C++ VirtioBusClass类代码示例

static void vhost_vsock_stop(VirtIODevice *vdev)
{
    VHostVSock *vsock = VHOST_VSOCK(vdev);
    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
    int ret;

    if (!k->set_guest_notifiers) {
        return;
    }

    ret = vhost_vsock_set_running(vsock, 0);
    if (ret < 0) {
        error_report("vhost vsock set running failed: %d", ret);
        return;
    }

    vhost_dev_stop(&vsock->vhost_dev, vdev);

    ret = k->set_guest_notifiers(qbus->parent, vsock->vhost_dev.nvqs, false);
    if (ret < 0) {
        error_report("vhost guest notifier cleanup failed: %d", ret);
        return;
    }

    vhost_dev_disable_notifiers(&vsock->vhost_dev, vdev);
}

/*
 * This function handles both assigning the ioeventfd handler and
 * registering it with the kernel.
 * assign: register/deregister ioeventfd with the kernel
 * set_handler: use the generic ioeventfd handler
 */
static int set_host_notifier_internal(DeviceState *proxy, VirtioBusState *bus,
                                      int n, bool assign, bool set_handler)
{
    VirtIODevice *vdev = virtio_bus_get_device(bus);
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
    VirtQueue *vq = virtio_get_queue(vdev, n);
    EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
    int r = 0;

    if (assign) {
        r = event_notifier_init(notifier, 1);
        if (r < 0) {
            error_report("%s: unable to init event notifier: %d", __func__, r);
            return r;
        }
        virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
        r = k->ioeventfd_assign(proxy, notifier, n, assign);
        if (r < 0) {
            error_report("%s: unable to assign ioeventfd: %d", __func__, r);
            virtio_queue_set_host_notifier_fd_handler(vq, false, false);
            event_notifier_cleanup(notifier);
            return r;
        }
    } else {
        k->ioeventfd_assign(proxy, notifier, n, assign);
        virtio_queue_set_host_notifier_fd_handler(vq, false, false);
        event_notifier_cleanup(notifier);
    }
    return r;
}

int virtio_bus_start_ioeventfd(VirtioBusState *bus)
{
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
    DeviceState *proxy = DEVICE(BUS(bus)->parent);
    VirtIODevice *vdev = virtio_bus_get_device(bus);
    VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
    int r;

    if (!k->ioeventfd_assign || !k->ioeventfd_enabled(proxy)) {
        return -ENOSYS;
    }
    if (bus->ioeventfd_started) {
        return 0;
    }

    /* Only set our notifier if we have ownership.  */
    if (!bus->ioeventfd_grabbed) {
        r = vdc->start_ioeventfd(vdev);
        if (r < 0) {
            error_report("%s: failed. Fallback to userspace (slower).", __func__);
            return r;
        }
    }
    bus->ioeventfd_started = true;
    return 0;
}

/* Plug the VirtIODevice */
int virtio_bus_plug_device(VirtIODevice *vdev)
{
    DeviceState *qdev = DEVICE(vdev);
    BusState *qbus = BUS(qdev_get_parent_bus(qdev));
    VirtioBusState *bus = VIRTIO_BUS(qbus);
    VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus);
    DPRINTF("%s: plug device.\n", qbus->name);

    bus->vdev = vdev;

    /*
     * The lines below will disappear when we drop VirtIOBindings, at the end
     * of the series.
     */
    bus->bindings.notify = klass->notify;
    bus->bindings.save_config = klass->save_config;
    bus->bindings.save_queue = klass->save_queue;
    bus->bindings.load_config = klass->load_config;
    bus->bindings.load_queue = klass->load_queue;
    bus->bindings.load_done = klass->load_done;
    bus->bindings.get_features = klass->get_features;
    bus->bindings.query_guest_notifiers = klass->query_guest_notifiers;
    bus->bindings.set_guest_notifiers = klass->set_guest_notifiers;
    bus->bindings.set_host_notifier = klass->set_host_notifier;
    bus->bindings.vmstate_change = klass->vmstate_change;
    virtio_bind_device(bus->vdev, &bus->bindings, qbus->parent);

