/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2010-2016 Intel Corporation
 */

#include <stdint.h>
#include <stdbool.h>
#include <linux/virtio_net.h>

#include <rte_mbuf.h>
#include <rte_memcpy.h>
#include <rte_net.h>
#include <rte_ether.h>
#include <rte_ip.h>
#include <rte_dmadev.h>
#include <rte_vhost.h>
#include <rte_tcp.h>
#include <rte_udp.h>
#include <rte_sctp.h>
#include <rte_arp.h>
#include <rte_spinlock.h>
#include <rte_malloc.h>
#include <rte_vhost_async.h>

#include "iotlb.h"
#include "vhost.h"

#define MAX_BATCH_LEN 256

static __rte_always_inline uint16_t
async_poll_dequeue_completed(struct virtio_net *dev, struct vhost_virtqueue *vq,
                struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
                uint16_t vchan_id, bool legacy_ol_flags);

/* DMA device copy operation tracking array. */
struct async_dma_info dma_copy_track[RTE_DMADEV_DEFAULT_MAX];

static  __rte_always_inline bool
rxvq_is_mergeable(struct virtio_net *dev)
{
        return dev->features & (1ULL << VIRTIO_NET_F_MRG_RXBUF);
}

static  __rte_always_inline bool
virtio_net_is_inorder(struct virtio_net *dev)
{
        return dev->features & (1ULL << VIRTIO_F_IN_ORDER);
}

static bool
is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t nr_vring)
{
        return (is_tx ^ (idx & 1)) == 0 && idx < nr_vring;
}

/*
 * This function must be called with virtqueue's access_lock taken.
 */
static inline void
vhost_queue_stats_update(struct virtio_net *dev, struct vhost_virtqueue *vq,
                struct rte_mbuf **pkts, uint16_t count)
{
        struct virtqueue_stats *stats = &vq->stats;
        int i;

        if (!(dev->flags & VIRTIO_DEV_STATS_ENABLED))
                return;

        for (i = 0; i < count; i++) {
                struct rte_ether_addr *ea;
                struct rte_mbuf *pkt = pkts[i];
                uint32_t pkt_len = rte_pktmbuf_pkt_len(pkt);

                stats->packets++;
                stats->bytes += pkt_len;

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

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

                ea = rte_pktmbuf_mtod(pkt, struct rte_ether_addr *);
                if (rte_is_multicast_ether_addr(ea)) {
                        if (rte_is_broadcast_ether_addr(ea))
                                stats->broadcast++;
                        else
                                stats->multicast++;
                }
        }
}

static __rte_always_inline int64_t
vhost_async_dma_transfer_one(struct virtio_net *dev, struct vhost_virtqueue *vq,
                int16_t dma_id, uint16_t vchan_id, uint16_t flag_idx,
                struct vhost_iov_iter *pkt)
{
        struct async_dma_vchan_info *dma_info = &dma_copy_track[dma_id].vchans[vchan_id];
        uint16_t ring_mask = dma_info->ring_mask;
        static bool vhost_async_dma_copy_log;


        struct vhost_iovec *iov = pkt->iov;
        int copy_idx = 0;
        uint32_t nr_segs = pkt->nr_segs;
        uint16_t i;

        if (rte_dma_burst_capacity(dma_id, vchan_id) < nr_segs)
                return -1;

        for (i = 0; i < nr_segs; i++) {
                copy_idx = rte_dma_copy(dma_id, vchan_id, (rte_iova_t)iov[i].src_addr,
                                (rte_iova_t)iov[i].dst_addr, iov[i].len, RTE_DMA_OP_FLAG_LLC);
                /**
                 * Since all memory is pinned and DMA vChannel
                 * ring has enough space, failure should be a
                 * rare case. If failure happens, it means DMA
                 * device encounters serious errors; in this
                 * case, please stop async data-path and check
                 * what has happened to DMA device.
                 */
                if (unlikely(copy_idx < 0)) {
                        if (!vhost_async_dma_copy_log) {
                                VHOST_LOG_DATA(dev->ifname, ERR,
                                        "DMA copy failed for channel %d:%u\n",
                                        dma_id, vchan_id);
                                vhost_async_dma_copy_log = true;
                        }
                        return -1;
                }
        }

        /**
         * Only store packet completion flag address in the last copy's
         * slot, and other slots are set to NULL.
         */
        dma_info->pkts_cmpl_flag_addr[copy_idx & ring_mask] = &vq->async->pkts_cmpl_flag[flag_idx];

        return nr_segs;
}

static __rte_always_inline uint16_t
vhost_async_dma_transfer(struct virtio_net *dev, struct vhost_virtqueue *vq,
                int16_t dma_id, uint16_t vchan_id, uint16_t head_idx,
                struct vhost_iov_iter *pkts, uint16_t nr_pkts)
{
        struct async_dma_vchan_info *dma_info = &dma_copy_track[dma_id].vchans[vchan_id];
        int64_t ret, nr_copies = 0;
        uint16_t pkt_idx;

        rte_spinlock_lock(&dma_info->dma_lock);

        for (pkt_idx = 0; pkt_idx < nr_pkts; pkt_idx++) {
                ret = vhost_async_dma_transfer_one(dev, vq, dma_id, vchan_id, head_idx,
                                &pkts[pkt_idx]);
                if (unlikely(ret < 0))
                        break;

                nr_copies += ret;
                head_idx++;
                if (head_idx >= vq->size)
                        head_idx -= vq->size;
        }

        if (likely(nr_copies > 0))
                rte_dma_submit(dma_id, vchan_id);

        rte_spinlock_unlock(&dma_info->dma_lock);

        return pkt_idx;
}

static __rte_always_inline uint16_t
vhost_async_dma_check_completed(struct virtio_net *dev, int16_t dma_id, uint16_t vchan_id,
                uint16_t max_pkts)
{
        struct async_dma_vchan_info *dma_info = &dma_copy_track[dma_id].vchans[vchan_id];
        uint16_t ring_mask = dma_info->ring_mask;
        uint16_t last_idx = 0;
        uint16_t nr_copies;
        uint16_t copy_idx;
        uint16_t i;
        bool has_error = false;
        static bool vhost_async_dma_complete_log;

        rte_spinlock_lock(&dma_info->dma_lock);

        /**
         * Print error log for debugging, if DMA reports error during
         * DMA transfer. We do not handle error in vhost level.
         */
        nr_copies = rte_dma_completed(dma_id, vchan_id, max_pkts, &last_idx, &has_error);
        if (unlikely(!vhost_async_dma_complete_log && has_error)) {
                VHOST_LOG_DATA(dev->ifname, ERR,
                        "DMA completion failure on channel %d:%u\n",
                        dma_id, vchan_id);
                vhost_async_dma_complete_log = true;
        } else if (nr_copies == 0) {
                goto out;
        }

        copy_idx = last_idx - nr_copies + 1;
        for (i = 0; i < nr_copies; i++) {
                bool *flag;

                flag = dma_info->pkts_cmpl_flag_addr[copy_idx & ring_mask];
                if (flag) {
                        /**
                         * Mark the packet flag as received. The flag
                         * could belong to another virtqueue but write
                         * is atomic.
                         */
                        *flag = true;
                        dma_info->pkts_cmpl_flag_addr[copy_idx & ring_mask] = NULL;
                }
                copy_idx++;
        }

out:
        rte_spinlock_unlock(&dma_info->dma_lock);
        return nr_copies;
}

static inline void
do_data_copy_enqueue(struct virtio_net *dev, struct vhost_virtqueue *vq)
{
        struct batch_copy_elem *elem = vq->batch_copy_elems;
        uint16_t count = vq->batch_copy_nb_elems;
        int i;

        for (i = 0; i < count; i++) {
                rte_memcpy(elem[i].dst, elem[i].src, elem[i].len);
                vhost_log_cache_write_iova(dev, vq, elem[i].log_addr,
                                           elem[i].len);
                PRINT_PACKET(dev, (uintptr_t)elem[i].dst, elem[i].len, 0);
        }

        vq->batch_copy_nb_elems = 0;
}

static inline void
do_data_copy_dequeue(struct vhost_virtqueue *vq)
{
        struct batch_copy_elem *elem = vq->batch_copy_elems;
        uint16_t count = vq->batch_copy_nb_elems;
        int i;

        for (i = 0; i < count; i++)
                rte_memcpy(elem[i].dst, elem[i].src, elem[i].len);

        vq->batch_copy_nb_elems = 0;
}

static __rte_always_inline void
do_flush_shadow_used_ring_split(struct virtio_net *dev,
                        struct vhost_virtqueue *vq,
                        uint16_t to, uint16_t from, uint16_t size)
{
        rte_memcpy(&vq->used->ring[to],
                        &vq->shadow_used_split[from],
                        size * sizeof(struct vring_used_elem));
        vhost_log_cache_used_vring(dev, vq,
                        offsetof(struct vring_used, ring[to]),
                        size * sizeof(struct vring_used_elem));
}

static __rte_always_inline void
flush_shadow_used_ring_split(struct virtio_net *dev, struct vhost_virtqueue *vq)
{
        uint16_t used_idx = vq->last_used_idx & (vq->size - 1);

        if (used_idx + vq->shadow_used_idx <= vq->size) {
                do_flush_shadow_used_ring_split(dev, vq, used_idx, 0,
                                          vq->shadow_used_idx);
        } else {
                uint16_t size;

                /* update used ring interval [used_idx, vq->size] */
                size = vq->size - used_idx;
                do_flush_shadow_used_ring_split(dev, vq, used_idx, 0, size);

                /* update the left half used ring interval [0, left_size] */
                do_flush_shadow_used_ring_split(dev, vq, 0, size,
                                          vq->shadow_used_idx - size);
        }
        vq->last_used_idx += vq->shadow_used_idx;

        vhost_log_cache_sync(dev, vq);

        __atomic_add_fetch(&vq->used->idx, vq->shadow_used_idx,
                           __ATOMIC_RELEASE);
        vq->shadow_used_idx = 0;
        vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
                sizeof(vq->used->idx));
}

static __rte_always_inline void
update_shadow_used_ring_split(struct vhost_virtqueue *vq,
                         uint16_t desc_idx, uint32_t len)
{
        uint16_t i = vq->shadow_used_idx++;

        vq->shadow_used_split[i].id  = desc_idx;
        vq->shadow_used_split[i].len = len;
}

static __rte_always_inline void
vhost_flush_enqueue_shadow_packed(struct virtio_net *dev,
                                  struct vhost_virtqueue *vq)
{
        int i;
        uint16_t used_idx = vq->last_used_idx;
        uint16_t head_idx = vq->last_used_idx;
        uint16_t head_flags = 0;

        /* Split loop in two to save memory barriers */
        for (i = 0; i < vq->shadow_used_idx; i++) {
                vq->desc_packed[used_idx].id = vq->shadow_used_packed[i].id;
                vq->desc_packed[used_idx].len = vq->shadow_used_packed[i].len;

                used_idx += vq->shadow_used_packed[i].count;
                if (used_idx >= vq->size)
                        used_idx -= vq->size;
        }

        /* The ordering for storing desc flags needs to be enforced. */
        rte_atomic_thread_fence(__ATOMIC_RELEASE);

        for (i = 0; i < vq->shadow_used_idx; i++) {
                uint16_t flags;

                if (vq->shadow_used_packed[i].len)
                        flags = VRING_DESC_F_WRITE;
                else
                        flags = 0;

                if (vq->used_wrap_counter) {
                        flags |= VRING_DESC_F_USED;
                        flags |= VRING_DESC_F_AVAIL;
                } else {
                        flags &= ~VRING_DESC_F_USED;
                        flags &= ~VRING_DESC_F_AVAIL;
                }

                if (i > 0) {
                        vq->desc_packed[vq->last_used_idx].flags = flags;

