Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 632 insertions, 0 deletions

diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
new file mode 100644
index 000000000..e1225b63b
--- /dev/null
+++ b/util/qemu-thread-posix.c
@@ -0,0 +1,632 @@
+/*
+ * Wrappers around mutex/cond/thread functions
+ *
+ * Copyright Red Hat, Inc. 2009
+ *
+ * Author:
+ *  Marcelo Tosatti <mtosatti@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+#include "qemu/osdep.h"
+#include "qemu/thread.h"
+#include "qemu/atomic.h"
+#include "qemu/notify.h"
+#include "qemu-thread-common.h"
+#include "qemu/tsan.h"
+
+static bool name_threads;
+
+void qemu_thread_naming(bool enable)
+{
+    name_threads = enable;
+
+#if !defined CONFIG_PTHREAD_SETNAME_NP_W_TID && \
+    !defined CONFIG_PTHREAD_SETNAME_NP_WO_TID
+    /* This is a debugging option, not fatal */
+    if (enable) {
+        fprintf(stderr, "qemu: thread naming not supported on this host\n");
+    }
+#endif
+}
+
+static void error_exit(int err, const char *msg)
+{
+    fprintf(stderr, "qemu: %s: %s\n", msg, strerror(err));
+    abort();
+}
+
+static void compute_abs_deadline(struct timespec *ts, int ms)
+{
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    ts->tv_nsec = tv.tv_usec * 1000 + (ms % 1000) * 1000000;
+    ts->tv_sec = tv.tv_sec + ms / 1000;
+    if (ts->tv_nsec >= 1000000000) {
+        ts->tv_sec++;
+        ts->tv_nsec -= 1000000000;
+    }
+}
+
+void qemu_mutex_init(QemuMutex *mutex)
+{
+    int err;
+
+    err = pthread_mutex_init(&mutex->lock, NULL);
+    if (err)
+        error_exit(err, __func__);
+    qemu_mutex_post_init(mutex);
+}
+
+void qemu_mutex_destroy(QemuMutex *mutex)
+{
+    int err;
+
+    assert(mutex->initialized);
+    mutex->initialized = false;
+    err = pthread_mutex_destroy(&mutex->lock);
+    if (err)
+        error_exit(err, __func__);
+}
+
+void qemu_mutex_lock_impl(QemuMutex *mutex, const char *file, const int line)
+{
+    int err;
+
+    assert(mutex->initialized);
+    qemu_mutex_pre_lock(mutex, file, line);
+    err = pthread_mutex_lock(&mutex->lock);
+    if (err)
+        error_exit(err, __func__);
+    qemu_mutex_post_lock(mutex, file, line);
+}
+
+int qemu_mutex_trylock_impl(QemuMutex *mutex, const char *file, const int line)
+{
+    int err;
+
+    assert(mutex->initialized);
+    err = pthread_mutex_trylock(&mutex->lock);
+    if (err == 0) {
+        qemu_mutex_post_lock(mutex, file, line);
+        return 0;
+    }
+    if (err != EBUSY) {
+        error_exit(err, __func__);
+    }
+    return -EBUSY;
+}
+
+void qemu_mutex_unlock_impl(QemuMutex *mutex, const char *file, const int line)
+{
+    int err;
+
+    assert(mutex->initialized);
+    qemu_mutex_pre_unlock(mutex, file, line);
+    err = pthread_mutex_unlock(&mutex->lock);
+    if (err)
+        error_exit(err, __func__);
+}
+
+void qemu_rec_mutex_init(QemuRecMutex *mutex)
+{
+    int err;
+    pthread_mutexattr_t attr;
+
+    pthread_mutexattr_init(&attr);
+    pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+    err = pthread_mutex_init(&mutex->m.lock, &attr);
+    pthread_mutexattr_destroy(&attr);
+    if (err) {
+        error_exit(err, __func__);
+    }
+    mutex->m.initialized = true;
+}
+
