Imported Upstream version 16.04

Change-Id: I77eadcd8538a9122e4773cbe55b24033dc451757
Signed-off-by: C.J. Collier <cjcollier@linuxfoundation.org>

1 files changed, 947 insertions, 0 deletions

diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
new file mode 100644
index 00000000..750821a4
--- /dev/null
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -0,0 +1,947 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <linux/virtio_net.h>
+
+#include <rte_mbuf.h>
+#include <rte_memcpy.h>
+#include <rte_ether.h>
+#include <rte_ip.h>
+#include <rte_virtio_net.h>
+#include <rte_tcp.h>
+#include <rte_udp.h>
+#include <rte_sctp.h>
+#include <rte_arp.h>
+
+#include "vhost-net.h"
+
+#define MAX_PKT_BURST 32
+#define VHOST_LOG_PAGE	4096
+
+static inline void __attribute__((always_inline))
+vhost_log_page(uint8_t *log_base, uint64_t page)
+{
+	log_base[page / 8] |= 1 << (page % 8);
+}
+
+static inline void __attribute__((always_inline))
+vhost_log_write(struct virtio_net *dev, uint64_t addr, uint64_t len)
+{
+	uint64_t page;
+
+	if (likely(((dev->features & (1ULL << VHOST_F_LOG_ALL)) == 0) ||
+		   !dev->log_base || !len))
+		return;
+
+	if (unlikely(dev->log_size <= ((addr + len - 1) / VHOST_LOG_PAGE / 8)))
+		return;
+
+	/* To make sure guest memory updates are committed before logging */
+	rte_smp_wmb();
+
+	page = addr / VHOST_LOG_PAGE;
+	while (page * VHOST_LOG_PAGE < addr + len) {
+		vhost_log_page((uint8_t *)(uintptr_t)dev->log_base, page);
+		page += 1;
+	}
+}
+
+static inline void __attribute__((always_inline))
+vhost_log_used_vring(struct virtio_net *dev, struct vhost_virtqueue *vq,
+		     uint64_t offset, uint64_t len)
+{
+	vhost_log_write(dev, vq->log_guest_addr + offset, len);
+}
+
+static bool
+is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t qp_nb)
+{
+	return (is_tx ^ (idx & 1)) == 0 && idx < qp_nb * VIRTIO_QNUM;
+}
+
+static void
+virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
+{
+	if (m_buf->ol_flags & PKT_TX_L4_MASK) {
+		net_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
+		net_hdr->csum_start = m_buf->l2_len + m_buf->l3_len;
+
+		switch (m_buf->ol_flags & PKT_TX_L4_MASK) {
+		case PKT_TX_TCP_CKSUM:
+			net_hdr->csum_offset = (offsetof(struct tcp_hdr,
+						cksum));
+			break;
+		case PKT_TX_UDP_CKSUM:
+			net_hdr->csum_offset = (offsetof(struct udp_hdr,
+						dgram_cksum));
+			break;
+		case PKT_TX_SCTP_CKSUM:
+			net_hdr->csum_offset = (offsetof(struct sctp_hdr,
+						cksum));
+			break;
+		}
+	}
+
+	if (m_buf->ol_flags & PKT_TX_TCP_SEG) {
+		if (m_buf->ol_flags & PKT_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;
+	}
+}
+
+static inline void
+copy_virtio_net_hdr(struct vhost_virtqueue *vq, uint64_t desc_addr,
+		    struct virtio_net_hdr_mrg_rxbuf hdr)
+{
+	if (vq->vhost_hlen == sizeof(struct virtio_net_hdr_mrg_rxbuf))
+		*(struct virtio_net_hdr_mrg_rxbuf *)(uintptr_t)desc_addr = hdr;
+	else
+		*(struct virtio_net_hdr *)(uintptr_t)desc_addr = hdr.hdr;
+}
+
+static inline int __attribute__((always_inline))
+copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
+		  struct rte_mbuf *m, uint16_t desc_idx, uint32_t *copied)
+{
+	uint32_t desc_avail, desc_offset;