                        vhost_log_cache_used_vring(dev, vq,
                                        vq->last_used_idx *
                                        sizeof(struct vring_packed_desc),
                                        sizeof(struct vring_packed_desc));
                } else {
                        head_idx = vq->last_used_idx;
                        head_flags = flags;
                }

                vq_inc_last_used_packed(vq, vq->shadow_used_packed[i].count);
        }

        vq->desc_packed[head_idx].flags = head_flags;

        vhost_log_cache_used_vring(dev, vq,
                                head_idx *
                                sizeof(struct vring_packed_desc),
                                sizeof(struct vring_packed_desc));

        vq->shadow_used_idx = 0;
        vhost_log_cache_sync(dev, vq);
}

static __rte_always_inline void
vhost_flush_dequeue_shadow_packed(struct virtio_net *dev,
                                  struct vhost_virtqueue *vq)
{
        struct vring_used_elem_packed *used_elem = &vq->shadow_used_packed[0];

        vq->desc_packed[vq->shadow_last_used_idx].id = used_elem->id;
        /* desc flags is the synchronization point for virtio packed vring */
        __atomic_store_n(&vq->desc_packed[vq->shadow_last_used_idx].flags,
                         used_elem->flags, __ATOMIC_RELEASE);

        vhost_log_cache_used_vring(dev, vq, vq->shadow_last_used_idx *
                                   sizeof(struct vring_packed_desc),
                                   sizeof(struct vring_packed_desc));
        vq->shadow_used_idx = 0;
        vhost_log_cache_sync(dev, vq);
}

static __rte_always_inline void
vhost_flush_enqueue_batch_packed(struct virtio_net *dev,
                                 struct vhost_virtqueue *vq,
                                 uint64_t *lens,
                                 uint16_t *ids)
{
        uint16_t i;
        uint16_t flags;
        uint16_t last_used_idx;
        struct vring_packed_desc *desc_base;

        last_used_idx = vq->last_used_idx;
        desc_base = &vq->desc_packed[last_used_idx];

        flags = PACKED_DESC_ENQUEUE_USED_FLAG(vq->used_wrap_counter);

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
                desc_base[i].id = ids[i];
                desc_base[i].len = lens[i];
        }

        rte_atomic_thread_fence(__ATOMIC_RELEASE);

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
                desc_base[i].flags = flags;
        }

        vhost_log_cache_used_vring(dev, vq, last_used_idx *
                                   sizeof(struct vring_packed_desc),
                                   sizeof(struct vring_packed_desc) *
                                   PACKED_BATCH_SIZE);
        vhost_log_cache_sync(dev, vq);

        vq_inc_last_used_packed(vq, PACKED_BATCH_SIZE);
}

static __rte_always_inline void
vhost_shadow_dequeue_batch_packed_inorder(struct vhost_virtqueue *vq,
                                          uint16_t id)
{
        vq->shadow_used_packed[0].id = id;

        if (!vq->shadow_used_idx) {
                vq->shadow_last_used_idx = vq->last_used_idx;
                vq->shadow_used_packed[0].flags =
                        PACKED_DESC_DEQUEUE_USED_FLAG(vq->used_wrap_counter);
                vq->shadow_used_packed[0].len = 0;
                vq->shadow_used_packed[0].count = 1;
                vq->shadow_used_idx++;
        }

        vq_inc_last_used_packed(vq, PACKED_BATCH_SIZE);
}

static __rte_always_inline void
vhost_shadow_dequeue_batch_packed(struct virtio_net *dev,
                                  struct vhost_virtqueue *vq,
                                  uint16_t *ids)
{
        uint16_t flags;
        uint16_t i;
        uint16_t begin;

        flags = PACKED_DESC_DEQUEUE_USED_FLAG(vq->used_wrap_counter);

        if (!vq->shadow_used_idx) {
                vq->shadow_last_used_idx = vq->last_used_idx;
                vq->shadow_used_packed[0].id  = ids[0];
                vq->shadow_used_packed[0].len = 0;
                vq->shadow_used_packed[0].count = 1;
                vq->shadow_used_packed[0].flags = flags;
                vq->shadow_used_idx++;
                begin = 1;
        } else
                begin = 0;

        vhost_for_each_try_unroll(i, begin, PACKED_BATCH_SIZE) {
                vq->desc_packed[vq->last_used_idx + i].id = ids[i];
                vq->desc_packed[vq->last_used_idx + i].len = 0;
        }

        rte_atomic_thread_fence(__ATOMIC_RELEASE);
        vhost_for_each_try_unroll(i, begin, PACKED_BATCH_SIZE)
                vq->desc_packed[vq->last_used_idx + i].flags = flags;

        vhost_log_cache_used_vring(dev, vq, vq->last_used_idx *
                                   sizeof(struct vring_packed_desc),
                                   sizeof(struct vring_packed_desc) *
                                   PACKED_BATCH_SIZE);
        vhost_log_cache_sync(dev, vq);

        vq_inc_last_used_packed(vq, PACKED_BATCH_SIZE);
}

static __rte_always_inline void
vhost_shadow_dequeue_single_packed(struct vhost_virtqueue *vq,
                                   uint16_t buf_id,
                                   uint16_t count)
{
        uint16_t flags;

        flags = vq->desc_packed[vq->last_used_idx].flags;
        if (vq->used_wrap_counter) {
                flags |= VRING_DESC_F_USED;
                flags |= VRING_DESC_F_AVAIL;
        } else {
                flags &= ~VRING_DESC_F_USED;
                flags &= ~VRING_DESC_F_AVAIL;
        }

        if (!vq->shadow_used_idx) {
                vq->shadow_last_used_idx = vq->last_used_idx;

                vq->shadow_used_packed[0].id  = buf_id;
                vq->shadow_used_packed[0].len = 0;
                vq->shadow_used_packed[0].flags = flags;
                vq->shadow_used_idx++;
        } else {
                vq->desc_packed[vq->last_used_idx].id = buf_id;
                vq->desc_packed[vq->last_used_idx].len = 0;
                vq->desc_packed[vq->last_used_idx].flags = flags;
        }

        vq_inc_last_used_packed(vq, count);
}

static __rte_always_inline void
vhost_shadow_dequeue_single_packed_inorder(struct vhost_virtqueue *vq,
                                           uint16_t buf_id,
                                           uint16_t count)
{
        uint16_t flags;

        vq->shadow_used_packed[0].id = buf_id;

        flags = vq->desc_packed[vq->last_used_idx].flags;
        if (vq->used_wrap_counter) {
                flags |= VRING_DESC_F_USED;
                flags |= VRING_DESC_F_AVAIL;
        } else {
                flags &= ~VRING_DESC_F_USED;
                flags &= ~VRING_DESC_F_AVAIL;
        }

        if (!vq->shadow_used_idx) {
                vq->shadow_last_used_idx = vq->last_used_idx;
                vq->shadow_used_packed[0].len = 0;
                vq->shadow_used_packed[0].flags = flags;
                vq->shadow_used_idx++;
        }

        vq_inc_last_used_packed(vq, count);
}

static __rte_always_inline void
vhost_shadow_enqueue_packed(struct vhost_virtqueue *vq,
                                   uint32_t *len,
                                   uint16_t *id,
                                   uint16_t *count,
                                   uint16_t num_buffers)
{
        uint16_t i;

        for (i = 0; i < num_buffers; i++) {
                /* enqueue shadow flush action aligned with batch num */
                if (!vq->shadow_used_idx)
                        vq->shadow_aligned_idx = vq->last_used_idx &
                                PACKED_BATCH_MASK;
                vq->shadow_used_packed[vq->shadow_used_idx].id  = id[i];
                vq->shadow_used_packed[vq->shadow_used_idx].len = len[i];
                vq->shadow_used_packed[vq->shadow_used_idx].count = count[i];
                vq->shadow_aligned_idx += count[i];
                vq->shadow_used_idx++;
        }
}

static __rte_always_inline void
vhost_shadow_enqueue_single_packed(struct virtio_net *dev,
                                   struct vhost_virtqueue *vq,
                                   uint32_t *len,
                                   uint16_t *id,
                                   uint16_t *count,
                                   uint16_t num_buffers)
{
        vhost_shadow_enqueue_packed(vq, len, id, count, num_buffers);

        if (vq->shadow_aligned_idx >= PACKED_BATCH_SIZE) {
                do_data_copy_enqueue(dev, vq);
                vhost_flush_enqueue_shadow_packed(dev, vq);
        }
}

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

static __rte_always_inline void
virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
{
        uint64_t csum_l4 = m_buf->ol_flags & RTE_MBUF_F_TX_L4_MASK;

        if (m_buf->ol_flags & RTE_MBUF_F_TX_TCP_SEG)
                csum_l4 |= RTE_MBUF_F_TX_TCP_CKSUM;

        if (csum_l4) {
                /*
                 * Pseudo-header checksum must be set as per Virtio spec.
                 *
                 * Note: We don't propagate rte_net_intel_cksum_prepare()
                 * errors, as it would have an impact on performance, and an
                 * error would mean the packet is dropped by the guest instead
                 * of being dropped here.
                 */
                rte_net_intel_cksum_prepare(m_buf);

                net_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
                net_hdr->csum_start = m_buf->l2_len + m_buf->l3_len;

                switch (csum_l4) {
                case RTE_MBUF_F_TX_TCP_CKSUM:
                        net_hdr->csum_offset = (offsetof(struct rte_tcp_hdr,
                                                cksum));
                        break;
                case RTE_MBUF_F_TX_UDP_CKSUM:
                        net_hdr->csum_offset = (offsetof(struct rte_udp_hdr,
                                                dgram_cksum));
                        break;
                case RTE_MBUF_F_TX_SCTP_CKSUM:
                        net_hdr->csum_offset = (offsetof(struct rte_sctp_hdr,
                                                cksum));
                        break;
                }
        } else {
                ASSIGN_UNLESS_EQUAL(net_hdr->csum_start, 0);
                ASSIGN_UNLESS_EQUAL(net_hdr->csum_offset, 0);
                ASSIGN_UNLESS_EQUAL(net_hdr->flags, 0);
        }

        /* IP cksum verification cannot be bypassed, then calculate here */
        if (m_buf->ol_flags & RTE_MBUF_F_TX_IP_CKSUM) {
                struct rte_ipv4_hdr *ipv4_hdr;

                ipv4_hdr = rte_pktmbuf_mtod_offset(m_buf, struct rte_ipv4_hdr *,
                                                   m_buf->l2_len);
                ipv4_hdr->hdr_checksum = 0;
                ipv4_hdr->hdr_checksum = rte_ipv4_cksum(ipv4_hdr);
        }

        if (m_buf->ol_flags & RTE_MBUF_F_TX_TCP_SEG) {
                if (m_buf->ol_flags & RTE_MBUF_F_TX_IPV4)
                        net_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
                else
                        net_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
                net_hdr->gso_size = m_buf->tso_segsz;
                net_hdr->hdr_len = m_buf->l2_len + m_buf->l3_len
                                        + m_buf->l4_len;
        } else if (m_buf->ol_flags & RTE_MBUF_F_TX_UDP_SEG) {
                net_hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
                net_hdr->gso_size = m_buf->tso_segsz;
                net_hdr->hdr_len = m_buf->l2_len + m_buf->l3_len +
                        m_buf->l4_len;
        } else {
                ASSIGN_UNLESS_EQUAL(net_hdr->gso_type, 0);
                ASSIGN_UNLESS_EQUAL(net_hdr->gso_size, 0);
                ASSIGN_UNLESS_EQUAL(net_hdr->hdr_len, 0);
        }
}

static __rte_always_inline int
map_one_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
                struct buf_vector *buf_vec, uint16_t *vec_idx,
                uint64_t desc_iova, uint64_t desc_len, uint8_t perm)
{
        uint16_t vec_id = *vec_idx;

        while (desc_len) {
                uint64_t desc_addr;
                uint64_t desc_chunck_len = desc_len;

                if (unlikely(vec_id >= BUF_VECTOR_MAX))
                        return -1;

                desc_addr = vhost_iova_to_vva(dev, vq,
                                desc_iova,
                                &desc_chunck_len,
                                perm);
                if (unlikely(!desc_addr))
                        return -1;

                rte_prefetch0((void *)(uintptr_t)desc_addr);

                buf_vec[vec_id].buf_iova = desc_iova;
                buf_vec[vec_id].buf_addr = desc_addr;
                buf_vec[vec_id].buf_len  = desc_chunck_len;

                desc_len -= desc_chunck_len;
                desc_iova += desc_chunck_len;
                vec_id++;
        }
        *vec_idx = vec_id;

        return 0;
}

static __rte_always_inline int
fill_vec_buf_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
                         uint32_t avail_idx, uint16_t *vec_idx,
                         struct buf_vector *buf_vec, uint16_t *desc_chain_head,
                         uint32_t *desc_chain_len, uint8_t perm)
{
        uint16_t idx = vq->avail->ring[avail_idx & (vq->size - 1)];
        uint16_t vec_id = *vec_idx;
        uint32_t len    = 0;
        uint64_t dlen;
        uint32_t nr_descs = vq->size;
        uint32_t cnt    = 0;
        struct vring_desc *descs = vq->desc;
        struct vring_desc *idesc = NULL;

        if (unlikely(idx >= vq->size))
                return -1;

        *desc_chain_head = idx;

        if (vq->desc[idx].flags & VRING_DESC_F_INDIRECT) {
                dlen = vq->desc[idx].len;
                nr_descs = dlen / sizeof(struct vring_desc);
                if (unlikely(nr_descs > vq->size))
                        return -1;

                descs = (struct vring_desc *)(uintptr_t)
                        vhost_iova_to_vva(dev, vq, vq->desc[idx].addr,
                                                &dlen,
                                                VHOST_ACCESS_RO);
                if (unlikely(!descs))
                        return -1;

                if (unlikely(dlen < vq->desc[idx].len)) {
                        /*
                         * The indirect desc table is not contiguous
                         * in process VA space, we have to copy it.
                         */
                        idesc = vhost_alloc_copy_ind_table(dev, vq,
                                        vq->desc[idx].addr, vq->desc[idx].len);
                        if (unlikely(!idesc))
                                return -1;

