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 int qemu_init_main_loop(void)
 121 {
 122     int ret;
 123     GSource *src;
 124
 125     init_clocks();
 126     if (init_timer_alarm() < 0) {
 127         fprintf(stderr, "could not initialize alarm timer\n");
 128         exit(1);
 129     }
 130
 131     ret = qemu_signal_init();
 132     if (ret) {
 133         return ret;
 134     }
 135
 136     qemu_aio_context = aio_context_new();
 137     src = aio_get_g_source(qemu_aio_context);
 138     g_source_attach(src, NULL);
 139     g_source_unref(src);
 140     return 0;
 141 }
 142
 143 static fd_set rfds, wfds, xfds;
 144 static int nfds;
 145 static GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
 146 static int n_poll_fds;
 147 static int max_priority;
 148
 149 #ifndef _WIN32
 150 static void glib_select_fill(int *max_fd, fd_set *rfds, fd_set *wfds,
 151                              fd_set *xfds, uint32_t *cur_timeout)
 152 {
 153     GMainContext *context = g_main_context_default();
 154     int i;
 155     int timeout = 0;
 156
 157     g_main_context_prepare(context, &max_priority);
 158
 159     n_poll_fds = g_main_context_query(context, max_priority, &timeout,
 160                                       poll_fds, ARRAY_SIZE(poll_fds));
 161     g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds));
 162
 163     for (i = 0; i < n_poll_fds; i++) {
 164         GPollFD *p = &poll_fds[i];
 165
 166         if ((p->events & G_IO_IN)) {
 167             FD_SET(p->fd, rfds);
 168             *max_fd = MAX(*max_fd, p->fd);
 169         }
 170         if ((p->events & G_IO_OUT)) {
 171             FD_SET(p->fd, wfds);
 172             *max_fd = MAX(*max_fd, p->fd);
 173         }
 174         if ((p->events & G_IO_ERR)) {
 175             FD_SET(p->fd, xfds);
 176             *max_fd = MAX(*max_fd, p->fd);
 177         }
 178     }
 179
 180     if (timeout >= 0 && timeout < *cur_timeout) {
 181         *cur_timeout = timeout;
 182     }
 183 }
 184
 185 static void glib_select_poll(fd_set *rfds, fd_set *wfds, fd_set *xfds,
 186                              bool err)
 187 {
 188     GMainContext *context = g_main_context_default();
 189
 190     if (!err) {
 191         int i;
 192
 193         for (i = 0; i < n_poll_fds; i++) {
 194             GPollFD *p = &poll_fds[i];
 195
 196             if ((p->events & G_IO_IN) && FD_ISSET(p->fd, rfds)) {
 197                 p->revents |= G_IO_IN;
 198             }
 199             if ((p->events & G_IO_OUT) && FD_ISSET(p->fd, wfds)) {
 200                 p->revents |= G_IO_OUT;
 201             }
 202             if ((p->events & G_IO_ERR) && FD_ISSET(p->fd, xfds)) {
 203                 p->revents |= G_IO_ERR;
 204             }
 205         }
 206     }
 207
 208     if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
 209         g_main_context_dispatch(context);
 210     }
 211 }
 212
 213 static int os_host_main_loop_wait(uint32_t timeout)
 214 {
 215     struct timeval tv, *tvarg = NULL;
 216     int ret;
 217
 218     glib_select_fill(&nfds, &rfds, &wfds, &xfds, &timeout);
 219
 220     if (timeout < UINT32_MAX) {
 221         tvarg = &tv;
 222         tv.tv_sec = timeout / 1000;
 223         tv.tv_usec = (timeout % 1000) * 1000;
 224     }
 225
 226     if (timeout > 0) {
 227         qemu_mutex_unlock_iothread();
 228     }
 229
 230     ret = select(nfds + 1, &rfds, &wfds, &xfds, tvarg);
 231
 232     if (timeout > 0) {
 233         qemu_mutex_lock_iothread();
 234     }
 235
 236     glib_select_poll(&rfds, &wfds, &xfds, (ret < 0));
 237     return ret;
 238 }
 239 #else
 240 /***********************************************************/
 241 /* Polling handling */
 242
 243 typedef struct PollingEntry {
 244     PollingFunc *func;
 245     void *opaque;
 246     struct PollingEntry *next;
 247 } PollingEntry;
 248
 249 static PollingEntry *first_polling_entry;
 250
 251 int qemu_add_polling_cb(PollingFunc *func, void *opaque)
 252 {
 253     PollingEntry **ppe, *pe;
 254     pe = g_malloc0(sizeof(PollingEntry));
 255     pe->func = func;
 256     pe->opaque = opaque;
 257     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next);
 258     *ppe = pe;
 259     return 0;
 260 }
 261
 262 void qemu_del_polling_cb(PollingFunc *func, void *opaque)
 263 {
 264     PollingEntry **ppe, *pe;
 265     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) {
 266         pe = *ppe;
 267         if (pe->func == func && pe->opaque == opaque) {
 268             *ppe = pe->next;
 269             g_free(pe);
 270             break;
 271         }
 272     }
 273 }
 274
 275 /***********************************************************/
 276 /* Wait objects support */
 277 typedef struct WaitObjects {
 278     int num;
 279     int revents[MAXIMUM_WAIT_OBJECTS + 1];
 280     HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
 281     WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1];
 282     void *opaque[MAXIMUM_WAIT_OBJECTS + 1];
 283 } WaitObjects;
 284
 285 static WaitObjects wait_objects = {0};
 286
 287 int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 288 {
 289     WaitObjects *w = &wait_objects;
