                          (void *)(intptr_t)sigfd);
  98
  99     return 0;
 100 }
 101
 102 #else /* _WIN32 */
 103
 104 static int qemu_signal_init(void)
 105 {
 106     return 0;
 107 }
 108 #endif
 109
 110 static AioContext *qemu_aio_context;
 111
 112 AioContext *qemu_get_aio_context(void)
 113 {
 114     return qemu_aio_context;
 115 }
 116
 117 void qemu_notify_event(void)
 118 {
 119     if (!qemu_aio_context) {
 120         return;
 121     }
 122     aio_notify(qemu_aio_context);
 123 }
 124
 125 static GArray *gpollfds;
 126
 127 int qemu_init_main_loop(void)
 128 {
 129     int ret;
 130     GSource *src;
 131
 132     init_clocks();
 133     if (init_timer_alarm() < 0) {
 134         fprintf(stderr, "could not initialize alarm timer\n");
 135         exit(1);
 136     }
 137
 138     ret = qemu_signal_init();
 139     if (ret) {
 140         return ret;
 141     }
 142
 143     gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
 144     qemu_aio_context = aio_context_new();
 145     src = aio_get_g_source(qemu_aio_context);
 146     g_source_attach(src, NULL);
 147     g_source_unref(src);
 148     return 0;
 149 }
 150
 151 static int max_priority;
 152
 153 #ifndef _WIN32
 154 static int glib_pollfds_idx;
 155 static int glib_n_poll_fds;
 156
 157 static void glib_pollfds_fill(uint32_t *cur_timeout)
 158 {
 159     GMainContext *context = g_main_context_default();
 160     int timeout = 0;
 161     int n;
 162
 163     g_main_context_prepare(context, &max_priority);
 164
 165     glib_pollfds_idx = gpollfds->len;
 166     n = glib_n_poll_fds;
 167     do {
 168         GPollFD *pfds;
 169         glib_n_poll_fds = n;
 170         g_array_set_size(gpollfds, glib_pollfds_idx + glib_n_poll_fds);
 171         pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);
 172         n = g_main_context_query(context, max_priority, &timeout, pfds,
 173                                  glib_n_poll_fds);
 174     } while (n != glib_n_poll_fds);
 175
 176     if (timeout >= 0 && timeout < *cur_timeout) {
 177         *cur_timeout = timeout;
 178     }
 179 }
 180
 181 static void glib_pollfds_poll(void)
 182 {
 183     GMainContext *context = g_main_context_default();
 184     GPollFD *pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);
 185
 186     if (g_main_context_check(context, max_priority, pfds, glib_n_poll_fds)) {
 187         g_main_context_dispatch(context);
 188     }
 189 }
 190
 191 static int os_host_main_loop_wait(uint32_t timeout)
 192 {
 193     int ret;
 194
 195     glib_pollfds_fill(&timeout);
 196
 197     if (timeout > 0) {
 198         qemu_mutex_unlock_iothread();
 199     }
 200
 201     ret = g_poll((GPollFD *)gpollfds->data, gpollfds->len, timeout);
 202
 203     if (timeout > 0) {
 204         qemu_mutex_lock_iothread();
 205     }
 206
 207     glib_pollfds_poll();
 208     return ret;
 209 }
 210 #else
 211 /***********************************************************/
 212 /* Polling handling */
 213
 214 typedef struct PollingEntry {
 215     PollingFunc *func;
 216     void *opaque;
 217     struct PollingEntry *next;
 218 } PollingEntry;
 219
 220 static PollingEntry *first_polling_entry;
 221
 222 int qemu_add_polling_cb(PollingFunc *func, void *opaque)
 223 {
 224     PollingEntry **ppe, *pe;
 225     pe = g_malloc0(sizeof(PollingEntry));
 226     pe->func = func;
 227     pe->opaque = opaque;
 228     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next);
 229     *ppe = pe;
 230     return 0;
 231 }
 232
 233 void qemu_del_polling_cb(PollingFunc *func, void *opaque)
 234 {
 235     PollingEntry **ppe, *pe;
 236     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) {
 237         pe = *ppe;
 238         if (pe->func == func && pe->opaque == opaque) {
 239             *ppe = pe->next;
 240             g_free(pe);