                        descs = idesc;
                }

                idx = 0;
        }

        while (1) {
                if (unlikely(idx >= nr_descs || cnt++ >= nr_descs)) {
                        free_ind_table(idesc);
                        return -1;
                }

                dlen = descs[idx].len;
                len += dlen;

                if (unlikely(map_one_desc(dev, vq, buf_vec, &vec_id,
                                                descs[idx].addr, dlen,
                                                perm))) {
                        free_ind_table(idesc);
                        return -1;
                }

                if ((descs[idx].flags & VRING_DESC_F_NEXT) == 0)
                        break;

                idx = descs[idx].next;
        }

        *desc_chain_len = len;
        *vec_idx = vec_id;

        if (unlikely(!!idesc))
                free_ind_table(idesc);

        return 0;
}

/*
 * Returns -1 on fail, 0 on success
 */
static inline int
reserve_avail_buf_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
                                uint32_t size, struct buf_vector *buf_vec,
                                uint16_t *num_buffers, uint16_t avail_head,
                                uint16_t *nr_vec)
{
        uint16_t cur_idx;
        uint16_t vec_idx = 0;
        uint16_t max_tries, tries = 0;

        uint16_t head_idx = 0;
        uint32_t len = 0;

        *num_buffers = 0;
        cur_idx  = vq->last_avail_idx;

        if (rxvq_is_mergeable(dev))
                max_tries = vq->size - 1;
        else
                max_tries = 1;

        while (size > 0) {
                if (unlikely(cur_idx == avail_head))
                        return -1;
                /*
                 * if we tried all available ring items, and still
                 * can't get enough buf, it means something abnormal
                 * happened.
                 */
                if (unlikely(++tries > max_tries))
                        return -1;

                if (unlikely(fill_vec_buf_split(dev, vq, cur_idx,
                                                &vec_idx, buf_vec,
                                                &head_idx, &len,
                                                VHOST_ACCESS_RW) < 0))
                        return -1;
                len = RTE_MIN(len, size);
                update_shadow_used_ring_split(vq, head_idx, len);
                size -= len;

                cur_idx++;
                *num_buffers += 1;
        }

        *nr_vec = vec_idx;

        return 0;
}

static __rte_always_inline int
fill_vec_buf_packed_indirect(struct virtio_net *dev,
                        struct vhost_virtqueue *vq,
                        struct vring_packed_desc *desc, uint16_t *vec_idx,
                        struct buf_vector *buf_vec, uint32_t *len, uint8_t perm)
{
        uint16_t i;
        uint32_t nr_descs;
        uint16_t vec_id = *vec_idx;
        uint64_t dlen;
        struct vring_packed_desc *descs, *idescs = NULL;

        dlen = desc->len;
        descs = (struct vring_packed_desc *)(uintptr_t)
                vhost_iova_to_vva(dev, vq, desc->addr, &dlen, VHOST_ACCESS_RO);
        if (unlikely(!descs))
                return -1;

        if (unlikely(dlen < desc->len)) {
                /*
                 * The indirect desc table is not contiguous
                 * in process VA space, we have to copy it.
                 */
                idescs = vhost_alloc_copy_ind_table(dev,
                                vq, desc->addr, desc->len);
                if (unlikely(!idescs))
                        return -1;

                descs = idescs;
        }

        nr_descs =  desc->len / sizeof(struct vring_packed_desc);
        if (unlikely(nr_descs >= vq->size)) {
                free_ind_table(idescs);
                return -1;
        }

        for (i = 0; i < nr_descs; i++) {
                if (unlikely(vec_id >= BUF_VECTOR_MAX)) {
                        free_ind_table(idescs);
                        return -1;
                }

                dlen = descs[i].len;
                *len += dlen;
                if (unlikely(map_one_desc(dev, vq, buf_vec, &vec_id,
                                                descs[i].addr, dlen,
                                                perm)))
                        return -1;
        }
        *vec_idx = vec_id;

        if (unlikely(!!idescs))
                free_ind_table(idescs);

        return 0;
}

static __rte_always_inline int
fill_vec_buf_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
                                uint16_t avail_idx, uint16_t *desc_count,
                                struct buf_vector *buf_vec, uint16_t *vec_idx,
                                uint16_t *buf_id, uint32_t *len, uint8_t perm)
{
        bool wrap_counter = vq->avail_wrap_counter;
        struct vring_packed_desc *descs = vq->desc_packed;
        uint16_t vec_id = *vec_idx;
        uint64_t dlen;

        if (avail_idx < vq->last_avail_idx)
                wrap_counter ^= 1;

        /*
         * Perform a load-acquire barrier in desc_is_avail to
         * enforce the ordering between desc flags and desc
         * content.
         */
        if (unlikely(!desc_is_avail(&descs[avail_idx], wrap_counter)))
                return -1;

        *desc_count = 0;
        *len = 0;

        while (1) {
                if (unlikely(vec_id >= BUF_VECTOR_MAX))
                        return -1;

                if (unlikely(*desc_count >= vq->size))
                        return -1;

                *desc_count += 1;
                *buf_id = descs[avail_idx].id;

                if (descs[avail_idx].flags & VRING_DESC_F_INDIRECT) {
                        if (unlikely(fill_vec_buf_packed_indirect(dev, vq,
                                                        &descs[avail_idx],
                                                        &vec_id, buf_vec,
                                                        len, perm) < 0))
                                return -1;
                } else {
                        dlen = descs[avail_idx].len;
                        *len += dlen;

                        if (unlikely(map_one_desc(dev, vq, buf_vec, &vec_id,
                                                        descs[avail_idx].addr,
                                                        dlen,
                                                        perm)))
                                return -1;
                }

                if ((descs[avail_idx].flags & VRING_DESC_F_NEXT) == 0)
                        break;

                if (++avail_idx >= vq->size) {
                        avail_idx -= vq->size;
                        wrap_counter ^= 1;
                }
        }

        *vec_idx = vec_id;

        return 0;
}

static __rte_noinline void
copy_vnet_hdr_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
                struct buf_vector *buf_vec,
                struct virtio_net_hdr_mrg_rxbuf *hdr)
{
        uint64_t len;
        uint64_t remain = dev->vhost_hlen;
        uint64_t src = (uint64_t)(uintptr_t)hdr, dst;
        uint64_t iova = buf_vec->buf_iova;

        while (remain) {
                len = RTE_MIN(remain,
                                buf_vec->buf_len);
                dst = buf_vec->buf_addr;
                rte_memcpy((void *)(uintptr_t)dst,
                                (void *)(uintptr_t)src,
                                len);

                PRINT_PACKET(dev, (uintptr_t)dst,
                                (uint32_t)len, 0);
                vhost_log_cache_write_iova(dev, vq,
                                iova, len);

                remain -= len;
                iova += len;
                src += len;
                buf_vec++;
        }
}

static __rte_always_inline int
async_iter_initialize(struct virtio_net *dev, struct vhost_async *async)
{
        struct vhost_iov_iter *iter;

        if (unlikely(async->iovec_idx >= VHOST_MAX_ASYNC_VEC)) {
                VHOST_LOG_DATA(dev->ifname, ERR, "no more async iovec available\n");
                return -1;
        }

        iter = async->iov_iter + async->iter_idx;
        iter->iov = async->iovec + async->iovec_idx;
        iter->nr_segs = 0;

        return 0;
}

static __rte_always_inline int
async_iter_add_iovec(struct virtio_net *dev, struct vhost_async *async,
                void *src, void *dst, size_t len)
{
        struct vhost_iov_iter *iter;
        struct vhost_iovec *iovec;

        if (unlikely(async->iovec_idx >= VHOST_MAX_ASYNC_VEC)) {
                static bool vhost_max_async_vec_log;

                if (!vhost_max_async_vec_log) {
                        VHOST_LOG_DATA(dev->ifname, ERR, "no more async iovec available\n");
                        vhost_max_async_vec_log = true;
                }

                return -1;
        }

        iter = async->iov_iter + async->iter_idx;
        iovec = async->iovec + async->iovec_idx;

        iovec->src_addr = src;
        iovec->dst_addr = dst;
        iovec->len = len;

        iter->nr_segs++;
        async->iovec_idx++;

        return 0;
}

static __rte_always_inline void
async_iter_finalize(struct vhost_async *async)
{
        async->iter_idx++;
}

static __rte_always_inline void
async_iter_cancel(struct vhost_async *async)
{
        struct vhost_iov_iter *iter;

        iter = async->iov_iter + async->iter_idx;
        async->iovec_idx -= iter->nr_segs;
        iter->nr_segs = 0;
        iter->iov = NULL;
}

static __rte_always_inline void
async_iter_reset(struct vhost_async *async)
{
        async->iter_idx = 0;
        async->iovec_idx = 0;
}

static __rte_always_inline int
async_fill_seg(struct virtio_net *dev, struct vhost_virtqueue *vq,
                struct rte_mbuf *m, uint32_t mbuf_offset,
                uint64_t buf_iova, uint32_t cpy_len, bool to_desc)
{
        struct vhost_async *async = vq->async;
        uint64_t mapped_len;
        uint32_t buf_offset = 0;
        void *src, *dst;
        void *host_iova;

        while (cpy_len) {
                host_iova = (void *)(uintptr_t)gpa_to_first_hpa(dev,
                                buf_iova + buf_offset, cpy_len, &mapped_len);
                if (unlikely(!host_iova)) {
                        VHOST_LOG_DATA(dev->ifname, ERR,
                                "%s: failed to get host iova.\n",
                                __func__);
                        return -1;
                }

                if (to_desc) {
                        src = (void *)(uintptr_t)rte_pktmbuf_iova_offset(m, mbuf_offset);
                        dst = host_iova;
                } else {
                        src = host_iova;
                        dst = (void *)(uintptr_t)rte_pktmbuf_iova_offset(m, mbuf_offset);
                }

                if (unlikely(async_iter_add_iovec(dev, async, src, dst, (size_t)mapped_len)))
                        return -1;

                cpy_len -= (uint32_t)mapped_len;
                mbuf_offset += (uint32_t)mapped_len;
                buf_offset += (uint32_t)mapped_len;
        }

        return 0;
}

static __rte_always_inline void
sync_fill_seg(struct virtio_net *dev, struct vhost_virtqueue *vq,
                struct rte_mbuf *m, uint32_t mbuf_offset,
                uint64_t buf_addr, uint64_t buf_iova, uint32_t cpy_len, bool to_desc)
{
        struct batch_copy_elem *batch_copy = vq->batch_copy_elems;

        if (likely(cpy_len > MAX_BATCH_LEN || vq->batch_copy_nb_elems >= vq->size)) {
                if (to_desc) {
                        rte_memcpy((void *)((uintptr_t)(buf_addr)),
                                rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
                                cpy_len);
                        vhost_log_cache_write_iova(dev, vq, buf_iova, cpy_len);
                        PRINT_PACKET(dev, (uintptr_t)(buf_addr), cpy_len, 0);
                } else {
                        rte_memcpy(rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
                                (void *)((uintptr_t)(buf_addr)),
                                cpy_len);
                }
        } else {
                if (to_desc) {
                        batch_copy[vq->batch_copy_nb_elems].dst =
                                (void *)((uintptr_t)(buf_addr));
                        batch_copy[vq->batch_copy_nb_elems].src =
                                rte_pktmbuf_mtod_offset(m, void *, mbuf_offset);
                        batch_copy[vq->batch_copy_nb_elems].log_addr = buf_iova;
                } else {
                        batch_copy[vq->batch_copy_nb_elems].dst =
                                rte_pktmbuf_mtod_offset(m, void *, mbuf_offset);
                        batch_copy[vq->batch_copy_nb_elems].src =
                                (void *)((uintptr_t)(buf_addr));
                }
                batch_copy[vq->batch_copy_nb_elems].len = cpy_len;
                vq->batch_copy_nb_elems++;
        }
}

static __rte_always_inline int
mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
                struct rte_mbuf *m, struct buf_vector *buf_vec,
                uint16_t nr_vec, uint16_t num_buffers, bool is_async)
{
        uint32_t vec_idx = 0;
        uint32_t mbuf_offset, mbuf_avail;
        uint32_t buf_offset, buf_avail;
        uint64_t buf_addr, buf_iova, buf_len;
        uint32_t cpy_len;
        uint64_t hdr_addr;
        struct rte_mbuf *hdr_mbuf;
        struct virtio_net_hdr_mrg_rxbuf tmp_hdr, *hdr = NULL;
        struct vhost_async *async = vq->async;

        if (unlikely(m == NULL))
                return -1;

        buf_addr = buf_vec[vec_idx].buf_addr;
        buf_iova = buf_vec[vec_idx].buf_iova;
        buf_len = buf_vec[vec_idx].buf_len;

        if (unlikely(buf_len < dev->vhost_hlen && nr_vec <= 1))
                return -1;

        hdr_mbuf = m;
        hdr_addr = buf_addr;
        if (unlikely(buf_len < dev->vhost_hlen)) {
                memset(&tmp_hdr, 0, sizeof(struct virtio_net_hdr_mrg_rxbuf));
                hdr = &tmp_hdr;
        } else
                hdr = (struct virtio_net_hdr_mrg_rxbuf *)(uintptr_t)hdr_addr;