+void qemu_rec_mutex_destroy(QemuRecMutex *mutex)
+{
+    qemu_mutex_destroy(&mutex->m);
+}
+
+void qemu_rec_mutex_lock_impl(QemuRecMutex *mutex, const char *file, int line)
+{
+    qemu_mutex_lock_impl(&mutex->m, file, line);
+}
+
+int qemu_rec_mutex_trylock_impl(QemuRecMutex *mutex, const char *file, int line)
+{
+    return qemu_mutex_trylock_impl(&mutex->m, file, line);
+}
+
+void qemu_rec_mutex_unlock_impl(QemuRecMutex *mutex, const char *file, int line)
+{
+    qemu_mutex_unlock_impl(&mutex->m, file, line);
+}
+
+void qemu_cond_init(QemuCond *cond)
+{
+    int err;
+
+    err = pthread_cond_init(&cond->cond, NULL);
+    if (err)
+        error_exit(err, __func__);
+    cond->initialized = true;
+}
+
+void qemu_cond_destroy(QemuCond *cond)
+{
+    int err;
+
+    assert(cond->initialized);
+    cond->initialized = false;
+    err = pthread_cond_destroy(&cond->cond);
+    if (err)
+        error_exit(err, __func__);
+}
+
+void qemu_cond_signal(QemuCond *cond)
+{
+    int err;
+
+    assert(cond->initialized);
+    err = pthread_cond_signal(&cond->cond);
+    if (err)
+        error_exit(err, __func__);
+}
+
+void qemu_cond_broadcast(QemuCond *cond)
+{
+    int err;
+
+    assert(cond->initialized);
+    err = pthread_cond_broadcast(&cond->cond);
+    if (err)
+        error_exit(err, __func__);
+}
+
+void qemu_cond_wait_impl(QemuCond *cond, QemuMutex *mutex, const char *file, const int line)
+{
+    int err;
+
+    assert(cond->initialized);
+    qemu_mutex_pre_unlock(mutex, file, line);
+    err = pthread_cond_wait(&cond->cond, &mutex->lock);
+    qemu_mutex_post_lock(mutex, file, line);
+    if (err)
+        error_exit(err, __func__);
+}
+
+bool qemu_cond_timedwait_impl(QemuCond *cond, QemuMutex *mutex, int ms,
+                              const char *file, const int line)
+{
+    int err;
+    struct timespec ts;
+
+    assert(cond->initialized);
+    trace_qemu_mutex_unlock(mutex, file, line);
+    compute_abs_deadline(&ts, ms);
+    err = pthread_cond_timedwait(&cond->cond, &mutex->lock, &ts);
+    trace_qemu_mutex_locked(mutex, file, line);
+    if (err && err != ETIMEDOUT) {
+        error_exit(err, __func__);
+    }
+    return err != ETIMEDOUT;
+}
+
+void qemu_sem_init(QemuSemaphore *sem, int init)
+{
+    int rc;
+
+#ifndef CONFIG_SEM_TIMEDWAIT
+    rc = pthread_mutex_init(&sem->lock, NULL);
+    if (rc != 0) {
+        error_exit(rc, __func__);
+    }
+    rc = pthread_cond_init(&sem->cond, NULL);
+    if (rc != 0) {
+        error_exit(rc, __func__);
+    }
+    if (init < 0) {
+        error_exit(EINVAL, __func__);
+    }
+    sem->count = init;
+#else
+    rc = sem_init(&sem->sem, 0, init);
+    if (rc < 0) {
+        error_exit(errno, __func__);
+    }
+#endif
+    sem->initialized = true;
+}
+
+void qemu_sem_destroy(QemuSemaphore *sem)
+{
+    int rc;
+
+    assert(sem->initialized);
+    sem->initialized = false;
+#ifndef CONFIG_SEM_TIMEDWAIT
+    rc = pthread_cond_destroy(&sem->cond);
+    if (rc < 0) {
+        error_exit(rc, __func__);
+    }
+    rc = pthread_mutex_destroy(&sem->lock);
+    if (rc < 0) {
+        error_exit(rc, __func__);
+    }
+#else
+    rc = sem_destroy(&sem->sem);
+    if (rc < 0) {
+        error_exit(errno, __func__);
+    }
+#endif
+}
+
