[ovs-dev] [PATCH] netdev-dpdk: vhost: Fix txq enabling in the absence of notifications.

[Ilya Maximets]

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: 585a5beaa2a4 ("netdev-dpdk: vhost-user: Fix sending packets to
                      queues not enabled by guest.")
Reported-by: Mauricio Vasquez B <mauricio.vasquezbernal at studenti.polito.it>
Signed-off-by: Ilya Maximets <i.maximets at samsung.com>
---
 lib/netdev-dpdk.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index f4ed210..ab60f85 100644
--- a/lib/netdev-dpdk.c
+++ b/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 */
@@ -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);
 
@@ -2119,10 +2126,15 @@ destroy_device(volatile struct virtio_net *dev)
     ovs_mutex_lock(&dpdk_mutex);
     LIST_FOR_EACH (vhost_dev, list_node, &dpdk_list) {
         if (netdev_dpdk_get_virtio(vhost_dev) == dev) {
+            int i;
 
             ovs_mutex_lock(&vhost_dev->mutex);
             dev->flags &= ~VIRTIO_DEV_RUNNING;
             ovsrcu_set(&vhost_dev->virtio_dev, NULL);
+            /* Clear mapping. */
+            for (i = 0; i < vhost_dev->real_n_txq; i++) {
+                vhost_dev->tx_q[i].map = OVS_VHOST_QUEUE_MAP_UNKNOWN;
+            }
             exists = true;
             ovs_mutex_unlock(&vhost_dev->mutex);
             break;
@@ -2169,7 +2181,7 @@ 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;
-- 
2.5.0