+	uint32_t mbuf_avail, mbuf_offset;
+	uint32_t cpy_len;
+	struct vring_desc *desc;
+	uint64_t desc_addr;
+	struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, 0, 0, 0, 0, 0}, 0};
+
+	desc = &vq->desc[desc_idx];
+	if (unlikely(desc->len < vq->vhost_hlen))
+		return -1;
+
+	desc_addr = gpa_to_vva(dev, desc->addr);
+	rte_prefetch0((void *)(uintptr_t)desc_addr);
+
+	virtio_enqueue_offload(m, &virtio_hdr.hdr);
+	copy_virtio_net_hdr(vq, desc_addr, virtio_hdr);
+	vhost_log_write(dev, desc->addr, vq->vhost_hlen);
+	PRINT_PACKET(dev, (uintptr_t)desc_addr, vq->vhost_hlen, 0);
+
+	desc_offset = vq->vhost_hlen;
+	desc_avail  = desc->len - vq->vhost_hlen;
+
+	*copied = rte_pktmbuf_pkt_len(m);
+	mbuf_avail  = rte_pktmbuf_data_len(m);
+	mbuf_offset = 0;
+	while (mbuf_avail != 0 || m->next != NULL) {
+		/* done with current mbuf, fetch next */
+		if (mbuf_avail == 0) {
+			m = m->next;
+
+			mbuf_offset = 0;
+			mbuf_avail  = rte_pktmbuf_data_len(m);
+		}
+
+		/* done with current desc buf, fetch next */
+		if (desc_avail == 0) {
+			if ((desc->flags & VRING_DESC_F_NEXT) == 0) {
+				/* Room in vring buffer is not enough */
+				return -1;
+			}
+			if (unlikely(desc->next >= vq->size))
+				return -1;
+
+			desc = &vq->desc[desc->next];
+			desc_addr   = gpa_to_vva(dev, desc->addr);
+			desc_offset = 0;
+			desc_avail  = desc->len;
+		}
+
+		cpy_len = RTE_MIN(desc_avail, mbuf_avail);
+		rte_memcpy((void *)((uintptr_t)(desc_addr + desc_offset)),
+			rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
+			cpy_len);
+		vhost_log_write(dev, desc->addr + desc_offset, cpy_len);
+		PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset),
+			     cpy_len, 0);
+
+		mbuf_avail  -= cpy_len;
+		mbuf_offset += cpy_len;
+		desc_avail  -= cpy_len;
+		desc_offset += cpy_len;
+	}
+
+	return 0;
+}
+
+/*
+ * As many data cores may want to access available buffers
+ * they need to be reserved.
+ */
+static inline uint32_t
+reserve_avail_buf(struct vhost_virtqueue *vq, uint32_t count,
+		  uint16_t *start, uint16_t *end)
+{
+	uint16_t res_start_idx;
+	uint16_t res_end_idx;
+	uint16_t avail_idx;
+	uint16_t free_entries;
+	int success;
+
+	count = RTE_MIN(count, (uint32_t)MAX_PKT_BURST);
+
+again:
+	res_start_idx = vq->last_used_idx_res;
+	avail_idx = *((volatile uint16_t *)&vq->avail->idx);
+
+	free_entries = avail_idx - res_start_idx;
+	count = RTE_MIN(count, free_entries);
+	if (count == 0)
+		return 0;
+
+	res_end_idx = res_start_idx + count;
+
+	/*
+	 * update vq->last_used_idx_res atomically; try again if failed.
+	 *
+	 * TODO: Allow to disable cmpset if no concurrency in application.
+	 */
+	success = rte_atomic16_cmpset(&vq->last_used_idx_res,
+				      res_start_idx, res_end_idx);
+	if (unlikely(!success))
+		goto again;
+
+	*start = res_start_idx;
+	*end   = res_end_idx;
+
+	return count;
+}
+
+/**
+ * This function adds buffers to the virtio devices RX virtqueue. Buffers can
+ * be received from the physical port or from another virtio device. A packet
+ * count is returned to indicate the number of packets that are succesfully
+ * added to the RX queue. This function works when the mbuf is scattered, but
+ * it doesn't support the mergeable feature.