+void qemu_sem_post(QemuSemaphore *sem)
+{
+    int rc;
+
+    assert(sem->initialized);
+#ifndef CONFIG_SEM_TIMEDWAIT
+    pthread_mutex_lock(&sem->lock);
+    if (sem->count == UINT_MAX) {
+        rc = EINVAL;
+    } else {
+        sem->count++;
+        rc = pthread_cond_signal(&sem->cond);
+    }
+    pthread_mutex_unlock(&sem->lock);
+    if (rc != 0) {
+        error_exit(rc, __func__);
+    }
+#else
+    rc = sem_post(&sem->sem);
+    if (rc < 0) {
+        error_exit(errno, __func__);
+    }
+#endif
+}
+
+int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
+{
+    int rc;
+    struct timespec ts;
+
+    assert(sem->initialized);
+#ifndef CONFIG_SEM_TIMEDWAIT
+    rc = 0;
+    compute_abs_deadline(&ts, ms);
+    pthread_mutex_lock(&sem->lock);
+    while (sem->count == 0) {
+        rc = pthread_cond_timedwait(&sem->cond, &sem->lock, &ts);
+        if (rc == ETIMEDOUT) {
+            break;
+        }
+        if (rc != 0) {
+            error_exit(rc, __func__);
+        }
+    }
+    if (rc != ETIMEDOUT) {
+        --sem->count;
+    }
+    pthread_mutex_unlock(&sem->lock);
+    return (rc == ETIMEDOUT ? -1 : 0);
+#else
+    if (ms <= 0) {
+        /* This is cheaper than sem_timedwait.  */
+        do {
+            rc = sem_trywait(&sem->sem);
+        } while (rc == -1 && errno == EINTR);
+        if (rc == -1 && errno == EAGAIN) {
+            return -1;
+        }
+    } else {
+        compute_abs_deadline(&ts, ms);
+        do {
+            rc = sem_timedwait(&sem->sem, &ts);
+        } while (rc == -1 && errno == EINTR);
+        if (rc == -1 && errno == ETIMEDOUT) {
+            return -1;
+        }
+    }
+    if (rc < 0) {
+        error_exit(errno, __func__);
+    }
+    return 0;
+#endif
+}
+
+void qemu_sem_wait(QemuSemaphore *sem)
+{
+    int rc;
+
+    assert(sem->initialized);
+#ifndef CONFIG_SEM_TIMEDWAIT
+    pthread_mutex_lock(&sem->lock);
+    while (sem->count == 0) {
+        rc = pthread_cond_wait(&sem->cond, &sem->lock);
+        if (rc != 0) {
+            error_exit(rc, __func__);
+        }
+    }
+    --sem->count;
+    pthread_mutex_unlock(&sem->lock);
+#else
+    do {
+        rc = sem_wait(&sem->sem);
+    } while (rc == -1 && errno == EINTR);
+    if (rc < 0) {
+        error_exit(errno, __func__);
+    }
+#endif
+}
+
+#ifdef __linux__
+#include "qemu/futex.h"
+#else
+static inline void qemu_futex_wake(QemuEvent *ev, int n)
+{
+    assert(ev->initialized);
+    pthread_mutex_lock(&ev->lock);
+    if (n == 1) {
+        pthread_cond_signal(&ev->cond);
+    } else {
+        pthread_cond_broadcast(&ev->cond);
+    }
+    pthread_mutex_unlock(&ev->lock);
+}
+
+static inline void qemu_futex_wait(QemuEvent *ev, unsigned val)
+{
+    assert(ev->initialized);
+    pthread_mutex_lock(&ev->lock);
+    if (ev->value == val) {
+        pthread_cond_wait(&ev->cond, &ev->lock);
+    }
+    pthread_mutex_unlock(&ev->lock);
+}
+#endif
+
+/* Valid transitions:
+ * - free->set, when setting the event
+ * - busy->set, when setting the event, followed by qemu_futex_wake
+ * - set->free, when resetting the event
+ * - free->busy, when waiting
+ *
+ * set->busy does not happen (it can be observed from the outside but
+ * it really is set->free->busy).
