net/mlx4: fix no Rx interrupts
[dpdk.git] / drivers / net / mlx4 / mlx4_rxq.c
index 9978e5d..7fe21b6 100644 (file)
 #ifdef PEDANTIC
 #pragma GCC diagnostic ignored "-Wpedantic"
 #endif
+#include <infiniband/mlx4dv.h>
 #include <infiniband/verbs.h>
 #ifdef PEDANTIC
 #pragma GCC diagnostic error "-Wpedantic"
 #endif
 
+#include <rte_byteorder.h>
 #include <rte_common.h>
 #include <rte_errno.h>
 #include <rte_ethdev.h>
 #include "mlx4_utils.h"
 
 /**
- * Allocate Rx queue elements.
+ * Historical RSS hash key.
+ *
+ * This used to be the default for mlx4 in Linux before v3.19 switched to
+ * generating random hash keys through netdev_rss_key_fill().
+ *
+ * It is used in this PMD for consistency with past DPDK releases but can
+ * now be overridden through user configuration.
+ *
+ * Note: this is not const to work around API quirks.
+ */
+uint8_t
+mlx4_rss_hash_key_default[MLX4_RSS_HASH_KEY_SIZE] = {
+       0x2c, 0xc6, 0x81, 0xd1,
+       0x5b, 0xdb, 0xf4, 0xf7,
+       0xfc, 0xa2, 0x83, 0x19,
+       0xdb, 0x1a, 0x3e, 0x94,
+       0x6b, 0x9e, 0x38, 0xd9,
+       0x2c, 0x9c, 0x03, 0xd1,
+       0xad, 0x99, 0x44, 0xa7,
+       0xd9, 0x56, 0x3d, 0x59,
+       0x06, 0x3c, 0x25, 0xf3,
+       0xfc, 0x1f, 0xdc, 0x2a,
+};
+
+/**
+ * Obtain a RSS context with specified properties.
+ *
+ * Used when creating a flow rule targeting one or several Rx queues.
+ *
+ * If a matching RSS context already exists, it is returned with its
+ * reference count incremented.
+ *
+ * @param priv
+ *   Pointer to private structure.
+ * @param fields
+ *   Fields for RSS processing (Verbs format).
+ * @param[in] key
+ *   Hash key to use (whose size is exactly MLX4_RSS_HASH_KEY_SIZE).
+ * @param queues
+ *   Number of target queues.
+ * @param[in] queue_id
+ *   Target queues.
+ *
+ * @return
+ *   Pointer to RSS context on success, NULL otherwise and rte_errno is set.
+ */
+struct mlx4_rss *
+mlx4_rss_get(struct priv *priv, uint64_t fields,
+            uint8_t key[MLX4_RSS_HASH_KEY_SIZE],
+            uint16_t queues, const uint16_t queue_id[])
+{
+       struct mlx4_rss *rss;
+       size_t queue_id_size = sizeof(queue_id[0]) * queues;
+
+       LIST_FOREACH(rss, &priv->rss, next)
+               if (fields == rss->fields &&
+                   queues == rss->queues &&
+                   !memcmp(key, rss->key, MLX4_RSS_HASH_KEY_SIZE) &&
+                   !memcmp(queue_id, rss->queue_id, queue_id_size)) {
+                       ++rss->refcnt;
+                       return rss;
+               }
+       rss = rte_malloc(__func__, offsetof(struct mlx4_rss, queue_id) +
+                        queue_id_size, 0);
+       if (!rss)
+               goto error;
+       *rss = (struct mlx4_rss){
+               .priv = priv,
+               .refcnt = 1,
+               .usecnt = 0,
+               .qp = NULL,
+               .ind = NULL,
+               .fields = fields,
+               .queues = queues,
+       };
+       memcpy(rss->key, key, MLX4_RSS_HASH_KEY_SIZE);
+       memcpy(rss->queue_id, queue_id, queue_id_size);
+       LIST_INSERT_HEAD(&priv->rss, rss, next);
+       return rss;
+error:
+       rte_errno = ENOMEM;
+       return NULL;
+}
+
+/**
+ * Release a RSS context instance.
