[dpdk-dev] [PATCH v9 5/8] net/virtio: implement transmit path for packed queues

[Jens Freimann <jfreimann@redhat.com>]

This implements the transmit path for devices with
support for packed virtqueues.

Signed-off-by: Jens Freiman <jfreimann@redhat.com>
---
 drivers/net/virtio/virtio_ethdev.c |  32 +++-
 drivers/net/virtio/virtio_ethdev.h |   2 +
 drivers/net/virtio/virtio_rxtx.c   | 285 +++++++++++++++++++++++++++++
 drivers/net/virtio/virtqueue.h     |  18 +-
 4 files changed, 325 insertions(+), 12 deletions(-)

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index 873b345b3..14cf3657e 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -384,6 +384,8 @@ 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
@@ -490,16 +492,22 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t vtpci_queue_idx)
 		memset(txr, 0, vq_size * sizeof(*txr));
 		for (i = 0; i < vq_size; i++) {
 			struct vring_desc *start_dp = txr[i].tx_indir;
-
-			vring_desc_init_split(start_dp, RTE_DIM(txr[i].tx_indir));
-
+			struct vring_desc_packed*start_dp_packed = txr[i].tx_indir_pq;
+	
 			/* first indirect descriptor is always the tx header */
-			start_dp->addr = txvq->virtio_net_hdr_mem
-				+ i * sizeof(*txr)
-				+ offsetof(struct virtio_tx_region, tx_hdr);
-
-			start_dp->len = hw->vtnet_hdr_size;
-			start_dp->flags = VRING_DESC_F_NEXT;
+			if (vtpci_packed_queue(hw)) {
+				start_dp_packed->addr = txvq->virtio_net_hdr_mem
+					+ i * sizeof(*txr)
+					+ offsetof(struct virtio_tx_region, tx_hdr);
+				start_dp_packed->len = hw->vtnet_hdr_size;
+			} else {
+				vring_desc_init_split(start_dp, RTE_DIM(txr[i].tx_indir));
+				start_dp->addr = txvq->virtio_net_hdr_mem
+					+ i * sizeof(*txr)
+					+ offsetof(struct virtio_tx_region, tx_hdr);
+				start_dp->len = hw->vtnet_hdr_size;
+				start_dp->flags = VRING_DESC_F_NEXT;
+			}
 		}
 	}
 
@@ -1338,7 +1346,11 @@ set_rxtx_funcs(struct rte_eth_dev *eth_dev)
 		eth_dev->rx_pkt_burst = &virtio_recv_pkts;
 	}
 
-	if (hw->use_inorder_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_inorder_tx) {
 		PMD_INIT_LOG(INFO, "virtio: using inorder Tx path on port %u",
 			eth_dev->data->port_id);
 		eth_dev->tx_pkt_burst = virtio_xmit_pkts_inorder;
diff --git a/drivers/net/virtio/virtio_ethdev.h b/drivers/net/virtio/virtio_ethdev.h
index e0f80e5a4..05d355180 100644
--- a/drivers/net/virtio/virtio_ethdev.h
+++ b/drivers/net/virtio/virtio_ethdev.h
@@ -82,6 +82,8 @@ uint16_t virtio_recv_mergeable_pkts_inorder(void *rx_queue,
 
 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_xmit_pkts_inorder(void *tx_queue, struct rte_mbuf **tx_pkts,
 		uint16_t nb_pkts);
diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index eb891433e..5c8151d2f 100644
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -88,6 +88,43 @@ vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx)
 	dp->next = VQ_RING_DESC_CHAIN_END;
 }
 
+void
+vq_ring_free_chain_packed(struct virtqueue *vq, uint16_t used_idx)
+{
+	struct vring_desc_packed *dp;
+	struct vq_desc_extra *dxp = NULL, *dxp_tail = NULL;
+	uint16_t desc_idx_last, desc_idx;
+	int i = 0;
+
+	dp  = &vq->vq_ring.desc_packed[used_idx];
+	dxp = &vq->vq_descx[dp->index];
+	desc_idx = desc_idx_last = dp->index;
+	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt + dxp->ndescs);
+	if ((dp->flags & VRING_DESC_F_INDIRECT) == 0) {
+		while (dxp->next != VQ_RING_DESC_CHAIN_END && i < dxp->ndescs) {
+			desc_idx_last = dxp->next;
+			dp = &vq->vq_ring.desc_packed[dxp->next];
+			dxp = &vq->vq_descx[dxp->next];
+			i++;
+		}
+	}
+
+	/*
+	 * We must append the existing free chain, if any, to the end of
+	 * newly freed chain. If the virtqueue was completely used, then
+	 * head would be VQ_RING_DESC_CHAIN_END (ASSERTed above).
+	 */
+	if (vq->vq_desc_tail_idx == VQ_RING_DESC_CHAIN_END) {
+		vq->vq_desc_head_idx = desc_idx;
+	} else {
+		dxp_tail = &vq->vq_descx[vq->vq_desc_tail_idx];
+		dxp_tail->next = desc_idx;
+	}
+
+	vq->vq_desc_tail_idx = desc_idx_last;
+	dxp->next = VQ_RING_DESC_CHAIN_END;
+}
+
 static uint16_t
 virtqueue_dequeue_burst_rx(struct virtqueue *vq, struct rte_mbuf **rx_pkts,
 			   uint32_t *len, uint16_t num)
@@ -165,6 +202,33 @@ virtqueue_dequeue_rx_inorder(struct virtqueue *vq,
 #endif
 