+ *
+ * busy->free provably cannot happen; to enforce it, the set->free transition
+ * is done with an OR, which becomes a no-op if the event has concurrently
+ * transitioned to free or busy.
+ */
+
+#define EV_SET         0
+#define EV_FREE        1
+#define EV_BUSY       -1
+
+void qemu_event_init(QemuEvent *ev, bool init)
+{
+#ifndef __linux__
+    pthread_mutex_init(&ev->lock, NULL);
+    pthread_cond_init(&ev->cond, NULL);
+#endif
+
+    ev->value = (init ? EV_SET : EV_FREE);
+    ev->initialized = true;
+}
+
+void qemu_event_destroy(QemuEvent *ev)
+{
+    assert(ev->initialized);
+    ev->initialized = false;
+#ifndef __linux__
+    pthread_mutex_destroy(&ev->lock);
+    pthread_cond_destroy(&ev->cond);
+#endif
+}
+
+void qemu_event_set(QemuEvent *ev)
+{
+    /* qemu_event_set has release semantics, but because it *loads*
+     * ev->value we need a full memory barrier here.
+     */
+    assert(ev->initialized);
+    smp_mb();
+    if (qatomic_read(&ev->value) != EV_SET) {
+        if (qatomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
+            /* There were waiters, wake them up.  */
+            qemu_futex_wake(ev, INT_MAX);
+        }
+    }
+}
+
+void qemu_event_reset(QemuEvent *ev)
+{
+    unsigned value;
+
+    assert(ev->initialized);
+    value = qatomic_read(&ev->value);
+    smp_mb_acquire();
+    if (value == EV_SET) {
+        /*
+         * If there was a concurrent reset (or even reset+wait),
+         * do nothing.  Otherwise change EV_SET->EV_FREE.
+         */
+        qatomic_or(&ev->value, EV_FREE);
+    }
+}
+
+void qemu_event_wait(QemuEvent *ev)
+{
+    unsigned value;
+
+    assert(ev->initialized);
+    value = qatomic_read(&ev->value);
+    smp_mb_acquire();
+    if (value != EV_SET) {
+        if (value == EV_FREE) {
+            /*
+             * Leave the event reset and tell qemu_event_set that there
+             * are waiters.  No need to retry, because there cannot be
+             * a concurrent busy->free transition.  After the CAS, the
+             * event will be either set or busy.
+             */
+            if (qatomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) {
+                return;
+            }
+        }
+        qemu_futex_wait(ev, EV_BUSY);
+    }
+}
+
+static __thread NotifierList thread_exit;
+
+/*
+ * Note that in this implementation you can register a thread-exit
+ * notifier for the main thread, but it will never be called.
+ * This is OK because main thread exit can only happen when the
+ * entire process is exiting, and the API allows notifiers to not
+ * be called on process exit.
+ */
+void qemu_thread_atexit_add(Notifier *notifier)
+{
+    notifier_list_add(&thread_exit, notifier);
+}
+
+void qemu_thread_atexit_remove(Notifier *notifier)
+{
+    notifier_remove(notifier);
+}
+
+static void qemu_thread_atexit_notify(void *arg)
+{
+    /*
+     * Called when non-main thread exits (via qemu_thread_exit()
+     * or by returning from its start routine.)
