numam-dpdk/drivers/net/virtio/virtio_rxtx.c

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2010-2014 Intel Corporation
 */

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include <rte_cycles.h>
#include <rte_memory.h>
#include <rte_branch_prediction.h>
#include <rte_mempool.h>
#include <rte_malloc.h>
#include <rte_mbuf.h>
#include <rte_ether.h>
#include <rte_ethdev_driver.h>
#include <rte_prefetch.h>
#include <rte_string_fns.h>
#include <rte_errno.h>
#include <rte_byteorder.h>
#include <rte_net.h>
#include <rte_ip.h>
#include <rte_udp.h>
#include <rte_tcp.h>

#include "virtio_logs.h"
#include "virtio_ethdev.h"
#include "virtio_pci.h"
#include "virtqueue.h"
#include "virtio_rxtx.h"
#include "virtio_rxtx_simple.h"
#include "virtio_ring.h"

#ifdef RTE_LIBRTE_VIRTIO_DEBUG_DUMP
#define VIRTIO_DUMP_PACKET(m, len) rte_pktmbuf_dump(stdout, m, len)
#else
#define  VIRTIO_DUMP_PACKET(m, len) do { } while (0)
#endif

int
virtio_dev_rx_queue_done(void *rxq, uint16_t offset)
{
	struct virtnet_rx *rxvq = rxq;
	struct virtqueue *vq = rxvq->vq;

	return VIRTQUEUE_NUSED(vq) >= offset;
}

void
vq_ring_free_inorder(struct virtqueue *vq, uint16_t desc_idx, uint16_t num)
{
	vq->vq_free_cnt += num;
	vq->vq_desc_tail_idx = desc_idx & (vq->vq_nentries - 1);
}

void
vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx)
{
	struct vring_desc *dp, *dp_tail;
	struct vq_desc_extra *dxp;
	uint16_t desc_idx_last = desc_idx;

	dp  = &vq->vq_ring.desc[desc_idx];
	dxp = &vq->vq_descx[desc_idx];
	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];
		}
	}
	dxp->ndescs = 0;

	/*
	 * 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 {
		dp_tail = &vq->vq_ring.desc[vq->vq_desc_tail_idx];
		dp_tail->next = desc_idx;
	}

	vq->vq_desc_tail_idx = desc_idx_last;
	dp->next = VQ_RING_DESC_CHAIN_END;
}

static void
vq_ring_free_id_packed(struct virtqueue *vq, uint16_t id)
{
	struct vq_desc_extra *dxp;

	dxp = &vq->vq_descx[id];
	vq->vq_free_cnt += dxp->ndescs;

	if (vq->vq_desc_tail_idx == VQ_RING_DESC_CHAIN_END)
		vq->vq_desc_head_idx = id;
	else
		vq->vq_descx[vq->vq_desc_tail_idx].next = id;

	vq->vq_desc_tail_idx = id;
	dxp->next = VQ_RING_DESC_CHAIN_END;
}

static uint16_t
virtqueue_dequeue_burst_rx_packed(struct virtqueue *vq,
				  struct rte_mbuf **rx_pkts,
				  uint32_t *len,
				  uint16_t num)
{
	struct rte_mbuf *cookie;
	uint16_t used_idx;
	uint16_t id;
	struct vring_packed_desc *desc;
	uint16_t i;

	desc = vq->ring_packed.desc_packed;

	for (i = 0; i < num; i++) {
		used_idx = vq->vq_used_cons_idx;
		if (!desc_is_used(&desc[used_idx], vq))
			return i;
		len[i] = desc[used_idx].len;
		id = desc[used_idx].id;
		cookie = (struct rte_mbuf *)vq->vq_descx[id].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;

		vq->vq_free_cnt++;
		vq->vq_used_cons_idx++;
		if (vq->vq_used_cons_idx >= vq->vq_nentries) {
			vq->vq_used_cons_idx -= vq->vq_nentries;
			vq->used_wrap_counter ^= 1;
		}
	}

	return i;
}

static uint16_t
virtqueue_dequeue_burst_rx(struct virtqueue *vq, struct rte_mbuf **rx_pkts,
			   uint32_t *len, uint16_t num)
{
	struct vring_used_elem *uep;
	struct rte_mbuf *cookie;
	uint16_t used_idx, desc_idx;
	uint16_t i;

	/*  Caller does the check */
	for (i = 0; i < num ; i++) {
		used_idx = (uint16_t)(vq->vq_used_cons_idx & (vq->vq_nentries - 1));
		uep = &vq->vq_ring.used->ring[used_idx];
		desc_idx = (uint16_t) uep->id;
		len[i] = uep->len;
		cookie = (struct rte_mbuf *)vq->vq_descx[desc_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;
		vq->vq_used_cons_idx++;
		vq_ring_free_chain(vq, desc_idx);
		vq->vq_descx[desc_idx].cookie = NULL;
	}

	return i;
}

static uint16_t
virtqueue_dequeue_rx_inorder(struct virtqueue *vq,
			struct rte_mbuf **rx_pkts,
			uint32_t *len,
			uint16_t num)
{
	struct vring_used_elem *uep;
	struct rte_mbuf *cookie;
	uint16_t used_idx = 0;
	uint16_t i;

	if (unlikely(num == 0))
		return 0;

	for (i = 0; i < num; i++) {
		used_idx = vq->vq_used_cons_idx & (vq->vq_nentries - 1);
		/* Desc idx same as used idx */
		uep = &vq->vq_ring.used->ring[used_idx];
		len[i] = uep->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;
		vq->vq_used_cons_idx++;
		vq->vq_descx[used_idx].cookie = NULL;
	}

	vq_ring_free_inorder(vq, used_idx, i);
	return i;
}

#ifndef DEFAULT_TX_FREE_THRESH
#define DEFAULT_TX_FREE_THRESH 32
#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_packed_desc *desc = vq->ring_packed.desc_packed;
	struct vq_desc_extra *dxp;

	used_idx = vq->vq_used_cons_idx;
	while (num-- && desc_is_used(&desc[used_idx], vq)) {
		used_idx = vq->vq_used_cons_idx;
		id = desc[used_idx].id;
		dxp = &vq->vq_descx[id];
		vq->vq_used_cons_idx += dxp->ndescs;
		if (vq->vq_used_cons_idx >= size) {
			vq->vq_used_cons_idx -= size;
			vq->used_wrap_counter ^= 1;
		}
		vq_ring_free_id_packed(vq, id);
		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)
{
	uint16_t i, used_idx, desc_idx;
	for (i = 0; i < num; i++) {
		struct vring_used_elem *uep;
		struct vq_desc_extra *dxp;

		used_idx = (uint16_t)(vq->vq_used_cons_idx & (vq->vq_nentries - 1));
		uep = &vq->vq_ring.used->ring[used_idx];

		desc_idx = (uint16_t) uep->id;
		dxp = &vq->vq_descx[desc_idx];
		vq->vq_used_cons_idx++;
		vq_ring_free_chain(vq, desc_idx);

		if (dxp->cookie != NULL) {
			rte_pktmbuf_free(dxp->cookie);
			dxp->cookie = NULL;
		}
	}
}