+ */
+static inline uint32_t __attribute__((always_inline))
+virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
+	      struct rte_mbuf **pkts, uint32_t count)
+{
+	struct vhost_virtqueue *vq;
+	uint16_t res_start_idx, res_end_idx;
+	uint16_t desc_indexes[MAX_PKT_BURST];
+	uint32_t i;
+
+	LOG_DEBUG(VHOST_DATA, "(%"PRIu64") virtio_dev_rx()\n", dev->device_fh);
+	if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->virt_qp_nb))) {
+		RTE_LOG(ERR, VHOST_DATA,
+			"%s (%"PRIu64"): virtqueue idx:%d invalid.\n",
+			__func__, dev->device_fh, queue_id);
+		return 0;
+	}
+
+	vq = dev->virtqueue[queue_id];
+	if (unlikely(vq->enabled == 0))
+		return 0;
+
+	count = reserve_avail_buf(vq, count, &res_start_idx, &res_end_idx);
+	if (count == 0)
+		return 0;
+
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") res_start_idx %d| res_end_idx Index %d\n",
+		dev->device_fh, res_start_idx, res_end_idx);
+
+	/* Retrieve all of the desc indexes first to avoid caching issues. */
+	rte_prefetch0(&vq->avail->ring[res_start_idx & (vq->size - 1)]);
+	for (i = 0; i < count; i++) {
+		desc_indexes[i] = vq->avail->ring[(res_start_idx + i) &
+						  (vq->size - 1)];
+	}
+
+	rte_prefetch0(&vq->desc[desc_indexes[0]]);
+	for (i = 0; i < count; i++) {
+		uint16_t desc_idx = desc_indexes[i];
+		uint16_t used_idx = (res_start_idx + i) & (vq->size - 1);
+		uint32_t copied;
+		int err;
+
+		err = copy_mbuf_to_desc(dev, vq, pkts[i], desc_idx, &copied);
+
+		vq->used->ring[used_idx].id = desc_idx;
+		if (unlikely(err))
+			vq->used->ring[used_idx].len = vq->vhost_hlen;
+		else
+			vq->used->ring[used_idx].len = copied + vq->vhost_hlen;
+		vhost_log_used_vring(dev, vq,
+			offsetof(struct vring_used, ring[used_idx]),
+			sizeof(vq->used->ring[used_idx]));
+
+		if (i + 1 < count)
+			rte_prefetch0(&vq->desc[desc_indexes[i+1]]);
+	}
+
+	rte_smp_wmb();
+
+	/* Wait until it's our turn to add our buffer to the used ring. */
+	while (unlikely(vq->last_used_idx != res_start_idx))
+		rte_pause();
+
+	*(volatile uint16_t *)&vq->used->idx += count;
+	vq->last_used_idx = res_end_idx;
+	vhost_log_used_vring(dev, vq,
+		offsetof(struct vring_used, idx),
+		sizeof(vq->used->idx));
+
+	/* flush used->idx update before we read avail->flags. */
+	rte_mb();
+
+	/* Kick the guest if necessary. */
+	if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+			&& (vq->callfd >= 0))
+		eventfd_write(vq->callfd, (eventfd_t)1);
+	return count;
+}
+
+static inline int
+fill_vec_buf(struct vhost_virtqueue *vq, uint32_t avail_idx,
+	     uint32_t *allocated, uint32_t *vec_idx)
+{
+	uint16_t idx = vq->avail->ring[avail_idx & (vq->size - 1)];
+	uint32_t vec_id = *vec_idx;
+	uint32_t len    = *allocated;
+
+	while (1) {
+		if (unlikely(vec_id >= BUF_VECTOR_MAX || idx >= vq->size))
+			return -1;
+
+		len += vq->desc[idx].len;
+		vq->buf_vec[vec_id].buf_addr = vq->desc[idx].addr;
+		vq->buf_vec[vec_id].buf_len  = vq->desc[idx].len;
+		vq->buf_vec[vec_id].desc_idx = idx;
+		vec_id++;
+
+		if ((vq->desc[idx].flags & VRING_DESC_F_NEXT) == 0)
+			break;
+
+		idx = vq->desc[idx].next;
+	}
+
+	*allocated = len;
+	*vec_idx   = vec_id;
+
+	return 0;
+}
+
+/*
+ * As many data cores may want to access available buffers concurrently,
+ * they need to be reserved.