+     */
+    notifier_list_notify(&thread_exit, NULL);
+}
+
+typedef struct {
+    void *(*start_routine)(void *);
+    void *arg;
+    char *name;
+} QemuThreadArgs;
+
+static void *qemu_thread_start(void *args)
+{
+    QemuThreadArgs *qemu_thread_args = args;
+    void *(*start_routine)(void *) = qemu_thread_args->start_routine;
+    void *arg = qemu_thread_args->arg;
+    void *r;
+
+    /* Attempt to set the threads name; note that this is for debug, so
+     * we're not going to fail if we can't set it.
+     */
+    if (name_threads && qemu_thread_args->name) {
+# if defined(CONFIG_PTHREAD_SETNAME_NP_W_TID)
+        pthread_setname_np(pthread_self(), qemu_thread_args->name);
+# elif defined(CONFIG_PTHREAD_SETNAME_NP_WO_TID)
+        pthread_setname_np(qemu_thread_args->name);
+# endif
+    }
+    QEMU_TSAN_ANNOTATE_THREAD_NAME(qemu_thread_args->name);
+    g_free(qemu_thread_args->name);
+    g_free(qemu_thread_args);
+
+    /*
+     * GCC 11 with glibc 2.17 on PowerPC reports
+     *
+     * qemu-thread-posix.c:540:5: error: ‘__sigsetjmp’ accessing 656 bytes
+     *   in a region of size 528 [-Werror=stringop-overflow=]
+     * 540 |     pthread_cleanup_push(qemu_thread_atexit_notify, NULL);
+     *     |     ^~~~~~~~~~~~~~~~~~~~
+     *
+     * which is clearly nonsense.
+     */
+#pragma GCC diagnostic push
+#ifndef __clang__
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
+#endif
+
+    pthread_cleanup_push(qemu_thread_atexit_notify, NULL);
+    r = start_routine(arg);
+    pthread_cleanup_pop(1);
+
+#pragma GCC diagnostic pop
+
+    return r;
+}
+
+void qemu_thread_create(QemuThread *thread, const char *name,
+                       void *(*start_routine)(void*),
+                       void *arg, int mode)
+{
+    sigset_t set, oldset;
+    int err;
+    pthread_attr_t attr;
+    QemuThreadArgs *qemu_thread_args;
+
+    err = pthread_attr_init(&attr);
+    if (err) {
+        error_exit(err, __func__);
+    }
+
+    if (mode == QEMU_THREAD_DETACHED) {
+        pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+    }
+
+    /* Leave signal handling to the iothread.  */
+    sigfillset(&set);
+    /* Blocking the signals can result in undefined behaviour. */
+    sigdelset(&set, SIGSEGV);
+    sigdelset(&set, SIGFPE);
+    sigdelset(&set, SIGILL);
+    /* TODO avoid SIGBUS loss on macOS */
+    pthread_sigmask(SIG_SETMASK, &set, &oldset);
+
+    qemu_thread_args = g_new0(QemuThreadArgs, 1);
+    qemu_thread_args->name = g_strdup(name);
+    qemu_thread_args->start_routine = start_routine;
+    qemu_thread_args->arg = arg;
+
+    err = pthread_create(&thread->thread, &attr,
+                         qemu_thread_start, qemu_thread_args);
+
+    if (err)
+        error_exit(err, __func__);
+
+    pthread_sigmask(SIG_SETMASK, &oldset, NULL);
+
+    pthread_attr_destroy(&attr);
+}
+
+void qemu_thread_get_self(QemuThread *thread)
+{
+    thread->thread = pthread_self();
+}
+
+bool qemu_thread_is_self(QemuThread *thread)
+{
+   return pthread_equal(pthread_self(), thread->thread);
+}
+
+void qemu_thread_exit(void *retval)
+{
+    pthread_exit(retval);
+}
+
+void *qemu_thread_join(QemuThread *thread)
+{
+    int err;
+    void *ret;
+
+    err = pthread_join(thread->thread, &ret);
+    if (err) {
+        error_exit(err, __func__);
+    }
+    return ret;
+}