Implement support for receiving merged buffers in virtio when packed virtqueues
are enabled. 

Signed-off-by: Jens Freimann <jfreim...@redhat.com>
---
 drivers/net/virtio/virtio_ethdev.c |   5 +-
 drivers/net/virtio/virtio_rxtx.c   | 107 +++++++++++++++++++++++++++++++++----
 drivers/net/virtio/virtqueue.h     |   1 +
 3 files changed, 103 insertions(+), 10 deletions(-)

diff --git a/drivers/net/virtio/virtio_ethdev.c 
b/drivers/net/virtio/virtio_ethdev.c
index 9f372a4..d9e7399 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -1360,7 +1360,10 @@ static int virtio_dev_xstats_get_names(struct 
rte_eth_dev *dev,
                        eth_dev->data->port_id);
                eth_dev->rx_pkt_burst = virtio_recv_pkts_vec;
        } else if (vtpci_packed_queue(hw)) {
-               eth_dev->rx_pkt_burst = &virtio_recv_pkts_packed;
+               if (vtpci_with_feature(hw, VIRTIO_NET_F_MRG_RXBUF))
+                       eth_dev->rx_pkt_burst = &virtio_recv_mergeable_pkts;
+               else
+                       eth_dev->rx_pkt_burst = &virtio_recv_pkts_packed;
        } else if (vtpci_with_feature(hw, VIRTIO_NET_F_MRG_RXBUF)) {
                PMD_INIT_LOG(INFO,
                        "virtio: using mergeable buffer Rx path on port %u",
diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index 7834747..5545aa4 100644
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -64,8 +64,8 @@
        vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt + dxp->ndescs);
        if ((dp->flags & VRING_DESC_F_INDIRECT) == 0) {
                while (dp->flags & VRING_DESC_F_NEXT) {
-                       desc_idx_last = dp->next;
-                       dp = &vq->vq_ring.desc[dp->next];
+                       desc_idx_last = desc_idx++;
+                       dp = &vq->vq_ring.desc[desc_idx];
                }
        }
        dxp->ndescs = 0;
@@ -86,6 +86,76 @@
        dp->next = VQ_RING_DESC_CHAIN_END;
 }
 
+static void
+virtio_refill_packed(struct virtqueue *vq, uint16_t used_idx, struct 
virtnet_rx *rxvq)
+{
+       struct vq_desc_extra *dxp;
+       struct vring_desc_packed *descs = vq->vq_ring.desc_packed;
+       struct vring_desc_packed *desc;
+       struct rte_mbuf *nmb;
+
+       nmb = rte_mbuf_raw_alloc(rxvq->mpool);
+       if (unlikely(nmb == NULL)) {
+               struct rte_eth_dev *dev
+                       = &rte_eth_devices[rxvq->port_id];
+               dev->data->rx_mbuf_alloc_failed++;
+               return;
+       }
+
+       desc = &descs[used_idx & (vq->vq_nentries - 1)];
+
+       dxp = &vq->vq_descx[used_idx & (vq->vq_nentries - 1)];
+
+       dxp->cookie = nmb;
+       dxp->ndescs = 1;
+
+       desc->addr = VIRTIO_MBUF_ADDR(nmb, vq) +
+               RTE_PKTMBUF_HEADROOM - vq->hw->vtnet_hdr_size;
+       desc->len = nmb->buf_len - RTE_PKTMBUF_HEADROOM +
+               vq->hw->vtnet_hdr_size;
+       desc->flags |= VRING_DESC_F_WRITE;
+
+
+}
+
+static uint16_t
+virtqueue_dequeue_burst_rx_packed(struct virtqueue *vq, struct rte_mbuf 
**rx_pkts,
+                          uint32_t *len, uint16_t num, struct virtnet_rx 
*rx_queue)
+{
+       struct rte_mbuf *cookie;
+       uint16_t used_idx;
+       struct vring_desc_packed *desc;
+       uint16_t i;
+
+       for (i = 0; i < num; i++) {
+               used_idx = (uint16_t)(vq->vq_used_cons_idx & (vq->vq_nentries - 
1));
+               desc = &vq->vq_ring.desc_packed[used_idx];
+               if (!desc_is_used(desc))
+                       return i;
+               len[i] = desc->len;
+               cookie = (struct rte_mbuf *)vq->vq_descx[used_idx].cookie;
+
+               if (unlikely(cookie == NULL)) {
+                       PMD_DRV_LOG(ERR, "vring descriptor with no mbuf cookie 
at %u",
+                               vq->vq_used_cons_idx);
+                       break;
+               }
+               rte_prefetch0(cookie);
+               rte_packet_prefetch(rte_pktmbuf_mtod(cookie, void *));
+               rx_pkts[i] = cookie;
+
+               virtio_refill_packed(vq, used_idx, rx_queue);
+
+               rte_smp_wmb();
+               if ((vq->vq_used_cons_idx & (vq->vq_nentries - 1)) == 0)
+                       toggle_wrap_counter(&vq->vq_ring);
+               set_desc_avail(&vq->vq_ring, desc);
+               vq->vq_used_cons_idx++;
+       }
+
+       return i;
+}
+
 static uint16_t
 virtqueue_dequeue_burst_rx(struct virtqueue *vq, struct rte_mbuf **rx_pkts,
                           uint32_t *len, uint16_t num)
@@ -968,12 +1038,16 @@
        uint32_t seg_res;
        uint32_t hdr_size;
        int offload;
+       uint32_t rx_num = 0;
 
