block: move AioContext, QEMUTimer, main-loop to libqemuutil

AioContext is fairly self contained, the only dependency is QEMUTimer but
that in turn doesn't need anything else.  So move them out of block-obj-y
to avoid introducing a dependency from io/ to block-obj-y.

main-loop and its dependency iohandler also need to be moved, because
later in this series io/ will call iohandler_get_aio_context.

[Changed copyright "the QEMU team" to "other QEMU contributors" as
suggested by Daniel Berrange and agreed by Paolo.
--Stefan]

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20170213135235.12274-2-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 526 insertions, 0 deletions

diff --git a/util/main-loop.c b/util/main-loop.c
new file mode 100644
index 0000000000..ad10bca211
--- /dev/null
+++ b/util/main-loop.c
@@ -0,0 +1,526 @@
+/*
+ * 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 "slirp/libslirp.h"
+#include "qemu/main-loop.h"
+#include "block/aio.h"
+
+#ifndef _WIN32
+
+#include "qemu/compatfd.h"
+
+/* 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) {
+            action.sa_sigaction(info.ssi_signo,
+                                (siginfo_t *)&info, NULL);
+        } 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();
+
+    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);
+}