+ *
+ * Used when destroying a flow rule targeting one or several Rx queues.
+ *
+ * This function decrements the reference count of the context and destroys
+ * it after reaching 0. The context must have no users at this point; all
+ * prior calls to mlx4_rss_attach() must have been followed by matching
+ * calls to mlx4_rss_detach().
+ *
+ * @param rss
+ *   RSS context to release.
+ */
+void mlx4_rss_put(struct mlx4_rss *rss)
+{
+       assert(rss->refcnt);
+       if (--rss->refcnt)
+               return;
+       assert(!rss->usecnt);
+       assert(!rss->qp);
+       assert(!rss->ind);
+       LIST_REMOVE(rss, next);
+       rte_free(rss);
+}
+
+/**
+ * Attach a user to a RSS context instance.
+ *
+ * Used when the RSS QP and indirection table objects must be instantiated,
+ * that is, when a flow rule must be enabled.
+ *
+ * This function increments the usage count of the context.
+ *
+ * @param rss
+ *   RSS context to attach to.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
+ */
+int mlx4_rss_attach(struct mlx4_rss *rss)
+{
+       assert(rss->refcnt);
+       if (rss->usecnt++) {
+               assert(rss->qp);
+               assert(rss->ind);
+               return 0;
+       }
+
+       struct ibv_wq *ind_tbl[rss->queues];
+       struct priv *priv = rss->priv;
+       const char *msg;
+       unsigned int i = 0;
+       int ret;
+
+       if (!rte_is_power_of_2(RTE_DIM(ind_tbl))) {
+               ret = EINVAL;
+               msg = "number of RSS queues must be a power of two";
+               goto error;
+       }
+       for (i = 0; i != RTE_DIM(ind_tbl); ++i) {
+               uint16_t id = rss->queue_id[i];
+               struct rxq *rxq = NULL;
+
+               if (id < priv->dev->data->nb_rx_queues)
+                       rxq = priv->dev->data->rx_queues[id];
+               if (!rxq) {
+                       ret = EINVAL;
+                       msg = "RSS target queue is not configured";
+                       goto error;
+               }
+               ret = mlx4_rxq_attach(rxq);
+               if (ret) {
+                       ret = -ret;
+                       msg = "unable to attach RSS target queue";
+                       goto error;
+               }
+               ind_tbl[i] = rxq->wq;
+       }
+       rss->ind = ibv_create_rwq_ind_table
+               (priv->ctx,
+                &(struct ibv_rwq_ind_table_init_attr){
+                       .log_ind_tbl_size = rte_log2_u32(RTE_DIM(ind_tbl)),
+                       .ind_tbl = ind_tbl,
+                       .comp_mask = 0,
+                });
+       if (!rss->ind) {
+               ret = errno ? errno : EINVAL;
+               msg = "RSS indirection table creation failure";
+               goto error;
+       }
+       rss->qp = ibv_create_qp_ex
+               (priv->ctx,
+                &(struct ibv_qp_init_attr_ex){
+                       .comp_mask = (IBV_QP_INIT_ATTR_PD |
+                                     IBV_QP_INIT_ATTR_RX_HASH |
+                                     IBV_QP_INIT_ATTR_IND_TABLE),
+                       .qp_type = IBV_QPT_RAW_PACKET,
+                       .pd = priv->pd,
+                       .rwq_ind_tbl = rss->ind,
+                       .rx_hash_conf = {
+                               .rx_hash_function = IBV_RX_HASH_FUNC_TOEPLITZ,
+                               .rx_hash_key_len = MLX4_RSS_HASH_KEY_SIZE,
+                               .rx_hash_key = rss->key,
+                               .rx_hash_fields_mask = rss->fields,
+                       },
+                });
+       if (!rss->qp) {
