Re: [dpdk-dev] [PATCH v6 2/2] vhost: introduce async enqueue for split ring

["Xia, Chenbo" <chenbo.xia@intel.com>]

> -----Original Message-----
> From: Fu, Patrick <patrick.fu@intel.com>
> Sent: Tuesday, July 7, 2020 1:07 PM
> To: dev@dpdk.org; maxime.coquelin@redhat.com; Xia, Chenbo
> <chenbo.xia@intel.com>; Wang, Zhihong <zhihong.wang@intel.com>
> Cc: Fu, Patrick <patrick.fu@intel.com>; Wang, Yinan <yinan.wang@intel.com>;
> Jiang, Cheng1 <cheng1.jiang@intel.com>; Liang, Cunming
> <cunming.liang@intel.com>
> Subject: [PATCH v6 2/2] vhost: introduce async enqueue for split ring
> 
> From: Patrick Fu <patrick.fu@intel.com>
> 
> This patch implements async enqueue data path for split ring. 2 new async data
> path APIs are defined, by which applications can submit and poll packets to/from
> async engines. The async engine is either a physical DMA device or it could also
> be a software emulated backend.
> The async enqueue data path leverages callback functions registered by
> applications to work with the async engine.
> 
> Signed-off-by: Patrick Fu <patrick.fu@intel.com>
> ---
>  lib/librte_vhost/rte_vhost_async.h |  40 +++
>  lib/librte_vhost/virtio_net.c      | 551 ++++++++++++++++++++++++++++-
>  2 files changed, 589 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/librte_vhost/rte_vhost_async.h
> b/lib/librte_vhost/rte_vhost_async.h
> index d5a59279a..c8ad8dbc7 100644
> --- a/lib/librte_vhost/rte_vhost_async.h
> +++ b/lib/librte_vhost/rte_vhost_async.h
> @@ -133,4 +133,44 @@ int rte_vhost_async_channel_register(int vid, uint16_t
> queue_id,  __rte_experimental  int rte_vhost_async_channel_unregister(int vid,
> uint16_t queue_id);
> 
> +/**
> + * This function submit enqueue data to async engine. This function has
> + * no guranttee to the transfer completion upon return. Applications
> + * should poll transfer status by rte_vhost_poll_enqueue_completed()
> + *
> + * @param vid
> + *  id of vhost device to enqueue data
> + * @param queue_id
> + *  queue id to enqueue data
> + * @param pkts
> + *  array of packets to be enqueued
> + * @param count
> + *  packets num to be enqueued
> + * @return
> + *  num of packets enqueued
> + */
> +__rte_experimental
> +uint16_t rte_vhost_submit_enqueue_burst(int vid, uint16_t queue_id,
> +		struct rte_mbuf **pkts, uint16_t count);
> +
> +/**
> + * This function check async completion status for a specific vhost
> + * device queue. Packets which finish copying (enqueue) operation
> + * will be returned in an array.
> + *
> + * @param vid
> + *  id of vhost device to enqueue data
> + * @param queue_id
> + *  queue id to enqueue data
> + * @param pkts
> + *  blank array to get return packet pointer
> + * @param count
> + *  size of the packet array
> + * @return
> + *  num of packets returned
> + */
> +__rte_experimental
> +uint16_t rte_vhost_poll_enqueue_completed(int vid, uint16_t queue_id,
> +		struct rte_mbuf **pkts, uint16_t count);
> +
>  #endif /* _RTE_VHOST_ASYNC_H_ */
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c index
> 751c1f373..236498f71 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -17,14 +17,15 @@
>  #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_PKT_BURST 32