        VHOST_LOG_DATA(dev->ifname, DEBUG, "RX: num merge buffers %d\n", num_buffers);

        if (unlikely(buf_len < dev->vhost_hlen)) {
                buf_offset = dev->vhost_hlen - buf_len;
                vec_idx++;
                buf_addr = buf_vec[vec_idx].buf_addr;
                buf_iova = buf_vec[vec_idx].buf_iova;
                buf_len = buf_vec[vec_idx].buf_len;
                buf_avail = buf_len - buf_offset;
        } else {
                buf_offset = dev->vhost_hlen;
                buf_avail = buf_len - dev->vhost_hlen;
        }

        mbuf_avail  = rte_pktmbuf_data_len(m);
        mbuf_offset = 0;

        if (is_async) {
                if (async_iter_initialize(dev, async))
                        return -1;
        }

        while (mbuf_avail != 0 || m->next != NULL) {
                /* done with current buf, get the next one */
                if (buf_avail == 0) {
                        vec_idx++;
                        if (unlikely(vec_idx >= nr_vec))
                                goto error;

                        buf_addr = buf_vec[vec_idx].buf_addr;
                        buf_iova = buf_vec[vec_idx].buf_iova;
                        buf_len = buf_vec[vec_idx].buf_len;

                        buf_offset = 0;
                        buf_avail  = buf_len;
                }

                /* done with current mbuf, get the next one */
                if (mbuf_avail == 0) {
                        m = m->next;

                        mbuf_offset = 0;
                        mbuf_avail  = rte_pktmbuf_data_len(m);
                }

                if (hdr_addr) {
                        virtio_enqueue_offload(hdr_mbuf, &hdr->hdr);
                        if (rxvq_is_mergeable(dev))
                                ASSIGN_UNLESS_EQUAL(hdr->num_buffers,
                                                num_buffers);

                        if (unlikely(hdr == &tmp_hdr)) {
                                copy_vnet_hdr_to_desc(dev, vq, buf_vec, hdr);
                        } else {
                                PRINT_PACKET(dev, (uintptr_t)hdr_addr,
                                                dev->vhost_hlen, 0);
                                vhost_log_cache_write_iova(dev, vq,
                                                buf_vec[0].buf_iova,
                                                dev->vhost_hlen);
                        }

                        hdr_addr = 0;
                }

                cpy_len = RTE_MIN(buf_avail, mbuf_avail);

                if (is_async) {
                        if (async_fill_seg(dev, vq, m, mbuf_offset,
                                           buf_iova + buf_offset, cpy_len, true) < 0)
                                goto error;
                } else {
                        sync_fill_seg(dev, vq, m, mbuf_offset,
                                      buf_addr + buf_offset,
                                      buf_iova + buf_offset, cpy_len, true);
                }

                mbuf_avail  -= cpy_len;
                mbuf_offset += cpy_len;
                buf_avail  -= cpy_len;
                buf_offset += cpy_len;
        }

        if (is_async)
                async_iter_finalize(async);

        return 0;
error:
        if (is_async)
                async_iter_cancel(async);

        return -1;
}

static __rte_always_inline int
vhost_enqueue_single_packed(struct virtio_net *dev,
                            struct vhost_virtqueue *vq,
                            struct rte_mbuf *pkt,
                            struct buf_vector *buf_vec,
                            uint16_t *nr_descs)
{
        uint16_t nr_vec = 0;
        uint16_t avail_idx = vq->last_avail_idx;
        uint16_t max_tries, tries = 0;
        uint16_t buf_id = 0;
        uint32_t len = 0;
        uint16_t desc_count;
        uint32_t size = pkt->pkt_len + sizeof(struct virtio_net_hdr_mrg_rxbuf);
        uint16_t num_buffers = 0;
        uint32_t buffer_len[vq->size];
        uint16_t buffer_buf_id[vq->size];
        uint16_t buffer_desc_count[vq->size];

        if (rxvq_is_mergeable(dev))
                max_tries = vq->size - 1;
        else
                max_tries = 1;

        while (size > 0) {
                /*
                 * if we tried all available ring items, and still
                 * can't get enough buf, it means something abnormal
                 * happened.
                 */
                if (unlikely(++tries > max_tries))
                        return -1;

                if (unlikely(fill_vec_buf_packed(dev, vq,
                                                avail_idx, &desc_count,
                                                buf_vec, &nr_vec,
                                                &buf_id, &len,
                                                VHOST_ACCESS_RW) < 0))
                        return -1;

                len = RTE_MIN(len, size);
                size -= len;

                buffer_len[num_buffers] = len;
                buffer_buf_id[num_buffers] = buf_id;
                buffer_desc_count[num_buffers] = desc_count;
                num_buffers += 1;

                *nr_descs += desc_count;
                avail_idx += desc_count;
                if (avail_idx >= vq->size)
                        avail_idx -= vq->size;
        }

        if (mbuf_to_desc(dev, vq, pkt, buf_vec, nr_vec, num_buffers, false) < 0)
                return -1;

        vhost_shadow_enqueue_single_packed(dev, vq, buffer_len, buffer_buf_id,
                                           buffer_desc_count, num_buffers);

        return 0;
}

static __rte_noinline uint32_t
virtio_dev_rx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
        struct rte_mbuf **pkts, uint32_t count)
{
        uint32_t pkt_idx = 0;
        uint16_t num_buffers;
        struct buf_vector buf_vec[BUF_VECTOR_MAX];
        uint16_t avail_head;

        /*
         * The ordering between avail index and
         * desc reads needs to be enforced.
         */
        avail_head = __atomic_load_n(&vq->avail->idx, __ATOMIC_ACQUIRE);

        rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);

        for (pkt_idx = 0; pkt_idx < count; pkt_idx++) {
                uint32_t pkt_len = pkts[pkt_idx]->pkt_len + dev->vhost_hlen;
                uint16_t nr_vec = 0;

                if (unlikely(reserve_avail_buf_split(dev, vq,
                                                pkt_len, buf_vec, &num_buffers,
                                                avail_head, &nr_vec) < 0)) {
                        VHOST_LOG_DATA(dev->ifname, DEBUG,
                                "failed to get enough desc from vring\n");
                        vq->shadow_used_idx -= num_buffers;
                        break;
                }

                VHOST_LOG_DATA(dev->ifname, DEBUG,
                        "current index %d | end index %d\n",
                        vq->last_avail_idx, vq->last_avail_idx + num_buffers);

                if (mbuf_to_desc(dev, vq, pkts[pkt_idx], buf_vec, nr_vec,
                                        num_buffers, false) < 0) {
                        vq->shadow_used_idx -= num_buffers;
                        break;
                }

                vq->last_avail_idx += num_buffers;
        }

        do_data_copy_enqueue(dev, vq);

        if (likely(vq->shadow_used_idx)) {
                flush_shadow_used_ring_split(dev, vq);
                vhost_vring_call_split(dev, vq);
        }

        return pkt_idx;
}

static __rte_always_inline int
virtio_dev_rx_sync_batch_check(struct virtio_net *dev,
                           struct vhost_virtqueue *vq,
                           struct rte_mbuf **pkts,
                           uint64_t *desc_addrs,
                           uint64_t *lens)
{
        bool wrap_counter = vq->avail_wrap_counter;
        struct vring_packed_desc *descs = vq->desc_packed;
        uint16_t avail_idx = vq->last_avail_idx;
        uint32_t buf_offset = sizeof(struct virtio_net_hdr_mrg_rxbuf);
        uint16_t i;

        if (unlikely(avail_idx & PACKED_BATCH_MASK))
                return -1;

        if (unlikely((avail_idx + PACKED_BATCH_SIZE) > vq->size))
                return -1;

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
                if (unlikely(pkts[i]->next != NULL))
                        return -1;
                if (unlikely(!desc_is_avail(&descs[avail_idx + i],
                                            wrap_counter)))
                        return -1;
        }

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
                lens[i] = descs[avail_idx + i].len;

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
                if (unlikely(pkts[i]->pkt_len > (lens[i] - buf_offset)))
                        return -1;
        }

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
                desc_addrs[i] = vhost_iova_to_vva(dev, vq,
                                                  descs[avail_idx + i].addr,
                                                  &lens[i],
                                                  VHOST_ACCESS_RW);

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
                if (unlikely(!desc_addrs[i]))
                        return -1;
                if (unlikely(lens[i] != descs[avail_idx + i].len))
                        return -1;
        }

        return 0;
}

static __rte_always_inline void
virtio_dev_rx_batch_packed_copy(struct virtio_net *dev,
                           struct vhost_virtqueue *vq,
                           struct rte_mbuf **pkts,
                           uint64_t *desc_addrs,
                           uint64_t *lens)
{
        uint32_t buf_offset = sizeof(struct virtio_net_hdr_mrg_rxbuf);
        struct virtio_net_hdr_mrg_rxbuf *hdrs[PACKED_BATCH_SIZE];
        struct vring_packed_desc *descs = vq->desc_packed;
        uint16_t avail_idx = vq->last_avail_idx;
        uint16_t ids[PACKED_BATCH_SIZE];
        uint16_t i;

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
                rte_prefetch0((void *)(uintptr_t)desc_addrs[i]);
                hdrs[i] = (struct virtio_net_hdr_mrg_rxbuf *)
                                        (uintptr_t)desc_addrs[i];
                lens[i] = pkts[i]->pkt_len +
                        sizeof(struct virtio_net_hdr_mrg_rxbuf);
        }

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
                virtio_enqueue_offload(pkts[i], &hdrs[i]->hdr);

        vq_inc_last_avail_packed(vq, PACKED_BATCH_SIZE);

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
                rte_memcpy((void *)(uintptr_t)(desc_addrs[i] + buf_offset),
                           rte_pktmbuf_mtod_offset(pkts[i], void *, 0),
                           pkts[i]->pkt_len);
        }

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
                vhost_log_cache_write_iova(dev, vq, descs[avail_idx + i].addr,
                                           lens[i]);

        vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
                ids[i] = descs[avail_idx + i].id;

        vhost_flush_enqueue_batch_packed(dev, vq, lens, ids);
}

static __rte_always_inline int
virtio_dev_rx_sync_batch_packed(struct virtio_net *dev,
                           struct vhost_virtqueue *vq,
                           struct rte_mbuf **pkts)
{
        uint64_t desc_addrs[PACKED_BATCH_SIZE];
        uint64_t lens[PACKED_BATCH_SIZE];

        if (virtio_dev_rx_sync_batch_check(dev, vq, pkts, desc_addrs, lens) == -1)
                return -1;

        if (vq->shadow_used_idx) {
                do_data_copy_enqueue(dev, vq);
                vhost_flush_enqueue_shadow_packed(dev, vq);
        }

        virtio_dev_rx_batch_packed_copy(dev, vq, pkts, desc_addrs, lens);

        return 0;
}

static __rte_always_inline int16_t
virtio_dev_rx_single_packed(struct virtio_net *dev,
                            struct vhost_virtqueue *vq,
                            struct rte_mbuf *pkt)
{
        struct buf_vector buf_vec[BUF_VECTOR_MAX];
        uint16_t nr_descs = 0;

        if (unlikely(vhost_enqueue_single_packed(dev, vq, pkt, buf_vec,
                                                 &nr_descs) < 0)) {
                VHOST_LOG_DATA(dev->ifname, DEBUG, "failed to get enough desc from vring\n");
                return -1;
        }