 /* Cleanup from completed transmits. */
+static void
+virtio_xmit_cleanup_packed(struct virtqueue *vq, int num)
+{
+	uint16_t used_idx, id;
+	uint16_t size = vq->vq_nentries;
+	struct vring_desc_packed *desc = vq->vq_ring.desc_packed;
+	struct vq_desc_extra *dxp;
+
+	used_idx = vq->vq_used_cons_idx;
+	while (num && desc_is_used(&desc[used_idx], &vq->vq_ring)) {
+		num --;
+		used_idx = vq->vq_used_cons_idx;
+		id = desc[used_idx].index;
+		dxp = &vq->vq_descx[id];
+		if (++vq->vq_used_cons_idx >= size) {
+			vq->vq_used_cons_idx -= size;
+			vq->vq_ring.used_wrap_counter ^= 1;
+		}
+		vq_ring_free_chain_packed(vq, used_idx);
+		if (dxp->cookie != NULL) {
+			rte_pktmbuf_free(dxp->cookie);
+			dxp->cookie = NULL;
+		}
+		used_idx = vq->vq_used_cons_idx;
+	}
+}
+
 static void
 virtio_xmit_cleanup(struct virtqueue *vq, uint16_t num)
 {
@@ -456,6 +520,134 @@ virtqueue_enqueue_xmit_inorder(struct virtnet_tx *txvq,
 	vq->vq_desc_head_idx = idx & (vq->vq_nentries - 1);
 }
 