+ *
+ * Returns -1 on fail, 0 on success
+ */
+static inline int
+reserve_avail_buf_mergeable(struct vhost_virtqueue *vq, uint32_t size,
+			    uint16_t *start, uint16_t *end)
+{
+	uint16_t res_start_idx;
+	uint16_t res_cur_idx;
+	uint16_t avail_idx;
+	uint32_t allocated;
+	uint32_t vec_idx;
+	uint16_t tries;
+
+again:
+	res_start_idx = vq->last_used_idx_res;
+	res_cur_idx  = res_start_idx;
+
+	allocated = 0;
+	vec_idx   = 0;
+	tries     = 0;
+	while (1) {
+		avail_idx = *((volatile uint16_t *)&vq->avail->idx);
+		if (unlikely(res_cur_idx == avail_idx))
+			return -1;
+
+		if (unlikely(fill_vec_buf(vq, res_cur_idx, &allocated,
+					  &vec_idx) < 0))
+			return -1;
+
+		res_cur_idx++;
+		tries++;
+
+		if (allocated >= size)
+			break;
+
+		/*
+		 * if we tried all available ring items, and still
+		 * can't get enough buf, it means something abnormal
+		 * happened.
+		 */
+		if (unlikely(tries >= vq->size))
+			return -1;
+	}
+
+	/*
+	 * update vq->last_used_idx_res atomically.
+	 * retry again if failed.
+	 */
+	if (rte_atomic16_cmpset(&vq->last_used_idx_res,
+				res_start_idx, res_cur_idx) == 0)
+		goto again;
+
+	*start = res_start_idx;
+	*end   = res_cur_idx;
+	return 0;
+}
+
+static inline uint32_t __attribute__((always_inline))
+copy_mbuf_to_desc_mergeable(struct virtio_net *dev, struct vhost_virtqueue *vq,
+			    uint16_t res_start_idx, uint16_t res_end_idx,
+			    struct rte_mbuf *m)
+{
+	struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, 0, 0, 0, 0, 0}, 0};
+	uint32_t vec_idx = 0;
+	uint16_t cur_idx = res_start_idx;
+	uint64_t desc_addr;
+	uint32_t mbuf_offset, mbuf_avail;
+	uint32_t desc_offset, desc_avail;
+	uint32_t cpy_len;
+	uint16_t desc_idx, used_idx;
+
+	if (unlikely(m == NULL))
+		return 0;
+
+	LOG_DEBUG(VHOST_DATA,
+		"(%"PRIu64") Current Index %d| End Index %d\n",
+		dev->device_fh, cur_idx, res_end_idx);
+
+	if (vq->buf_vec[vec_idx].buf_len < vq->vhost_hlen)
+		return -1;
+
+	desc_addr = gpa_to_vva(dev, vq->buf_vec[vec_idx].buf_addr);
+	rte_prefetch0((void *)(uintptr_t)desc_addr);
+
+	virtio_hdr.num_buffers = res_end_idx - res_start_idx;
+	LOG_DEBUG(VHOST_DATA, "(%"PRIu64") RX: Num merge buffers %d\n",
+		dev->device_fh, virtio_hdr.num_buffers);
+
+	virtio_enqueue_offload(m, &virtio_hdr.hdr);
+	copy_virtio_net_hdr(vq, desc_addr, virtio_hdr);
+	vhost_log_write(dev, vq->buf_vec[vec_idx].buf_addr, vq->vhost_hlen);
+	PRINT_PACKET(dev, (uintptr_t)desc_addr, vq->vhost_hlen, 0);
+
+	desc_avail  = vq->buf_vec[vec_idx].buf_len - vq->vhost_hlen;
+	desc_offset = vq->vhost_hlen;
+
+	mbuf_avail  = rte_pktmbuf_data_len(m);
+	mbuf_offset = 0;
+	while (mbuf_avail != 0 || m->next != NULL) {
+		/* done with current desc buf, get the next one */
+		if (desc_avail == 0) {