+               ret = errno ? errno : EINVAL;
+               msg = "RSS hash QP creation failure";
+               goto error;
+       }
+       ret = ibv_modify_qp
+               (rss->qp,
+                &(struct ibv_qp_attr){
+                       .qp_state = IBV_QPS_INIT,
+                       .port_num = priv->port,
+                },
+                IBV_QP_STATE | IBV_QP_PORT);
+       if (ret) {
+               msg = "failed to switch RSS hash QP to INIT state";
+               goto error;
+       }
+       ret = ibv_modify_qp
+               (rss->qp,
+                &(struct ibv_qp_attr){
+                       .qp_state = IBV_QPS_RTR,
+                },
+                IBV_QP_STATE);
+       if (ret) {
+               msg = "failed to switch RSS hash QP to RTR state";
+               goto error;
+       }
+       return 0;
+error:
+       if (rss->qp) {
+               claim_zero(ibv_destroy_qp(rss->qp));
+               rss->qp = NULL;
+       }
+       if (rss->ind) {
+               claim_zero(ibv_destroy_rwq_ind_table(rss->ind));
+               rss->ind = NULL;
+       }
+       while (i--)
+               mlx4_rxq_detach(priv->dev->data->rx_queues[rss->queue_id[i]]);
+       ERROR("mlx4: %s", msg);
+       --rss->usecnt;
+       rte_errno = ret;
+       return -ret;
+}
+
+/**
+ * Detach a user from a RSS context instance.
+ *
+ * Used when disabling (not destroying) a flow rule.
+ *
+ * This function decrements the usage count of the context and destroys
+ * usage resources after reaching 0.
+ *
+ * @param rss
+ *   RSS context to detach from.
+ */
+void mlx4_rss_detach(struct mlx4_rss *rss)
+{
+       struct priv *priv = rss->priv;
+       unsigned int i;
+
+       assert(rss->refcnt);
+       assert(rss->qp);
+       assert(rss->ind);
+       if (--rss->usecnt)
+               return;
+       claim_zero(ibv_destroy_qp(rss->qp));
+       rss->qp = NULL;
+       claim_zero(ibv_destroy_rwq_ind_table(rss->ind));
+       rss->ind = NULL;
+       for (i = 0; i != rss->queues; ++i)
+               mlx4_rxq_detach(priv->dev->data->rx_queues[rss->queue_id[i]]);
+}
+
+/**
+ * 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.
  *
  * @param rxq
  *   Pointer to Rx queue structure.
  * @return
  *   0 on success, negative errno value otherwise and rte_errno is set.
  */
-static int
-mlx4_rxq_alloc_elts(struct rxq *rxq)
+int
+mlx4_rxq_attach(struct rxq *rxq)
 {
-       struct rxq_elt (*elts)[rxq->elts_n] = rxq->elts;
+       if (rxq->usecnt++) {
+               assert(rxq->cq);
+               assert(rxq->wq);
+               assert(rxq->wqes);
+               assert(rxq->rq_db);
+               return 0;
+       }
+
+       struct priv *priv = rxq->priv;
+       const uint32_t elts_n = 1 << rxq->elts_n;
+       const uint32_t sges_n = 1 << rxq->sges_n;
+       struct rte_mbuf *(*elts)[elts_n] = rxq->elts;
+       struct mlx4dv_obj mlxdv;
+       struct mlx4dv_rwq dv_rwq;
+       struct mlx4dv_cq dv_cq = { .comp_mask = MLX4DV_CQ_MASK_UAR, };
+       const char *msg;
+       struct ibv_cq *cq = NULL;
+       struct ibv_wq *wq = NULL;
+       volatile struct mlx4_wqe_data_seg (*wqes)[];
        unsigned int i;
+       int ret;
 
-       /* For each WR (packet). */
+       assert(rte_is_power_of_2(elts_n));
+       cq = ibv_create_cq(priv->ctx, elts_n / sges_n, NULL, rxq->channel, 0);
+       if (!cq) {
+               ret = ENOMEM;
+               msg = "CQ creation failure";
+               goto error;
+       }
+       wq = ibv_create_wq
+               (priv->ctx,
+                &(struct ibv_wq_init_attr){
