summaryrefslogtreecommitdiff
path: root/util/main-loop.c
blob: 4534c8930844cf3105414d94488a32d73348b48d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
/*
 * QEMU System Emulator
 *
 * Copyright (c) 2003-2008 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/cutils.h"
#include "qemu/timer.h"
#include "qemu/sockets.h"	// struct in_addr needed for libslirp.h
#include "sysemu/qtest.h"
#include "sysemu/cpus.h"
#include "slirp/libslirp.h"
#include "qemu/main-loop.h"
#include "block/aio.h"

#ifndef _WIN32

/* If we have signalfd, we mask out the signals we want to handle and then
 * use signalfd to listen for them.  We rely on whatever the current signal
 * handler is to dispatch the signals when we receive them.
 */
static void sigfd_handler(void *opaque)
{
    int fd = (intptr_t)opaque;
    struct qemu_signalfd_siginfo info;
    struct sigaction action;
    ssize_t len;

    while (1) {
        do {
            len = read(fd, &info, sizeof(info));
        } while (len == -1 && errno == EINTR);

        if (len == -1 && errno == EAGAIN) {
            break;
        }

        if (len != sizeof(info)) {
            printf("read from sigfd returned %zd: %m\n", len);
            return;
        }

        sigaction(info.ssi_signo, NULL, &action);
        if ((action.sa_flags & SA_SIGINFO) && action.sa_sigaction) {
            sigaction_invoke(&action, &info);
        } else if (action.sa_handler) {
            action.sa_handler(info.ssi_signo);
        }
    }
}

static int qemu_signal_init(void)
{
    int sigfd;
    sigset_t set;

    /*
     * SIG_IPI must be blocked in the main thread and must not be caught
     * by sigwait() in the signal thread. Otherwise, the cpu thread will
     * not catch it reliably.
     */
    sigemptyset(&set);
    sigaddset(&set, SIG_IPI);
    sigaddset(&set, SIGIO);
    sigaddset(&set, SIGALRM);
    sigaddset(&set, SIGBUS);
    /* SIGINT cannot be handled via signalfd, so that ^C can be used
     * to interrupt QEMU when it is being run under gdb.  SIGHUP and
     * SIGTERM are also handled asynchronously, even though it is not
     * strictly necessary, because they use the same handler as SIGINT.
     */
    pthread_sigmask(SIG_BLOCK, &set, NULL);

    sigdelset(&set, SIG_IPI);
    sigfd = qemu_signalfd(&set);
    if (sigfd == -1) {
        fprintf(stderr, "failed to create signalfd\n");
        return -errno;
    }

    fcntl_setfl(sigfd, O_NONBLOCK);

    qemu_set_fd_handler(sigfd, sigfd_handler, NULL, (void *)(intptr_t)sigfd);

    return 0;
}

#else /* _WIN32 */

static int qemu_signal_init(void)
{
    return 0;
}
#endif

static AioContext *qemu_aio_context;
static QEMUBH *qemu_notify_bh;

static void notify_event_cb(void *opaque)
{
    /* No need to do anything; this bottom half is only used to
     * kick the kernel out of ppoll/poll/WaitForMultipleObjects.
     */
}

AioContext *qemu_get_aio_context(void)
{
    return qemu_aio_context;
}

void qemu_notify_event(void)
{
    if (!qemu_aio_context) {
        return;
    }
    qemu_bh_schedule(qemu_notify_bh);
}

static GArray *gpollfds;

int qemu_init_main_loop(Error **errp)
{
    int ret;
    GSource *src;
    Error *local_error = NULL;

    init_clocks(qemu_timer_notify_cb);

    ret = qemu_signal_init();
    if (ret) {
        return ret;
    }

    qemu_aio_context = aio_context_new(&local_error);
    if (!qemu_aio_context) {
        error_propagate(errp, local_error);
        return -EMFILE;
    }
    qemu_notify_bh = qemu_bh_new(notify_event_cb, NULL);
    gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
    src = aio_get_g_source(qemu_aio_context);
    g_source_set_name(src, "aio-context");
    g_source_attach(src, NULL);
    g_source_unref(src);
    src = iohandler_get_g_source();
    g_source_set_name(src, "io-handler");
    g_source_attach(src, NULL);
    g_source_unref(src);
    return 0;
}

static int max_priority;

#ifndef _WIN32
static int glib_pollfds_idx;
static int glib_n_poll_fds;

static void glib_pollfds_fill(int64_t *cur_timeout)
{
    GMainContext *context = g_main_context_default();
    int timeout = 0;
    int64_t timeout_ns;
    int n;

    g_main_context_prepare(context, &max_priority);

    glib_pollfds_idx = gpollfds->len;
    n = glib_n_poll_fds;
    do {
        GPollFD *pfds;
        glib_n_poll_fds = n;
        g_array_set_size(gpollfds, glib_pollfds_idx + glib_n_poll_fds);
        pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);
        n = g_main_context_query(context, max_priority, &timeout, pfds,
                                 glib_n_poll_fds);
    } while (n != glib_n_poll_fds);

    if (timeout < 0) {
        timeout_ns = -1;
    } else {
        timeout_ns = (int64_t)timeout * (int64_t)SCALE_MS;
    }

