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 void qemu_notify_event(void)
 113 {
 114     if (!qemu_aio_context) {
 115         return;
 116     }
 117     aio_notify(qemu_aio_context);
 118 }
 119
 120 static GArray *gpollfds;
 121
 122 int qemu_init_main_loop(void)
 123 {
 124     int ret;
 125     GSource *src;
 126
 127     init_clocks();
 128     if (init_timer_alarm() < 0) {
 129         fprintf(stderr, "could not initialize alarm timer\n");
 130         exit(1);
 131     }
 132
 133     ret = qemu_signal_init();
 134     if (ret) {
 135         return ret;
 136     }
 137
 138     gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
 139     qemu_aio_context = aio_context_new();
 140     src = aio_get_g_source(qemu_aio_context);
 141     g_source_attach(src, NULL);
 142     g_source_unref(src);
 143     return 0;
 144 }
 145
 146 static int max_priority;
 147
 148 #ifndef _WIN32
 149 static int glib_pollfds_idx;
 150 static int glib_n_poll_fds;
 151
 152 static void glib_pollfds_fill(uint32_t *cur_timeout)
 153 {
 154     GMainContext *context = g_main_context_default();
 155     int timeout = 0;
 156     int n;
 157
 158     g_main_context_prepare(context, &max_priority);
 159
 160     glib_pollfds_idx = gpollfds->len;
 161     n = glib_n_poll_fds;
 162     do {
 163         GPollFD *pfds;
 164         glib_n_poll_fds = n;
 165         g_array_set_size(gpollfds, glib_pollfds_idx + glib_n_poll_fds);
 166         pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);
 167         n = g_main_context_query(context, max_priority, &timeout, pfds,
 168                                  glib_n_poll_fds);
 169     } while (n != glib_n_poll_fds);
 170
 171     if (timeout >= 0 && timeout < *cur_timeout) {
 172         *cur_timeout = timeout;
 173     }
 174 }
 175
 176 static void glib_pollfds_poll(void)
 177 {
 178     GMainContext *context = g_main_context_default();
 179     GPollFD *pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);
 180
 181     if (g_main_context_check(context, max_priority, pfds, glib_n_poll_fds)) {
 182         g_main_context_dispatch(context);
 183     }
 184 }
 185
 186 static int os_host_main_loop_wait(uint32_t timeout)
 187 {
 188     int ret;
 189
 190     glib_pollfds_fill(&timeout);
 191
 192     if (timeout > 0) {
 193         qemu_mutex_unlock_iothread();
 194     }
 195
 196     ret = g_poll((GPollFD *)gpollfds->data, gpollfds->len, timeout);
 197
 198     if (timeout > 0) {
 199         qemu_mutex_lock_iothread();
 200     }
 201
 202     glib_pollfds_poll();
 203     return ret;
 204 }
 205 #else
 206 /***********************************************************/
 207 /* Polling handling */
 208
 209 typedef struct PollingEntry {
 210     PollingFunc *func;
 211     void *opaque;
 212     struct PollingEntry *next;
 213 } PollingEntry;
 214
 215 static PollingEntry *first_polling_entry;
 216
 217 int qemu_add_polling_cb(PollingFunc *func, void *opaque)
 218 {
 219     PollingEntry **ppe, *pe;
 220     pe = g_malloc0(sizeof(PollingEntry));
 221     pe->func = func;
 222     pe->opaque = opaque;
 223     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next);
 224     *ppe = pe;
 225     return 0;
 226 }
 227
 228 void qemu_del_polling_cb(PollingFunc *func, void *opaque)
 229 {
 230     PollingEntry **ppe, *pe;
 231     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) {
 232         pe = *ppe;
 233         if (pe->func == func && pe->opaque == opaque) {
 234             *ppe = pe->next;
 235             g_free(pe);
 236             break;
 237         }
 238     }
 239 }
 240
 241 /***********************************************************/
 242 /* Wait objects support */
 243 typedef struct WaitObjects {