        VHOST_LOG_DATA(dev->ifname, DEBUG,
                "current index %d | end index %d\n",
                vq->last_avail_idx, vq->last_avail_idx + nr_descs);

        vq_inc_last_avail_packed(vq, nr_descs);

        return 0;
}

static __rte_noinline uint32_t
virtio_dev_rx_packed(struct virtio_net *dev,
                     struct vhost_virtqueue *__rte_restrict vq,
                     struct rte_mbuf **__rte_restrict pkts,
                     uint32_t count)
{
        uint32_t pkt_idx = 0;

        do {
                rte_prefetch0(&vq->desc_packed[vq->last_avail_idx]);

                if (count - pkt_idx >= PACKED_BATCH_SIZE) {
                        if (!virtio_dev_rx_sync_batch_packed(dev, vq,
                                                        &pkts[pkt_idx])) {
                                pkt_idx += PACKED_BATCH_SIZE;
                                continue;
                        }
                }

                if (virtio_dev_rx_single_packed(dev, vq, pkts[pkt_idx]))
                        break;
                pkt_idx++;

        } while (pkt_idx < count);

        if (vq->shadow_used_idx) {
                do_data_copy_enqueue(dev, vq);
                vhost_flush_enqueue_shadow_packed(dev, vq);
        }

        if (pkt_idx)
                vhost_vring_call_packed(dev, vq);

        return pkt_idx;
}

static __rte_always_inline uint32_t
virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
        struct rte_mbuf **pkts, uint32_t count)
{
        struct vhost_virtqueue *vq;
        uint32_t nb_tx = 0;

        VHOST_LOG_DATA(dev->ifname, DEBUG, "%s\n", __func__);
        if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->nr_vring))) {
                VHOST_LOG_DATA(dev->ifname, ERR,
                        "%s: invalid virtqueue idx %d.\n",
                        __func__, queue_id);
                return 0;
        }

        vq = dev->virtqueue[queue_id];

        rte_spinlock_lock(&vq->access_lock);

        if (unlikely(!vq->enabled))
                goto out_access_unlock;

        if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
                vhost_user_iotlb_rd_lock(vq);

        if (unlikely(!vq->access_ok))
                if (unlikely(vring_translate(dev, vq) < 0))
                        goto out;

        count = RTE_MIN((uint32_t)MAX_PKT_BURST, count);
        if (count == 0)
                goto out;

        if (vq_is_packed(dev))
                nb_tx = virtio_dev_rx_packed(dev, vq, pkts, count);
        else
                nb_tx = virtio_dev_rx_split(dev, vq, pkts, count);

        vhost_queue_stats_update(dev, vq, pkts, nb_tx);

out:
        if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
                vhost_user_iotlb_rd_unlock(vq);

out_access_unlock:
        rte_spinlock_unlock(&vq->access_lock);

        return nb_tx;
}

uint16_t
rte_vhost_enqueue_burst(int vid, uint16_t queue_id,
        struct rte_mbuf **__rte_restrict pkts, uint16_t count)
{
        struct virtio_net *dev = get_device(vid);

        if (!dev)
                return 0;

        if (unlikely(!(dev->flags & VIRTIO_DEV_BUILTIN_VIRTIO_NET))) {
                VHOST_LOG_DATA(dev->ifname, ERR,
                        "%s: built-in vhost net backend is disabled.\n",
                        __func__);
                return 0;
        }

        return virtio_dev_rx(dev, queue_id, pkts, count);
}

static __rte_always_inline uint16_t
async_get_first_inflight_pkt_idx(struct vhost_virtqueue *vq)
{
        struct vhost_async *async = vq->async;

        if (async->pkts_idx >= async->pkts_inflight_n)
                return async->pkts_idx - async->pkts_inflight_n;
        else
                return vq->size - async->pkts_inflight_n + async->pkts_idx;
}

static __rte_always_inline void
store_dma_desc_info_split(struct vring_used_elem *s_ring, struct vring_used_elem *d_ring,
                uint16_t ring_size, uint16_t s_idx, uint16_t d_idx, uint16_t count)
{
        size_t elem_size = sizeof(struct vring_used_elem);

        if (d_idx + count <= ring_size) {
                rte_memcpy(d_ring + d_idx, s_ring + s_idx, count * elem_size);
        } else {
                uint16_t size = ring_size - d_idx;

                rte_memcpy(d_ring + d_idx, s_ring + s_idx, size * elem_size);
                rte_memcpy(d_ring, s_ring + s_idx + size, (count - size) * elem_size);
        }
}

static __rte_always_inline void
store_dma_desc_info_packed(struct vring_used_elem_packed *s_ring,
                struct vring_used_elem_packed *d_ring,
                uint16_t ring_size, uint16_t s_idx, uint16_t d_idx, uint16_t count)
{
        size_t elem_size = sizeof(struct vring_used_elem_packed);

        if (d_idx + count <= ring_size) {
                rte_memcpy(d_ring + d_idx, s_ring + s_idx, count * elem_size);
        } else {
                uint16_t size = ring_size - d_idx;

                rte_memcpy(d_ring + d_idx, s_ring + s_idx, size * elem_size);
                rte_memcpy(d_ring, s_ring + s_idx + size, (count - size) * elem_size);
        }
}

static __rte_noinline uint32_t
virtio_dev_rx_async_submit_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
                uint16_t queue_id, struct rte_mbuf **pkts, uint32_t count,
                int16_t dma_id, uint16_t vchan_id)
{
        struct buf_vector buf_vec[BUF_VECTOR_MAX];
        uint32_t pkt_idx = 0;
        uint16_t num_buffers;
        uint16_t avail_head;

        struct vhost_async *async = vq->async;
        struct async_inflight_info *pkts_info = async->pkts_info;
        uint32_t pkt_err = 0;
        uint16_t n_xfer;
        uint16_t slot_idx = 0;

        /*
         * The ordering between avail index and desc reads need to be enforced.
         */
        avail_head = __atomic_load_n(&vq->avail->idx, __ATOMIC_ACQUIRE);

        rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);

        async_iter_reset(async);

        for (pkt_idx = 0; pkt_idx < count; pkt_idx++) {
                uint32_t pkt_len = pkts[pkt_idx]->pkt_len + dev->vhost_hlen;
                uint16_t nr_vec = 0;

                if (unlikely(reserve_avail_buf_split(dev, vq, pkt_len, buf_vec,
                                                &num_buffers, avail_head, &nr_vec) < 0)) {
                        VHOST_LOG_DATA(dev->ifname, DEBUG,
                                "failed to get enough desc from vring\n");
                        vq->shadow_used_idx -= num_buffers;
                        break;
                }

                VHOST_LOG_DATA(dev->ifname, DEBUG,
                        "current index %d | end index %d\n",
                        vq->last_avail_idx, vq->last_avail_idx + num_buffers);

                if (mbuf_to_desc(dev, vq, pkts[pkt_idx], buf_vec, nr_vec, num_buffers, true) < 0) {
                        vq->shadow_used_idx -= num_buffers;
                        break;
                }

                slot_idx = (async->pkts_idx + pkt_idx) & (vq->size - 1);
                pkts_info[slot_idx].descs = num_buffers;
                pkts_info[slot_idx].mbuf = pkts[pkt_idx];

                vq->last_avail_idx += num_buffers;
        }

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

        n_xfer = vhost_async_dma_transfer(dev, vq, dma_id, vchan_id, async->pkts_idx,
                        async->iov_iter, pkt_idx);

        pkt_err = pkt_idx - n_xfer;
        if (unlikely(pkt_err)) {
                uint16_t num_descs = 0;

                VHOST_LOG_DATA(dev->ifname, DEBUG,
                        "%s: failed to transfer %u packets for queue %u.\n",
                        __func__, pkt_err, queue_id);

                /* update number of completed packets */
                pkt_idx = n_xfer;

                /* calculate the sum of descriptors to revert */
                while (pkt_err-- > 0) {
                        num_descs += pkts_info[slot_idx & (vq->size - 1)].descs;
                        slot_idx--;
                }

                /* recover shadow used ring and available ring */
                vq->shadow_used_idx -= num_descs;
                vq->last_avail_idx -= num_descs;
        }

        /* keep used descriptors */
        if (likely(vq->shadow_used_idx)) {
                uint16_t to = async->desc_idx_split & (vq->size - 1);

                store_dma_desc_info_split(vq->shadow_used_split,
                                async->descs_split, vq->size, 0, to,
                                vq->shadow_used_idx);

                async->desc_idx_split += vq->shadow_used_idx;

                async->pkts_idx += pkt_idx;
                if (async->pkts_idx >= vq->size)
                        async->pkts_idx -= vq->size;

                async->pkts_inflight_n += pkt_idx;
                vq->shadow_used_idx = 0;
        }

        return pkt_idx;
}


static __rte_always_inline int
vhost_enqueue_async_packed(struct virtio_net *dev,
                            struct vhost_virtqueue *vq,
                            struct rte_mbuf *pkt,
                            struct buf_vector *buf_vec,
                            uint16_t *nr_descs,
                            uint16_t *nr_buffers)
{
        uint16_t nr_vec = 0;
        uint16_t avail_idx = vq->last_avail_idx;
        uint16_t max_tries, tries = 0;
        uint16_t buf_id = 0;
        uint32_t len = 0;
        uint16_t desc_count = 0;
        uint32_t size = pkt->pkt_len + sizeof(struct virtio_net_hdr_mrg_rxbuf);
        uint32_t buffer_len[vq->size];
        uint16_t buffer_buf_id[vq->size];
        uint16_t buffer_desc_count[vq->size];

        if (rxvq_is_mergeable(dev))
                max_tries = vq->size - 1;
        else
                max_tries = 1;

        while (size > 0) {
                /*
                 * if we tried all available ring items, and still
                 * can't get enough buf, it means something abnormal
                 * happened.
                 */
                if (unlikely(++tries > max_tries))
                        return -1;

                if (unlikely(fill_vec_buf_packed(dev, vq,
                                                avail_idx, &desc_count,
                                                buf_vec, &nr_vec,
                                                &buf_id, &len,
                                                VHOST_ACCESS_RW) < 0))
                        return -1;

                len = RTE_MIN(len, size);
                size -= len;

                buffer_len[*nr_buffers] = len;
                buffer_buf_id[*nr_buffers] = buf_id;
                buffer_desc_count[*nr_buffers] = desc_count;
                *nr_buffers += 1;
                *nr_descs += desc_count;
                avail_idx += desc_count;
                if (avail_idx >= vq->size)
                        avail_idx -= vq->size;
        }

        if (unlikely(mbuf_to_desc(dev, vq, pkt, buf_vec, nr_vec, *nr_buffers, true) < 0))
                return -1;

        vhost_shadow_enqueue_packed(vq, buffer_len, buffer_buf_id, buffer_desc_count, *nr_buffers);

        return 0;
}

static __rte_always_inline int16_t
virtio_dev_rx_async_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
                            struct rte_mbuf *pkt, uint16_t *nr_descs, uint16_t *nr_buffers)
{
        struct buf_vector buf_vec[BUF_VECTOR_MAX];

        if (unlikely(vhost_enqueue_async_packed(dev, vq, pkt, buf_vec,
                                        nr_descs, nr_buffers) < 0)) {
                VHOST_LOG_DATA(dev->ifname, DEBUG, "failed to get enough desc from vring\n");
                return -1;
        }

        VHOST_LOG_DATA(dev->ifname, DEBUG,
                "current index %d | end index %d\n",
                vq->last_avail_idx, vq->last_avail_idx + *nr_descs);

        return 0;
}

static __rte_always_inline void
dma_error_handler_packed(struct vhost_virtqueue *vq, uint16_t slot_idx,
                        uint32_t nr_err, uint32_t *pkt_idx)
{
        uint16_t descs_err = 0;
        uint16_t buffers_err = 0;
        struct async_inflight_info *pkts_info = vq->async->pkts_info;

        *pkt_idx -= nr_err;
        /* calculate the sum of buffers and descs of DMA-error packets. */
        while (nr_err-- > 0) {
                descs_err += pkts_info[slot_idx % vq->size].descs;
                buffers_err += pkts_info[slot_idx % vq->size].nr_buffers;
                slot_idx--;
        }

        if (vq->last_avail_idx >= descs_err) {
                vq->last_avail_idx -= descs_err;
        } else {
                vq->last_avail_idx = vq->last_avail_idx + vq->size - descs_err;
                vq->avail_wrap_counter ^= 1;
        }

        vq->shadow_used_idx -= buffers_err;
}

static __rte_noinline uint32_t
virtio_dev_rx_async_submit_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
                uint16_t queue_id, struct rte_mbuf **pkts, uint32_t count,
                int16_t dma_id, uint16_t vchan_id)
{
        uint32_t pkt_idx = 0;
        uint32_t remained = count;
        uint16_t n_xfer;
        uint16_t num_buffers;
        uint16_t num_descs;

        struct vhost_async *async = vq->async;
        struct async_inflight_info *pkts_info = async->pkts_info;
        uint32_t pkt_err = 0;
        uint16_t slot_idx = 0;

        do {
                rte_prefetch0(&vq->desc_packed[vq->last_avail_idx]);

                num_buffers = 0;
                num_descs = 0;
                if (unlikely(virtio_dev_rx_async_packed(dev, vq, pkts[pkt_idx],
                                                &num_descs, &num_buffers) < 0))
                        break;

                slot_idx = (async->pkts_idx + pkt_idx) % vq->size;

                pkts_info[slot_idx].descs = num_descs;
                pkts_info[slot_idx].nr_buffers = num_buffers;
                pkts_info[slot_idx].mbuf = pkts[pkt_idx];

                pkt_idx++;
                remained--;
                vq_inc_last_avail_packed(vq, num_descs);
        } while (pkt_idx < count);