+                       .wq_type = IBV_WQT_RQ,
+                       .max_wr = elts_n / sges_n,
+                       .max_sge = sges_n,
+                       .pd = priv->pd,
+                       .cq = cq,
+                });
+       if (!wq) {
+               ret = errno ? errno : EINVAL;
+               msg = "WQ creation failure";
+               goto error;
+       }
+       ret = ibv_modify_wq
+               (wq,
+                &(struct ibv_wq_attr){
+                       .attr_mask = IBV_WQ_ATTR_STATE,
+                       .wq_state = IBV_WQS_RDY,
+                });
+       if (ret) {
+               msg = "WQ state change to IBV_WQS_RDY failed";
+               goto error;
+       }
+       /* Retrieve device queue information. */
+       mlxdv.cq.in = cq;
+       mlxdv.cq.out = &dv_cq;
+       mlxdv.rwq.in = wq;
+       mlxdv.rwq.out = &dv_rwq;
+       ret = mlx4dv_init_obj(&mlxdv, MLX4DV_OBJ_RWQ | MLX4DV_OBJ_CQ);
+       if (ret) {
+               msg = "failed to obtain device information from WQ/CQ objects";
+               goto error;
+       }
+       wqes = (volatile struct mlx4_wqe_data_seg (*)[])
+               ((uintptr_t)dv_rwq.buf.buf + dv_rwq.rq.offset);
        for (i = 0; i != RTE_DIM(*elts); ++i) {
-               struct rxq_elt *elt = &(*elts)[i];
-               struct ibv_recv_wr *wr = &elt->wr;
-               struct ibv_sge *sge = &(*elts)[i].sge;
+               volatile struct mlx4_wqe_data_seg *scat = &(*wqes)[i];
                struct rte_mbuf *buf = rte_pktmbuf_alloc(rxq->mp);
 
                if (buf == NULL) {
                        while (i--) {
-                               rte_pktmbuf_free_seg((*elts)[i].buf);
-                               (*elts)[i].buf = NULL;
+                               rte_pktmbuf_free_seg((*elts)[i]);
+                               (*elts)[i] = NULL;
                        }
-                       rte_errno = ENOMEM;
-                       return -rte_errno;
+                       ret = ENOMEM;
+                       msg = "cannot allocate mbuf";
+                       goto error;
                }
-               elt->buf = buf;
-               wr->next = &(*elts)[(i + 1)].wr;
-               wr->sg_list = sge;
-               wr->num_sge = 1;
                /* Headroom is reserved by rte_pktmbuf_alloc(). */
                assert(buf->data_off == RTE_PKTMBUF_HEADROOM);
                /* Buffer is supposed to be empty. */
                assert(rte_pktmbuf_data_len(buf) == 0);
                assert(rte_pktmbuf_pkt_len(buf) == 0);
-               /* sge->addr must be able to store a pointer. */
-               assert(sizeof(sge->addr) >= sizeof(uintptr_t));
-               /* SGE keeps its headroom. */
-               sge->addr = (uintptr_t)
-                       ((uint8_t *)buf->buf_addr + RTE_PKTMBUF_HEADROOM);
-               sge->length = (buf->buf_len - RTE_PKTMBUF_HEADROOM);
-               sge->lkey = rxq->mr->lkey;
-               /* Redundant check for tailroom. */
-               assert(sge->length == rte_pktmbuf_tailroom(buf));
+               /* Only the first segment keeps headroom. */
+               if (i % sges_n)
+                       buf->data_off = 0;
+               buf->port = rxq->port_id;
+               buf->data_len = rte_pktmbuf_tailroom(buf);
+               buf->pkt_len = rte_pktmbuf_tailroom(buf);
+               buf->nb_segs = 1;
+               *scat = (struct mlx4_wqe_data_seg){
+                       .addr = rte_cpu_to_be_64(rte_pktmbuf_mtod(buf,
+                                                                 uintptr_t)),
