netdev-dpdk: vhost: Fix txq enabling in the absence of notifications.

According to QEMU documentation (docs/specs/vhost-user.txt) one queue
should be enabled initially. More queues are enabled dynamically, by
sending message VHOST_USER_SET_VRING_ENABLE.

Currently all queues in OVS disabled by default. This breaks above
specification. So, queue #0 should be enabled by default to support
QEMU versions less than 2.5 and fix probable issues if QEMU will not
send VHOST_USER_SET_VRING_ENABLE for queue #0 according to documentation.
Also this will fix currently broken vhost-cuse support in OVS.

Fixes: 585a5be ("netdev-dpdk: vhost-user: Fix sending packets to
                      queues not enabled by guest.")
Reported-by: Mauricio Vasquez B <[email protected]>
Signed-off-by: Ilya Maximets <[email protected]>
Acked-by: Flavio Leitner <[email protected]>
Acked-by: Daniele Di Proietto <[email protected]>

lib/netdev-dpdk.c

@@ -103,6 +103,9 @@ BUILD_ASSERT_DECL((MAX_NB_MBUF / ROUND_DOWN_POW2(MAX_NB_MBUF/MIN_NB_MBUF))
 #define NIC_PORT_TX_Q_SIZE 2048  /* Size of Physical NIC TX Queue, Max (n+32<=4096)*/
 
 #define OVS_VHOST_MAX_QUEUE_NUM 1024  /* Maximum number of vHost TX queues. */
+#define OVS_VHOST_QUEUE_MAP_UNKNOWN (-1) /* Mapping not initialized. */
+#define OVS_VHOST_QUEUE_DISABLED    (-2) /* Queue was disabled by guest and not
+                                          * yet mapped to another queue. */
 
 static char *cuse_dev_name = NULL;    /* Character device cuse_dev_name. */
 static char *vhost_sock_dir = NULL;   /* Location of vhost-user sockets */
@@ -671,7 +674,7 @@ netdev_dpdk_alloc_txq(struct netdev_dpdk *netdev, unsigned int n_txqs)
         }
 
         /* Initialize map for vhost devices. */
-        netdev->tx_q[i].map = -1;
+        netdev->tx_q[i].map = OVS_VHOST_QUEUE_MAP_UNKNOWN;
         rte_spinlock_init(&netdev->tx_q[i].tx_lock);
     }
 }
@@ -1265,7 +1268,7 @@ __netdev_dpdk_vhost_send(struct netdev *netdev, int qid,
 
     qid = vhost_dev->tx_q[qid % vhost_dev->real_n_txq].map;
 
-    if (OVS_UNLIKELY(!is_vhost_running(virtio_dev) || qid == -1)) {
+    if (OVS_UNLIKELY(!is_vhost_running(virtio_dev) || qid < 0)) {
         rte_spinlock_lock(&vhost_dev->stats_lock);
         vhost_dev->stats.tx_dropped+= cnt;
         rte_spinlock_unlock(&vhost_dev->stats_lock);
@@ -2019,7 +2022,7 @@ netdev_dpdk_remap_txqs(struct netdev_dpdk *netdev)
     }
 
     if (n_enabled == 0 && total_txqs != 0) {
-        enabled_queues[0] = -1;
+        enabled_queues[0] = OVS_VHOST_QUEUE_DISABLED;
         n_enabled = 1;
     }
 
@@ -2056,6 +2059,10 @@ netdev_dpdk_vhost_set_queues(struct netdev_dpdk *netdev, struct virtio_net *dev)
     netdev->real_n_rxq = qp_num;
     netdev->real_n_txq = qp_num;
     netdev->txq_needs_locking = true;
+    /* Enable TX queue 0 by default if it wasn't disabled. */
+    if (netdev->tx_q[0].map == OVS_VHOST_QUEUE_MAP_UNKNOWN) {
+        netdev->tx_q[0].map = 0;
+    }
 
     netdev_dpdk_remap_txqs(netdev);
 
@@ -2104,6 +2111,18 @@ new_device(struct virtio_net *dev)
     return 0;
 }
 
+/* Clears mapping for all available queues of vhost interface. */
+static void
+netdev_dpdk_txq_map_clear(struct netdev_dpdk *dev)
+    OVS_REQUIRES(dev->mutex)
+{
+    int i;
+
+    for (i = 0; i < dev->real_n_txq; i++) {
+        dev->tx_q[i].map = OVS_VHOST_QUEUE_MAP_UNKNOWN;
+    }
+}
+
 /*
  * Remove a virtio-net device from the specific vhost port.  Use dev->remove
  * flag to stop any more packets from being sent or received to/from a VM and
@@ -2123,6 +2142,7 @@ destroy_device(volatile struct virtio_net *dev)
             ovs_mutex_lock(&vhost_dev->mutex);
             dev->flags &= ~VIRTIO_DEV_RUNNING;
             ovsrcu_set(&vhost_dev->virtio_dev, NULL);
+            netdev_dpdk_txq_map_clear(vhost_dev);
             exists = true;
             ovs_mutex_unlock(&vhost_dev->mutex);
             break;
@@ -2169,7 +2189,7 @@ vring_state_changed(struct virtio_net *dev, uint16_t queue_id, int enable)
             if (enable) {
                 vhost_dev->tx_q[qid].map = qid;
             } else {
-                vhost_dev->tx_q[qid].map = -1;
+                vhost_dev->tx_q[qid].map = OVS_VHOST_QUEUE_DISABLED;
             }
             netdev_dpdk_remap_txqs(vhost_dev);
             exists = true;