/* Cleanup from completed inorder transmits. */
static void
virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num)
{
	uint16_t i, used_idx, desc_idx = 0, last_idx;
	int16_t free_cnt = 0;
	struct vq_desc_extra *dxp = NULL;

	if (unlikely(num == 0))
		return;

	for (i = 0; i < num; i++) {
		struct vring_used_elem *uep;

		used_idx = vq->vq_used_cons_idx & (vq->vq_nentries - 1);
		uep = &vq->vq_ring.used->ring[used_idx];
		desc_idx = (uint16_t)uep->id;

		dxp = &vq->vq_descx[desc_idx];
		vq->vq_used_cons_idx++;

		if (dxp->cookie != NULL) {
			rte_pktmbuf_free(dxp->cookie);
			dxp->cookie = NULL;
		}
	}

	last_idx = desc_idx + dxp->ndescs - 1;
	free_cnt = last_idx - vq->vq_desc_tail_idx;
	if (free_cnt <= 0)
		free_cnt += vq->vq_nentries;

	vq_ring_free_inorder(vq, last_idx, free_cnt);
}

static inline int
virtqueue_enqueue_refill_inorder(struct virtqueue *vq,
			struct rte_mbuf **cookies,
			uint16_t num)
{
	struct vq_desc_extra *dxp;
	struct virtio_hw *hw = vq->hw;
	struct vring_desc *start_dp;
	uint16_t head_idx, idx, i = 0;

	if (unlikely(vq->vq_free_cnt == 0))
		return -ENOSPC;
	if (unlikely(vq->vq_free_cnt < num))
		return -EMSGSIZE;

	head_idx = vq->vq_desc_head_idx & (vq->vq_nentries - 1);
	start_dp = vq->vq_ring.desc;

	while (i < num) {
		idx = head_idx & (vq->vq_nentries - 1);
		dxp = &vq->vq_descx[idx];
		dxp->cookie = (void *)cookies[i];
		dxp->ndescs = 1;

		start_dp[idx].addr =
				VIRTIO_MBUF_ADDR(cookies[i], vq) +
				RTE_PKTMBUF_HEADROOM - hw->vtnet_hdr_size;
		start_dp[idx].len =
				cookies[i]->buf_len -
				RTE_PKTMBUF_HEADROOM +
				hw->vtnet_hdr_size;
		start_dp[idx].flags =  VRING_DESC_F_WRITE;

		vq_update_avail_ring(vq, idx);
		head_idx++;
		i++;
	}

	vq->vq_desc_head_idx += num;
	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - num);
	return 0;
}

static inline int
virtqueue_enqueue_recv_refill(struct virtqueue *vq, struct rte_mbuf *cookie)
{
	struct vq_desc_extra *dxp;
	struct virtio_hw *hw = vq->hw;
	struct vring_desc *start_dp;
	uint16_t needed = 1;
	uint16_t head_idx, idx;

	if (unlikely(vq->vq_free_cnt == 0))
		return -ENOSPC;
	if (unlikely(vq->vq_free_cnt < needed))
		return -EMSGSIZE;

	head_idx = vq->vq_desc_head_idx;
	if (unlikely(head_idx >= vq->vq_nentries))
		return -EFAULT;

	idx = head_idx;
	dxp = &vq->vq_descx[idx];
	dxp->cookie = (void *)cookie;
	dxp->ndescs = needed;

	start_dp = vq->vq_ring.desc;
	start_dp[idx].addr =
		VIRTIO_MBUF_ADDR(cookie, vq) +
		RTE_PKTMBUF_HEADROOM - hw->vtnet_hdr_size;
	start_dp[idx].len =
		cookie->buf_len - RTE_PKTMBUF_HEADROOM + hw->vtnet_hdr_size;
	start_dp[idx].flags =  VRING_DESC_F_WRITE;
	idx = start_dp[idx].next;
	vq->vq_desc_head_idx = idx;
	if (vq->vq_desc_head_idx == VQ_RING_DESC_CHAIN_END)
		vq->vq_desc_tail_idx = idx;
	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - needed);
	vq_update_avail_ring(vq, head_idx);

	return 0;
}

static inline int
virtqueue_enqueue_recv_refill_packed(struct virtqueue *vq,
				     struct rte_mbuf **cookie, uint16_t num)
{
	struct vring_packed_desc *start_dp = vq->ring_packed.desc_packed;
	uint16_t flags = VRING_DESC_F_WRITE | vq->avail_used_flags;
	struct virtio_hw *hw = vq->hw;
	struct vq_desc_extra *dxp;
	uint16_t idx;
	int i;

	if (unlikely(vq->vq_free_cnt == 0))
		return -ENOSPC;
	if (unlikely(vq->vq_free_cnt < num))
		return -EMSGSIZE;

	for (i = 0; i < num; i++) {
		idx = vq->vq_avail_idx;
		dxp = &vq->vq_descx[idx];
		dxp->cookie = (void *)cookie[i];
		dxp->ndescs = 1;

		start_dp[idx].addr = VIRTIO_MBUF_ADDR(cookie[i], vq) +
				RTE_PKTMBUF_HEADROOM - hw->vtnet_hdr_size;
		start_dp[idx].len = cookie[i]->buf_len - RTE_PKTMBUF_HEADROOM
					+ hw->vtnet_hdr_size;

		vq->vq_desc_head_idx = dxp->next;
		if (vq->vq_desc_head_idx == VQ_RING_DESC_CHAIN_END)
			vq->vq_desc_tail_idx = vq->vq_desc_head_idx;
		rte_smp_wmb();
		start_dp[idx].flags = flags;
		if (++vq->vq_avail_idx >= vq->vq_nentries) {
			vq->vq_avail_idx -= vq->vq_nentries;
			vq->avail_wrap_counter ^= 1;
			vq->avail_used_flags =
				VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
				VRING_DESC_F_USED(!vq->avail_wrap_counter);
			flags = VRING_DESC_F_WRITE | vq->avail_used_flags;
		}
	}
	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - num);
	return 0;
}

/* When doing TSO, the IP length is not included in the pseudo header
 * checksum of the packet given to the PMD, but for virtio it is
 * expected.
 */
static void
virtio_tso_fix_cksum(struct rte_mbuf *m)
{
	/* common case: header is not fragmented */
	if (likely(rte_pktmbuf_data_len(m) >= m->l2_len + m->l3_len +
			m->l4_len)) {
		struct ipv4_hdr *iph;
		struct ipv6_hdr *ip6h;
		struct tcp_hdr *th;
		uint16_t prev_cksum, new_cksum, ip_len, ip_paylen;
		uint32_t tmp;

		iph = rte_pktmbuf_mtod_offset(m, struct ipv4_hdr *, m->l2_len);
		th = RTE_PTR_ADD(iph, m->l3_len);
		if ((iph->version_ihl >> 4) == 4) {
			iph->hdr_checksum = 0;
			iph->hdr_checksum = rte_ipv4_cksum(iph);
			ip_len = iph->total_length;
			ip_paylen = rte_cpu_to_be_16(rte_be_to_cpu_16(ip_len) -
				m->l3_len);
		} else {
			ip6h = (struct ipv6_hdr *)iph;
			ip_paylen = ip6h->payload_len;
		}

		/* calculate the new phdr checksum not including ip_paylen */
		prev_cksum = th->cksum;
		tmp = prev_cksum;
		tmp += ip_paylen;
		tmp = (tmp & 0xffff) + (tmp >> 16);
		new_cksum = tmp;

		/* replace it in the packet */
		th->cksum = new_cksum;
	}
}


/* avoid write operation when necessary, to lessen cache issues */
#define ASSIGN_UNLESS_EQUAL(var, val) do {	\
	if ((var) != (val))			\
		(var) = (val);			\
} while (0)

static inline void
virtqueue_xmit_offload(struct virtio_net_hdr *hdr,
			struct rte_mbuf *cookie,
			bool offload)
{
	if (offload) {
		if (cookie->ol_flags & PKT_TX_TCP_SEG)
			cookie->ol_flags |= PKT_TX_TCP_CKSUM;

		switch (cookie->ol_flags & PKT_TX_L4_MASK) {
		case PKT_TX_UDP_CKSUM:
			hdr->csum_start = cookie->l2_len + cookie->l3_len;
			hdr->csum_offset = offsetof(struct udp_hdr,
				dgram_cksum);
			hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
			break;

		case PKT_TX_TCP_CKSUM:
			hdr->csum_start = cookie->l2_len + cookie->l3_len;
			hdr->csum_offset = offsetof(struct tcp_hdr, cksum);
			hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
			break;

		default:
			ASSIGN_UNLESS_EQUAL(hdr->csum_start, 0);
			ASSIGN_UNLESS_EQUAL(hdr->csum_offset, 0);
			ASSIGN_UNLESS_EQUAL(hdr->flags, 0);
			break;
		}