    if (klass->device_plugged != NULL) {
        klass->device_plugged(qbus->parent);
    }

    return 0;
}

bool virtio_bus_ioeventfd_enabled(VirtioBusState *bus)
{
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
    DeviceState *proxy = DEVICE(BUS(bus)->parent);

    return k->ioeventfd_assign && k->ioeventfd_enabled(proxy);
}

/* Context: QEMU global mutex held */
void virtio_scsi_dataplane_start(VirtIOSCSI *s)
{
    int i;
    int rc;
    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);

    if (s->dataplane_started ||
        s->dataplane_starting ||
        s->dataplane_fenced ||
        s->ctx != iothread_get_aio_context(vs->conf.iothread)) {
        return;
    }

    s->dataplane_starting = true;

    /* Set up guest notifier (irq) */
    rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
    if (rc != 0) {
        fprintf(stderr, "virtio-scsi: Failed to set guest notifiers (%d), "
                "ensure -enable-kvm is set\n", rc);
        goto fail_guest_notifiers;
    }

    aio_context_acquire(s->ctx);
    rc = virtio_scsi_vring_init(s, vs->ctrl_vq, 0);
    if (rc) {
        goto fail_vrings;
    }
    rc = virtio_scsi_vring_init(s, vs->event_vq, 1);
    if (rc) {
        goto fail_vrings;
    }
    for (i = 0; i < vs->conf.num_queues; i++) {
        rc = virtio_scsi_vring_init(s, vs->cmd_vqs[i], i + 2);
        if (rc) {
            goto fail_vrings;
        }
    }

    s->dataplane_starting = false;
    s->dataplane_started = true;
    aio_context_release(s->ctx);
    return;

fail_vrings:
    virtio_scsi_clear_aio(s);
    aio_context_release(s->ctx);
    for (i = 0; i < vs->conf.num_queues + 2; i++) {
        k->set_host_notifier(qbus->parent, i, false);
    }
    k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
fail_guest_notifiers:
    s->dataplane_fenced = true;
    s->dataplane_starting = false;
    s->dataplane_started = true;
}

static void vhost_vsock_start(VirtIODevice *vdev)
{
    VHostVSock *vsock = VHOST_VSOCK(vdev);
    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
    int ret;
    int i;

    if (!k->set_guest_notifiers) {
        error_report("binding does not support guest notifiers");
        return;
    }

    ret = vhost_dev_enable_notifiers(&vsock->vhost_dev, vdev);
    if (ret < 0) {
        error_report("Error enabling host notifiers: %d", -ret);
        return;
    }

    ret = k->set_guest_notifiers(qbus->parent, vsock->vhost_dev.nvqs, true);
    if (ret < 0) {
        error_report("Error binding guest notifier: %d", -ret);
        goto err_host_notifiers;
    }

    vsock->vhost_dev.acked_features = vdev->guest_features;
    ret = vhost_dev_start(&vsock->vhost_dev, vdev);
    if (ret < 0) {
        error_report("Error starting vhost: %d", -ret);
        goto err_guest_notifiers;
    }

    ret = vhost_vsock_set_running(vsock, 1);
    if (ret < 0) {
        error_report("Error starting vhost vsock: %d", -ret);
        goto err_dev_start;
    }

