[dpdk-dev] [PATCH v4 07/20] net/virtio: implement transmit path for packed queues

[Jens Freimann]

This implements the transmit path for devices with
support for Virtio 1.1.

Add the feature bit for Virtio 1.1 and enable code to
add buffers to vring and mark descriptors as available.

This is based on a patch by Yuanhan Liu.

Signed-off-by: Jens Freiman <jfreimann at redhat.com>
---
 drivers/net/virtio/virtio_ethdev.c |   8 ++-
 drivers/net/virtio/virtio_ethdev.h |   2 +
 drivers/net/virtio/virtio_rxtx.c   | 104 ++++++++++++++++++++++++++++++++++++-
 3 files changed, 112 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index 0c9540b89..c5c2a268b 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -383,6 +383,8 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t vtpci_queue_idx)
 	vq->hw = hw;
 	vq->vq_queue_index = vtpci_queue_idx;
 	vq->vq_nentries = vq_size;
+	if (vtpci_packed_queue(hw))
+		vq->vq_ring.avail_wrap_counter = 1;
 
 	/*
 	 * Reserve a memzone for vring elements
@@ -1329,7 +1331,11 @@ set_rxtx_funcs(struct rte_eth_dev *eth_dev)
 		eth_dev->rx_pkt_burst = &virtio_recv_pkts;
 	}
 
-	if (hw->use_simple_tx) {
+	if (vtpci_packed_queue(hw)) {
+		PMD_INIT_LOG(INFO, "virtio: using virtio 1.1 Tx path on port %u",
+			eth_dev->data->port_id);
+		eth_dev->tx_pkt_burst = virtio_xmit_pkts_packed;
+	} else if (hw->use_simple_tx) {
 		PMD_INIT_LOG(INFO, "virtio: using simple Tx path on port %u",
 			eth_dev->data->port_id);
 		eth_dev->tx_pkt_burst = virtio_xmit_pkts_simple;
diff --git a/drivers/net/virtio/virtio_ethdev.h b/drivers/net/virtio/virtio_ethdev.h
index bb40064ea..5420d7648 100644
--- a/drivers/net/virtio/virtio_ethdev.h
+++ b/drivers/net/virtio/virtio_ethdev.h
@@ -85,6 +85,8 @@ uint16_t virtio_recv_mergeable_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 
 uint16_t virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 		uint16_t nb_pkts);
+uint16_t virtio_xmit_pkts_packed(void *tx_queue, struct rte_mbuf **tx_pkts,
+		uint16_t nb_pkts);
 
 uint16_t virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
 		uint16_t nb_pkts);
diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index a8aa87b32..b749babf3 100644
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -38,6 +38,103 @@
 #define  VIRTIO_DUMP_PACKET(m, len) do { } while (0)
 #endif
 
+
+/* Cleanup from completed transmits. */
+static void
+virtio_xmit_cleanup_packed(struct virtqueue *vq)
+{
+	uint16_t idx;
+	uint16_t size = vq->vq_nentries;
+	struct vring_desc_packed *desc = vq->vq_ring.desc_packed;
+	struct vq_desc_extra *dxp;
+
+	idx = vq->vq_used_cons_idx;
+	while (desc_is_used(&desc[idx]) &&
+	       vq->vq_free_cnt < size) {
+		dxp = &vq->vq_descx[idx];
+		vq->vq_free_cnt += dxp->ndescs;
+		idx = vq->vq_used_cons_idx + dxp->ndescs;
+		idx = idx >= size ? idx - size : idx;
+	}
+}
+
+uint16_t
+virtio_xmit_pkts_packed(void *tx_queue, struct rte_mbuf **tx_pkts,
+		     uint16_t nb_pkts)
+{
+	struct virtnet_tx *txvq = tx_queue;
+	struct virtqueue *vq = txvq->vq;
+	uint16_t i;
+	struct vring_desc_packed *desc = vq->vq_ring.desc_packed;
+	uint16_t idx;
+	struct vq_desc_extra *dxp;
+
+	if (unlikely(nb_pkts < 1))
+		return nb_pkts;
+
+	PMD_TX_LOG(DEBUG, "%d packets to xmit", nb_pkts);
+
+	if (likely(vq->vq_free_cnt < vq->vq_free_thresh))
+		virtio_xmit_cleanup_packed(vq);
+
+	for (i = 0; i < nb_pkts; i++) {
+		struct rte_mbuf *txm = tx_pkts[i];
+		struct virtio_tx_region *txr = txvq->virtio_net_hdr_mz->addr;
+		uint16_t head_idx;
+		int wrap_counter;
+		int descs_used;
+
+		if (unlikely(txm->nb_segs + 1 > vq->vq_free_cnt)) {
+			virtio_xmit_cleanup_packed(vq);
+
+			if (unlikely(txm->nb_segs + 1 > vq->vq_free_cnt)) {
+				PMD_TX_LOG(ERR,
+					   "No free tx descriptors to transmit");
+				break;
+			}
+		}
+
+		txvq->stats.bytes += txm->pkt_len;
+
+		vq->vq_free_cnt -= txm->nb_segs + 1;
+
+		wrap_counter = vq->vq_ring.avail_wrap_counter;
+		idx = update_pq_avail_index(vq);
+		head_idx = idx;
+
+		dxp = &vq->vq_descx[idx];
+		if (dxp->cookie != NULL)
+			rte_pktmbuf_free(dxp->cookie);
+		dxp->cookie = txm;
+
+		desc[idx].addr  = txvq->virtio_net_hdr_mem +
+				  RTE_PTR_DIFF(&txr[idx].tx_hdr, txr);
+		desc[idx].len   = vq->hw->vtnet_hdr_size;
+		desc[idx].flags = VRING_DESC_F_NEXT;
+		descs_used = 1;
+
+		do {
+			idx = update_pq_avail_index(vq);
+			desc[idx].addr  = VIRTIO_MBUF_DATA_DMA_ADDR(txm, vq);
+			desc[idx].len   = txm->data_len;
+			desc[idx].flags = VRING_DESC_F_NEXT;
+			desc[idx].index = head_idx;
+			descs_used++;
+		} while ((txm = txm->next) != NULL);
+
+		desc[idx].flags &= ~VRING_DESC_F_NEXT;
+
+		rte_smp_wmb();
+		_set_desc_avail(&desc[head_idx], wrap_counter);
+		vq->vq_descx[head_idx].ndescs = descs_used;
+	}
+
+	txvq->stats.packets += i;
+	txvq->stats.errors  += nb_pkts - i;
+
+	return i;
+}
+
 int
 virtio_dev_rx_queue_done(void *rxq, uint16_t offset)
 {
@@ -547,6 +644,10 @@ virtio_dev_tx_queue_setup_finish(struct rte_eth_dev *dev,
 
 	PMD_INIT_FUNC_TRACE();
 
+	if (vtpci_packed_queue(hw)) {
+		vq->vq_ring.avail_wrap_counter = 1;
+	}
+
 	if (hw->use_simple_tx) {
 		for (desc_idx = 0; desc_idx < mid_idx; desc_idx++) {
 			vq->vq_ring.avail->ring[desc_idx] =
@@ -567,7 +668,8 @@ virtio_dev_tx_queue_setup_finish(struct rte_eth_dev *dev,
 			vq->vq_ring.avail->ring[desc_idx] = desc_idx;
 	}
 
-	VIRTQUEUE_DUMP(vq);
+	if (!vtpci_packed_queue(hw))
+		VIRTQUEUE_DUMP(vq);
 
 	return 0;
 }
-- 
2.14.3