+			desc_idx = vq->buf_vec[vec_idx].desc_idx;
+
+			if (!(vq->desc[desc_idx].flags & VRING_DESC_F_NEXT)) {
+				/* Update used ring with desc information */
+				used_idx = cur_idx++ & (vq->size - 1);
+				vq->used->ring[used_idx].id  = desc_idx;
+				vq->used->ring[used_idx].len = desc_offset;
+				vhost_log_used_vring(dev, vq,
+					offsetof(struct vring_used,
+						 ring[used_idx]),
+					sizeof(vq->used->ring[used_idx]));
+			}
+
+			vec_idx++;
+			desc_addr = gpa_to_vva(dev, vq->buf_vec[vec_idx].buf_addr);
+
+			/* Prefetch buffer address. */
+			rte_prefetch0((void *)(uintptr_t)desc_addr);
+			desc_offset = 0;
+			desc_avail  = vq->buf_vec[vec_idx].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);
+		}
+
+		cpy_len = RTE_MIN(desc_avail, mbuf_avail);
+		rte_memcpy((void *)((uintptr_t)(desc_addr + desc_offset)),
+			rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
+			cpy_len);
+		vhost_log_write(dev, vq->buf_vec[vec_idx].buf_addr + desc_offset,
+			cpy_len);
+		PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset),
+			cpy_len, 0);
+
+		mbuf_avail  -= cpy_len;
+		mbuf_offset += cpy_len;
+		desc_avail  -= cpy_len;
+		desc_offset += cpy_len;
+	}
+
+	used_idx = cur_idx & (vq->size - 1);
+	vq->used->ring[used_idx].id = vq->buf_vec[vec_idx].desc_idx;
+	vq->used->ring[used_idx].len = desc_offset;
+	vhost_log_used_vring(dev, vq,
+		offsetof(struct vring_used, ring[used_idx]),
+		sizeof(vq->used->ring[used_idx]));
+
+	return res_end_idx - res_start_idx;
+}
+
+static inline uint32_t __attribute__((always_inline))
+virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
+	struct rte_mbuf **pkts, uint32_t count)
+{
+	struct vhost_virtqueue *vq;
+	uint32_t pkt_idx = 0, nr_used = 0;
+	uint16_t start, end;
+
+	LOG_DEBUG(VHOST_DATA, "(%"PRIu64") virtio_dev_merge_rx()\n",
+		dev->device_fh);
+	if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->virt_qp_nb))) {
+		RTE_LOG(ERR, VHOST_DATA,
+			"%s (%"PRIu64"): virtqueue idx:%d invalid.\n",
+			__func__, dev->device_fh, queue_id);
+		return 0;
+	}
+
+	vq = dev->virtqueue[queue_id];
+	if (unlikely(vq->enabled == 0))
+		return 0;
+
+	count = RTE_MIN((uint32_t)MAX_PKT_BURST, count);
+	if (count == 0)
+		return 0;
+
+	for (pkt_idx = 0; pkt_idx < count; pkt_idx++) {
+		uint32_t pkt_len = pkts[pkt_idx]->pkt_len + vq->vhost_hlen;
+
+		if (unlikely(reserve_avail_buf_mergeable(vq, pkt_len,
+							 &start, &end) < 0)) {
+			LOG_DEBUG(VHOST_DATA,
+				"(%" PRIu64 ") Failed to get enough desc from vring\n",
+				dev->device_fh);
+			break;
+		}
+
+		nr_used = copy_mbuf_to_desc_mergeable(dev, vq, start, end,
+						      pkts[pkt_idx]);
+		rte_smp_wmb();
+
+		/*
+		 * Wait until it's our turn to add our buffer
+		 * to the used ring.
