+ * Initialize common RSS context resources.
+ *
+ * Because ConnectX-3 hardware limitations require a fixed order in the
+ * indirection table, WQs must be allocated sequentially to be part of a
+ * common RSS context.
+ *
+ * Since a newly created WQ cannot be moved to a different context, this
+ * function allocates them all at once, one for each configured Rx queue,
+ * as well as all related resources (CQs and mbufs).
+ *
+ * This must therefore be done before creating any Rx flow rules relying on
+ * indirection tables.
+ *
+ * @param priv
+ * Pointer to private structure.
+ *
+ * @return
+ * 0 on success, a negative errno value otherwise and rte_errno is set.
+ */
+int
+mlx4_rss_init(struct priv *priv)
+{
+ struct rte_eth_dev *dev = priv->dev;
+ uint8_t log2_range = rte_log2_u32(dev->data->nb_rx_queues);
+ uint32_t wq_num_prev = 0;
+ const char *msg;
+ unsigned int i;
+ int ret;
+
+ /* Prepare range for RSS contexts before creating the first WQ. */
+ ret = mlx4dv_set_context_attr(priv->ctx,
+ MLX4DV_SET_CTX_ATTR_LOG_WQS_RANGE_SZ,
+ &log2_range);
+ if (ret) {
+ ERROR("cannot set up range size for RSS context to %u"
+ " (for %u Rx queues), error: %s",
+ 1 << log2_range, dev->data->nb_rx_queues, strerror(ret));
+ rte_errno = ret;
+ return -ret;
+ }
+ for (i = 0; i != priv->dev->data->nb_rx_queues; ++i) {
+ struct rxq *rxq = priv->dev->data->rx_queues[i];
+ struct ibv_cq *cq;
+ struct ibv_wq *wq;
+ uint32_t wq_num;
+
+ /* Attach the configured Rx queues. */
+ if (rxq) {
+ assert(!rxq->usecnt);
+ ret = mlx4_rxq_attach(rxq);
+ if (!ret) {
+ wq_num = rxq->wq->wq_num;
+ goto wq_num_check;
+ }
+ ret = -ret;
+ msg = "unable to create Rx queue resources";
+ goto error;
+ }
+ /*
+ * WQs are temporarily allocated for unconfigured Rx queues
+ * to maintain proper index alignment in indirection table
+ * by skipping unused WQ numbers.
+ *
+ * The reason this works at all even though these WQs are
+ * immediately destroyed is that WQNs are allocated
+ * sequentially and are guaranteed to never be reused in the
+ * same context by the underlying implementation.
+ */
+ cq = ibv_create_cq(priv->ctx, 1, NULL, NULL, 0);
+ if (!cq) {
+ ret = ENOMEM;
+ msg = "placeholder CQ creation failure";
+ goto error;
+ }
+ wq = ibv_create_wq
+ (priv->ctx,
+ &(struct ibv_wq_init_attr){
+ .wq_type = IBV_WQT_RQ,
+ .max_wr = 1,
+ .max_sge = 1,
+ .pd = priv->pd,
+ .cq = cq,
+ });
+ if (wq) {
+ wq_num = wq->wq_num;
+ claim_zero(ibv_destroy_wq(wq));
+ } else {
+ wq_num = 0; /* Shut up GCC 4.8 warnings. */
+ }
+ claim_zero(ibv_destroy_cq(cq));
+ if (!wq) {
+ ret = ENOMEM;
+ msg = "placeholder WQ creation failure";
+ goto error;
+ }
+wq_num_check:
+ /*
+ * While guaranteed by the implementation, make sure WQ
+ * numbers are really sequential (as the saying goes,
+ * trust, but verify).
+ */
+ if (i && wq_num - wq_num_prev != 1) {
+ if (rxq)
+ mlx4_rxq_detach(rxq);
+ ret = ERANGE;
+ msg = "WQ numbers are not sequential";
+ goto error;
+ }
+ wq_num_prev = wq_num;
+ }
+ return 0;
+error:
+ ERROR("cannot initialize common RSS resources (queue %u): %s: %s",
+ i, msg, strerror(ret));
+ while (i--) {
+ struct rxq *rxq = priv->dev->data->rx_queues[i];
+
+ if (rxq)
+ mlx4_rxq_detach(rxq);
+ }
+ rte_errno = ret;
+ return -ret;
+}
+
+/**
+ * Release common RSS context resources.
+ *
+ * As the reverse of mlx4_rss_init(), this must be done after removing all
+ * flow rules relying on indirection tables.
+ *
+ * @param priv
+ * Pointer to private structure.
+ */
+void
+mlx4_rss_deinit(struct priv *priv)
+{
+ unsigned int i;
+
+ for (i = 0; i != priv->dev->data->nb_rx_queues; ++i) {
+ struct rxq *rxq = priv->dev->data->rx_queues[i];
+
+ if (rxq) {
+ assert(rxq->usecnt == 1);
+ mlx4_rxq_detach(rxq);
+ }
+ }
+}
+
+/**
+ * Attach a user to a Rx queue.
+ *
+ * Used when the resources of an Rx queue must be instantiated for it to
+ * become in a usable state.
+ *
+ * This function increments the usage count of the Rx queue.