+static inline void
+virtqueue_enqueue_xmit_packed(struct virtnet_tx *txvq, struct rte_mbuf *cookie,
+			uint16_t needed, int use_indirect, int can_push,
+			int in_order)
+{
+	struct virtio_tx_region *txr = txvq->virtio_net_hdr_mz->addr;
+	struct vq_desc_extra *dxp, *head_dxp;
+	struct virtqueue *vq = txvq->vq;
+	struct vring_desc_packed *start_dp, *head_dp;
+	uint16_t seg_num = cookie->nb_segs;
+	uint16_t idx, head_id, head_flags;
+	uint16_t head_size = vq->hw->vtnet_hdr_size;
+	struct virtio_net_hdr *hdr;
+	uint16_t prev;
+
+	head_id = vq->vq_desc_head_idx;
+	idx = head_id;
+	prev = idx;
+	start_dp = vq->vq_ring.desc_packed;
+	dxp = &vq->vq_descx[idx];
+	dxp->ndescs = needed;
+
+	head_dp = &vq->vq_ring.desc_packed[head_id];
+	head_dxp = &vq->vq_descx[head_id];
+	head_dxp->cookie = (void *) cookie;
+	head_flags = cookie->next ? VRING_DESC_F_NEXT: 0;
+	head_flags |= VRING_DESC_F_AVAIL(vq->vq_ring.avail_wrap_counter) |
+		     VRING_DESC_F_USED(!vq->vq_ring.avail_wrap_counter);
+
+	if (can_push) {
+		/* prepend cannot fail, checked by caller */
+		hdr = (struct virtio_net_hdr *)
+			rte_pktmbuf_prepend(cookie, head_size);
+		/* rte_pktmbuf_prepend() counts the hdr size to the pkt length,
+		 * which is wrong. Below subtract restores correct pkt size.
+		 */
+		cookie->pkt_len -= head_size;
+
+		/* if offload disabled, it is not zeroed below, do it now */
+		if (!vq->hw->has_tx_offload) {
+			ASSIGN_UNLESS_EQUAL(hdr->csum_start, 0);
+			ASSIGN_UNLESS_EQUAL(hdr->csum_offset, 0);
+			ASSIGN_UNLESS_EQUAL(hdr->flags, 0);
+			ASSIGN_UNLESS_EQUAL(hdr->gso_type, 0);
+			ASSIGN_UNLESS_EQUAL(hdr->gso_size, 0);
+			ASSIGN_UNLESS_EQUAL(hdr->hdr_len, 0);
+		}
+	} else if (use_indirect) {
+		/* setup tx ring slot to point to indirect
+		 * descriptor list stored in reserved region.
+		 *
+		 * the first slot in indirect ring is already preset
+		 * to point to the header in reserved region
+		 */
+		start_dp[idx].addr  = txvq->virtio_net_hdr_mem +
+			RTE_PTR_DIFF(&txr[idx].tx_indir_pq, txr);
+		start_dp[idx].len   = (seg_num + 1) * sizeof(struct vring_desc_packed);
+		start_dp[idx].flags = VRING_DESC_F_INDIRECT;
+		hdr = (struct virtio_net_hdr *)&txr[idx].tx_hdr;
+
+		/* loop below will fill in rest of the indirect elements */
+		start_dp = txr[idx].tx_indir_pq;
+		idx = 1;
+	} else {
+		/* setup first tx ring slot to point to header
+		 * stored in reserved region.
+		 */
+		start_dp[idx].addr  = txvq->virtio_net_hdr_mem +
+			RTE_PTR_DIFF(&txr[idx].tx_hdr, txr);
+		start_dp[idx].len   = vq->hw->vtnet_hdr_size;
+		hdr = (struct virtio_net_hdr *)&txr[idx].tx_hdr;
+		idx = dxp->next;
+	}
+
+	virtqueue_xmit_offload(hdr, cookie, vq->hw->has_tx_offload);
+
+	do {
+		uint16_t flags;
+		if (idx >= vq->vq_nentries) {
+			idx = 0;
+			vq->vq_ring.avail_wrap_counter ^= 1;
+		}
+		start_dp[idx].addr  = VIRTIO_MBUF_DATA_DMA_ADDR(cookie, vq);
+		start_dp[idx].len   = cookie->data_len;
+		if (likely(idx != head_id)) {
+			flags = cookie->next ? VRING_DESC_F_NEXT : 0;
+			flags |= VRING_DESC_F_AVAIL(vq->vq_ring.avail_wrap_counter) |
+				 VRING_DESC_F_USED(!vq->vq_ring.avail_wrap_counter);
+			start_dp[idx].flags = flags;
+		}
+		if (use_indirect) {
+			if (++idx >= (seg_num + 1))
+				break;
+		} else {
+			dxp = &vq->vq_descx[idx];
+			if (idx == (vq->vq_nentries -1) && dxp->next == 0)
+				vq->vq_ring.avail_wrap_counter ^= 1;
+			prev = idx;
+			idx = dxp->next;
+		}
+	} while ((cookie = cookie->next) != NULL);
+
+        start_dp[prev].index = head_id;
+
+	if (use_indirect)
+		idx = vq->vq_ring.desc_packed[head_id].index;
+
+	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - needed);
+
+	if (!in_order) {
+		if (vq->vq_desc_head_idx == VQ_RING_DESC_CHAIN_END)
+			vq->vq_desc_tail_idx = idx;
+	}
+	vq->vq_avail_idx += needed;
+	if (idx==VQ_RING_DESC_CHAIN_END)
+		idx = vq->vq_avail_idx;
+	if (vq->vq_avail_idx >= vq->vq_nentries) {
+		vq->vq_avail_idx -= vq->vq_nentries;
+		idx = vq->vq_avail_idx;
+		vq->vq_ring.avail_wrap_counter ^= 1;
+	}
+	vq->vq_desc_head_idx = idx;
+
+	rte_smp_wmb();
+	head_dp->flags = head_flags;
+}
+
+
 static inline void
 virtqueue_enqueue_xmit(struct virtnet_tx *txvq, struct rte_mbuf *cookie,
 			uint16_t needed, int use_indirect, int can_push,
@@ -1346,6 +1538,99 @@ virtio_recv_mergeable_pkts(void *rx_queue,
 	return nb_rx;
 }
 