    *cur_timeout = qemu_soonest_timeout(timeout_ns, *cur_timeout);
}

static void glib_pollfds_poll(void)
{
    GMainContext *context = g_main_context_default();
    GPollFD *pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);

    if (g_main_context_check(context, max_priority, pfds, glib_n_poll_fds)) {
        g_main_context_dispatch(context);
    }
}

#define MAX_MAIN_LOOP_SPIN (1000)

static int os_host_main_loop_wait(int64_t timeout)
{
    int ret;
    static int spin_counter;

    glib_pollfds_fill(&timeout);

    /* If the I/O thread is very busy or we are incorrectly busy waiting in
     * the I/O thread, this can lead to starvation of the BQL such that the
     * VCPU threads never run.  To make sure we can detect the later case,
     * print a message to the screen.  If we run into this condition, create
     * a fake timeout in order to give the VCPU threads a chance to run.
     */
    if (!timeout && (spin_counter > MAX_MAIN_LOOP_SPIN)) {
        static bool notified;

        if (!notified && !qtest_enabled() && !qtest_driver()) {
            fprintf(stderr,
                    "main-loop: WARNING: I/O thread spun for %d iterations\n",
                    MAX_MAIN_LOOP_SPIN);
            notified = true;
        }

        timeout = SCALE_MS;
    }

    if (timeout) {
        spin_counter = 0;
        qemu_mutex_unlock_iothread();
    } else {
        spin_counter++;
    }

    ret = qemu_poll_ns((GPollFD *)gpollfds->data, gpollfds->len, timeout);

    if (timeout) {
        qemu_mutex_lock_iothread();
    }

    glib_pollfds_poll();
    return ret;
}
#else
/***********************************************************/
/* Polling handling */

typedef struct PollingEntry {
    PollingFunc *func;
    void *opaque;
    struct PollingEntry *next;
} PollingEntry;

static PollingEntry *first_polling_entry;

int qemu_add_polling_cb(PollingFunc *func, void *opaque)
{
    PollingEntry **ppe, *pe;
    pe = g_malloc0(sizeof(PollingEntry));
    pe->func = func;
    pe->opaque = opaque;
    for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next);
    *ppe = pe;
    return 0;
}

void qemu_del_polling_cb(PollingFunc *func, void *opaque)
{
    PollingEntry **ppe, *pe;
    for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) {
        pe = *ppe;
        if (pe->func == func && pe->opaque == opaque) {
            *ppe = pe->next;
            g_free(pe);
            break;
        }
    }
}

/***********************************************************/
/* Wait objects support */
typedef struct WaitObjects {
    int num;
    int revents[MAXIMUM_WAIT_OBJECTS + 1];
    HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
    WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1];
    void *opaque[MAXIMUM_WAIT_OBJECTS + 1];
} WaitObjects;

static WaitObjects wait_objects = {0};

int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
{
    WaitObjects *w = &wait_objects;
    if (w->num >= MAXIMUM_WAIT_OBJECTS) {
        return -1;
    }
    w->events[w->num] = handle;
    w->func[w->num] = func;
    w->opaque[w->num] = opaque;
    w->revents[w->num] = 0;
    w->num++;
    return 0;
}

void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
{
    int i, found;
    WaitObjects *w = &wait_objects;

    found = 0;
    for (i = 0; i < w->num; i++) {
        if (w->events[i] == handle) {
            found = 1;
        }
        if (found) {
            w->events[i] = w->events[i + 1];
            w->func[i] = w->func[i + 1];
            w->opaque[i] = w->opaque[i + 1];
            w->revents[i] = w->revents[i + 1];
        }
    }
    if (found) {
        w->num--;
    }
}

void qemu_fd_register(int fd)
{
    WSAEventSelect(fd, event_notifier_get_handle(&qemu_aio_context->notifier),
                   FD_READ | FD_ACCEPT | FD_CLOSE |
                   FD_CONNECT | FD_WRITE | FD_OOB);
}

static int pollfds_fill(GArray *pollfds, fd_set *rfds, fd_set *wfds,
                        fd_set *xfds)
{
    int nfds = -1;
    int i;