> -
>  #define MAX_BATCH_LEN 256
> 
> +#define VHOST_ASYNC_BATCH_THRESHOLD 32
> +
>  static  __rte_always_inline bool
>  rxvq_is_mergeable(struct virtio_net *dev)  { @@ -116,6 +117,31 @@
> flush_shadow_used_ring_split(struct virtio_net *dev, struct vhost_virtqueue *vq)
>  		sizeof(vq->used->idx));
>  }
> 
> +static __rte_always_inline void
> +async_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;
> +	vq->shadow_used_idx = 0;
> +}
> +
>  static __rte_always_inline void
>  update_shadow_used_ring_split(struct vhost_virtqueue *vq,
>  			 uint16_t desc_idx, uint32_t len)
> @@ -905,6 +931,200 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct
> vhost_virtqueue *vq,
>  	return error;
>  }
> 
> +static __rte_always_inline void
> +async_fill_vec(struct iovec *v, void *base, size_t len) {
> +	v->iov_base = base;
> +	v->iov_len = len;
> +}
> +
> +static __rte_always_inline void
> +async_fill_iter(struct rte_vhost_iov_iter *it, size_t count,
> +	struct iovec *vec, unsigned long nr_seg) {
> +	it->offset = 0;
> +	it->count = count;
> +
> +	if (count) {
> +		it->iov = vec;
> +		it->nr_segs = nr_seg;
> +	} else {
> +		it->iov = 0;
> +		it->nr_segs = 0;
> +	}
> +}
> +
> +static __rte_always_inline void
> +async_fill_desc(struct rte_vhost_async_desc *desc,
> +	struct rte_vhost_iov_iter *src, struct rte_vhost_iov_iter *dst) {
> +	desc->src = src;
> +	desc->dst = dst;
> +}
> +
> +static __rte_always_inline int
> +async_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,
> +			struct iovec *src_iovec, struct iovec *dst_iovec,
> +			struct rte_vhost_iov_iter *src_it,
> +			struct rte_vhost_iov_iter *dst_it)
> +{
> +	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, cpy_threshold;
> +	uint64_t hdr_addr;
> +	struct rte_mbuf *hdr_mbuf;
> +	struct batch_copy_elem *batch_copy = vq->batch_copy_elems;
> +	struct virtio_net_hdr_mrg_rxbuf tmp_hdr, *hdr = NULL;
> +	int error = 0;
> +
> +	uint32_t tlen = 0;
> +	int tvec_idx = 0;
> +	void *hpa;
> +
> +	if (unlikely(m == NULL)) {
> +		error = -1;
> +		goto out;
> +	}
> +
> +	cpy_threshold = vq->async_threshold;
> +
> +	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)) {
> +		error = -1;
> +		goto out;
> +	}
> +
> +	hdr_mbuf = m;
> +	hdr_addr = buf_addr;
> +	if (unlikely(buf_len < dev->vhost_hlen))
> +		hdr = &tmp_hdr;
> +	else
> +		hdr = (struct virtio_net_hdr_mrg_rxbuf *)(uintptr_t)hdr_addr;
> +
> +	VHOST_LOG_DATA(DEBUG, "(%d) RX: num merge buffers %d\n",
> +		dev->vid, 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;
> +
> +	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)) {
> +				error = -1;
> +				goto out;
> +			}
> +
> +			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 (unlikely(cpy_len >= cpy_threshold)) {
> +			hpa = (void *)(uintptr_t)gpa_to_hpa(dev,
> +					buf_iova + buf_offset, cpy_len);
> +
> +			if (unlikely(!hpa)) {
> +				error = -1;
> +				goto out;
> +			}
> +
> +			async_fill_vec(src_iovec + tvec_idx,
> +				(void *)(uintptr_t)rte_pktmbuf_iova_offset(m,
> +						mbuf_offset), cpy_len);
> +
> +			async_fill_vec(dst_iovec + tvec_idx, hpa, cpy_len);
> +
> +			tlen += cpy_len;
> +			tvec_idx++;
> +		} else {
> +			if (unlikely(vq->batch_copy_nb_elems >= vq->size)) {