        nb_rx = 0;
        if (unlikely(hw->started == 0))
                return nb_rx;
 
-       nb_used = VIRTQUEUE_NUSED(vq);
+       if (vtpci_packed_queue(vq->hw))
+               nb_used = VIRTIO_MBUF_BURST_SZ; //FIXME
+       else
+               nb_used = VIRTQUEUE_NUSED(vq);
 
        virtio_rmb();
 
@@ -987,14 +1061,23 @@
        hdr_size = hw->vtnet_hdr_size;
        offload = rx_offload_enabled(hw);
 
+       vq->vq_used_idx = vq->vq_used_cons_idx;
+
        while (i < nb_used) {
                struct virtio_net_hdr_mrg_rxbuf *header;
 
                if (nb_rx == nb_pkts)
                        break;
 
-               num = virtqueue_dequeue_burst_rx(vq, rcv_pkts, len, 1);
-               if (num != 1)
+               if (vtpci_packed_queue(vq->hw))
+                       num = virtqueue_dequeue_burst_rx_packed(vq, rcv_pkts, 
len, 1, 
+                               (struct virtnet_rx *) rx_queue);
+               else
+                       num = virtqueue_dequeue_burst_rx(vq, rcv_pkts, len, 1);
+               if (num == 0) {
+                       return nb_rx;
+               }
+               if (num != 1 )
                        continue;
 
                i++;
@@ -1045,9 +1128,13 @@
                        uint16_t  rcv_cnt =
                                RTE_MIN(seg_res, RTE_DIM(rcv_pkts));
                        if (likely(VIRTQUEUE_NUSED(vq) >= rcv_cnt)) {
-                               uint32_t rx_num =
-                                       virtqueue_dequeue_burst_rx(vq,
-                                       rcv_pkts, len, rcv_cnt);
+                               if (vtpci_packed_queue(vq->hw))
+                                       rx_num = 
virtqueue_dequeue_burst_rx_packed(vq,
+                                                            rcv_pkts, len, 
rcv_cnt,
+                                                            (struct virtnet_rx 
*) rx_queue);
+                               else
+                                       rx_num = virtqueue_dequeue_burst_rx(vq,
+                                                             rcv_pkts, len, 
rcv_cnt);
                                i += rx_num;
                                rcv_cnt = rx_num;
                        } else {
@@ -1091,6 +1178,9 @@
 
        rxvq->stats.packets += nb_rx;
 
+       if (vtpci_packed_queue(vq->hw))
+               return nb_rx;
+
        /* Allocate new mbuf for the used descriptor */
        error = ENOSPC;
        while (likely(!virtqueue_full(vq))) {
@@ -1111,7 +1201,6 @@
 
        if (likely(nb_enqueued)) {
                vq_update_avail_idx(vq);
-
                if (unlikely(virtqueue_kick_prepare(vq))) {
                        virtqueue_notify(vq);
                        PMD_RX_LOG(DEBUG, "Notified");
diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index 82160ca..13cadf8 100644
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -171,6 +171,7 @@ struct virtqueue {
         * trails vq_ring.used->idx.
         */
        uint16_t vq_used_cons_idx;
+       uint16_t vq_used_idx;
        uint16_t vq_nentries;  /**< vring desc numbers */
        uint16_t vq_free_cnt;  /**< num of desc available */
        uint16_t vq_avail_idx; /**< sync until needed */
-- 
1.8.3.1

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