    for (i = 0; i < pollfds->len; i++) {
        GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
        int fd = pfd->fd;
        int events = pfd->events;
        if (events & G_IO_IN) {
            FD_SET(fd, rfds);
            nfds = MAX(nfds, fd);
        }
        if (events & G_IO_OUT) {
            FD_SET(fd, wfds);
            nfds = MAX(nfds, fd);
        }
        if (events & G_IO_PRI) {
            FD_SET(fd, xfds);
            nfds = MAX(nfds, fd);
        }
    }
    return nfds;
}

static void pollfds_poll(GArray *pollfds, int nfds, fd_set *rfds,
                         fd_set *wfds, fd_set *xfds)
{
    int i;

    for (i = 0; i < pollfds->len; i++) {
        GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
        int fd = pfd->fd;
        int revents = 0;

        if (FD_ISSET(fd, rfds)) {
            revents |= G_IO_IN;
        }
        if (FD_ISSET(fd, wfds)) {
            revents |= G_IO_OUT;
        }
        if (FD_ISSET(fd, xfds)) {
            revents |= G_IO_PRI;
        }
        pfd->revents = revents & pfd->events;
    }
}

static int os_host_main_loop_wait(int64_t timeout)
{
    GMainContext *context = g_main_context_default();
    GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
    int select_ret = 0;
    int g_poll_ret, ret, i, n_poll_fds;
    PollingEntry *pe;
    WaitObjects *w = &wait_objects;
    gint poll_timeout;
    int64_t poll_timeout_ns;
    static struct timeval tv0;
    fd_set rfds, wfds, xfds;
    int nfds;

    /* XXX: need to suppress polling by better using win32 events */
    ret = 0;
    for (pe = first_polling_entry; pe != NULL; pe = pe->next) {
        ret |= pe->func(pe->opaque);
    }
    if (ret != 0) {
        return ret;
    }

    FD_ZERO(&rfds);
    FD_ZERO(&wfds);
    FD_ZERO(&xfds);
    nfds = pollfds_fill(gpollfds, &rfds, &wfds, &xfds);
    if (nfds >= 0) {
        select_ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0);
        if (select_ret != 0) {
            timeout = 0;
        }
        if (select_ret > 0) {
            pollfds_poll(gpollfds, nfds, &rfds, &wfds, &xfds);
        }
    }

    g_main_context_prepare(context, &max_priority);
    n_poll_fds = g_main_context_query(context, max_priority, &poll_timeout,
                                      poll_fds, ARRAY_SIZE(poll_fds));
    g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds));

    for (i = 0; i < w->num; i++) {
        poll_fds[n_poll_fds + i].fd = (DWORD_PTR)w->events[i];
        poll_fds[n_poll_fds + i].events = G_IO_IN;
    }

    if (poll_timeout < 0) {
        poll_timeout_ns = -1;
    } else {
        poll_timeout_ns = (int64_t)poll_timeout * (int64_t)SCALE_MS;
    }

    poll_timeout_ns = qemu_soonest_timeout(poll_timeout_ns, timeout);

    qemu_mutex_unlock_iothread();
    g_poll_ret = qemu_poll_ns(poll_fds, n_poll_fds + w->num, poll_timeout_ns);

    qemu_mutex_lock_iothread();
    if (g_poll_ret > 0) {
        for (i = 0; i < w->num; i++) {
            w->revents[i] = poll_fds[n_poll_fds + i].revents;
        }
        for (i = 0; i < w->num; i++) {
            if (w->revents[i] && w->func[i]) {
                w->func[i](w->opaque[i]);
            }
        }
    }

    if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
        g_main_context_dispatch(context);
    }

    return select_ret || g_poll_ret;
}
#endif

int main_loop_wait(int nonblocking)
{
    int ret;
    uint32_t timeout = UINT32_MAX;
    int64_t timeout_ns;

    if (nonblocking) {
        timeout = 0;
    }

    /* poll any events */
    g_array_set_size(gpollfds, 0); /* reset for new iteration */
    /* XXX: separate device handlers from system ones */
#ifdef CONFIG_SLIRP
    slirp_pollfds_fill(gpollfds, &timeout);
#endif

    if (timeout == UINT32_MAX) {
        timeout_ns = -1;
    } else {
        timeout_ns = (uint64_t)timeout * (int64_t)(SCALE_MS);
    }

    timeout_ns = qemu_soonest_timeout(timeout_ns,
                                      timerlistgroup_deadline_ns(
                                          &main_loop_tlg));

    ret = os_host_main_loop_wait(timeout_ns);
#ifdef CONFIG_SLIRP
    slirp_pollfds_poll(gpollfds, (ret < 0));
#endif

    /* CPU thread can infinitely wait for event after
       missing the warp */
    qemu_start_warp_timer();
    qemu_clock_run_all_timers();

    return ret;
}

/* Functions to operate on the main QEMU AioContext.  */

QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
{
    return aio_bh_new(qemu_aio_context, cb, opaque);
}