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

        n_xfer = vhost_async_dma_transfer(dev, vq, dma_id, vchan_id, async->pkts_idx,
                        async->iov_iter, pkt_idx);

        async_iter_reset(async);

        pkt_err = pkt_idx - n_xfer;
        if (unlikely(pkt_err)) {
                VHOST_LOG_DATA(dev->ifname, DEBUG,
                        "%s: failed to transfer %u packets for queue %u.\n",
                        __func__, pkt_err, queue_id);
                dma_error_handler_packed(vq, slot_idx, pkt_err, &pkt_idx);
        }

        if (likely(vq->shadow_used_idx)) {
                /* keep used descriptors. */
                store_dma_desc_info_packed(vq->shadow_used_packed, async->buffers_packed,
                                        vq->size, 0, async->buffer_idx_packed,
                                        vq->shadow_used_idx);

                async->buffer_idx_packed += vq->shadow_used_idx;
                if (async->buffer_idx_packed >= vq->size)
                        async->buffer_idx_packed -= vq->size;

                async->pkts_idx += pkt_idx;
                if (async->pkts_idx >= vq->size)
                        async->pkts_idx -= vq->size;

                vq->shadow_used_idx = 0;
                async->pkts_inflight_n += pkt_idx;
        }

        return pkt_idx;
}

static __rte_always_inline void
write_back_completed_descs_split(struct vhost_virtqueue *vq, uint16_t n_descs)
{
        struct vhost_async *async = vq->async;
        uint16_t nr_left = n_descs;
        uint16_t nr_copy;
        uint16_t to, from;

        do {
                from = async->last_desc_idx_split & (vq->size - 1);
                nr_copy = nr_left + from <= vq->size ? nr_left : vq->size - from;
                to = vq->last_used_idx & (vq->size - 1);

                if (to + nr_copy <= vq->size) {
                        rte_memcpy(&vq->used->ring[to], &async->descs_split[from],
                                        nr_copy * sizeof(struct vring_used_elem));
                } else {
                        uint16_t size = vq->size - to;

                        rte_memcpy(&vq->used->ring[to], &async->descs_split[from],
                                        size * sizeof(struct vring_used_elem));
                        rte_memcpy(&vq->used->ring[0], &async->descs_split[from + size],
                                        (nr_copy - size) * sizeof(struct vring_used_elem));
                }

                async->last_desc_idx_split += nr_copy;
                vq->last_used_idx += nr_copy;
                nr_left -= nr_copy;
        } while (nr_left > 0);
}

static __rte_always_inline void
write_back_completed_descs_packed(struct vhost_virtqueue *vq,
                                uint16_t n_buffers)
{
        struct vhost_async *async = vq->async;
        uint16_t from = async->last_buffer_idx_packed;
        uint16_t used_idx = vq->last_used_idx;
        uint16_t head_idx = vq->last_used_idx;
        uint16_t head_flags = 0;
        uint16_t i;

        /* Split loop in two to save memory barriers */
        for (i = 0; i < n_buffers; i++) {
                vq->desc_packed[used_idx].id = async->buffers_packed[from].id;
                vq->desc_packed[used_idx].len = async->buffers_packed[from].len;

                used_idx += async->buffers_packed[from].count;
                if (used_idx >= vq->size)

                        used_idx -= vq->size;

                from++;
                if (from >= vq->size)
                        from = 0;
        }

        /* The ordering for storing desc flags needs to be enforced. */
        rte_atomic_thread_fence(__ATOMIC_RELEASE);

        from = async->last_buffer_idx_packed;

        for (i = 0; i < n_buffers; i++) {
                uint16_t flags;

                if (async->buffers_packed[from].len)
                        flags = VRING_DESC_F_WRITE;
                else
                        flags = 0;

                if (vq->used_wrap_counter) {
                        flags |= VRING_DESC_F_USED;
                        flags |= VRING_DESC_F_AVAIL;
                } else {
                        flags &= ~VRING_DESC_F_USED;
                        flags &= ~VRING_DESC_F_AVAIL;
                }

                if (i > 0) {
                        vq->desc_packed[vq->last_used_idx].flags = flags;
                } else {
                        head_idx = vq->last_used_idx;
                        head_flags = flags;
                }

                vq_inc_last_used_packed(vq, async->buffers_packed[from].count);

                from++;
                if (from == vq->size)
                        from = 0;
        }

        vq->desc_packed[head_idx].flags = head_flags;
        async->last_buffer_idx_packed = from;
}

static __rte_always_inline uint16_t
vhost_poll_enqueue_completed(struct virtio_net *dev, uint16_t queue_id,
                struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
                uint16_t vchan_id)
{
        struct vhost_virtqueue *vq = dev->virtqueue[queue_id];
        struct vhost_async *async = vq->async;
        struct async_inflight_info *pkts_info = async->pkts_info;
        uint16_t nr_cpl_pkts = 0;
        uint16_t n_descs = 0, n_buffers = 0;
        uint16_t start_idx, from, i;

        /* Check completed copies for the given DMA vChannel */
        vhost_async_dma_check_completed(dev, dma_id, vchan_id, VHOST_DMA_MAX_COPY_COMPLETE);

        start_idx = async_get_first_inflight_pkt_idx(vq);
        /**
         * Calculate the number of copy completed packets.
         * Note that there may be completed packets even if
         * no copies are reported done by the given DMA vChannel,
         * as it's possible that a virtqueue uses multiple DMA
         * vChannels.
         */
        from = start_idx;
        while (vq->async->pkts_cmpl_flag[from] && count--) {
                vq->async->pkts_cmpl_flag[from] = false;
                from++;
                if (from >= vq->size)
                        from -= vq->size;
                nr_cpl_pkts++;
        }

        if (nr_cpl_pkts == 0)
                return 0;

        for (i = 0; i < nr_cpl_pkts; i++) {
                from = (start_idx + i) % vq->size;
                /* Only used with packed ring */
                n_buffers += pkts_info[from].nr_buffers;
                /* Only used with split ring */
                n_descs += pkts_info[from].descs;
                pkts[i] = pkts_info[from].mbuf;
        }

        async->pkts_inflight_n -= nr_cpl_pkts;

        if (likely(vq->enabled && vq->access_ok)) {
                if (vq_is_packed(dev)) {
                        write_back_completed_descs_packed(vq, n_buffers);
                        vhost_vring_call_packed(dev, vq);
                } else {
                        write_back_completed_descs_split(vq, n_descs);
                        __atomic_add_fetch(&vq->used->idx, n_descs, __ATOMIC_RELEASE);
                        vhost_vring_call_split(dev, vq);
                }
        } else {
                if (vq_is_packed(dev)) {
                        async->last_buffer_idx_packed += n_buffers;
                        if (async->last_buffer_idx_packed >= vq->size)
                                async->last_buffer_idx_packed -= vq->size;
                } else {
                        async->last_desc_idx_split += n_descs;
                }
        }

        return nr_cpl_pkts;
}

uint16_t
rte_vhost_poll_enqueue_completed(int vid, uint16_t queue_id,
                struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
                uint16_t vchan_id)
{
        struct virtio_net *dev = get_device(vid);
        struct vhost_virtqueue *vq;
        uint16_t n_pkts_cpl = 0;

        if (unlikely(!dev))
                return 0;

        VHOST_LOG_DATA(dev->ifname, DEBUG, "%s\n", __func__);
        if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->nr_vring))) {
                VHOST_LOG_DATA(dev->ifname, ERR,
                        "%s: invalid virtqueue idx %d.\n",
                        __func__, queue_id);
                return 0;
        }

        if (unlikely(!dma_copy_track[dma_id].vchans ||
                                !dma_copy_track[dma_id].vchans[vchan_id].pkts_cmpl_flag_addr)) {
                VHOST_LOG_DATA(dev->ifname, ERR,
                        "%s: invalid channel %d:%u.\n",
                        __func__, dma_id, vchan_id);
                return 0;
        }

        vq = dev->virtqueue[queue_id];

        if (!rte_spinlock_trylock(&vq->access_lock)) {
                VHOST_LOG_DATA(dev->ifname, DEBUG,
                        "%s: virtqueue %u is busy.\n",
                        __func__, queue_id);
                return 0;
        }

        if (unlikely(!vq->async)) {
                VHOST_LOG_DATA(dev->ifname, ERR,
                        "%s: async not registered for virtqueue %d.\n",
                        __func__, queue_id);
                goto out;
        }

        n_pkts_cpl = vhost_poll_enqueue_completed(dev, queue_id, pkts, count, dma_id, vchan_id);

        vhost_queue_stats_update(dev, vq, pkts, n_pkts_cpl);
        vq->stats.inflight_completed += n_pkts_cpl;

out:
        rte_spinlock_unlock(&vq->access_lock);

        return n_pkts_cpl;
}

uint16_t
rte_vhost_clear_queue_thread_unsafe(int vid, uint16_t queue_id,
                struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
                uint16_t vchan_id)
{
        struct virtio_net *dev = get_device(vid);
        struct vhost_virtqueue *vq;
        uint16_t n_pkts_cpl = 0;

        if (!dev)
                return 0;

        VHOST_LOG_DATA(dev->ifname, DEBUG, "%s\n", __func__);
        if (unlikely(queue_id >= dev->nr_vring)) {
                VHOST_LOG_DATA(dev->ifname, ERR, "%s: invalid virtqueue idx %d.\n",
                        __func__, queue_id);
                return 0;
        }

        if (unlikely(dma_id < 0 || dma_id >= RTE_DMADEV_DEFAULT_MAX)) {
                VHOST_LOG_DATA(dev->ifname, ERR, "%s: invalid dma id %d.\n",
                        __func__, dma_id);
                return 0;
        }

        vq = dev->virtqueue[queue_id];

        if (unlikely(!rte_spinlock_is_locked(&vq->access_lock))) {
                VHOST_LOG_DATA(dev->ifname, ERR, "%s() called without access lock taken.\n",
                        __func__);
                return -1;
        }

        if (unlikely(!vq->async)) {
                VHOST_LOG_DATA(dev->ifname, ERR,
                        "%s: async not registered for virtqueue %d.\n",
                        __func__, queue_id);
                return 0;
        }

        if (unlikely(!dma_copy_track[dma_id].vchans ||
                                !dma_copy_track[dma_id].vchans[vchan_id].pkts_cmpl_flag_addr)) {
                VHOST_LOG_DATA(dev->ifname, ERR,
                        "%s: invalid channel %d:%u.\n",
                        __func__, dma_id, vchan_id);
                return 0;
        }

        if ((queue_id & 1) == 0)
                n_pkts_cpl = vhost_poll_enqueue_completed(dev, queue_id,
                                        pkts, count, dma_id, vchan_id);
        else {
                n_pkts_cpl = async_poll_dequeue_completed(dev, vq, pkts, count,
                                        dma_id, vchan_id, dev->flags & VIRTIO_DEV_LEGACY_OL_FLAGS);
        }

        vhost_queue_stats_update(dev, vq, pkts, n_pkts_cpl);
        vq->stats.inflight_completed += n_pkts_cpl;

        return n_pkts_cpl;
}

uint16_t
rte_vhost_clear_queue(int vid, uint16_t queue_id, struct rte_mbuf **pkts,
                uint16_t count, int16_t dma_id, uint16_t vchan_id)
{
        struct virtio_net *dev = get_device(vid);
        struct vhost_virtqueue *vq;
        uint16_t n_pkts_cpl = 0;

        if (!dev)
                return 0;

