Function virtio_dev_start

dpdk/drivers/net/virtio/virtio_ethdev.c:2331–2429

static int
virtio_dev_start(struct rte_eth_dev *dev)
{
	uint16_t nb_queues, i;
	struct virtqueue *vq;
	struct virtio_hw *hw = dev->data->dev_private;
	int ret;

	/* Finish the initialization of the queues */
	for (i = 0; i < dev->data->nb_rx_queues; i++) {
		ret = virtio_dev_rx_queue_setup_finish(dev, i);
		if (ret < 0)
			return ret;
	}
	for (i = 0; i < dev->data->nb_tx_queues; i++) {
		ret = virtio_dev_tx_queue_setup_finish(dev, i);
		if (ret < 0)
			return ret;
	}

	/* check if lsc interrupt feature is enabled */
	if (dev->data->dev_conf.intr_conf.lsc) {
		if (!(dev->data->dev_flags & RTE_ETH_DEV_INTR_LSC)) {
			PMD_DRV_LOG(ERR, "link status not supported by host");
			return -ENOTSUP;
		}
	}

	/* Enable uio/vfio intr/eventfd mapping: although we already did that
	 * in device configure, but it could be unmapped  when device is
	 * stopped.
	 */
	if (dev->data->dev_conf.intr_conf.lsc ||
	    dev->data->dev_conf.intr_conf.rxq) {
		virtio_intr_disable(dev);

		/* Setup interrupt callback  */
		if (dev->data->dev_flags & RTE_ETH_DEV_INTR_LSC)
			rte_intr_callback_register(dev->intr_handle,
						   virtio_interrupt_handler,
						   dev);

		if (virtio_intr_enable(dev) < 0) {
			PMD_DRV_LOG(ERR, "interrupt enable failed");
			return -EIO;
		}
	}

	/*Notify the backend
	 *Otherwise the tap backend might already stop its queue due to fullness.
	 *vhost backend will have no chance to be waked up
	 */
	nb_queues = RTE_MAX(dev->data->nb_rx_queues, dev->data->nb_tx_queues);
	if (hw->max_queue_pairs > 1) {
		if (virtio_set_multiple_queues(dev, nb_queues) != 0)
			return -EINVAL;
	}