+                       .byte_count = rte_cpu_to_be_32(buf->data_len),
+                       .lkey = rte_cpu_to_be_32(rxq->mr->lkey),
+               };
+               (*elts)[i] = buf;
        }
-       /* The last WR pointer must be NULL. */
-       (*elts)[(i - 1)].wr.next = NULL;
+       DEBUG("%p: allocated and configured %u segments (max %u packets)",
+             (void *)rxq, elts_n, elts_n / sges_n);
+       rxq->cq = cq;
+       rxq->wq = wq;
+       rxq->wqes = wqes;
+       rxq->rq_db = dv_rwq.rdb;
+       rxq->mcq.buf = dv_cq.buf.buf;
+       rxq->mcq.cqe_cnt = dv_cq.cqe_cnt;
+       rxq->mcq.set_ci_db = dv_cq.set_ci_db;
+       rxq->mcq.cqe_64 = (dv_cq.cqe_size & 64) ? 1 : 0;
+       rxq->mcq.arm_db = dv_cq.arm_db;
+       rxq->mcq.arm_sn = dv_cq.arm_sn;
+       rxq->mcq.cqn = dv_cq.cqn;
+       rxq->mcq.cq_uar = dv_cq.cq_uar;
+       rxq->mcq.cq_db_reg = (uint8_t *)dv_cq.cq_uar + MLX4_CQ_DOORBELL;
+       /* Update doorbell counter. */
+       rxq->rq_ci = elts_n / sges_n;
+       rte_wmb();
+       *rxq->rq_db = rte_cpu_to_be_32(rxq->rq_ci);
        return 0;
+error:
+       if (wq)
+               claim_zero(ibv_destroy_wq(wq));
+       if (cq)
+               claim_zero(ibv_destroy_cq(cq));
+       rte_errno = ret;
+       ERROR("error while attaching Rx queue %p: %s: %s",
+             (void *)rxq, msg, strerror(ret));
+       return -ret;
 }
 
 /**
- * Free Rx queue elements.
+ * Detach a user from a Rx queue.
+ *
+ * This function decrements the usage count of the Rx queue and destroys
+ * usage resources after reaching 0.
  *
  * @param rxq
  *   Pointer to Rx queue structure.
  */
-static void
-mlx4_rxq_free_elts(struct rxq *rxq)
+void
+mlx4_rxq_detach(struct rxq *rxq)
 {
        unsigned int i;
-       struct rxq_elt (*elts)[rxq->elts_n] = rxq->elts;
+       struct rte_mbuf *(*elts)[1 << rxq->elts_n] = rxq->elts;
 
-       DEBUG("%p: freeing WRs", (void *)rxq);
+       if (--rxq->usecnt)
+               return;
+       rxq->rq_ci = 0;
+       memset(&rxq->mcq, 0, sizeof(rxq->mcq));
+       rxq->rq_db = NULL;
+       rxq->wqes = NULL;
+       claim_zero(ibv_destroy_wq(rxq->wq));
+       rxq->wq = NULL;
+       claim_zero(ibv_destroy_cq(rxq->cq));
+       rxq->cq = NULL;
+       DEBUG("%p: freeing Rx queue elements", (void *)rxq);
        for (i = 0; (i != RTE_DIM(*elts)); ++i) {
-               if (!(*elts)[i].buf)
+               if (!(*elts)[i])
                        continue;
-               rte_pktmbuf_free_seg((*elts)[i].buf);
-               (*elts)[i].buf = NULL;
+               rte_pktmbuf_free_seg((*elts)[i]);
+               (*elts)[i] = NULL;
        }
 }
 
@@ -165,8 +685,7 @@ mlx4_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
 {
        struct priv *priv = dev->data->dev_private;
        uint32_t mb_len = rte_pktmbuf_data_room_size(mp);
-       struct rxq_elt (*elts)[desc];
-       struct rte_flow_error error;
+       struct rte_mbuf *(*elts)[rte_align32pow2(desc)];
        struct rxq *rxq;
        struct mlx4_malloc_vec vec[] = {
                {
@@ -203,6 +722,12 @@ mlx4_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
                ERROR("%p: invalid number of Rx descriptors", (void *)dev);
                return -rte_errno;
        }
+       if (desc != RTE_DIM(*elts)) {
+               desc = RTE_DIM(*elts);
+               WARN("%p: increased number of descriptors in Rx queue %u"
+                    " to the next power of two (%u)",
+                    (void *)dev, idx, desc);
+       }
        /* Allocate and initialize Rx queue. */
        mlx4_zmallocv_socket("RXQ", vec, RTE_DIM(vec), socket);