        VHOST_LOG_DATA(dev->ifname, DEBUG, "%s\n", __func__);
        if (unlikely(queue_id >= dev->nr_vring)) {
                VHOST_LOG_DATA(dev->ifname, ERR, "%s: invalid virtqueue idx %u.\n",
                        __func__, queue_id);
                return 0;
        }

        if (unlikely(dma_id < 0 || dma_id >= RTE_DMADEV_DEFAULT_MAX)) {
                VHOST_LOG_DATA(dev->ifname, ERR, "%s: invalid dma id %d.\n",
                        __func__, dma_id);
                return 0;
        }

        vq = dev->virtqueue[queue_id];

        if (!rte_spinlock_trylock(&vq->access_lock)) {
                VHOST_LOG_DATA(dev->ifname, DEBUG, "%s: virtqueue %u is busy.\n",
                        __func__, queue_id);
                return 0;
        }

        if (unlikely(!vq->async)) {
                VHOST_LOG_DATA(dev->ifname, ERR, "%s: async not registered for queue id %u.\n",
                        __func__, queue_id);
                goto out_access_unlock;
        }

        if (unlikely(!dma_copy_track[dma_id].vchans ||
                                !dma_copy_track[dma_id].vchans[vchan_id].pkts_cmpl_flag_addr)) {
                VHOST_LOG_DATA(dev->ifname, ERR, "%s: invalid channel %d:%u.\n",
                        __func__, dma_id, vchan_id);
                goto out_access_unlock;
        }

        if ((queue_id & 1) == 0)
                n_pkts_cpl = vhost_poll_enqueue_completed(dev, queue_id,
                                pkts, count, dma_id, vchan_id);
        else {
                n_pkts_cpl = async_poll_dequeue_completed(dev, vq, pkts, count,
                                        dma_id, vchan_id, dev->flags & VIRTIO_DEV_LEGACY_OL_FLAGS);
        }

        vhost_queue_stats_update(dev, vq, pkts, n_pkts_cpl);
        vq->stats.inflight_completed += n_pkts_cpl;

out_access_unlock:
        rte_spinlock_unlock(&vq->access_lock);

        return n_pkts_cpl;
}

static __rte_always_inline uint32_t
virtio_dev_rx_async_submit(struct virtio_net *dev, uint16_t queue_id,
        struct rte_mbuf **pkts, uint32_t count, int16_t dma_id, uint16_t vchan_id)
{
        struct vhost_virtqueue *vq;
        uint32_t nb_tx = 0;

        VHOST_LOG_DATA(dev->ifname, DEBUG, "%s\n", __func__);
        if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->nr_vring))) {
                VHOST_LOG_DATA(dev->ifname, ERR,
                        "%s: invalid virtqueue idx %d.\n",
                        __func__, queue_id);
                return 0;
        }

        if (unlikely(!dma_copy_track[dma_id].vchans ||
                                !dma_copy_track[dma_id].vchans[vchan_id].pkts_cmpl_flag_addr)) {
                VHOST_LOG_DATA(dev->ifname, ERR,
                        "%s: invalid channel %d:%u.\n",
                         __func__, dma_id, vchan_id);
                return 0;
        }

        vq = dev->virtqueue[queue_id];

        rte_spinlock_lock(&vq->access_lock);

        if (unlikely(!vq->enabled || !vq->async))
                goto out_access_unlock;

        if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
                vhost_user_iotlb_rd_lock(vq);

        if (unlikely(!vq->access_ok))
                if (unlikely(vring_translate(dev, vq) < 0))
                        goto out;

        count = RTE_MIN((uint32_t)MAX_PKT_BURST, count);
        if (count == 0)
                goto out;

        if (vq_is_packed(dev))
                nb_tx = virtio_dev_rx_async_submit_packed(dev, vq, queue_id,
                                pkts, count, dma_id, vchan_id);
        else
                nb_tx = virtio_dev_rx_async_submit_split(dev, vq, queue_id,
                                pkts, count, dma_id, vchan_id);

        vq->stats.inflight_submitted += nb_tx;

out:
        if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
                vhost_user_iotlb_rd_unlock(vq);

out_access_unlock:
        rte_spinlock_unlock(&vq->access_lock);

        return nb_tx;
}

uint16_t
rte_vhost_submit_enqueue_burst(int vid, uint16_t queue_id,
                struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
                uint16_t vchan_id)
{
        struct virtio_net *dev = get_device(vid);

        if (!dev)
                return 0;

        if (unlikely(!(dev->flags & VIRTIO_DEV_BUILTIN_VIRTIO_NET))) {
                VHOST_LOG_DATA(dev->ifname, ERR,
                        "%s: built-in vhost net backend is disabled.\n",
                        __func__);
                return 0;
        }

        return virtio_dev_rx_async_submit(dev, queue_id, pkts, count, dma_id, vchan_id);
}

static inline bool
virtio_net_with_host_offload(struct virtio_net *dev)
{
        if (dev->features &
                        ((1ULL << VIRTIO_NET_F_CSUM) |
                         (1ULL << VIRTIO_NET_F_HOST_ECN) |
                         (1ULL << VIRTIO_NET_F_HOST_TSO4) |
                         (1ULL << VIRTIO_NET_F_HOST_TSO6) |
                         (1ULL << VIRTIO_NET_F_HOST_UFO)))
                return true;

        return false;
}

static int
parse_headers(struct rte_mbuf *m, uint8_t *l4_proto)
{
        struct rte_ipv4_hdr *ipv4_hdr;
        struct rte_ipv6_hdr *ipv6_hdr;
        struct rte_ether_hdr *eth_hdr;
        uint16_t ethertype;
        uint16_t data_len = rte_pktmbuf_data_len(m);

        if (data_len < sizeof(struct rte_ether_hdr))
                return -EINVAL;

        eth_hdr = rte_pktmbuf_mtod(m, struct rte_ether_hdr *);

        m->l2_len = sizeof(struct rte_ether_hdr);
        ethertype = rte_be_to_cpu_16(eth_hdr->ether_type);

        if (ethertype == RTE_ETHER_TYPE_VLAN) {
                if (data_len < sizeof(struct rte_ether_hdr) +
                                sizeof(struct rte_vlan_hdr))
                        goto error;

                struct rte_vlan_hdr *vlan_hdr =
                        (struct rte_vlan_hdr *)(eth_hdr + 1);

                m->l2_len += sizeof(struct rte_vlan_hdr);
                ethertype = rte_be_to_cpu_16(vlan_hdr->eth_proto);
        }

        switch (ethertype) {
        case RTE_ETHER_TYPE_IPV4:
                if (data_len < m->l2_len + sizeof(struct rte_ipv4_hdr))
                        goto error;
                ipv4_hdr = rte_pktmbuf_mtod_offset(m, struct rte_ipv4_hdr *,
                                m->l2_len);
                m->l3_len = rte_ipv4_hdr_len(ipv4_hdr);
                if (data_len < m->l2_len + m->l3_len)
                        goto error;
                m->ol_flags |= RTE_MBUF_F_TX_IPV4;
                *l4_proto = ipv4_hdr->next_proto_id;
                break;
        case RTE_ETHER_TYPE_IPV6:
                if (data_len < m->l2_len + sizeof(struct rte_ipv6_hdr))
                        goto error;
                ipv6_hdr = rte_pktmbuf_mtod_offset(m, struct rte_ipv6_hdr *,
                                m->l2_len);
                m->l3_len = sizeof(struct rte_ipv6_hdr);
                m->ol_flags |= RTE_MBUF_F_TX_IPV6;
                *l4_proto = ipv6_hdr->proto;
                break;
        default:
                /* a valid L3 header is needed for further L4 parsing */
                goto error;
        }

        /* both CSUM and GSO need a valid L4 header */
        switch (*l4_proto) {
        case IPPROTO_TCP:
                if (data_len < m->l2_len + m->l3_len +
                                sizeof(struct rte_tcp_hdr))
                        goto error;
                break;
        case IPPROTO_UDP:
                if (data_len < m->l2_len + m->l3_len +
                                sizeof(struct rte_udp_hdr))
                        goto error;
                break;
        case IPPROTO_SCTP:
                if (data_len < m->l2_len + m->l3_len +
                                sizeof(struct rte_sctp_hdr))
                        goto error;
                break;
        default:
                goto error;
        }

        return 0;

error:
        m->l2_len = 0;
        m->l3_len = 0;
        m->ol_flags = 0;
        return -EINVAL;
}

static __rte_always_inline void
vhost_dequeue_offload_legacy(struct virtio_net *dev, struct virtio_net_hdr *hdr,
                struct rte_mbuf *m)
{
        uint8_t l4_proto = 0;
        struct rte_tcp_hdr *tcp_hdr = NULL;
        uint16_t tcp_len;
        uint16_t data_len = rte_pktmbuf_data_len(m);

        if (parse_headers(m, &l4_proto) < 0)
                return;

        if (hdr->flags == VIRTIO_NET_HDR_F_NEEDS_CSUM) {
                if (hdr->csum_start == (m->l2_len + m->l3_len)) {
                        switch (hdr->csum_offset) {
                        case (offsetof(struct rte_tcp_hdr, cksum)):
                                if (l4_proto != IPPROTO_TCP)
                                        goto error;
                                m->ol_flags |= RTE_MBUF_F_TX_TCP_CKSUM;
                                break;
                        case (offsetof(struct rte_udp_hdr, dgram_cksum)):
                                if (l4_proto != IPPROTO_UDP)
                                        goto error;
                                m->ol_flags |= RTE_MBUF_F_TX_UDP_CKSUM;
                                break;
                        case (offsetof(struct rte_sctp_hdr, cksum)):
                                if (l4_proto != IPPROTO_SCTP)
                                        goto error;
                                m->ol_flags |= RTE_MBUF_F_TX_SCTP_CKSUM;
                                break;
                        default:
                                goto error;
                        }
                } else {
                        goto error;
                }
        }

        if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
                switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
                case VIRTIO_NET_HDR_GSO_TCPV4:
                case VIRTIO_NET_HDR_GSO_TCPV6:
                        if (l4_proto != IPPROTO_TCP)
                                goto error;
                        tcp_hdr = rte_pktmbuf_mtod_offset(m,
                                        struct rte_tcp_hdr *,
                                        m->l2_len + m->l3_len);
                        tcp_len = (tcp_hdr->data_off & 0xf0) >> 2;
                        if (data_len < m->l2_len + m->l3_len + tcp_len)
                                goto error;
                        m->ol_flags |= RTE_MBUF_F_TX_TCP_SEG;
                        m->tso_segsz = hdr->gso_size;
                        m->l4_len = tcp_len;
                        break;
                case VIRTIO_NET_HDR_GSO_UDP:
                        if (l4_proto != IPPROTO_UDP)
                                goto error;
                        m->ol_flags |= RTE_MBUF_F_TX_UDP_SEG;
                        m->tso_segsz = hdr->gso_size;
                        m->l4_len = sizeof(struct rte_udp_hdr);
                        break;
                default:
                        VHOST_LOG_DATA(dev->ifname, WARNING,
                                "unsupported gso type %u.\n",
                                hdr->gso_type);
                        goto error;
                }
        }
        return;

error:
        m->l2_len = 0;
        m->l3_len = 0;
        m->ol_flags = 0;
}

static __rte_always_inline void
vhost_dequeue_offload(struct virtio_net *dev, struct virtio_net_hdr *hdr,
                struct rte_mbuf *m, bool legacy_ol_flags)
{
        struct rte_net_hdr_lens hdr_lens;
        int l4_supported = 0;
        uint32_t ptype;

        if (hdr->flags == 0 && hdr->gso_type == VIRTIO_NET_HDR_GSO_NONE)
                return;

        if (legacy_ol_flags) {
                vhost_dequeue_offload_legacy(dev, hdr, m);
                return;
        }

        m->ol_flags |= RTE_MBUF_F_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;

        /* According to Virtio 1.1 spec, the device only needs to look at
         * VIRTIO_NET_HDR_F_NEEDS_CSUM in the packet transmission path.
         * This differs from the processing incoming packets path where the
         * driver could rely on VIRTIO_NET_HDR_F_DATA_VALID flag set by the
         * device.
         *
         * 5.1.6.2.1 Driver Requirements: Packet Transmission
         * The driver MUST NOT set the VIRTIO_NET_HDR_F_DATA_VALID and
         * VIRTIO_NET_HDR_F_RSC_INFO bits in flags.
         *
         * 5.1.6.2.2 Device Requirements: Packet Transmission
         * The device MUST ignore flag bits that it does not recognize.
         */
        if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
                uint32_t hdrlen;

                hdrlen = hdr_lens.l2_len + hdr_lens.l3_len + hdr_lens.l4_len;
                if (hdr->csum_start <= hdrlen && l4_supported != 0) {
                        m->ol_flags |= RTE_MBUF_F_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;