    /* guest_notifier_mask/pending not used yet, so just unmask
     * everything here.  virtio-pci will do the right thing by
     * enabling/disabling irqfd.
     */
    for (i = 0; i < vsock->vhost_dev.nvqs; i++) {
        vhost_virtqueue_mask(&vsock->vhost_dev, vdev, i, false);
    }

    return;

err_dev_start:
    vhost_dev_stop(&vsock->vhost_dev, vdev);
err_guest_notifiers:
    k->set_guest_notifiers(qbus->parent, vsock->vhost_dev.nvqs, false);
err_host_notifiers:
    vhost_dev_disable_notifiers(&vsock->vhost_dev, vdev);
}

static void vhost_net_stop_one(struct vhost_net *net,
                               VirtIODevice *dev)
{
    struct vhost_vring_file file = { .fd = -1 };

    if (!net->dev.started) {
        return;
    }

    for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
        int r = ioctl(net->dev.control, VHOST_NET_SET_BACKEND, &file);
        assert(r >= 0);
    }
    net->nc->info->poll(net->nc, true);
    vhost_dev_stop(&net->dev, dev);
    vhost_dev_disable_notifiers(&net->dev, dev);
}

int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
                    int total_queues)
{
    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(dev)));
    VirtioBusState *vbus = VIRTIO_BUS(qbus);
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
    int r, i = 0;

    if (!k->set_guest_notifiers) {
        error_report("binding does not support guest notifiers");
        r = -ENOSYS;
        goto err;
    }

    for (i = 0; i < total_queues; i++) {
        r = vhost_net_start_one(tap_get_vhost_net(ncs[i].peer), dev, i * 2);

        if (r < 0) {
            goto err;
        }
    }

    r = k->set_guest_notifiers(qbus->parent, total_queues * 2, true);
    if (r < 0) {
        error_report("Error binding guest notifier: %d", -r);
        goto err;
    }

    return 0;

err:
    while (--i >= 0) {
        vhost_net_stop_one(tap_get_vhost_net(ncs[i].peer), dev);
    }
    return r;
}

/* Context: QEMU global mutex held */
void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
{
    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
    VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
    int r;

    if (vblk->dataplane_started || s->starting) {
        return;
    }

    s->starting = true;
    s->vq = virtio_get_queue(s->vdev, 0);

    /* Set up guest notifier (irq) */
    r = k->set_guest_notifiers(qbus->parent, 1, true);
    if (r != 0) {
        fprintf(stderr, "virtio-blk failed to set guest notifier (%d), "
                "ensure -enable-kvm is set\n", r);
        goto fail_guest_notifiers;
    }
    s->guest_notifier = virtio_queue_get_guest_notifier(s->vq);

    /* Set up virtqueue notify */
    r = k->set_host_notifier(qbus->parent, 0, true);
    if (r != 0) {
        fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
        goto fail_host_notifier;
    }

    s->starting = false;
    vblk->dataplane_started = true;
    trace_virtio_blk_data_plane_start(s);

    blk_set_aio_context(s->conf->conf.blk, s->ctx);

    /* Kick right away to begin processing requests already in vring */
    event_notifier_set(virtio_queue_get_host_notifier(s->vq));

    /* Get this show started by hooking up our callbacks */
    aio_context_acquire(s->ctx);
    virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx,
                                               virtio_blk_data_plane_handle_output);
    aio_context_release(s->ctx);
    return;

  fail_host_notifier:
    k->set_guest_notifiers(qbus->parent, 1, false);
  fail_guest_notifiers:
    vblk->dataplane_disabled = true;
    s->starting = false;
    vblk->dataplane_started = true;
}

/* A VirtIODevice is being plugged */
int virtio_bus_device_plugged(VirtIODevice *vdev)
{
    DeviceState *qdev = DEVICE(vdev);
    BusState *qbus = BUS(qdev_get_parent_bus(qdev));
    VirtioBusState *bus = VIRTIO_BUS(qbus);
    VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus);
    DPRINTF("%s: plug device.\n", qbus->name);

    if (klass->device_plugged != NULL) {
        klass->device_plugged(qbus->parent);
    }

    return 0;
}

/* A VirtIODevice is being unplugged */
void virtio_bus_device_unplugged(VirtIODevice *vdev)
{
    DeviceState *qdev = DEVICE(vdev);
    BusState *qbus = BUS(qdev_get_parent_bus(qdev));
    VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(qbus);