		/* TCP Segmentation Offload */
		if (cookie->ol_flags & PKT_TX_TCP_SEG) {
			virtio_tso_fix_cksum(cookie);
			hdr->gso_type = (cookie->ol_flags & PKT_TX_IPV6) ?
				VIRTIO_NET_HDR_GSO_TCPV6 :
				VIRTIO_NET_HDR_GSO_TCPV4;
			hdr->gso_size = cookie->tso_segsz;
			hdr->hdr_len =
				cookie->l2_len +
				cookie->l3_len +
				cookie->l4_len;
		} else {
			ASSIGN_UNLESS_EQUAL(hdr->gso_type, 0);
			ASSIGN_UNLESS_EQUAL(hdr->gso_size, 0);
			ASSIGN_UNLESS_EQUAL(hdr->hdr_len, 0);
		}
	}
}

static inline void
virtqueue_enqueue_xmit_inorder(struct virtnet_tx *txvq,
			struct rte_mbuf **cookies,
			uint16_t num)
{
	struct vq_desc_extra *dxp;
	struct virtqueue *vq = txvq->vq;
	struct vring_desc *start_dp;
	struct virtio_net_hdr *hdr;
	uint16_t idx;
	uint16_t head_size = vq->hw->vtnet_hdr_size;
	uint16_t i = 0;

	idx = vq->vq_desc_head_idx;
	start_dp = vq->vq_ring.desc;

	while (i < num) {
		idx = idx & (vq->vq_nentries - 1);
		dxp = &vq->vq_descx[idx];
		dxp->cookie = (void *)cookies[i];
		dxp->ndescs = 1;

		hdr = (struct virtio_net_hdr *)
			rte_pktmbuf_prepend(cookies[i], head_size);
		cookies[i]->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);
		}

		virtqueue_xmit_offload(hdr, cookies[i],
				vq->hw->has_tx_offload);

		start_dp[idx].addr  = VIRTIO_MBUF_DATA_DMA_ADDR(cookies[i], vq);
		start_dp[idx].len   = cookies[i]->data_len;
		start_dp[idx].flags = 0;

		vq_update_avail_ring(vq, idx);

		idx++;
		i++;
	};

	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - num);
	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 can_push)
{
	struct virtio_tx_region *txr = txvq->virtio_net_hdr_mz->addr;
	struct vq_desc_extra *dxp;
	struct virtqueue *vq = txvq->vq;
	struct vring_packed_desc *start_dp, *head_dp;
	uint16_t idx, id, head_idx, head_flags;
	uint16_t head_size = vq->hw->vtnet_hdr_size;
	struct virtio_net_hdr *hdr;
	uint16_t prev;

	id = vq->vq_desc_head_idx;

	dxp = &vq->vq_descx[id];
	dxp->ndescs = needed;
	dxp->cookie = cookie;

	head_idx = vq->vq_avail_idx;
	idx = head_idx;
	prev = head_idx;
	start_dp = vq->ring_packed.desc_packed;

	head_dp = &vq->ring_packed.desc_packed[idx];
	head_flags = cookie->next ? VRING_DESC_F_NEXT : 0;
	head_flags |= vq->avail_used_flags;

	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 {
		/* 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++;
		if (idx >= vq->vq_nentries) {
			idx -= vq->vq_nentries;
			vq->avail_wrap_counter ^= 1;
			vq->avail_used_flags =
				VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
				VRING_DESC_F_USED(!vq->avail_wrap_counter);
		}
	}

	virtqueue_xmit_offload(hdr, cookie, vq->hw->has_tx_offload);

	do {
		uint16_t flags;

		start_dp[idx].addr = VIRTIO_MBUF_DATA_DMA_ADDR(cookie, vq);
		start_dp[idx].len  = cookie->data_len;
		if (likely(idx != head_idx)) {
			flags = cookie->next ? VRING_DESC_F_NEXT : 0;
			flags |= vq->avail_used_flags;
			start_dp[idx].flags = flags;
		}
		prev = idx;
		idx++;
		if (idx >= vq->vq_nentries) {
			idx -= vq->vq_nentries;
			vq->avail_wrap_counter ^= 1;
			vq->avail_used_flags =
				VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
				VRING_DESC_F_USED(!vq->avail_wrap_counter);
		}
	} while ((cookie = cookie->next) != NULL);

	start_dp[prev].id = id;

	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - needed);

	vq->vq_desc_head_idx = dxp->next;
	if (vq->vq_desc_head_idx == VQ_RING_DESC_CHAIN_END)
		vq->vq_desc_tail_idx = VQ_RING_DESC_CHAIN_END;

	vq->vq_avail_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,
			int in_order)
{
	struct virtio_tx_region *txr = txvq->virtio_net_hdr_mz->addr;
	struct vq_desc_extra *dxp;
	struct virtqueue *vq = txvq->vq;
	struct vring_desc *start_dp;
	uint16_t seg_num = cookie->nb_segs;
	uint16_t head_idx, idx;
	uint16_t head_size = vq->hw->vtnet_hdr_size;
	struct virtio_net_hdr *hdr;

	head_idx = vq->vq_desc_head_idx;
	idx = head_idx;
	dxp = &vq->vq_descx[idx];
	dxp->cookie = (void *)cookie;
	dxp->ndescs = needed;

	start_dp = vq->vq_ring.desc;

	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, txr);
		start_dp[idx].len   = (seg_num + 1) * sizeof(struct vring_desc);
		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;
		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;
		start_dp[idx].flags = VRING_DESC_F_NEXT;
		hdr = (struct virtio_net_hdr *)&txr[idx].tx_hdr;

		idx = start_dp[idx].next;
	}

	virtqueue_xmit_offload(hdr, cookie, vq->hw->has_tx_offload);

	do {
		start_dp[idx].addr  = VIRTIO_MBUF_DATA_DMA_ADDR(cookie, vq);
		start_dp[idx].len   = cookie->data_len;
		start_dp[idx].flags = cookie->next ? VRING_DESC_F_NEXT : 0;
		idx = start_dp[idx].next;
	} while ((cookie = cookie->next) != NULL);

	if (use_indirect)
		idx = vq->vq_ring.desc[head_idx].next;

	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - needed);

	vq->vq_desc_head_idx = idx;
	vq_update_avail_ring(vq, head_idx);

	if (!in_order) {
		if (vq->vq_desc_head_idx == VQ_RING_DESC_CHAIN_END)
			vq->vq_desc_tail_idx = idx;
	}
}

void
virtio_dev_cq_start(struct rte_eth_dev *dev)
{
	struct virtio_hw *hw = dev->data->dev_private;

	if (hw->cvq && hw->cvq->vq) {
		rte_spinlock_init(&hw->cvq->lock);
		VIRTQUEUE_DUMP((struct virtqueue *)hw->cvq->vq);
	}
}

int
virtio_dev_rx_queue_setup(struct rte_eth_dev *dev,
			uint16_t queue_idx,
			uint16_t nb_desc,
			unsigned int socket_id __rte_unused,
			const struct rte_eth_rxconf *rx_conf __rte_unused,
			struct rte_mempool *mp)
{
	uint16_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_RQ_QUEUE_IDX;
	struct virtio_hw *hw = dev->data->dev_private;
	struct virtqueue *vq = hw->vqs[vtpci_queue_idx];
	struct virtnet_rx *rxvq;

	PMD_INIT_FUNC_TRACE();

	if (nb_desc == 0 || nb_desc > vq->vq_nentries)
		nb_desc = vq->vq_nentries;
	vq->vq_free_cnt = RTE_MIN(vq->vq_free_cnt, nb_desc);

	rxvq = &vq->rxq;
	rxvq->queue_id = queue_idx;
	rxvq->mpool = mp;
	if (rxvq->mpool == NULL) {
		rte_exit(EXIT_FAILURE,
			"Cannot allocate mbufs for rx virtqueue");
	}

	dev->data->rx_queues[queue_idx] = rxvq;

	return 0;
}

int
virtio_dev_rx_queue_setup_finish(struct rte_eth_dev *dev, uint16_t queue_idx)
{
	uint16_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_RQ_QUEUE_IDX;
	struct virtio_hw *hw = dev->data->dev_private;
	struct virtqueue *vq = hw->vqs[vtpci_queue_idx];
	struct virtnet_rx *rxvq = &vq->rxq;
	struct rte_mbuf *m;
	uint16_t desc_idx;
	int error, nbufs, i;