 244     int num;
 245     int revents[MAXIMUM_WAIT_OBJECTS + 1];
 246     HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
 247     WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1];
 248     void *opaque[MAXIMUM_WAIT_OBJECTS + 1];
 249 } WaitObjects;
 250
 251 static WaitObjects wait_objects = {0};
 252
 253 int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 254 {
 255     WaitObjects *w = &wait_objects;
 256     if (w->num >= MAXIMUM_WAIT_OBJECTS) {
 257         return -1;
 258     }
 259     w->events[w->num] = handle;
 260     w->func[w->num] = func;
 261     w->opaque[w->num] = opaque;
 262     w->revents[w->num] = 0;
 263     w->num++;
 264     return 0;
 265 }
 266
 267 void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 268 {
 269     int i, found;
 270     WaitObjects *w = &wait_objects;
 271
 272     found = 0;
 273     for (i = 0; i < w->num; i++) {
 274         if (w->events[i] == handle) {
 275             found = 1;
 276         }
 277         if (found) {
 278             w->events[i] = w->events[i + 1];
 279             w->func[i] = w->func[i + 1];
 280             w->opaque[i] = w->opaque[i + 1];
 281             w->revents[i] = w->revents[i + 1];
 282         }
 283     }
 284     if (found) {
 285         w->num--;
 286     }
 287 }
 288
 289 void qemu_fd_register(int fd)
 290 {
 291     WSAEventSelect(fd, event_notifier_get_handle(&qemu_aio_context->notifier),
 292                    FD_READ | FD_ACCEPT | FD_CLOSE |
 293                    FD_CONNECT | FD_WRITE | FD_OOB);
 294 }
 295
 296 static int pollfds_fill(GArray *pollfds, fd_set *rfds, fd_set *wfds,
 297                         fd_set *xfds)
 298 {
 299     int nfds = -1;
 300     int i;
 301
 302     for (i = 0; i < pollfds->len; i++) {
 303         GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
 304         int fd = pfd->fd;
 305         int events = pfd->events;
 306         if (events & (G_IO_IN | G_IO_HUP | G_IO_ERR)) {
 307             FD_SET(fd, rfds);
 308             nfds = MAX(nfds, fd);
 309         }
 310         if (events & (G_IO_OUT | G_IO_ERR)) {
 311             FD_SET(fd, wfds);
 312             nfds = MAX(nfds, fd);
 313         }
 314         if (events & G_IO_PRI) {
 315             FD_SET(fd, xfds);
 316             nfds = MAX(nfds, fd);
 317         }
 318     }
 319     return nfds;
 320 }
 321
 322 static void pollfds_poll(GArray *pollfds, int nfds, fd_set *rfds,
 323                          fd_set *wfds, fd_set *xfds)
 324 {
 325     int i;
 326
 327     for (i = 0; i < pollfds->len; i++) {
 328         GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
 329         int fd = pfd->fd;
 330         int revents = 0;
 331
 332         if (FD_ISSET(fd, rfds)) {
 333             revents |= G_IO_IN | G_IO_HUP | G_IO_ERR;
 334         }
 335         if (FD_ISSET(fd, wfds)) {
 336             revents |= G_IO_OUT | G_IO_ERR;
 337         }
 338         if (FD_ISSET(fd, xfds)) {
 339             revents |= G_IO_PRI;
 340         }
 341         pfd->revents = revents & pfd->events;
 342     }
 343 }
 344
 345 static int os_host_main_loop_wait(uint32_t timeout)
 346 {
 347     GMainContext *context = g_main_context_default();
 348     GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
 349     int select_ret = 0;
 350     int g_poll_ret, ret, i, n_poll_fds;
 351     PollingEntry *pe;
 352     WaitObjects *w = &wait_objects;
 353     gint poll_timeout;
 354     static struct timeval tv0;
 355     fd_set rfds, wfds, xfds;
 356     int nfds;
 357
 358     /* XXX: need to suppress polling by better using win32 events */
 359     ret = 0;
 360     for (pe = first_polling_entry; pe != NULL; pe = pe->next) {
 361         ret |= pe->func(pe->opaque);