> +				rte_memcpy(
> +				(void *)((uintptr_t)(buf_addr + buf_offset)),
> +				rte_pktmbuf_mtod_offset(m, void *,
> mbuf_offset),
> +				cpy_len);
> +
> +				PRINT_PACKET(dev,
> +					(uintptr_t)(buf_addr + buf_offset),
> +					cpy_len, 0);
> +			} else {
> +				batch_copy[vq->batch_copy_nb_elems].dst =
> +				(void *)((uintptr_t)(buf_addr + buf_offset));
> +				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 + buf_offset;
> +				batch_copy[vq->batch_copy_nb_elems].len =
> +					cpy_len;
> +				vq->batch_copy_nb_elems++;
> +			}
> +		}
> +
> +		mbuf_avail  -= cpy_len;
> +		mbuf_offset += cpy_len;
> +		buf_avail  -= cpy_len;
> +		buf_offset += cpy_len;
> +	}
> +
> +out:
> +	async_fill_iter(src_it, tlen, src_iovec, tvec_idx);
> +	async_fill_iter(dst_it, tlen, dst_iovec, tvec_idx);
> +
> +	return error;
> +}
> +
>  static __rte_always_inline int
>  vhost_enqueue_single_packed(struct virtio_net *dev,
>  			    struct vhost_virtqueue *vq,
> @@ -1236,6 +1456,333 @@ rte_vhost_enqueue_burst(int vid, uint16_t
> queue_id,
>  	return virtio_dev_rx(dev, queue_id, pkts, count);  }
> 
> +static __rte_always_inline uint16_t
> +virtio_dev_rx_async_get_info_idx(uint16_t pkts_idx,
> +	uint16_t vq_size, uint16_t n_inflight) {
> +	return pkts_idx > n_inflight ? (pkts_idx - n_inflight) :
> +		(vq_size - n_inflight + pkts_idx) & (vq_size - 1); }
> +
> +static __rte_always_inline void
> +virtio_dev_rx_async_submit_split_err(struct virtio_net *dev,
> +	struct vhost_virtqueue *vq, uint16_t queue_id,
> +	uint16_t last_idx, uint16_t shadow_idx) {
> +	uint16_t start_idx, pkts_idx, vq_size;
> +	uint64_t *async_pending_info;
> +
> +	pkts_idx = vq->async_pkts_idx;
> +	async_pending_info = vq->async_pending_info;
> +	vq_size = vq->size;
> +	start_idx = virtio_dev_rx_async_get_info_idx(pkts_idx,
> +		vq_size, vq->async_pkts_inflight_n);
> +
> +	while (likely((start_idx & (vq_size - 1)) != pkts_idx)) {
> +		uint64_t n_seg =
> +			async_pending_info[(start_idx) & (vq_size - 1)] >>
> +			ASYNC_PENDING_INFO_N_SFT;
> +
> +		while (n_seg)
> +			n_seg -= vq->async_ops.check_completed_copies(dev-
> >vid,
> +				queue_id, 0, 1);
> +	}
> +
> +	vq->async_pkts_inflight_n = 0;
> +	vq->batch_copy_nb_elems = 0;
> +
> +	vq->shadow_used_idx = shadow_idx;
> +	vq->last_avail_idx = last_idx;
> +}
> +
> +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) {
> +	uint32_t pkt_idx = 0, pkt_burst_idx = 0;
> +	uint16_t num_buffers;
> +	struct buf_vector buf_vec[BUF_VECTOR_MAX];
> +	uint16_t avail_head, last_idx, shadow_idx;
> +
> +	struct rte_vhost_iov_iter *it_pool = vq->it_pool;
> +	struct iovec *vec_pool = vq->vec_pool;
> +	struct rte_vhost_async_desc tdes[MAX_PKT_BURST];
> +	struct iovec *src_iovec = vec_pool;
> +	struct iovec *dst_iovec = vec_pool + (VHOST_MAX_ASYNC_VEC >> 1);
> +	struct rte_vhost_iov_iter *src_it = it_pool;
> +	struct rte_vhost_iov_iter *dst_it = it_pool + 1;
> +	uint16_t n_free_slot, slot_idx;
> +	int n_pkts = 0;
> +
> +	avail_head = __atomic_load_n(&vq->avail->idx, __ATOMIC_ACQUIRE);
> +	last_idx = vq->last_avail_idx;
> +	shadow_idx = vq->shadow_used_idx;
> +
> +	/*
> +	 * The ordering between avail index and
> +	 * desc reads needs to be enforced.