+		 */
+		while (unlikely(vq->last_used_idx != start))
+			rte_pause();
+
+		*(volatile uint16_t *)&vq->used->idx += nr_used;
+		vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
+			sizeof(vq->used->idx));
+		vq->last_used_idx = end;
+	}
+
+	if (likely(pkt_idx)) {
+		/* flush used->idx update before we read avail->flags. */
+		rte_mb();
+
+		/* Kick the guest if necessary. */
+		if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+				&& (vq->callfd >= 0))
+			eventfd_write(vq->callfd, (eventfd_t)1);
+	}
+
+	return pkt_idx;
+}
+
+uint16_t
+rte_vhost_enqueue_burst(struct virtio_net *dev, uint16_t queue_id,
+	struct rte_mbuf **pkts, uint16_t count)
+{
+	if (dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF))
+		return virtio_dev_merge_rx(dev, queue_id, pkts, count);
+	else
+		return virtio_dev_rx(dev, queue_id, pkts, count);
+}
+
+static void
+parse_ethernet(struct rte_mbuf *m, uint16_t *l4_proto, void **l4_hdr)
+{
+	struct ipv4_hdr *ipv4_hdr;
+	struct ipv6_hdr *ipv6_hdr;
+	void *l3_hdr = NULL;
+	struct ether_hdr *eth_hdr;
+	uint16_t ethertype;
+
+	eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
+
+	m->l2_len = sizeof(struct ether_hdr);
+	ethertype = rte_be_to_cpu_16(eth_hdr->ether_type);
+
+	if (ethertype == ETHER_TYPE_VLAN) {
+		struct vlan_hdr *vlan_hdr = (struct vlan_hdr *)(eth_hdr + 1);
+
+		m->l2_len += sizeof(struct vlan_hdr);
+		ethertype = rte_be_to_cpu_16(vlan_hdr->eth_proto);
+	}
+
+	l3_hdr = (char *)eth_hdr + m->l2_len;
+
+	switch (ethertype) {
+	case ETHER_TYPE_IPv4:
+		ipv4_hdr = (struct ipv4_hdr *)l3_hdr;
+		*l4_proto = ipv4_hdr->next_proto_id;
+		m->l3_len = (ipv4_hdr->version_ihl & 0x0f) * 4;
+		*l4_hdr = (char *)l3_hdr + m->l3_len;
+		m->ol_flags |= PKT_TX_IPV4;
+		break;
+	case ETHER_TYPE_IPv6:
+		ipv6_hdr = (struct ipv6_hdr *)l3_hdr;
+		*l4_proto = ipv6_hdr->proto;
+		m->l3_len = sizeof(struct ipv6_hdr);
+		*l4_hdr = (char *)l3_hdr + m->l3_len;
+		m->ol_flags |= PKT_TX_IPV6;
+		break;
+	default:
+		m->l3_len = 0;
+		*l4_proto = 0;
+		break;
+	}
+}
+
+static inline void __attribute__((always_inline))
+vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
+{
+	uint16_t l4_proto = 0;
+	void *l4_hdr = NULL;
+	struct tcp_hdr *tcp_hdr = NULL;
+
+	parse_ethernet(m, &l4_proto, &l4_hdr);
+	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 tcp_hdr, cksum)):
+				if (l4_proto == IPPROTO_TCP)
+					m->ol_flags |= PKT_TX_TCP_CKSUM;
+				break;
+			case (offsetof(struct udp_hdr, dgram_cksum)):
+				if (l4_proto == IPPROTO_UDP)
+					m->ol_flags |= PKT_TX_UDP_CKSUM;
+				break;
+			case (offsetof(struct sctp_hdr, cksum)):
+				if (l4_proto == IPPROTO_SCTP)
+					m->ol_flags |= PKT_TX_SCTP_CKSUM;
+				break;
+			default:
+				break;
+			}
+		}
+	}