	PMD_INIT_FUNC_TRACE();

	/* Allocate blank mbufs for the each rx descriptor */
	nbufs = 0;

	if (hw->use_simple_rx) {
		for (desc_idx = 0; desc_idx < vq->vq_nentries;
		     desc_idx++) {
			vq->vq_ring.avail->ring[desc_idx] = desc_idx;
			vq->vq_ring.desc[desc_idx].flags =
				VRING_DESC_F_WRITE;
		}

		virtio_rxq_vec_setup(rxvq);
	}

	memset(&rxvq->fake_mbuf, 0, sizeof(rxvq->fake_mbuf));
	for (desc_idx = 0; desc_idx < RTE_PMD_VIRTIO_RX_MAX_BURST;
	     desc_idx++) {
		vq->sw_ring[vq->vq_nentries + desc_idx] =
			&rxvq->fake_mbuf;
	}

	if (hw->use_simple_rx) {
		while (vq->vq_free_cnt >= RTE_VIRTIO_VPMD_RX_REARM_THRESH) {
			virtio_rxq_rearm_vec(rxvq);
			nbufs += RTE_VIRTIO_VPMD_RX_REARM_THRESH;
		}
	} else if (hw->use_inorder_rx) {
		if ((!virtqueue_full(vq))) {
			uint16_t free_cnt = vq->vq_free_cnt;
			struct rte_mbuf *pkts[free_cnt];

			if (!rte_pktmbuf_alloc_bulk(rxvq->mpool, pkts,
				free_cnt)) {
				error = virtqueue_enqueue_refill_inorder(vq,
						pkts,
						free_cnt);
				if (unlikely(error)) {
					for (i = 0; i < free_cnt; i++)
						rte_pktmbuf_free(pkts[i]);
				}
			}

			nbufs += free_cnt;
			vq_update_avail_idx(vq);
		}
	} else {
		while (!virtqueue_full(vq)) {
			m = rte_mbuf_raw_alloc(rxvq->mpool);
			if (m == NULL)
				break;

			/* Enqueue allocated buffers */
			if (vtpci_packed_queue(vq->hw))
				error = virtqueue_enqueue_recv_refill_packed(vq,
						&m, 1);
			else
				error = virtqueue_enqueue_recv_refill(vq, m);
			if (error) {
				rte_pktmbuf_free(m);
				break;
			}
			nbufs++;
		}

		if (!vtpci_packed_queue(vq->hw))
			vq_update_avail_idx(vq);
	}

	PMD_INIT_LOG(DEBUG, "Allocated %d bufs", nbufs);

	VIRTQUEUE_DUMP(vq);

	return 0;
}

/*
 * struct rte_eth_dev *dev: Used to update dev
 * uint16_t nb_desc: Defaults to values read from config space
 * unsigned int socket_id: Used to allocate memzone
 * const struct rte_eth_txconf *tx_conf: Used to setup tx engine
 * uint16_t queue_idx: Just used as an index in dev txq list
 */
int
virtio_dev_tx_queue_setup(struct rte_eth_dev *dev,
			uint16_t queue_idx,
			uint16_t nb_desc,
			unsigned int socket_id __rte_unused,
			const struct rte_eth_txconf *tx_conf)
{
	uint8_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_TQ_QUEUE_IDX;
	struct virtio_hw *hw = dev->data->dev_private;
	struct virtqueue *vq = hw->vqs[vtpci_queue_idx];
	struct virtnet_tx *txvq;
	uint16_t tx_free_thresh;

	PMD_INIT_FUNC_TRACE();

	if (nb_desc == 0 || nb_desc > vq->vq_nentries)
		nb_desc = vq->vq_nentries;
	vq->vq_free_cnt = RTE_MIN(vq->vq_free_cnt, nb_desc);

	txvq = &vq->txq;
	txvq->queue_id = queue_idx;

	tx_free_thresh = tx_conf->tx_free_thresh;
	if (tx_free_thresh == 0)
		tx_free_thresh =
			RTE_MIN(vq->vq_nentries / 4, DEFAULT_TX_FREE_THRESH);

	if (tx_free_thresh >= (vq->vq_nentries - 3)) {
		RTE_LOG(ERR, PMD, "tx_free_thresh must be less than the "
			"number of TX entries minus 3 (%u)."
			" (tx_free_thresh=%u port=%u queue=%u)\n",
			vq->vq_nentries - 3,
			tx_free_thresh, dev->data->port_id, queue_idx);
		return -EINVAL;
	}

	vq->vq_free_thresh = tx_free_thresh;

	dev->data->tx_queues[queue_idx] = txvq;
	return 0;
}

int
virtio_dev_tx_queue_setup_finish(struct rte_eth_dev *dev,
				uint16_t queue_idx)
{
	uint8_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_TQ_QUEUE_IDX;
	struct virtio_hw *hw = dev->data->dev_private;
	struct virtqueue *vq = hw->vqs[vtpci_queue_idx];

	PMD_INIT_FUNC_TRACE();

	if (!vtpci_packed_queue(hw)) {
		if (hw->use_inorder_tx)
			vq->vq_ring.desc[vq->vq_nentries - 1].next = 0;
	}

	VIRTQUEUE_DUMP(vq);

	return 0;
}

static void
virtio_discard_rxbuf(struct virtqueue *vq, struct rte_mbuf *m)
{
	int error;
	/*
	 * Requeue the discarded mbuf. This should always be
	 * successful since it was just dequeued.
	 */
	if (vtpci_packed_queue(vq->hw))
		error = virtqueue_enqueue_recv_refill_packed(vq, &m, 1);
	else
		error = virtqueue_enqueue_recv_refill(vq, m);

	if (unlikely(error)) {
		RTE_LOG(ERR, PMD, "cannot requeue discarded mbuf");
		rte_pktmbuf_free(m);
	}
}

static void
virtio_discard_rxbuf_inorder(struct virtqueue *vq, struct rte_mbuf *m)
{
	int error;

	error = virtqueue_enqueue_refill_inorder(vq, &m, 1);
	if (unlikely(error)) {
		RTE_LOG(ERR, PMD, "cannot requeue discarded mbuf");
		rte_pktmbuf_free(m);
	}
}

static void
virtio_update_packet_stats(struct virtnet_stats *stats, struct rte_mbuf *mbuf)
{
	uint32_t s = mbuf->pkt_len;
	struct ether_addr *ea;

	stats->bytes += s;

	if (s == 64) {
		stats->size_bins[1]++;
	} else if (s > 64 && s < 1024) {
		uint32_t bin;

		/* count zeros, and offset into correct bin */
		bin = (sizeof(s) * 8) - __builtin_clz(s) - 5;
		stats->size_bins[bin]++;
	} else {
		if (s < 64)
			stats->size_bins[0]++;
		else if (s < 1519)
			stats->size_bins[6]++;
		else if (s >= 1519)
			stats->size_bins[7]++;
	}

	ea = rte_pktmbuf_mtod(mbuf, struct ether_addr *);
	if (is_multicast_ether_addr(ea)) {
		if (is_broadcast_ether_addr(ea))
			stats->broadcast++;
		else
			stats->multicast++;
	}
}

static inline void
virtio_rx_stats_updated(struct virtnet_rx *rxvq, struct rte_mbuf *m)
{
	VIRTIO_DUMP_PACKET(m, m->data_len);

	virtio_update_packet_stats(&rxvq->stats, m);
}

/* Optionally fill offload information in structure */
static int
virtio_rx_offload(struct rte_mbuf *m, struct virtio_net_hdr *hdr)
{
	struct rte_net_hdr_lens hdr_lens;
	uint32_t hdrlen, ptype;
	int l4_supported = 0;