                        if (rte_raw_cksum_mbuf(m, hdr->csum_start,
                                        rte_pktmbuf_pkt_len(m) - hdr->csum_start, &csum) < 0)
                                return;
                        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;
                }
        }

        if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
                if (hdr->gso_size == 0)
                        return;

                switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
                case VIRTIO_NET_HDR_GSO_TCPV4:
                case VIRTIO_NET_HDR_GSO_TCPV6:
                        if ((ptype & RTE_PTYPE_L4_MASK) != RTE_PTYPE_L4_TCP)
                                break;
                        m->ol_flags |= RTE_MBUF_F_RX_LRO | RTE_MBUF_F_RX_L4_CKSUM_NONE;
                        m->tso_segsz = hdr->gso_size;
                        break;
                case VIRTIO_NET_HDR_GSO_UDP:
                        if ((ptype & RTE_PTYPE_L4_MASK) != RTE_PTYPE_L4_UDP)
                                break;
                        m->ol_flags |= RTE_MBUF_F_RX_LRO | RTE_MBUF_F_RX_L4_CKSUM_NONE;
                        m->tso_segsz = hdr->gso_size;
                        break;
                default:
                        break;
                }
        }
}

static __rte_noinline void
copy_vnet_hdr_from_desc(struct virtio_net_hdr *hdr,
                struct buf_vector *buf_vec)
{
        uint64_t len;
        uint64_t remain = sizeof(struct virtio_net_hdr);
        uint64_t src;
        uint64_t dst = (uint64_t)(uintptr_t)hdr;

        while (remain) {
                len = RTE_MIN(remain, buf_vec->buf_len);
                src = buf_vec->buf_addr;
                rte_memcpy((void *)(uintptr_t)dst,
                                (void *)(uintptr_t)src, len);

                remain -= len;
                dst += len;
                buf_vec++;
        }
}

static __rte_always_inline int
desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
                  struct buf_vector *buf_vec, uint16_t nr_vec,
                  struct rte_mbuf *m, struct rte_mempool *mbuf_pool,
                  bool legacy_ol_flags, uint16_t slot_idx, bool is_async)
{
        uint32_t buf_avail, buf_offset, buf_len;
        uint64_t buf_addr, buf_iova;
        uint32_t mbuf_avail, mbuf_offset;
        uint32_t cpy_len;
        struct rte_mbuf *cur = m, *prev = m;
        struct virtio_net_hdr tmp_hdr;
        struct virtio_net_hdr *hdr = NULL;
        /* A counter to avoid desc dead loop chain */
        uint16_t vec_idx = 0;
        struct vhost_async *async = vq->async;
        struct async_inflight_info *pkts_info;

        buf_addr = buf_vec[vec_idx].buf_addr;
        buf_iova = buf_vec[vec_idx].buf_iova;
        buf_len = buf_vec[vec_idx].buf_len;

        if (unlikely(buf_len < dev->vhost_hlen && nr_vec <= 1))
                return -1;

        if (virtio_net_with_host_offload(dev)) {
                if (unlikely(buf_len < sizeof(struct virtio_net_hdr))) {
                        /*
                         * No luck, the virtio-net header doesn't fit
                         * in a contiguous virtual area.
                         */
                        copy_vnet_hdr_from_desc(&tmp_hdr, buf_vec);
                        hdr = &tmp_hdr;
                } else {
                        hdr = (struct virtio_net_hdr *)((uintptr_t)buf_addr);
                }
        }

        /*
         * A virtio driver normally uses at least 2 desc buffers
         * for Tx: the first for storing the header, and others
         * for storing the data.
         */
        if (unlikely(buf_len < dev->vhost_hlen)) {
                buf_offset = dev->vhost_hlen - buf_len;
                vec_idx++;
                buf_addr = buf_vec[vec_idx].buf_addr;
                buf_iova = buf_vec[vec_idx].buf_iova;
                buf_len = buf_vec[vec_idx].buf_len;
                buf_avail  = buf_len - buf_offset;
        } else if (buf_len == dev->vhost_hlen) {
                if (unlikely(++vec_idx >= nr_vec))
                        goto error;
                buf_addr = buf_vec[vec_idx].buf_addr;
                buf_iova = buf_vec[vec_idx].buf_iova;
                buf_len = buf_vec[vec_idx].buf_len;

                buf_offset = 0;
                buf_avail = buf_len;
        } else {
                buf_offset = dev->vhost_hlen;
                buf_avail = buf_vec[vec_idx].buf_len - dev->vhost_hlen;
        }

        PRINT_PACKET(dev,
                        (uintptr_t)(buf_addr + buf_offset),
                        (uint32_t)buf_avail, 0);

        mbuf_offset = 0;
        mbuf_avail  = m->buf_len - RTE_PKTMBUF_HEADROOM;

        if (is_async) {
                pkts_info = async->pkts_info;
                if (async_iter_initialize(dev, async))
                        return -1;
        }

        while (1) {
                cpy_len = RTE_MIN(buf_avail, mbuf_avail);

                if (is_async) {
                        if (async_fill_seg(dev, vq, cur, mbuf_offset,
                                           buf_iova + buf_offset, cpy_len, false) < 0)
                                goto error;
                } else if (likely(hdr && cur == m)) {
                        rte_memcpy(rte_pktmbuf_mtod_offset(cur, void *, mbuf_offset),
                                (void *)((uintptr_t)(buf_addr + buf_offset)),
                                cpy_len);
                } else {
                        sync_fill_seg(dev, vq, cur, mbuf_offset,
                                      buf_addr + buf_offset,
                                      buf_iova + buf_offset, cpy_len, false);
                }

                mbuf_avail  -= cpy_len;
                mbuf_offset += cpy_len;
                buf_avail -= cpy_len;
                buf_offset += cpy_len;

                /* This buf reaches to its end, get the next one */
                if (buf_avail == 0) {
                        if (++vec_idx >= nr_vec)
                                break;

                        buf_addr = buf_vec[vec_idx].buf_addr;
                        buf_iova = buf_vec[vec_idx].buf_iova;
                        buf_len = buf_vec[vec_idx].buf_len;

                        buf_offset = 0;
                        buf_avail  = buf_len;

                        PRINT_PACKET(dev, (uintptr_t)buf_addr,
                                        (uint32_t)buf_avail, 0);
                }

                /*
                 * This mbuf reaches to its end, get a new one
                 * to hold more data.
                 */
                if (mbuf_avail == 0) {
                        cur = rte_pktmbuf_alloc(mbuf_pool);
                        if (unlikely(cur == NULL)) {
                                VHOST_LOG_DATA(dev->ifname, ERR,
                                        "failed to allocate memory for mbuf.\n");
                                goto error;
                        }

                        prev->next = cur;
                        prev->data_len = mbuf_offset;
                        m->nb_segs += 1;
                        m->pkt_len += mbuf_offset;
                        prev = cur;

                        mbuf_offset = 0;
                        mbuf_avail  = cur->buf_len - RTE_PKTMBUF_HEADROOM;
                }
        }

        prev->data_len = mbuf_offset;
        m->pkt_len    += mbuf_offset;

        if (is_async) {
                async_iter_finalize(async);
                if (hdr)
                        pkts_info[slot_idx].nethdr = *hdr;
        } else if (hdr) {
                vhost_dequeue_offload(dev, hdr, m, legacy_ol_flags);
        }

        return 0;
error:
        if (is_async)
                async_iter_cancel(async);

        return -1;
}

static void
virtio_dev_extbuf_free(void *addr __rte_unused, void *opaque)
{
        rte_free(opaque);
}

static int
virtio_dev_extbuf_alloc(struct virtio_net *dev, struct rte_mbuf *pkt, uint32_t size)
{
        struct rte_mbuf_ext_shared_info *shinfo = NULL;
        uint32_t total_len = RTE_PKTMBUF_HEADROOM + size;
        uint16_t buf_len;
        rte_iova_t iova;
        void *buf;

        total_len += sizeof(*shinfo) + sizeof(uintptr_t);
        total_len = RTE_ALIGN_CEIL(total_len, sizeof(uintptr_t));

        if (unlikely(total_len > UINT16_MAX))
                return -ENOSPC;

        buf_len = total_len;
        buf = rte_malloc(NULL, buf_len, RTE_CACHE_LINE_SIZE);
        if (unlikely(buf == NULL))
                return -ENOMEM;

        /* Initialize shinfo */
        shinfo = rte_pktmbuf_ext_shinfo_init_helper(buf, &buf_len,
                                                virtio_dev_extbuf_free, buf);
        if (unlikely(shinfo == NULL)) {
                rte_free(buf);
                VHOST_LOG_DATA(dev->ifname, ERR, "failed to init shinfo\n");
                return -1;
        }

        iova = rte_malloc_virt2iova(buf);
        rte_pktmbuf_attach_extbuf(pkt, buf, iova, buf_len, shinfo);
        rte_pktmbuf_reset_headroom(pkt);

        return 0;
}

/*
 * Prepare a host supported pktmbuf.
 */
static __rte_always_inline int
virtio_dev_pktmbuf_prep(struct virtio_net *dev, struct rte_mbuf *pkt,
                         uint32_t data_len)
{
        if (rte_pktmbuf_tailroom(pkt) >= data_len)
                return 0;

        /* attach an external buffer if supported */
        if (dev->extbuf && !virtio_dev_extbuf_alloc(dev, pkt, data_len))
                return 0;

        /* check if chained buffers are allowed */
        if (!dev->linearbuf)
                return 0;

        return -1;
}

__rte_always_inline
static uint16_t
virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
        struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count,
        bool legacy_ol_flags)
{
        uint16_t i;
        uint16_t avail_entries;
        uint16_t dropped = 0;
        static bool allocerr_warned;

        /*
         * The ordering between avail index and
         * desc reads needs to be enforced.
         */
        avail_entries = __atomic_load_n(&vq->avail->idx, __ATOMIC_ACQUIRE) -
                        vq->last_avail_idx;
        if (avail_entries == 0)
                return 0;

        rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);

        VHOST_LOG_DATA(dev->ifname, DEBUG, "%s\n", __func__);

        count = RTE_MIN(count, MAX_PKT_BURST);
        count = RTE_MIN(count, avail_entries);
        VHOST_LOG_DATA(dev->ifname, DEBUG, "about to dequeue %u buffers\n", count);

        if (rte_pktmbuf_alloc_bulk(mbuf_pool, pkts, count))
                return 0;

        for (i = 0; i < count; i++) {
                struct buf_vector buf_vec[BUF_VECTOR_MAX];
                uint16_t head_idx;
                uint32_t buf_len;
                uint16_t nr_vec = 0;
                int err;

                if (unlikely(fill_vec_buf_split(dev, vq,
                                                vq->last_avail_idx + i,
                                                &nr_vec, buf_vec,
                                                &head_idx, &buf_len,
                                                VHOST_ACCESS_RO) < 0))
                        break;

                update_shadow_used_ring_split(vq, head_idx, 0);

                err = virtio_dev_pktmbuf_prep(dev, pkts[i], buf_len);
                if (unlikely(err)) {
                        /*
                         * mbuf allocation fails for jumbo packets when external
                         * buffer allocation is not allowed and linear buffer
                         * is required. Drop this packet.
                         */
                        if (!allocerr_warned) {
                                VHOST_LOG_DATA(dev->ifname, ERR,
                                        "failed mbuf alloc of size %d from %s.\n",
                                        buf_len, mbuf_pool->name);
                                allocerr_warned = true;
                        }
                        dropped += 1;
                        i++;
                        break;
                }

                err = desc_to_mbuf(dev, vq, buf_vec, nr_vec, pkts[i],
                                   mbuf_pool, legacy_ol_flags, 0, false);
                if (unlikely(err)) {
                        if (!allocerr_warned) {
                                VHOST_LOG_DATA(dev->ifname, ERR, "failed to copy desc to mbuf.\n");
                                allocerr_warned = true;
                        }
                        dropped += 1;
                        i++;
                        break;
                }

        }

        if (dropped)
                rte_pktmbuf_free_bulk(&pkts[i - 1], count - i + 1);

        vq->last_avail_idx += i;

        do_data_copy_dequeue(vq);
        if (unlikely(i < count))
                vq->shadow_used_idx = i;
        if (likely(vq->shadow_used_idx)) {
                flush_shadow_used_ring_split(dev, vq);
                vhost_vring_call_split(dev, vq);
        }

        return (i - dropped);
}

__rte_noinline
static uint16_t
virtio_dev_tx_split_legacy(struct virtio_net *dev,
        struct vhost_virtqueue *vq, struct rte_mempool *mbuf_pool,
        struct rte_mbuf **pkts, uint16_t count)
{
        return virtio_dev_tx_split(dev, vq, mbuf_pool, pkts, count, true);
}

__rte_noinline
static uint16_t
virtio_dev_tx_split_compliant(struct virtio_net *dev,
        struct vhost_virtqueue *vq, struct rte_mempool *mbuf_pool,
        struct rte_mbuf **pkts, uint16_t count)
{
        return virtio_dev_tx_split(dev, vq, mbuf_pool, pkts, count, false);
}

static __rte_always_inline int
vhost_reserve_avail_batch_packed(struct virtio_net *dev,
                                 struct vhost_virtqueue *vq,
                                 struct rte_mbuf **pkts,
                                 uint16_t avail_idx,
                                 uintptr_t *desc_addrs,
                                 uint16_t *ids)
{
        bool wrap = vq->avail_wrap_counter;
        struct vring_packed_desc *descs = vq->desc_packed;