    DPRINTF("%s: remove device.\n", qbus->name);

    if (vdev != NULL) {
        if (klass->device_unplugged != NULL) {
            klass->device_unplugged(qbus->parent);
        }
    }
}

/* Destroy the VirtIODevice */
void virtio_bus_destroy_device(VirtioBusState *bus)
{
    DeviceState *qdev;
    BusState *qbus = BUS(bus);
    VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus);
    DPRINTF("%s: remove device.\n", qbus->name);

    if (bus->vdev != NULL) {
        if (klass->device_unplug != NULL) {
            klass->device_unplug(qbus->parent);
        }
        qdev = DEVICE(bus->vdev);
        qdev_free(qdev);
        bus->vdev = NULL;
    }
}

int vhost_scsi_common_start(VHostSCSICommon *vsc)
{
    int ret, i;
    VirtIODevice *vdev = VIRTIO_DEVICE(vsc);
    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);

    if (!k->set_guest_notifiers) {
        error_report("binding does not support guest notifiers");
        return -ENOSYS;
    }

    ret = vhost_dev_enable_notifiers(&vsc->dev, vdev);
    if (ret < 0) {
        return ret;
    }

    ret = k->set_guest_notifiers(qbus->parent, vsc->dev.nvqs, true);
    if (ret < 0) {
        error_report("Error binding guest notifier");
        goto err_host_notifiers;
    }

    vsc->dev.acked_features = vdev->guest_features;
    ret = vhost_dev_start(&vsc->dev, vdev);
    if (ret < 0) {
        error_report("Error start vhost dev");
        goto err_guest_notifiers;
    }

    /* guest_notifier_mask/pending not used yet, so just unmask
     * everything here.  virtio-pci will do the right thing by
     * enabling/disabling irqfd.
     */
    for (i = 0; i < vsc->dev.nvqs; i++) {
        vhost_virtqueue_mask(&vsc->dev, vdev, vsc->dev.vq_index + i, false);
    }

    return ret;

err_guest_notifiers:
    k->set_guest_notifiers(qbus->parent, vsc->dev.nvqs, false);
err_host_notifiers:
    vhost_dev_disable_notifiers(&vsc->dev, vdev);
    return ret;
}

/* Context: QEMU global mutex held */
void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
{
    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
    VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
    unsigned i;
    unsigned nvqs = s->conf->num_queues;

    if (!vblk->dataplane_started || s->stopping) {
        return;
    }

    /* Better luck next time. */
    if (vblk->dataplane_disabled) {
        vblk->dataplane_disabled = false;
        vblk->dataplane_started = false;
        return;
    }
    s->stopping = true;
    trace_virtio_blk_data_plane_stop(s);

    aio_context_acquire(s->ctx);

    /* Stop notifications for new requests from guest */
    for (i = 0; i < nvqs; i++) {
        VirtQueue *vq = virtio_get_queue(s->vdev, i);

        virtio_queue_aio_set_host_notifier_handler(vq, s->ctx, NULL);
    }

    /* Drain and switch bs back to the QEMU main loop */
    blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());

    aio_context_release(s->ctx);

    for (i = 0; i < nvqs; i++) {
        virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
    }

    /* Clean up guest notifier (irq) */
    k->set_guest_notifiers(qbus->parent, nvqs, false);

    vblk->dataplane_started = false;
    s->stopping = false;
}

static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n)
{
    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
    int rc;

    /* Set up virtqueue notify */
    rc = k->set_host_notifier(qbus->parent, n, true);
    if (rc != 0) {
        fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
                rc);
        s->dataplane_fenced = true;
        return rc;
    }

    virtio_queue_aio_set_host_notifier_handler(vq, s->ctx, true, true);
    return 0;
}