> +	 */
> +	rte_smp_rmb();
> +
> +	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(DEBUG,
> +				"(%d) failed to get enough desc from vring\n",
> +				dev->vid);
> +			vq->shadow_used_idx -= num_buffers;
> +			break;
> +		}
> +
> +		VHOST_LOG_DATA(DEBUG, "(%d) current index %d | end
> index %d\n",
> +			dev->vid, vq->last_avail_idx,
> +			vq->last_avail_idx + num_buffers);
> +
> +		if (async_mbuf_to_desc(dev, vq, pkts[pkt_idx],
> +				buf_vec, nr_vec, num_buffers,
> +				src_iovec, dst_iovec, src_it, dst_it) < 0) {
> +			vq->shadow_used_idx -= num_buffers;
> +			break;
> +		}
> +
> +		slot_idx = (vq->async_pkts_idx + pkt_idx) & (vq->size - 1);
> +		if (src_it->count) {
> +			async_fill_desc(&tdes[pkt_burst_idx], src_it, dst_it);
> +			pkt_burst_idx++;
> +			vq->async_pending_info[slot_idx] =
> +				num_buffers | (src_it->nr_segs << 16);
> +			src_iovec += src_it->nr_segs;
> +			dst_iovec += dst_it->nr_segs;
> +			src_it += 2;
> +			dst_it += 2;
> +		} else {
> +			vq->async_pending_info[slot_idx] = num_buffers;
> +			vq->async_pkts_inflight_n++;
> +		}
> +
> +		vq->last_avail_idx += num_buffers;
> +
> +		if (pkt_burst_idx >= VHOST_ASYNC_BATCH_THRESHOLD ||
> +				(pkt_idx == count - 1 && pkt_burst_idx)) {
> +			n_pkts = vq->async_ops.transfer_data(dev->vid,
> +					queue_id, tdes, 0, pkt_burst_idx);
> +			src_iovec = vec_pool;
> +			dst_iovec = vec_pool + (VHOST_MAX_ASYNC_VEC >> 1);
> +			src_it = it_pool;
> +			dst_it = it_pool + 1;
> +
> +			if (unlikely(n_pkts < (int)pkt_burst_idx)) {
> +				vq->async_pkts_inflight_n +=
> +					n_pkts > 0 ? n_pkts : 0;
> +				virtio_dev_rx_async_submit_split_err(dev,
> +					vq, queue_id, last_idx, shadow_idx);
> +				return 0;
> +			}
> +
> +			pkt_burst_idx = 0;
> +			vq->async_pkts_inflight_n += n_pkts;
> +		}
> +	}
> +
> +	if (pkt_burst_idx) {
> +		n_pkts = vq->async_ops.transfer_data(dev->vid,
> +				queue_id, tdes, 0, pkt_burst_idx);
> +		if (unlikely(n_pkts < (int)pkt_burst_idx)) {
> +			vq->async_pkts_inflight_n += n_pkts > 0 ? n_pkts : 0;
> +			virtio_dev_rx_async_submit_split_err(dev, vq, queue_id,
> +				last_idx, shadow_idx);
> +			return 0;
> +		}
> +
> +		vq->async_pkts_inflight_n += n_pkts;
> +	}
> +
> +	do_data_copy_enqueue(dev, vq);
> +
> +	n_free_slot = vq->size - vq->async_pkts_idx;
> +	if (n_free_slot > pkt_idx) {
> +		rte_memcpy(&vq->async_pkts_pending[vq->async_pkts_idx],
> +			pkts, pkt_idx * sizeof(uintptr_t));
> +		vq->async_pkts_idx += pkt_idx;
> +	} else {
> +		rte_memcpy(&vq->async_pkts_pending[vq->async_pkts_idx],
> +			pkts, n_free_slot * sizeof(uintptr_t));
> +		rte_memcpy(&vq->async_pkts_pending[0],
> +			&pkts[n_free_slot],
> +			(pkt_idx - n_free_slot) * sizeof(uintptr_t));
> +		vq->async_pkts_idx = pkt_idx - n_free_slot;
> +	}
> +
> +	if (likely(vq->shadow_used_idx))
> +		async_flush_shadow_used_ring_split(dev, vq);
> +
> +	return pkt_idx;
> +}
> +
> +uint16_t rte_vhost_poll_enqueue_completed(int vid, uint16_t queue_id,
> +		struct rte_mbuf **pkts, uint16_t count) {
> +	struct virtio_net *dev = get_device(vid);
> +	struct vhost_virtqueue *vq;
> +	uint16_t n_pkts_cpl, n_pkts_put = 0, n_descs = 0;
> +	uint16_t start_idx, pkts_idx, vq_size;
> +	uint64_t *async_pending_info;
> +
> +	VHOST_LOG_DATA(DEBUG, "(%d) %s\n", dev->vid, __func__);
> +	if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->nr_vring))) {
> +		VHOST_LOG_DATA(ERR, "(%d) %s: invalid virtqueue idx %d.\n",
> +			dev->vid, __func__, queue_id);
> +		return 0;
> +	}
> +
> +	vq = dev->virtqueue[queue_id];
> +
> +	rte_spinlock_lock(&vq->access_lock);
> +
> +	pkts_idx = vq->async_pkts_idx;
> +	async_pending_info = vq->async_pending_info;