 362     }
 363     if (ret != 0) {
 364         return ret;
 365     }
 366
 367     g_main_context_prepare(context, &max_priority);
 368     n_poll_fds = g_main_context_query(context, max_priority, &poll_timeout,
 369                                       poll_fds, ARRAY_SIZE(poll_fds));
 370     g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds));
 371
 372     for (i = 0; i < w->num; i++) {
 373         poll_fds[n_poll_fds + i].fd = (DWORD_PTR)w->events[i];
 374         poll_fds[n_poll_fds + i].events = G_IO_IN;
 375     }
 376
 377     if (poll_timeout < 0 || timeout < poll_timeout) {
 378         poll_timeout = timeout;
 379     }
 380
 381     qemu_mutex_unlock_iothread();
 382     g_poll_ret = g_poll(poll_fds, n_poll_fds + w->num, poll_timeout);
 383     qemu_mutex_lock_iothread();
 384     if (g_poll_ret > 0) {
 385         for (i = 0; i < w->num; i++) {
 386             w->revents[i] = poll_fds[n_poll_fds + i].revents;
 387         }
 388         for (i = 0; i < w->num; i++) {
 389             if (w->revents[i] && w->func[i]) {
 390                 w->func[i](w->opaque[i]);
 391             }
 392         }
 393     }
 394
 395     if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
 396         g_main_context_dispatch(context);
 397     }
 398
 399     /* Call select after g_poll to avoid a useless iteration and therefore
 400      * improve socket latency.
 401      */
 402
 403     FD_ZERO(&rfds);
 404     FD_ZERO(&wfds);
 405     FD_ZERO(&xfds);
 406     nfds = pollfds_fill(gpollfds, &rfds, &wfds, &xfds);
 407     if (nfds >= 0) {
 408         select_ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0);
 409         if (select_ret != 0) {
 410             timeout = 0;
 411         }
 412         if (select_ret > 0) {
 413             pollfds_poll(gpollfds, nfds, &rfds, &wfds, &xfds);
 414         }
 415     }
 416
 417     return select_ret || g_poll_ret;
 418 }
 419 #endif
 420
 421 int main_loop_wait(int nonblocking)
 422 {
 423     int ret;
 424     uint32_t timeout = UINT32_MAX;
 425
 426     if (nonblocking) {
 427         timeout = 0;
 428     }
 429
 430     /* poll any events */
 431     g_array_set_size(gpollfds, 0); /* reset for new iteration */
 432     /* XXX: separate device handlers from system ones */
 433 #ifdef CONFIG_SLIRP
 434     slirp_update_timeout(&timeout);
 435     slirp_pollfds_fill(gpollfds);
 436 #endif
 437     qemu_iohandler_fill(gpollfds);
 438     ret = os_host_main_loop_wait(timeout);
 439     qemu_iohandler_poll(gpollfds, ret);
 440 #ifdef CONFIG_SLIRP
 441     slirp_pollfds_poll(gpollfds, (ret < 0));
 442 #endif
 443
 444     qemu_run_all_timers();
 445
 446     return ret;
 447 }
 448
 449 /* Functions to operate on the main QEMU AioContext.  */
 450
 451 QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
 452 {
 453     return aio_bh_new(qemu_aio_context, cb, opaque);
 454 }
 455
 456 bool qemu_aio_wait(void)
 457 {
 458     return aio_poll(qemu_aio_context, true);
 459 }
 460
 461 #ifdef CONFIG_POSIX
 462 void qemu_aio_set_fd_handler(int fd,
 463                              IOHandler *io_read,
 464                              IOHandler *io_write,
 465                              AioFlushHandler *io_flush,
 466                              void *opaque)
 467 {
 468     aio_set_fd_handler(qemu_aio_context, fd, io_read, io_write, io_flush,
 469                        opaque);
 470 }
 471 #endif
 472
 473 void qemu_aio_set_event_notifier(EventNotifier *notifier,
 474                                  EventNotifierHandler *io_read,
 475                                  AioFlushEventNotifierHandler *io_flush)
 476 {
 477     aio_set_event_notifier(qemu_aio_context, notifier, io_read, io_flush);
 478 }