 241             break;
 242         }
 243     }
 244 }
 245
 246 /***********************************************************/
 247 /* Wait objects support */
 248 typedef struct WaitObjects {
 249     int num;
 250     int revents[MAXIMUM_WAIT_OBJECTS + 1];
 251     HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
 252     WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1];
 253     void *opaque[MAXIMUM_WAIT_OBJECTS + 1];
 254 } WaitObjects;
 255
 256 static WaitObjects wait_objects = {0};
 257
 258 int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 259 {
 260     WaitObjects *w = &wait_objects;
 261     if (w->num >= MAXIMUM_WAIT_OBJECTS) {
 262         return -1;
 263     }
 264     w->events[w->num] = handle;
 265     w->func[w->num] = func;
 266     w->opaque[w->num] = opaque;
 267     w->revents[w->num] = 0;
 268     w->num++;
 269     return 0;
 270 }
 271
 272 void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 273 {
 274     int i, found;
 275     WaitObjects *w = &wait_objects;
 276
 277     found = 0;
 278     for (i = 0; i < w->num; i++) {
 279         if (w->events[i] == handle) {
 280             found = 1;
 281         }
 282         if (found) {
 283             w->events[i] = w->events[i + 1];
 284             w->func[i] = w->func[i + 1];
 285             w->opaque[i] = w->opaque[i + 1];
 286             w->revents[i] = w->revents[i + 1];
 287         }
 288     }
 289     if (found) {
 290         w->num--;
 291     }
 292 }
 293
 294 void qemu_fd_register(int fd)
 295 {
 296     WSAEventSelect(fd, event_notifier_get_handle(&qemu_aio_context->notifier),
 297                    FD_READ | FD_ACCEPT | FD_CLOSE |
 298                    FD_CONNECT | FD_WRITE | FD_OOB);
 299 }
 300
 301 static int pollfds_fill(GArray *pollfds, fd_set *rfds, fd_set *wfds,
 302                         fd_set *xfds)
 303 {
 304     int nfds = -1;
 305     int i;
 306
 307     for (i = 0; i < pollfds->len; i++) {
 308         GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
 309         int fd = pfd->fd;
 310         int events = pfd->events;
 311         if (events & (G_IO_IN | G_IO_HUP | G_IO_ERR)) {
 312             FD_SET(fd, rfds);
 313             nfds = MAX(nfds, fd);
 314         }
 315         if (events & (G_IO_OUT | G_IO_ERR)) {
 316             FD_SET(fd, wfds);
 317             nfds = MAX(nfds, fd);
 318         }
 319         if (events & G_IO_PRI) {
 320             FD_SET(fd, xfds);
 321             nfds = MAX(nfds, fd);
 322         }
 323     }
 324     return nfds;
 325 }
 326
 327 static void pollfds_poll(GArray *pollfds, int nfds, fd_set *rfds,
 328                          fd_set *wfds, fd_set *xfds)
 329 {
 330     int i;
 331
 332     for (i = 0; i < pollfds->len; i++) {
 333         GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
 334         int fd = pfd->fd;
 335         int revents = 0;
 336
 337         if (FD_ISSET(fd, rfds)) {
 338             revents |= G_IO_IN | G_IO_HUP | G_IO_ERR;
 339         }
 340         if (FD_ISSET(fd, wfds)) {
 341             revents |= G_IO_OUT | G_IO_ERR;
 342         }
 343         if (FD_ISSET(fd, xfds)) {
 344             revents |= G_IO_PRI;
 345         }
 346         pfd->revents = revents & pfd->events;
 347     }
 348 }
 349
 350 static int os_host_main_loop_wait(uint32_t timeout)
 351 {
 352     GMainContext *context = g_main_context_default();
 353     GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
 354     int select_ret = 0;
 355     int g_poll_ret, ret, i, n_poll_fds;
 356     PollingEntry *pe;
 357     WaitObjects *w = &wait_objects;
 358     gint poll_timeout;
 359     static struct timeval tv0;
 360     fd_set rfds, wfds, xfds;
 361     int nfds;
 362
 363     /* XXX: need to suppress polling by better using win32 events */
 364     ret = 0;
