+/**
+ * Callback function to initialize mbufs for Multi-Packet RQ.
+ */
+static inline void
+mlx5_mprq_buf_init(struct rte_mempool *mp, void *opaque_arg __rte_unused,
+ void *_m, unsigned int i __rte_unused)
+{
+ struct mlx5_mprq_buf *buf = _m;
+
+ memset(_m, 0, sizeof(*buf));
+ buf->mp = mp;
+ rte_atomic16_set(&buf->refcnt, 1);
+}
+
+/**
+ * Free mempool of Multi-Packet RQ.
+ *
+ * @param dev
+ * Pointer to Ethernet device.
+ *
+ * @return
+ * 0 on success, negative errno value on failure.
+ */
+int
+mlx5_mprq_free_mp(struct rte_eth_dev *dev)
+{
+ struct priv *priv = dev->data->dev_private;
+ struct rte_mempool *mp = priv->mprq_mp;
+ unsigned int i;
+
+ if (mp == NULL)
+ return 0;
+ DRV_LOG(DEBUG, "port %u freeing mempool (%s) for Multi-Packet RQ",
+ dev->data->port_id, mp->name);
+ /*
+ * If a buffer in the pool has been externally attached to a mbuf and it
+ * is still in use by application, destroying the Rx qeueue can spoil
+ * the packet. It is unlikely to happen but if application dynamically
+ * creates and destroys with holding Rx packets, this can happen.
+ *
+ * TODO: It is unavoidable for now because the mempool for Multi-Packet
+ * RQ isn't provided by application but managed by PMD.
+ */
+ if (!rte_mempool_full(mp)) {
+ DRV_LOG(ERR,
+ "port %u mempool for Multi-Packet RQ is still in use",
+ dev->data->port_id);
+ rte_errno = EBUSY;
+ return -rte_errno;
+ }
+ rte_mempool_free(mp);
+ /* Unset mempool for each Rx queue. */
+ for (i = 0; i != priv->rxqs_n; ++i) {
+ struct mlx5_rxq_data *rxq = (*priv->rxqs)[i];
+
+ if (rxq == NULL)
+ continue;
+ rxq->mprq_mp = NULL;
+ }
+ return 0;
+}
+
+/**
+ * Allocate a mempool for Multi-Packet RQ. All configured Rx queues share the
+ * mempool. If already allocated, reuse it if there're enough elements.
+ * Otherwise, resize it.
+ *
+ * @param dev
+ * Pointer to Ethernet device.
+ *
+ * @return
+ * 0 on success, negative errno value on failure.
+ */
+int
+mlx5_mprq_alloc_mp(struct rte_eth_dev *dev)
+{
+ struct priv *priv = dev->data->dev_private;
+ struct rte_mempool *mp = priv->mprq_mp;
+ char name[RTE_MEMPOOL_NAMESIZE];
+ unsigned int desc = 0;
+ unsigned int buf_len;
+ unsigned int obj_num;
+ unsigned int obj_size;
+ unsigned int strd_num_n = 0;
+ unsigned int strd_sz_n = 0;
+ unsigned int i;
+
+ if (!mlx5_mprq_enabled(dev))
+ return 0;
+ /* Count the total number of descriptors configured. */
+ for (i = 0; i != priv->rxqs_n; ++i) {
+ struct mlx5_rxq_data *rxq = (*priv->rxqs)[i];
+
+ if (rxq == NULL)
+ continue;
+ desc += 1 << rxq->elts_n;
+ /* Get the max number of strides. */
+ if (strd_num_n < rxq->strd_num_n)
+ strd_num_n = rxq->strd_num_n;
+ /* Get the max size of a stride. */
+ if (strd_sz_n < rxq->strd_sz_n)
+ strd_sz_n = rxq->strd_sz_n;
+ }
+ assert(strd_num_n && strd_sz_n);
+ buf_len = (1 << strd_num_n) * (1 << strd_sz_n);
+ obj_size = buf_len + sizeof(struct mlx5_mprq_buf);
+ /*
+ * Received packets can be either memcpy'd or externally referenced. In
+ * case that the packet is attached to an mbuf as an external buffer, as
+ * it isn't possible to predict how the buffers will be queued by
+ * application, there's no option to exactly pre-allocate needed buffers
+ * in advance but to speculatively prepares enough buffers.
+ *
+ * In the data path, if this Mempool is depleted, PMD will try to memcpy
+ * received packets to buffers provided by application (rxq->mp) until
+ * this Mempool gets available again.
+ */
+ desc *= 4;
+ obj_num = desc + MLX5_MPRQ_MP_CACHE_SZ * priv->rxqs_n;
+ /* Check a mempool is already allocated and if it can be resued. */
+ if (mp != NULL && mp->elt_size >= obj_size && mp->size >= obj_num) {
+ DRV_LOG(DEBUG, "port %u mempool %s is being reused",
+ dev->data->port_id, mp->name);
+ /* Reuse. */
+ goto exit;
+ } else if (mp != NULL) {
+ DRV_LOG(DEBUG, "port %u mempool %s should be resized, freeing it",
+ dev->data->port_id, mp->name);
+ /*
+ * If failed to free, which means it may be still in use, no way
+ * but to keep using the existing one. On buffer underrun,
+ * packets will be memcpy'd instead of external buffer
+ * attachment.
+ */
+ if (mlx5_mprq_free_mp(dev)) {
+ if (mp->elt_size >= obj_size)
+ goto exit;
+ else
+ return -rte_errno;
+ }
+ }
+ snprintf(name, sizeof(name), "%s-mprq", dev->device->name);
+ mp = rte_mempool_create(name, obj_num, obj_size, MLX5_MPRQ_MP_CACHE_SZ,
+ 0, NULL, NULL, mlx5_mprq_buf_init, NULL,
+ dev->device->numa_node, 0);
+ if (mp == NULL) {
+ DRV_LOG(ERR,
+ "port %u failed to allocate a mempool for"
+ " Multi-Packet RQ, count=%u, size=%u",
+ dev->data->port_id, obj_num, obj_size);
+ rte_errno = ENOMEM;
+ return -rte_errno;
+ }
+ priv->mprq_mp = mp;
+exit:
+ /* Set mempool for each Rx queue. */
+ for (i = 0; i != priv->rxqs_n; ++i) {
+ struct mlx5_rxq_data *rxq = (*priv->rxqs)[i];
+
+ if (rxq == NULL)
+ continue;
+ rxq->mprq_mp = mp;
+ }
+ DRV_LOG(INFO, "port %u Multi-Packet RQ is configured",
+ dev->data->port_id);
+ return 0;
+}
+