vhost: remove a hack on queue allocation

We used to allocate queues based on the index from SET_VRING_CALL
request: if corresponding queue hasn't been allocated, allocate it.

Though it's pratically right (it's the first per-vring request we
will get from QEMU for vhost-user negotiation), but it's not technically
right: it's not documented in the vhost-user spec that it will always
be the first per-vring request. For example, SET_VRING_ADDR could also
be the first per-vring request.

Thus, we should not depend the SET_VRING_CALL on queue allocation.
Instead, we could catch all the per-vring messages at the entrance of
request handler, and allocate one if it hasn't been allocated before.

By that, we could remove a hack.

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

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index cb2156a..2767cca 100644 (file)
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -635,7 +635,6 @@ vhost_user_set_vring_call(struct virtio_net *dev, struct VhostUserMsg *pmsg)
 {
        struct vhost_vring_file file;
        struct vhost_virtqueue *vq;
-       uint32_t cur_qp_idx;
 
        file.index = pmsg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
        if (pmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)
@@ -645,19 +644,7 @@ vhost_user_set_vring_call(struct virtio_net *dev, struct VhostUserMsg *pmsg)
        RTE_LOG(INFO, VHOST_CONFIG,
                "vring call idx:%d file:%d\n", file.index, file.fd);
 
-       /*
-        * FIXME: VHOST_SET_VRING_CALL is the first per-vring message
-        * we get, so we do vring queue pair allocation here.
-        */
-       cur_qp_idx = file.index / VIRTIO_QNUM;
-       if (cur_qp_idx + 1 > dev->virt_qp_nb) {
-               if (alloc_vring_queue_pair(dev, cur_qp_idx) < 0)
-                       return;
-       }
-
        vq = dev->virtqueue[file.index];
-       assert(vq != NULL);
-
        if (vq->callfd >= 0)
                close(vq->callfd);
 
@@ -914,6 +901,46 @@ send_vhost_message(int sockfd, struct VhostUserMsg *msg)
        return ret;
 }
 
+/*
+ * Allocate a queue pair if it hasn't been allocated yet
+ */
+static int
+vhost_user_check_and_alloc_queue_pair(struct virtio_net *dev, VhostUserMsg *msg)
+{
+       uint16_t vring_idx;
+       uint16_t qp_idx;
+
+       switch (msg->request) {
+       case VHOST_USER_SET_VRING_KICK:
+       case VHOST_USER_SET_VRING_CALL:
+       case VHOST_USER_SET_VRING_ERR:
+               vring_idx = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
+               break;
+       case VHOST_USER_SET_VRING_NUM:
+       case VHOST_USER_SET_VRING_BASE:
+       case VHOST_USER_SET_VRING_ENABLE:
+               vring_idx = msg->payload.state.index;
+               break;
+       case VHOST_USER_SET_VRING_ADDR:
+               vring_idx = msg->payload.addr.index;
+               break;
+       default:
+               return 0;
+       }
+
+       qp_idx = vring_idx / VIRTIO_QNUM;
+       if (qp_idx >= VHOST_MAX_QUEUE_PAIRS) {
+               RTE_LOG(ERR, VHOST_CONFIG,
+                       "invalid vring index: %u\n", vring_idx);
+               return -1;
+       }
+
+       if (dev->virtqueue[qp_idx * VIRTIO_QNUM])
+               return 0;
+
+       return alloc_vring_queue_pair(dev, qp_idx);
+}
+
 int
 vhost_user_msg_handler(int vid, int fd)
 {
@@ -943,6 +970,14 @@ vhost_user_msg_handler(int vid, int fd)
        ret = 0;
        RTE_LOG(INFO, VHOST_CONFIG, "read message %s\n",
                vhost_message_str[msg.request]);
+
+       ret = vhost_user_check_and_alloc_queue_pair(dev, &msg);
+       if (ret < 0) {
+               RTE_LOG(ERR, VHOST_CONFIG,
+                       "failed to alloc queue\n");
+               return -1;
+       }
+
        switch (msg.request) {
        case VHOST_USER_GET_FEATURES:
                msg.payload.u64 = vhost_user_get_features();