        if (!rxq) {
@@ -214,10 +739,17 @@ mlx4_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
                .priv = priv,
                .mp = mp,
                .port_id = dev->data->port_id,
-               .elts_n = desc,
-               .elts_head = 0,
+               .sges_n = 0,
+               .elts_n = rte_log2_u32(desc),
                .elts = elts,
-               .stats.idx = idx,
+               /* Toggle Rx checksum offload if hardware supports it. */
+               .csum = (priv->hw_csum &&
+                        dev->data->dev_conf.rxmode.hw_ip_checksum),
+               .csum_l2tun = (priv->hw_csum_l2tun &&
+                              dev->data->dev_conf.rxmode.hw_ip_checksum),
+               .stats = {
+                       .idx = idx,
+               },
                .socket = socket,
        };
        /* Enable scattered packets support for this queue if necessary. */
@@ -226,9 +758,29 @@ mlx4_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
            (mb_len - RTE_PKTMBUF_HEADROOM)) {
                ;
        } else if (dev->data->dev_conf.rxmode.enable_scatter) {
-               WARN("%p: scattered mode has been requested but is"
-                    " not supported, this may lead to packet loss",
-                    (void *)dev);
+               uint32_t size =
+                       RTE_PKTMBUF_HEADROOM +
+                       dev->data->dev_conf.rxmode.max_rx_pkt_len;
+               uint32_t sges_n;
+
+               /*
+                * Determine the number of SGEs needed for a full packet
+                * and round it to the next power of two.
+                */
+               sges_n = rte_log2_u32((size / mb_len) + !!(size % mb_len));
+               rxq->sges_n = sges_n;
+               /* Make sure sges_n did not overflow. */
+               size = mb_len * (1 << rxq->sges_n);
+               size -= RTE_PKTMBUF_HEADROOM;
+               if (size < dev->data->dev_conf.rxmode.max_rx_pkt_len) {
+                       rte_errno = EOVERFLOW;
+                       ERROR("%p: too many SGEs (%u) needed to handle"
+                             " requested maximum packet size %u",
+                             (void *)dev,
+                             1 << sges_n,
+                             dev->data->dev_conf.rxmode.max_rx_pkt_len);
+                       goto error;
+               }
        } else {
                WARN("%p: the requested maximum Rx packet size (%u) is"
                     " larger than a single mbuf (%u) and scattered"
@@ -237,6 +789,17 @@ mlx4_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
                     dev->data->dev_conf.rxmode.max_rx_pkt_len,
                     mb_len - RTE_PKTMBUF_HEADROOM);
        }
+       DEBUG("%p: maximum number of segments per packet: %u",
+             (void *)dev, 1 << rxq->sges_n);
+       if (desc % (1 << rxq->sges_n)) {
+               rte_errno = EINVAL;
+               ERROR("%p: number of Rx queue descriptors (%u) is not a"
+                     " multiple of maximum segments per packet (%u)",
+                     (void *)dev,
+                     desc,
+                     1 << rxq->sges_n);
+               goto error;
+       }
        /* Use the entire Rx mempool as the memory region. */
        rxq->mr = mlx4_mp2mr(priv->pd, mp);
        if (!rxq->mr) {
@@ -261,82 +824,9 @@ mlx4_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
                        goto error;
                }
        }
-       rxq->cq = ibv_create_cq(priv->ctx, desc, NULL, rxq->channel, 0);
-       if (!rxq->cq) {