 365     for (pe = first_polling_entry; pe != NULL; pe = pe->next) {
 366         ret |= pe->func(pe->opaque);
 367     }
 368     if (ret != 0) {
 369         return ret;
 370     }
 371
 372     g_main_context_prepare(context, &max_priority);
 373     n_poll_fds = g_main_context_query(context, max_priority, &poll_timeout,
 374                                       poll_fds, ARRAY_SIZE(poll_fds));
 375     g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds));
 376
 377     for (i = 0; i < w->num; i++) {
 378         poll_fds[n_poll_fds + i].fd = (DWORD_PTR)w->events[i];
 379         poll_fds[n_poll_fds + i].events = G_IO_IN;
 380     }
 381
 382     if (poll_timeout < 0 || timeout < poll_timeout) {
 383         poll_timeout = timeout;
 384     }
 385
 386     qemu_mutex_unlock_iothread();
 387     g_poll_ret = g_poll(poll_fds, n_poll_fds + w->num, poll_timeout);
 388     qemu_mutex_lock_iothread();
 389     if (g_poll_ret > 0) {
 390         for (i = 0; i < w->num; i++) {
 391             w->revents[i] = poll_fds[n_poll_fds + i].revents;
 392         }
 393         for (i = 0; i < w->num; i++) {
 394             if (w->revents[i] && w->func[i]) {
 395                 w->func[i](w->opaque[i]);
 396             }
 397         }
 398     }
 399
 400     if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
 401         g_main_context_dispatch(context);
 402     }
 403
 404     /* Call select after g_poll to avoid a useless iteration and therefore
 405      * improve socket latency.
 406      */
 407
 408     FD_ZERO(&rfds);
 409     FD_ZERO(&wfds);
 410     FD_ZERO(&xfds);
 411     nfds = pollfds_fill(gpollfds, &rfds, &wfds, &xfds);
 412     if (nfds >= 0) {
 413         select_ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0);
 414         if (select_ret != 0) {
 415             timeout = 0;
 416         }
 417         if (select_ret > 0) {
 418             pollfds_poll(gpollfds, nfds, &rfds, &wfds, &xfds);
 419         }
 420     }
 421
 422     return select_ret || g_poll_ret;
 423 }
 424 #endif
 425
 426 int main_loop_wait(int nonblocking)
 427 {
 428     int ret;
 429     uint32_t timeout = UINT32_MAX;
 430
 431     if (nonblocking) {
 432         timeout = 0;
 433     }
 434
 435     /* poll any events */
 436     g_array_set_size(gpollfds, 0); /* reset for new iteration */
 437     /* XXX: separate device handlers from system ones */
 438 #ifdef CONFIG_SLIRP
 439     slirp_update_timeout(&timeout);
 440     slirp_pollfds_fill(gpollfds);
 441 #endif
 442     qemu_iohandler_fill(gpollfds);
 443     ret = os_host_main_loop_wait(timeout);
 444     qemu_iohandler_poll(gpollfds, ret);
 445 #ifdef CONFIG_SLIRP
 446     slirp_pollfds_poll(gpollfds, (ret < 0));
 447 #endif
 448
 449     qemu_run_all_timers();
 450
 451     return ret;
 452 }
 453
 454 /* Functions to operate on the main QEMU AioContext.  */
 455
 456 QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
 457 {
 458     return aio_bh_new(qemu_aio_context, cb, opaque);
 459 }
 460
 461 bool qemu_aio_wait(void)
 462 {
 463     return aio_poll(qemu_aio_context, true);
 464 }
 465
 466 #ifdef CONFIG_POSIX
 467 void qemu_aio_set_fd_handler(int fd,
 468                              IOHandler *io_read,
 469                              IOHandler *io_write,
 470                              AioFlushHandler *io_flush,
 471                              void *opaque)
 472 {
 473     aio_set_fd_handler(qemu_aio_context, fd, io_read, io_write, io_flush,
 474                        opaque);
 475 }
 476 #endif
 477
 478 void qemu_aio_set_event_notifier(EventNotifier *notifier,
 479                                  EventNotifierHandler *io_read,
 480                                  AioFlushEventNotifierHandler *io_flush)
 481 {
 482     aio_set_event_notifier(qemu_aio_context, notifier, io_read, io_flush);
 483 }