	/* nothing to do */
	if (hdr->flags == 0 && hdr->gso_type == VIRTIO_NET_HDR_GSO_NONE)
		return 0;

	m->ol_flags |= PKT_RX_IP_CKSUM_UNKNOWN;

	ptype = rte_net_get_ptype(m, &hdr_lens, RTE_PTYPE_ALL_MASK);
	m->packet_type = ptype;
	if ((ptype & RTE_PTYPE_L4_MASK) == RTE_PTYPE_L4_TCP ||
	    (ptype & RTE_PTYPE_L4_MASK) == RTE_PTYPE_L4_UDP ||
	    (ptype & RTE_PTYPE_L4_MASK) == RTE_PTYPE_L4_SCTP)
		l4_supported = 1;

	if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
		hdrlen = hdr_lens.l2_len + hdr_lens.l3_len + hdr_lens.l4_len;
		if (hdr->csum_start <= hdrlen && l4_supported) {
			m->ol_flags |= PKT_RX_L4_CKSUM_NONE;
		} else {
			/* Unknown proto or tunnel, do sw cksum. We can assume
			 * the cksum field is in the first segment since the
			 * buffers we provided to the host are large enough.
			 * In case of SCTP, this will be wrong since it's a CRC
			 * but there's nothing we can do.
			 */
			uint16_t csum = 0, off;

			rte_raw_cksum_mbuf(m, hdr->csum_start,
				rte_pktmbuf_pkt_len(m) - hdr->csum_start,
				&csum);
			if (likely(csum != 0xffff))
				csum = ~csum;
			off = hdr->csum_offset + hdr->csum_start;
			if (rte_pktmbuf_data_len(m) >= off + 1)
				*rte_pktmbuf_mtod_offset(m, uint16_t *,
					off) = csum;
		}
	} else if (hdr->flags & VIRTIO_NET_HDR_F_DATA_VALID && l4_supported) {
		m->ol_flags |= PKT_RX_L4_CKSUM_GOOD;
	}

	/* GSO request, save required information in mbuf */
	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
		/* Check unsupported modes */
		if ((hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN) ||
		    (hdr->gso_size == 0)) {
			return -EINVAL;
		}

		/* Update mss lengthes in mbuf */
		m->tso_segsz = hdr->gso_size;
		switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
			case VIRTIO_NET_HDR_GSO_TCPV4:
			case VIRTIO_NET_HDR_GSO_TCPV6:
				m->ol_flags |= PKT_RX_LRO | \
					PKT_RX_L4_CKSUM_NONE;
				break;
			default:
				return -EINVAL;
		}
	}

	return 0;
}

#define VIRTIO_MBUF_BURST_SZ 64
#define DESC_PER_CACHELINE (RTE_CACHE_LINE_SIZE / sizeof(struct vring_desc))
uint16_t
virtio_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
{
	struct virtnet_rx *rxvq = rx_queue;
	struct virtqueue *vq = rxvq->vq;
	struct virtio_hw *hw = vq->hw;
	struct rte_mbuf *rxm, *new_mbuf;
	uint16_t nb_used, num, nb_rx;
	uint32_t len[VIRTIO_MBUF_BURST_SZ];
	struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
	int error;
	uint32_t i, nb_enqueued;
	uint32_t hdr_size;
	struct virtio_net_hdr *hdr;

	nb_rx = 0;
	if (unlikely(hw->started == 0))
		return nb_rx;

	nb_used = VIRTQUEUE_NUSED(vq);

	virtio_rmb();

	num = likely(nb_used <= nb_pkts) ? nb_used : nb_pkts;
	if (unlikely(num > VIRTIO_MBUF_BURST_SZ))
		num = VIRTIO_MBUF_BURST_SZ;
	if (likely(num > DESC_PER_CACHELINE))
		num = num - ((vq->vq_used_cons_idx + num) % DESC_PER_CACHELINE);

	num = virtqueue_dequeue_burst_rx(vq, rcv_pkts, len, num);
	PMD_RX_LOG(DEBUG, "used:%d dequeue:%d", nb_used, num);

	nb_enqueued = 0;
	hdr_size = hw->vtnet_hdr_size;

	for (i = 0; i < num ; i++) {
		rxm = rcv_pkts[i];

		PMD_RX_LOG(DEBUG, "packet len:%d", len[i]);

		if (unlikely(len[i] < hdr_size + ETHER_HDR_LEN)) {
			PMD_RX_LOG(ERR, "Packet drop");
			nb_enqueued++;
			virtio_discard_rxbuf(vq, rxm);
			rxvq->stats.errors++;
			continue;
		}

		rxm->port = rxvq->port_id;
		rxm->data_off = RTE_PKTMBUF_HEADROOM;
		rxm->ol_flags = 0;
		rxm->vlan_tci = 0;

		rxm->pkt_len = (uint32_t)(len[i] - hdr_size);
		rxm->data_len = (uint16_t)(len[i] - hdr_size);

		hdr = (struct virtio_net_hdr *)((char *)rxm->buf_addr +
			RTE_PKTMBUF_HEADROOM - hdr_size);

		if (hw->vlan_strip)
			rte_vlan_strip(rxm);

		if (hw->has_rx_offload && virtio_rx_offload(rxm, hdr) < 0) {
			virtio_discard_rxbuf(vq, rxm);
			rxvq->stats.errors++;
			continue;
		}

		virtio_rx_stats_updated(rxvq, rxm);

		rx_pkts[nb_rx++] = rxm;
	}

	rxvq->stats.packets += nb_rx;

	/* Allocate new mbuf for the used descriptor */
	while (likely(!virtqueue_full(vq))) {
		new_mbuf = rte_mbuf_raw_alloc(rxvq->mpool);
		if (unlikely(new_mbuf == NULL)) {
			struct rte_eth_dev *dev
				= &rte_eth_devices[rxvq->port_id];
			dev->data->rx_mbuf_alloc_failed++;
			break;
		}
		error = virtqueue_enqueue_recv_refill(vq, new_mbuf);
		if (unlikely(error)) {
			rte_pktmbuf_free(new_mbuf);
			break;
		}
		nb_enqueued++;
	}

	if (likely(nb_enqueued)) {
		vq_update_avail_idx(vq);

		if (unlikely(virtqueue_kick_prepare(vq))) {
			virtqueue_notify(vq);
			PMD_RX_LOG(DEBUG, "Notified");
		}
	}

	return nb_rx;
}

uint16_t
virtio_recv_pkts_packed(void *rx_queue, struct rte_mbuf **rx_pkts,
			uint16_t nb_pkts)
{
	struct virtnet_rx *rxvq = rx_queue;
	struct virtqueue *vq = rxvq->vq;
	struct virtio_hw *hw = vq->hw;
	struct rte_mbuf *rxm, *new_mbuf;
	uint16_t num, nb_rx;
	uint32_t len[VIRTIO_MBUF_BURST_SZ];
	struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
	int error;
	uint32_t i, nb_enqueued;
	uint32_t hdr_size;
	struct virtio_net_hdr *hdr;

	nb_rx = 0;
	if (unlikely(hw->started == 0))
		return nb_rx;

	num = RTE_MIN(VIRTIO_MBUF_BURST_SZ, nb_pkts);
	if (likely(num > DESC_PER_CACHELINE))
		num = num - ((vq->vq_used_cons_idx + num) % DESC_PER_CACHELINE);

	num = virtqueue_dequeue_burst_rx_packed(vq, rcv_pkts, len, num);
	PMD_RX_LOG(DEBUG, "dequeue:%d", num);

	nb_enqueued = 0;
	hdr_size = hw->vtnet_hdr_size;

	for (i = 0; i < num; i++) {
		rxm = rcv_pkts[i];