> +	vq_size = vq->size;
> +	start_idx = virtio_dev_rx_async_get_info_idx(pkts_idx,
> +		vq_size, vq->async_pkts_inflight_n);
> +
> +	n_pkts_cpl =
> +		vq->async_ops.check_completed_copies(vid, queue_id, 0,
> count);
> +
> +	rte_smp_wmb();
> +
> +	while (likely(((start_idx + n_pkts_put) & (vq_size - 1)) != pkts_idx)) {
> +		uint64_t info = async_pending_info[
> +			(start_idx + n_pkts_put) & (vq_size - 1)];
> +		uint64_t n_segs;
> +		n_pkts_put++;
> +		n_descs += info & ASYNC_PENDING_INFO_N_MSK;
> +		n_segs = info >> ASYNC_PENDING_INFO_N_SFT;
> +
> +		if (n_segs) {
> +			if (!n_pkts_cpl || n_pkts_cpl < n_segs) {
> +				n_pkts_put--;
> +				n_descs -= info &
> ASYNC_PENDING_INFO_N_MSK;
> +				if (n_pkts_cpl) {
> +					async_pending_info[
> +						(start_idx + n_pkts_put) &
> +						(vq_size - 1)] =
> +					((n_segs - n_pkts_cpl) <<
> +					 ASYNC_PENDING_INFO_N_SFT) |
> +					(info &
> ASYNC_PENDING_INFO_N_MSK);
> +					n_pkts_cpl = 0;
> +				}
> +				break;
> +			}
> +			n_pkts_cpl -= n_segs;
> +		}
> +	}
> +
> +	if (n_pkts_put) {
> +		vq->async_pkts_inflight_n -= n_pkts_put;
> +		__atomic_add_fetch(&vq->used->idx, n_descs,
> __ATOMIC_RELEASE);
> +
> +		vhost_vring_call_split(dev, vq);
> +	}
> +
> +	if (start_idx + n_pkts_put <= vq_size) {
> +		rte_memcpy(pkts, &vq->async_pkts_pending[start_idx],
> +			n_pkts_put * sizeof(uintptr_t));
> +	} else {
> +		rte_memcpy(pkts, &vq->async_pkts_pending[start_idx],
> +			(vq_size - start_idx) * sizeof(uintptr_t));
> +		rte_memcpy(&pkts[vq_size - start_idx], vq-
> >async_pkts_pending,
> +			(n_pkts_put - vq_size + start_idx) * sizeof(uintptr_t));
> +	}
> +
> +	rte_spinlock_unlock(&vq->access_lock);
> +
> +	return n_pkts_put;
> +}
> +
> +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) {
> +	struct vhost_virtqueue *vq;
> +	uint32_t nb_tx = 0;
> +	bool drawback = false;
> +
> +	VHOST_LOG_DATA(DEBUG, "(%d) %s\n", dev->vid, __func__);
> +	if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->nr_vring))) {
> +		VHOST_LOG_DATA(ERR, "(%d) %s: invalid virtqueue idx %d.\n",
> +			dev->vid, __func__, queue_id);
> +		return 0;
> +	}
> +
> +	vq = dev->virtqueue[queue_id];
> +
> +	rte_spinlock_lock(&vq->access_lock);
> +
> +	if (unlikely(vq->enabled == 0))
> +		goto out_access_unlock;
> +
> +	if (unlikely(!vq->async_registered)) {
> +		drawback = true;
> +		goto out_access_unlock;
> +	}
> +
> +	if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
> +		vhost_user_iotlb_rd_lock(vq);
> +
> +	if (unlikely(vq->access_ok == 0))
> +		if (unlikely(vring_translate(dev, vq) < 0))
> +			goto out;
> +
> +	count = RTE_MIN((uint32_t)MAX_PKT_BURST, count);
> +	if (count == 0)
> +		goto out;
> +
> +	/* TODO: packed queue not implemented */
> +	if (vq_is_packed(dev))
> +		nb_tx = 0;
> +	else
> +		nb_tx = virtio_dev_rx_async_submit_split(dev,
> +				vq, queue_id, pkts, count);
> +
> +out:
> +	if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
> +		vhost_user_iotlb_rd_unlock(vq);
> +
> +out_access_unlock:
> +	rte_spinlock_unlock(&vq->access_lock);
> +
> +	if (drawback)
> +		return rte_vhost_enqueue_burst(dev->vid, queue_id, pkts,
> count);
> +
> +	return nb_tx;
> +}
> +
> +uint16_t
> +rte_vhost_submit_enqueue_burst(int vid, uint16_t queue_id,
> +		struct rte_mbuf **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(ERR,
> +			"(%d) %s: built-in vhost net backend is disabled.\n",
> +			dev->vid, __func__);
> +		return 0;
> +	}
> +
> +	return virtio_dev_rx_async_submit(dev, queue_id, pkts, count); }
> +
>  static inline bool
>  virtio_net_with_host_offload(struct virtio_net *dev)  {
> --
> 2.18.4

Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>