-               rte_errno = ENOMEM;
-               ERROR("%p: CQ creation failure: %s",
-                     (void *)dev, strerror(rte_errno));
-               goto error;
-       }
-       rxq->qp = ibv_create_qp
-               (priv->pd,
-                &(struct ibv_qp_init_attr){
-                       .send_cq = rxq->cq,
-                       .recv_cq = rxq->cq,
-                       .cap = {
-                               .max_recv_wr =
-                                       RTE_MIN(priv->device_attr.max_qp_wr,
-                                               desc),
-                               .max_recv_sge = 1,
-                       },
-                       .qp_type = IBV_QPT_RAW_PACKET,
-                });
-       if (!rxq->qp) {
-               rte_errno = errno ? errno : EINVAL;
-               ERROR("%p: QP creation failure: %s",
-                     (void *)dev, strerror(rte_errno));
-               goto error;
-       }
-       ret = ibv_modify_qp
-               (rxq->qp,
-                &(struct ibv_qp_attr){
-                       .qp_state = IBV_QPS_INIT,
-                       .port_num = priv->port,
-                },
-                IBV_QP_STATE | IBV_QP_PORT);
-       if (ret) {
-               rte_errno = ret;
-               ERROR("%p: QP state to IBV_QPS_INIT failed: %s",
-                     (void *)dev, strerror(rte_errno));
-               goto error;
-       }
-       ret = mlx4_rxq_alloc_elts(rxq);
-       if (ret) {
-               ERROR("%p: RXQ allocation failed: %s",
-                     (void *)dev, strerror(rte_errno));
-               goto error;
-       }
-       ret = ibv_post_recv(rxq->qp, &(*rxq->elts)[0].wr,
-                           &(struct ibv_recv_wr *){ NULL });
-       if (ret) {
-               rte_errno = ret;
-               ERROR("%p: ibv_post_recv() failed: %s",
-                     (void *)dev,
-                     strerror(rte_errno));
-               goto error;
-       }
-       ret = ibv_modify_qp
-               (rxq->qp,
-                &(struct ibv_qp_attr){
-                       .qp_state = IBV_QPS_RTR,
-                },
-                IBV_QP_STATE);
-       if (ret) {
-               rte_errno = ret;
-               ERROR("%p: QP state to IBV_QPS_RTR failed: %s",
-                     (void *)dev, strerror(rte_errno));
-               goto error;
-       }
        DEBUG("%p: adding Rx queue %p to list", (void *)dev, (void *)rxq);
        dev->data->rx_queues[idx] = rxq;
-       /* Enable associated flows. */
-       ret = mlx4_flow_sync(priv, &error);
-       if (!ret)
-               return 0;
-       ERROR("cannot re-attach flow rules to queue %u"
-             " (code %d, \"%s\"), flow error type %d, cause %p, message: %s",
-             idx, -ret, strerror(-ret), error.type, error.cause,
-             error.message ? error.message : "(unspecified)");
+       return 0;
 error:
        dev->data->rx_queues[idx] = NULL;
        ret = rte_errno;
@@ -369,12 +859,10 @@ mlx4_rx_queue_release(void *dpdk_rxq)
                        priv->dev->data->rx_queues[i] = NULL;
                        break;
                }
-       mlx4_flow_sync(priv, NULL);
-       mlx4_rxq_free_elts(rxq);
-       if (rxq->qp)
-               claim_zero(ibv_destroy_qp(rxq->qp));
-       if (rxq->cq)
-               claim_zero(ibv_destroy_cq(rxq->cq));
+       assert(!rxq->cq);
+       assert(!rxq->wq);
+       assert(!rxq->wqes);
+       assert(!rxq->rq_db);
        if (rxq->channel)
                claim_zero(ibv_destroy_comp_channel(rxq->channel));
        if (rxq->mr)