		PMD_RX_LOG(DEBUG, "packet len:%d", len[i]);

		if (unlikely(len[i] < hdr_size + ETHER_HDR_LEN)) {
			PMD_RX_LOG(ERR, "Packet drop");
			nb_enqueued++;
			virtio_discard_rxbuf(vq, rxm);
			rxvq->stats.errors++;
			continue;
		}

		rxm->port = rxvq->port_id;
		rxm->data_off = RTE_PKTMBUF_HEADROOM;
		rxm->ol_flags = 0;
		rxm->vlan_tci = 0;

		rxm->pkt_len = (uint32_t)(len[i] - hdr_size);
		rxm->data_len = (uint16_t)(len[i] - hdr_size);

		hdr = (struct virtio_net_hdr *)((char *)rxm->buf_addr +
			RTE_PKTMBUF_HEADROOM - hdr_size);

		if (hw->vlan_strip)
			rte_vlan_strip(rxm);

		if (hw->has_rx_offload && virtio_rx_offload(rxm, hdr) < 0) {
			virtio_discard_rxbuf(vq, rxm);
			rxvq->stats.errors++;
			continue;
		}

		virtio_rx_stats_updated(rxvq, rxm);

		rx_pkts[nb_rx++] = rxm;
	}

	rxvq->stats.packets += nb_rx;

	/* Allocate new mbuf for the used descriptor */
	while (likely(!virtqueue_full(vq))) {
		new_mbuf = rte_mbuf_raw_alloc(rxvq->mpool);
		if (unlikely(new_mbuf == NULL)) {
			struct rte_eth_dev *dev =
				&rte_eth_devices[rxvq->port_id];
			dev->data->rx_mbuf_alloc_failed++;
			break;
		}
		error = virtqueue_enqueue_recv_refill_packed(vq, &new_mbuf, 1);
		if (unlikely(error)) {
			rte_pktmbuf_free(new_mbuf);
			break;
		}
		nb_enqueued++;
	}

	if (likely(nb_enqueued)) {
		if (unlikely(virtqueue_kick_prepare_packed(vq))) {
			virtqueue_notify(vq);
			PMD_RX_LOG(DEBUG, "Notified");
		}
	}

	return nb_rx;
}


uint16_t
virtio_recv_mergeable_pkts_inorder(void *rx_queue,
			struct rte_mbuf **rx_pkts,
			uint16_t nb_pkts)
{
	struct virtnet_rx *rxvq = rx_queue;
	struct virtqueue *vq = rxvq->vq;
	struct virtio_hw *hw = vq->hw;
	struct rte_mbuf *rxm;
	struct rte_mbuf *prev;
	uint16_t nb_used, num, nb_rx;
	uint32_t len[VIRTIO_MBUF_BURST_SZ];
	struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
	int error;
	uint32_t nb_enqueued;
	uint32_t seg_num;
	uint32_t seg_res;
	uint32_t hdr_size;
	int32_t i;

	nb_rx = 0;
	if (unlikely(hw->started == 0))
		return nb_rx;

	nb_used = VIRTQUEUE_NUSED(vq);
	nb_used = RTE_MIN(nb_used, nb_pkts);
	nb_used = RTE_MIN(nb_used, VIRTIO_MBUF_BURST_SZ);

	virtio_rmb();

	PMD_RX_LOG(DEBUG, "used:%d", nb_used);

	nb_enqueued = 0;
	seg_num = 1;
	seg_res = 0;
	hdr_size = hw->vtnet_hdr_size;

	num = virtqueue_dequeue_rx_inorder(vq, rcv_pkts, len, nb_used);

	for (i = 0; i < num; i++) {
		struct virtio_net_hdr_mrg_rxbuf *header;

		PMD_RX_LOG(DEBUG, "dequeue:%d", num);
		PMD_RX_LOG(DEBUG, "packet len:%d", len[i]);

		rxm = rcv_pkts[i];

		if (unlikely(len[i] < hdr_size + ETHER_HDR_LEN)) {
			PMD_RX_LOG(ERR, "Packet drop");
			nb_enqueued++;
			virtio_discard_rxbuf_inorder(vq, rxm);
			rxvq->stats.errors++;
			continue;
		}

		header = (struct virtio_net_hdr_mrg_rxbuf *)
			 ((char *)rxm->buf_addr + RTE_PKTMBUF_HEADROOM
			 - hdr_size);
		seg_num = header->num_buffers;

		if (seg_num == 0)
			seg_num = 1;

		rxm->data_off = RTE_PKTMBUF_HEADROOM;
		rxm->nb_segs = seg_num;
		rxm->ol_flags = 0;
		rxm->vlan_tci = 0;
		rxm->pkt_len = (uint32_t)(len[i] - hdr_size);
		rxm->data_len = (uint16_t)(len[i] - hdr_size);

		rxm->port = rxvq->port_id;

		rx_pkts[nb_rx] = rxm;
		prev = rxm;

		if (vq->hw->has_rx_offload &&
				virtio_rx_offload(rxm, &header->hdr) < 0) {
			virtio_discard_rxbuf_inorder(vq, rxm);
			rxvq->stats.errors++;
			continue;
		}

		if (hw->vlan_strip)
			rte_vlan_strip(rx_pkts[nb_rx]);

		seg_res = seg_num - 1;

		/* Merge remaining segments */
		while (seg_res != 0 && i < (num - 1)) {
			i++;

			rxm = rcv_pkts[i];
			rxm->data_off = RTE_PKTMBUF_HEADROOM - hdr_size;
			rxm->pkt_len = (uint32_t)(len[i]);
			rxm->data_len = (uint16_t)(len[i]);

			rx_pkts[nb_rx]->pkt_len += (uint32_t)(len[i]);
			rx_pkts[nb_rx]->data_len += (uint16_t)(len[i]);

			if (prev)
				prev->next = rxm;

			prev = rxm;
			seg_res -= 1;
		}

		if (!seg_res) {
			virtio_rx_stats_updated(rxvq, rx_pkts[nb_rx]);
			nb_rx++;
		}
	}

	/* Last packet still need merge segments */
	while (seg_res != 0) {
		uint16_t rcv_cnt = RTE_MIN((uint16_t)seg_res,
					VIRTIO_MBUF_BURST_SZ);

		prev = rcv_pkts[nb_rx];
		if (likely(VIRTQUEUE_NUSED(vq) >= rcv_cnt)) {
			num = virtqueue_dequeue_rx_inorder(vq, rcv_pkts, len,
							   rcv_cnt);
			uint16_t extra_idx = 0;

			rcv_cnt = num;
			while (extra_idx < rcv_cnt) {
				rxm = rcv_pkts[extra_idx];
				rxm->data_off =
					RTE_PKTMBUF_HEADROOM - hdr_size;
				rxm->pkt_len = (uint32_t)(len[extra_idx]);
				rxm->data_len = (uint16_t)(len[extra_idx]);
				prev->next = rxm;
				prev = rxm;
				rx_pkts[nb_rx]->pkt_len += len[extra_idx];
				rx_pkts[nb_rx]->data_len += len[extra_idx];
				extra_idx += 1;
			};
			seg_res -= rcv_cnt;

			if (!seg_res) {
				virtio_rx_stats_updated(rxvq, rx_pkts[nb_rx]);
				nb_rx++;
			}
		} else {
			PMD_RX_LOG(ERR,
					"No enough segments for packet.");
			virtio_discard_rxbuf_inorder(vq, prev);
			rxvq->stats.errors++;
			break;
		}
	}

	rxvq->stats.packets += nb_rx;