+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;
+	struct virtio_hw *hw = vq->hw;
+	uint16_t hdr_size = hw->vtnet_hdr_size;
+	uint16_t nb_tx = 0;
+	int error;
+	int nb_clean;
+
+	if (unlikely(hw->started == 0 && tx_pkts != hw->inject_pkts))
+		return nb_tx;
+
+	if (unlikely(nb_pkts < 1))
+		return nb_pkts;
+
+	PMD_TX_LOG(DEBUG, "%d packets to xmit", nb_pkts);
+
+	virtio_rmb();
+	//nb_clean = vq->vq_nentries - vq->vq_free_cnt;
+	nb_clean = nb_pkts <= vq->vq_free_cnt ? 0: nb_pkts - vq->vq_free_cnt;
+	if (nb_clean)
+		virtio_xmit_cleanup_packed(vq, nb_clean);
+
+	for (nb_tx = 0; nb_tx < nb_pkts; nb_tx++) {
+		struct rte_mbuf *txm = tx_pkts[nb_tx];
+		int can_push = 0, use_indirect = 0, slots, need;
+
+		/* Do VLAN tag insertion */
+		if (unlikely(txm->ol_flags & PKT_TX_VLAN_PKT)) {
+			error = rte_vlan_insert(&txm);
+			if (unlikely(error)) {
+				rte_pktmbuf_free(txm);
+				continue;
+			}
+		}
+
+		/* optimize ring usage */
+		if ((vtpci_with_feature(hw, VIRTIO_F_ANY_LAYOUT) ||
+		      vtpci_with_feature(hw, VIRTIO_F_VERSION_1)) &&
+		    rte_mbuf_refcnt_read(txm) == 1 &&
+		    RTE_MBUF_DIRECT(txm) &&
+		    txm->nb_segs == 1 &&
+		    rte_pktmbuf_headroom(txm) >= hdr_size &&
+		    rte_is_aligned(rte_pktmbuf_mtod(txm, char *),
+				   __alignof__(struct virtio_net_hdr_mrg_rxbuf)))
+			can_push = 1;
+		else if (vtpci_with_feature(hw, VIRTIO_RING_F_INDIRECT_DESC) &&
+			 txm->nb_segs < VIRTIO_MAX_TX_INDIRECT)
+			use_indirect = 1;
+
+		/* How many main ring entries are needed to this Tx?
+		 * any_layout => number of segments
+		 * indirect   => 1
+		 * default    => number of segments + 1
+		 */
+		slots = use_indirect ? 1 : (txm->nb_segs + !can_push);
+		need = slots - vq->vq_free_cnt;
+
+		/* Positive value indicates it need free vring descriptors */
+		if (unlikely(need > 0)) {
+			virtio_rmb();
+			need = RTE_MIN(need, (int)nb_pkts);
+			virtio_xmit_cleanup_packed(vq, need);
+			need = slots - vq->vq_free_cnt;
+			if (unlikely(need > 0)) {
+				PMD_TX_LOG(ERR,
+					   "No free tx descriptors to transmit");
+				break;
+			}
+		}
+
+		/* Enqueue Packet buffers */
+		virtqueue_enqueue_xmit_packed(txvq, txm, slots, use_indirect,
+			can_push, 0);
+
+		txvq->stats.bytes += txm->pkt_len;
+		virtio_update_packet_stats(&txvq->stats, txm);
+	}
+
+	txvq->stats.packets += nb_tx;
+
+	if (likely(nb_tx)) {
+		if (unlikely(virtqueue_kick_prepare_packed(vq))) {
+			virtqueue_notify(vq);
+			PMD_TX_LOG(DEBUG, "Notified backend after xmit");
+		}
+	}
+
+	return nb_tx;
+}
+
 uint16_t
 virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 {
diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index 2af1bc259..9debbc3f9 100644
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -242,8 +242,12 @@ struct virtio_net_hdr_mrg_rxbuf {
 #define VIRTIO_MAX_TX_INDIRECT 8
 struct virtio_tx_region {
 	struct virtio_net_hdr_mrg_rxbuf tx_hdr;
-	struct vring_desc tx_indir[VIRTIO_MAX_TX_INDIRECT]
-			   __attribute__((__aligned__(16)));
+	union {
+		struct vring_desc tx_indir[VIRTIO_MAX_TX_INDIRECT]
+			__attribute__((__aligned__(16)));
+		struct vring_desc_packed tx_indir_pq[VIRTIO_MAX_TX_INDIRECT]
+			__attribute__((__aligned__(16)));
+	};
 };
 
 static inline void
@@ -319,6 +323,7 @@ virtio_get_queue_type(struct virtio_hw *hw, uint16_t vtpci_queue_idx)
 #define VIRTQUEUE_NUSED(vq) ((uint16_t)((vq)->vq_ring.used->idx - (vq)->vq_used_cons_idx))
 
 void vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx);
+void vq_ring_free_chain_packed(struct virtqueue *vq, uint16_t desc_idx);
 void vq_ring_free_inorder(struct virtqueue *vq, uint16_t desc_idx,
 			  uint16_t num);
 
@@ -352,6 +357,15 @@ virtqueue_kick_prepare(struct virtqueue *vq)
 	return !(vq->vq_ring.used->flags & VRING_USED_F_NO_NOTIFY);
 }
 
+static inline int
+virtqueue_kick_prepare_packed(struct virtqueue *vq)
+{
+	uint16_t flags;
+
+	flags = vq->vq_ring.device_event->desc_event_flags & RING_EVENT_FLAGS_DESC;
+	return (flags != RING_EVENT_FLAGS_DISABLE);
+}
+
 static inline void
 virtqueue_notify(struct virtqueue *vq)
 {
-- 
2.17.1