net/virtio: fix less queues being enabled

From the virtio spec of view, multiple-queue is always enabled/disabled
in queue pairs. DPDK somehow allows the case when Tx and Rx queue number
are different.

Currently, virtio PMD get the queue pair number from the nb_rx_queues
field, which could be an issue when Tx queue number > Rx queue number.
Say, 2 Tx queues and 1 Rx queues. This would end up with 1 quues being
enabled. Which is wrong.

The fix is straightforward. Just pick a bigger number and enable that many
of queues.

Fixes: 823ad647950a ("virtio: support multiple queues")

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index 1d525dd..8a0098a 100644 (file)
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -1493,7 +1493,7 @@ virtio_dev_start(struct rte_eth_dev *dev)
         *Otherwise the tap backend might already stop its queue due to fullness.
         *vhost backend will have no chance to be waked up
         */
-       nb_queues = dev->data->nb_rx_queues;
+       nb_queues = RTE_MAX(dev->data->nb_rx_queues, dev->data->nb_tx_queues);
        if (nb_queues > 1) {
                if (virtio_set_multiple_queues(dev, nb_queues) != 0)
                        return -EINVAL;
@@ -1501,7 +1501,7 @@ virtio_dev_start(struct rte_eth_dev *dev)
 
        PMD_INIT_LOG(DEBUG, "nb_queues=%d", nb_queues);
 
-       for (i = 0; i < nb_queues; i++) {
+       for (i = 0; i < dev->data->nb_rx_queues; i++) {
                rxvq = dev->data->rx_queues[i];
                virtqueue_notify(rxvq->vq);
        }