	/* Allocate new mbuf for the used descriptor */

	if (likely(!virtqueue_full(vq))) {
		/* free_cnt may include mrg descs */
		uint16_t free_cnt = vq->vq_free_cnt;
		struct rte_mbuf *new_pkts[free_cnt];

		if (!rte_pktmbuf_alloc_bulk(rxvq->mpool, new_pkts, free_cnt)) {
			error = virtqueue_enqueue_refill_inorder(vq, new_pkts,
					free_cnt);
			if (unlikely(error)) {
				for (i = 0; i < free_cnt; i++)
					rte_pktmbuf_free(new_pkts[i]);
			}
			nb_enqueued += free_cnt;
		} else {
			struct rte_eth_dev *dev =
				&rte_eth_devices[rxvq->port_id];
			dev->data->rx_mbuf_alloc_failed += free_cnt;
		}
	}

	if (likely(nb_enqueued)) {
		vq_update_avail_idx(vq);

		if (unlikely(virtqueue_kick_prepare(vq))) {
			virtqueue_notify(vq);
			PMD_RX_LOG(DEBUG, "Notified");
		}
	}

	return nb_rx;
}

uint16_t
virtio_recv_mergeable_pkts(void *rx_queue,
			struct rte_mbuf **rx_pkts,
			uint16_t nb_pkts)
{
	struct virtnet_rx *rxvq = rx_queue;
	struct virtqueue *vq = rxvq->vq;
	struct virtio_hw *hw = vq->hw;
	struct rte_mbuf *rxm, *new_mbuf;
	uint16_t nb_used, num, nb_rx;
	uint32_t len[VIRTIO_MBUF_BURST_SZ];
	struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
	struct rte_mbuf *prev;
	int error;
	uint32_t i, nb_enqueued;
	uint32_t seg_num;
	uint16_t extra_idx;
	uint32_t seg_res;
	uint32_t hdr_size;

	nb_rx = 0;
	if (unlikely(hw->started == 0))
		return nb_rx;

	nb_used = VIRTQUEUE_NUSED(vq);

	virtio_rmb();

	PMD_RX_LOG(DEBUG, "used:%d", nb_used);

	i = 0;
	nb_enqueued = 0;
	seg_num = 0;
	extra_idx = 0;
	seg_res = 0;
	hdr_size = hw->vtnet_hdr_size;

	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)
			continue;

		i++;

		PMD_RX_LOG(DEBUG, "dequeue:%d", num);
		PMD_RX_LOG(DEBUG, "packet len:%d", len[0]);

		rxm = rcv_pkts[0];

		if (unlikely(len[0] < hdr_size + ETHER_HDR_LEN)) {
			PMD_RX_LOG(ERR, "Packet drop");
			nb_enqueued++;
			virtio_discard_rxbuf(vq, rxm);
			rxvq->stats.errors++;
			continue;
		}

		header = (struct virtio_net_hdr_mrg_rxbuf *)((char *)rxm->buf_addr +
			RTE_PKTMBUF_HEADROOM - hdr_size);
		seg_num = header->num_buffers;

		if (seg_num == 0)
			seg_num = 1;

		rxm->data_off = RTE_PKTMBUF_HEADROOM;
		rxm->nb_segs = seg_num;
		rxm->ol_flags = 0;
		rxm->vlan_tci = 0;
		rxm->pkt_len = (uint32_t)(len[0] - hdr_size);
		rxm->data_len = (uint16_t)(len[0] - hdr_size);

		rxm->port = rxvq->port_id;
		rx_pkts[nb_rx] = rxm;
		prev = rxm;

		if (hw->has_rx_offload &&
				virtio_rx_offload(rxm, &header->hdr) < 0) {
			virtio_discard_rxbuf(vq, rxm);
			rxvq->stats.errors++;
			continue;
		}

		seg_res = seg_num - 1;

		while (seg_res != 0) {
			/*
			 * Get extra segments for current uncompleted packet.
			 */
			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);
				i += rx_num;
				rcv_cnt = rx_num;
			} else {
				PMD_RX_LOG(ERR,
					   "No enough segments for packet.");
				nb_enqueued++;
				virtio_discard_rxbuf(vq, rxm);
				rxvq->stats.errors++;
				break;
			}

			extra_idx = 0;

			while (extra_idx < rcv_cnt) {
				rxm = rcv_pkts[extra_idx];

				rxm->data_off = RTE_PKTMBUF_HEADROOM - hdr_size;
				rxm->pkt_len = (uint32_t)(len[extra_idx]);
				rxm->data_len = (uint16_t)(len[extra_idx]);

				if (prev)
					prev->next = rxm;

				prev = rxm;
				rx_pkts[nb_rx]->pkt_len += rxm->pkt_len;
				extra_idx++;
			};
			seg_res -= rcv_cnt;
		}

		if (hw->vlan_strip)
			rte_vlan_strip(rx_pkts[nb_rx]);

		VIRTIO_DUMP_PACKET(rx_pkts[nb_rx],
			rx_pkts[nb_rx]->data_len);

		virtio_update_packet_stats(&rxvq->stats, rx_pkts[nb_rx]);
		nb_rx++;
	}

	rxvq->stats.packets += nb_rx;

	/* Allocate new mbuf for the used descriptor */
	while (likely(!virtqueue_full(vq))) {
		new_mbuf = rte_mbuf_raw_alloc(rxvq->mpool);
		if (unlikely(new_mbuf == NULL)) {
			struct rte_eth_dev *dev
				= &rte_eth_devices[rxvq->port_id];
			dev->data->rx_mbuf_alloc_failed++;
			break;
		}
		error = virtqueue_enqueue_recv_refill(vq, new_mbuf);
		if (unlikely(error)) {
			rte_pktmbuf_free(new_mbuf);
			break;
		}
		nb_enqueued++;
	}

	if (likely(nb_enqueued)) {
		vq_update_avail_idx(vq);

		if (unlikely(virtqueue_kick_prepare(vq))) {
			virtqueue_notify(vq);
			PMD_RX_LOG(DEBUG, "Notified");
		}
	}

	return nb_rx;
}

uint16_t
virtio_recv_mergeable_pkts_packed(void *rx_queue,
			struct rte_mbuf **rx_pkts,
			uint16_t nb_pkts)
{
	struct virtnet_rx *rxvq = rx_queue;
	struct virtqueue *vq = rxvq->vq;
	struct virtio_hw *hw = vq->hw;
	struct rte_mbuf *rxm;
	struct rte_mbuf *prev = NULL;
	uint16_t num, nb_rx = 0;
	uint32_t len[VIRTIO_MBUF_BURST_SZ];
	struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
	uint32_t nb_enqueued = 0;
	uint32_t seg_num = 0;
	uint32_t seg_res = 0;
	uint32_t hdr_size = hw->vtnet_hdr_size;
	int32_t i;
	int error;

	if (unlikely(hw->started == 0))
		return nb_rx;


	num = nb_pkts;
	if (unlikely(num > VIRTIO_MBUF_BURST_SZ))
		num = VIRTIO_MBUF_BURST_SZ;
	if (likely(num > DESC_PER_CACHELINE))
		num = num - ((vq->vq_used_cons_idx + num) % DESC_PER_CACHELINE);

	num = virtqueue_dequeue_burst_rx_packed(vq, rcv_pkts, len, num);

	for (i = 0; i < num; i++) {
		struct virtio_net_hdr_mrg_rxbuf *header;

		PMD_RX_LOG(DEBUG, "dequeue:%d", num);
		PMD_RX_LOG(DEBUG, "packet len:%d", len[i]);

		rxm = rcv_pkts[i];

		if (unlikely(len[i] < hdr_size + ETHER_HDR_LEN)) {
			PMD_RX_LOG(ERR, "Packet drop");
			nb_enqueued++;
			virtio_discard_rxbuf(vq, rxm);
			rxvq->stats.errors++;
			continue;
		}

		header = (struct virtio_net_hdr_mrg_rxbuf *)((char *)
			  rxm->buf_addr + RTE_PKTMBUF_HEADROOM - hdr_size);
		seg_num = header->num_buffers;

		if (seg_num == 0)
			seg_num = 1;

		rxm->data_off = RTE_PKTMBUF_HEADROOM;
		rxm->nb_segs = seg_num;
		rxm->ol_flags = 0;
		rxm->vlan_tci = 0;
		rxm->pkt_len = (uint32_t)(len[i] - hdr_size);
		rxm->data_len = (uint16_t)(len[i] - hdr_size);

		rxm->port = rxvq->port_id;
		rx_pkts[nb_rx] = rxm;
		prev = rxm;

		if (hw->has_rx_offload &&
				virtio_rx_offload(rxm, &header->hdr) < 0) {
			virtio_discard_rxbuf(vq, rxm);
			rxvq->stats.errors++;
			continue;
		}

		if (hw->vlan_strip)
			rte_vlan_strip(rx_pkts[nb_rx]);

		seg_res = seg_num - 1;