 290     if (w->num >= MAXIMUM_WAIT_OBJECTS) {
 291         return -1;
 292     }
 293     w->events[w->num] = handle;
 294     w->func[w->num] = func;
 295     w->opaque[w->num] = opaque;
 296     w->revents[w->num] = 0;
 297     w->num++;
 298     return 0;
 299 }
 300
 301 void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 302 {
 303     int i, found;
 304     WaitObjects *w = &wait_objects;
 305
 306     found = 0;
 307     for (i = 0; i < w->num; i++) {
 308         if (w->events[i] == handle) {
 309             found = 1;
 310         }
 311         if (found) {
 312             w->events[i] = w->events[i + 1];
 313             w->func[i] = w->func[i + 1];
 314             w->opaque[i] = w->opaque[i + 1];
 315             w->revents[i] = w->revents[i + 1];
 316         }
 317     }
 318     if (found) {
 319         w->num--;
 320     }
 321 }
 322
 323 void qemu_fd_register(int fd)
 324 {
 325     WSAEventSelect(fd, event_notifier_get_handle(&qemu_aio_context->notifier),
 326                    FD_READ | FD_ACCEPT | FD_CLOSE |
 327                    FD_CONNECT | FD_WRITE | FD_OOB);
 328 }
 329
 330 static int os_host_main_loop_wait(uint32_t timeout)
 331 {
 332     GMainContext *context = g_main_context_default();
 333     int select_ret, g_poll_ret, ret, i;
 334     PollingEntry *pe;
 335     WaitObjects *w = &wait_objects;
 336     gint poll_timeout;
 337     static struct timeval tv0;
 338
 339     /* XXX: need to suppress polling by better using win32 events */
 340     ret = 0;
 341     for (pe = first_polling_entry; pe != NULL; pe = pe->next) {
 342         ret |= pe->func(pe->opaque);
 343     }
 344     if (ret != 0) {
 345         return ret;
 346     }
 347
 348     g_main_context_prepare(context, &max_priority);
 349     n_poll_fds = g_main_context_query(context, max_priority, &poll_timeout,
 350                                       poll_fds, ARRAY_SIZE(poll_fds));
 351     g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds));
 352
 353     for (i = 0; i < w->num; i++) {
 354         poll_fds[n_poll_fds + i].fd = (DWORD_PTR)w->events[i];
 355         poll_fds[n_poll_fds + i].events = G_IO_IN;
 356     }
 357
 358     if (poll_timeout < 0 || timeout < poll_timeout) {
 359         poll_timeout = timeout;
 360     }
 361
 362     qemu_mutex_unlock_iothread();
 363     g_poll_ret = g_poll(poll_fds, n_poll_fds + w->num, poll_timeout);
 364     qemu_mutex_lock_iothread();
 365     if (g_poll_ret > 0) {
 366         for (i = 0; i < w->num; i++) {
 367             w->revents[i] = poll_fds[n_poll_fds + i].revents;
 368         }
 369         for (i = 0; i < w->num; i++) {
 370             if (w->revents[i] && w->func[i]) {
 371                 w->func[i](w->opaque[i]);
 372             }
 373         }
 374     }
 375
 376     if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
 377         g_main_context_dispatch(context);
 378     }
 379
 380     /* Call select after g_poll to avoid a useless iteration and therefore
 381      * improve socket latency.
 382      */
 383
 384     if (nfds >= 0) {
 385         select_ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0);
 386         if (select_ret != 0) {
 387             timeout = 0;
 388         }
 389     }
 390
 391     return select_ret || g_poll_ret;
 392 }
 393 #endif
 394
 395 int main_loop_wait(int nonblocking)
 396 {
 397     int ret;
 398     uint32_t timeout = UINT32_MAX;
 399
 400     if (nonblocking) {
 401         timeout = 0;
 402     }
 403
 404     /* poll any events */
 405     /* XXX: separate device handlers from system ones */
 406     nfds = -1;
 407     FD_ZERO(&rfds);
 408     FD_ZERO(&wfds);
 409     FD_ZERO(&xfds);
 410
 411 #ifdef CONFIG_SLIRP
 412     slirp_update_timeout(&timeout);
 413     slirp_select_fill(&nfds, &rfds, &wfds, &xfds);
 414 #endif
 415     qemu_iohandler_fill(&nfds, &rfds, &wfds, &xfds);
 416     ret = os_host_main_loop_wait(timeout);
 417     qemu_iohandler_poll(&rfds, &wfds, &xfds, ret);
 418 #ifdef CONFIG_SLIRP
 419     slirp_select_poll(&rfds, &wfds, &xfds, (ret < 0));
 420 #endif
 421
 422     qemu_run_all_timers();
 423
 424     return ret;
 425 }
 426
 427 /* Functions to operate on the main QEMU AioContext.  */
 428
 429 QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
 430 {
 431     return aio_bh_new(qemu_aio_context, cb, opaque);
 432 }
 433
 434 bool qemu_aio_wait(void)
 435 {
 436     return aio_poll(qemu_aio_context, true);
 437 }
 438
 439 #ifdef CONFIG_POSIX
 440 void qemu_aio_set_fd_handler(int fd,
 441                              IOHandler *io_read,
 442                              IOHandler *io_write,
 443                              AioFlushHandler *io_flush,
 444                              void *opaque)
 445 {
 446     aio_set_fd_handler(qemu_aio_context, fd, io_read, io_write, io_flush,
 447                        opaque);
 448 }
 449 #endif
 450
 451 void qemu_aio_set_event_notifier(EventNotifier *notifier,
 452                                  EventNotifierHandler *io_read,
 453                                  AioFlushEventNotifierHandler *io_flush)
 454 {
 455     aio_set_event_notifier(qemu_aio_context, notifier, io_read, io_flush);
 456 }