		/* Merge remaining segments */
		while (seg_res != 0 && i < (num - 1)) {
			i++;

			rxm = rcv_pkts[i];
			rxm->data_off = RTE_PKTMBUF_HEADROOM - hdr_size;
			rxm->pkt_len = (uint32_t)(len[i]);
			rxm->data_len = (uint16_t)(len[i]);

			rx_pkts[nb_rx]->pkt_len += (uint32_t)(len[i]);
			rx_pkts[nb_rx]->data_len += (uint16_t)(len[i]);

			if (prev)
				prev->next = rxm;

			prev = rxm;
			seg_res -= 1;
		}

		if (!seg_res) {
			virtio_rx_stats_updated(rxvq, rx_pkts[nb_rx]);
			nb_rx++;
		}
	}

	/* Last packet still need merge segments */
	while (seg_res != 0) {
		uint16_t rcv_cnt = RTE_MIN((uint16_t)seg_res,
					VIRTIO_MBUF_BURST_SZ);
		if (likely(vq->vq_free_cnt >= rcv_cnt)) {
			num = virtqueue_dequeue_burst_rx_packed(vq, rcv_pkts,
					len, rcv_cnt);
			uint16_t extra_idx = 0;

			rcv_cnt = num;

			while (extra_idx < rcv_cnt) {
				rxm = rcv_pkts[extra_idx];

				rxm->data_off =
					RTE_PKTMBUF_HEADROOM - hdr_size;
				rxm->pkt_len = (uint32_t)(len[extra_idx]);
				rxm->data_len = (uint16_t)(len[extra_idx]);

				prev->next = rxm;
				prev = rxm;
				rx_pkts[nb_rx]->pkt_len += len[extra_idx];
				rx_pkts[nb_rx]->data_len += len[extra_idx];
				extra_idx += 1;
			}
			seg_res -= rcv_cnt;
			if (!seg_res) {
				virtio_rx_stats_updated(rxvq, rx_pkts[nb_rx]);
				nb_rx++;
			}
		} else {
			PMD_RX_LOG(ERR,
					"No enough segments for packet.");
			if (prev)
				virtio_discard_rxbuf(vq, prev);
			rxvq->stats.errors++;
			break;
		}
	}

	rxvq->stats.packets += nb_rx;

	/* Allocate new mbuf for the used descriptor */
	if (likely(!virtqueue_full(vq))) {
		/* free_cnt may include mrg descs */
		uint16_t free_cnt = vq->vq_free_cnt;
		struct rte_mbuf *new_pkts[free_cnt];

		if (!rte_pktmbuf_alloc_bulk(rxvq->mpool, new_pkts, free_cnt)) {
			error = virtqueue_enqueue_recv_refill_packed(vq,
					new_pkts, free_cnt);
			if (unlikely(error)) {
				for (i = 0; i < free_cnt; i++)
					rte_pktmbuf_free(new_pkts[i]);
			}
			nb_enqueued += free_cnt;
		} else {
			struct rte_eth_dev *dev =
				&rte_eth_devices[rxvq->port_id];
			dev->data->rx_mbuf_alloc_failed += free_cnt;
		}
	}

	if (likely(nb_enqueued)) {
		if (unlikely(virtqueue_kick_prepare_packed(vq))) {
			virtqueue_notify(vq);
			PMD_RX_LOG(DEBUG, "Notified");
		}
	}

	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;

	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);

	if (nb_pkts > vq->vq_free_cnt)
		virtio_xmit_cleanup_packed(vq, nb_pkts - vq->vq_free_cnt);

	for (nb_tx = 0; nb_tx < nb_pkts; nb_tx++) {
		struct rte_mbuf *txm = tx_pkts[nb_tx];
		int can_push = 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;

		/* How many main ring entries are needed to this Tx?
		 * any_layout => number of segments
		 * default    => number of segments + 1
		 */
		slots = 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, can_push);

		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)
{
	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_used, nb_tx = 0;
	int error;

	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);
	nb_used = VIRTQUEUE_NUSED(vq);

	virtio_rmb();
	if (likely(nb_used > vq->vq_nentries - vq->vq_free_thresh))
		virtio_xmit_cleanup(vq, nb_used);

	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)) {
			nb_used = VIRTQUEUE_NUSED(vq);
			virtio_rmb();
			need = RTE_MIN(need, (int)nb_used);

			virtio_xmit_cleanup(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(txvq, txm, slots, use_indirect,
			can_push, 0);

		virtio_update_packet_stats(&txvq->stats, txm);
	}

	txvq->stats.packets += nb_tx;

	if (likely(nb_tx)) {
		vq_update_avail_idx(vq);

		if (unlikely(virtqueue_kick_prepare(vq))) {
			virtqueue_notify(vq);
			PMD_TX_LOG(DEBUG, "Notified backend after xmit");
		}
	}

	return nb_tx;
}

uint16_t
virtio_xmit_pkts_inorder(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_used, nb_avail, nb_tx = 0, nb_inorder_pkts = 0;
	struct rte_mbuf *inorder_pkts[nb_pkts];
	int error;

	if (unlikely(hw->started == 0 && tx_pkts != hw->inject_pkts))
		return nb_tx;

	if (unlikely(nb_pkts < 1))
		return nb_pkts;

	VIRTQUEUE_DUMP(vq);
	PMD_TX_LOG(DEBUG, "%d packets to xmit", nb_pkts);
	nb_used = VIRTQUEUE_NUSED(vq);

	virtio_rmb();
	if (likely(nb_used > vq->vq_nentries - vq->vq_free_thresh))
		virtio_xmit_cleanup_inorder(vq, nb_used);

	if (unlikely(!vq->vq_free_cnt))
		virtio_xmit_cleanup_inorder(vq, nb_used);

	nb_avail = RTE_MIN(vq->vq_free_cnt, nb_pkts);

	for (nb_tx = 0; nb_tx < nb_avail; nb_tx++) {
		struct rte_mbuf *txm = tx_pkts[nb_tx];
		int 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))) {
			inorder_pkts[nb_inorder_pkts] = txm;
			nb_inorder_pkts++;

			virtio_update_packet_stats(&txvq->stats, txm);
			continue;
		}

		if (nb_inorder_pkts) {
			virtqueue_enqueue_xmit_inorder(txvq, inorder_pkts,
							nb_inorder_pkts);
			nb_inorder_pkts = 0;
		}

		slots = txm->nb_segs + 1;
		need = slots - vq->vq_free_cnt;
		if (unlikely(need > 0)) {
			nb_used = VIRTQUEUE_NUSED(vq);
			virtio_rmb();
			need = RTE_MIN(need, (int)nb_used);

			virtio_xmit_cleanup_inorder(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(txvq, txm, slots, 0, 0, 1);

		virtio_update_packet_stats(&txvq->stats, txm);
	}

	/* Transmit all inorder packets */
	if (nb_inorder_pkts)
		virtqueue_enqueue_xmit_inorder(txvq, inorder_pkts,
						nb_inorder_pkts);

	txvq->stats.packets += nb_tx;

	if (likely(nb_tx)) {
		vq_update_avail_idx(vq);

		if (unlikely(virtqueue_kick_prepare(vq))) {
			virtqueue_notify(vq);
			PMD_TX_LOG(DEBUG, "Notified backend after xmit");
		}
	}

	VIRTQUEUE_DUMP(vq);

	return nb_tx;
}