+
+	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:
+			tcp_hdr = (struct tcp_hdr *)l4_hdr;
+			m->ol_flags |= PKT_TX_TCP_SEG;
+			m->tso_segsz = hdr->gso_size;
+			m->l4_len = (tcp_hdr->data_off & 0xf0) >> 2;
+			break;
+		default:
+			RTE_LOG(WARNING, VHOST_DATA,
+				"unsupported gso type %u.\n", hdr->gso_type);
+			break;
+		}
+	}
+}
+
+#define RARP_PKT_SIZE	64
+
+static int
+make_rarp_packet(struct rte_mbuf *rarp_mbuf, const struct ether_addr *mac)
+{
+	struct ether_hdr *eth_hdr;
+	struct arp_hdr  *rarp;
+
+	if (rarp_mbuf->buf_len < 64) {
+		RTE_LOG(WARNING, VHOST_DATA,
+			"failed to make RARP; mbuf size too small %u (< %d)\n",
+			rarp_mbuf->buf_len, RARP_PKT_SIZE);
+		return -1;
+	}
+
+	/* Ethernet header. */
+	eth_hdr = rte_pktmbuf_mtod_offset(rarp_mbuf, struct ether_hdr *, 0);
+	memset(eth_hdr->d_addr.addr_bytes, 0xff, ETHER_ADDR_LEN);
+	ether_addr_copy(mac, &eth_hdr->s_addr);
+	eth_hdr->ether_type = htons(ETHER_TYPE_RARP);
+
+	/* RARP header. */
+	rarp = (struct arp_hdr *)(eth_hdr + 1);
+	rarp->arp_hrd = htons(ARP_HRD_ETHER);
+	rarp->arp_pro = htons(ETHER_TYPE_IPv4);
+	rarp->arp_hln = ETHER_ADDR_LEN;
+	rarp->arp_pln = 4;
+	rarp->arp_op  = htons(ARP_OP_REVREQUEST);
+
+	ether_addr_copy(mac, &rarp->arp_data.arp_sha);
+	ether_addr_copy(mac, &rarp->arp_data.arp_tha);
+	memset(&rarp->arp_data.arp_sip, 0x00, 4);
+	memset(&rarp->arp_data.arp_tip, 0x00, 4);
+
+	rarp_mbuf->pkt_len  = rarp_mbuf->data_len = RARP_PKT_SIZE;
+
+	return 0;
+}
+
+static inline int __attribute__((always_inline))
+copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
+		  struct rte_mbuf *m, uint16_t desc_idx,
+		  struct rte_mempool *mbuf_pool)
+{
+	struct vring_desc *desc;
+	uint64_t desc_addr;
+	uint32_t desc_avail, desc_offset;
+	uint32_t mbuf_avail, mbuf_offset;
+	uint32_t cpy_len;
+	struct rte_mbuf *cur = m, *prev = m;
+	struct virtio_net_hdr *hdr;
+	/* A counter to avoid desc dead loop chain */
+	uint32_t nr_desc = 1;
+
+	desc = &vq->desc[desc_idx];
+	if (unlikely(desc->len < vq->vhost_hlen))
+		return -1;
+
+	desc_addr = gpa_to_vva(dev, desc->addr);
+	rte_prefetch0((void *)(uintptr_t)desc_addr);
+
+	/* Retrieve virtio net header */
+	hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
+	desc_avail  = desc->len - vq->vhost_hlen;
+	desc_offset = vq->vhost_hlen;
+
+	mbuf_offset = 0;
+	mbuf_avail  = m->buf_len - RTE_PKTMBUF_HEADROOM;
+	while (desc_avail != 0 || (desc->flags & VRING_DESC_F_NEXT) != 0) {
+		/* This desc reaches to its end, get the next one */
+		if (desc_avail == 0) {
+			if (unlikely(desc->next >= vq->size ||
+				     ++nr_desc >= vq->size))
+				return -1;
+			desc = &vq->desc[desc->next];
+
+			desc_addr = gpa_to_vva(dev, desc->addr);
+			rte_prefetch0((void *)(uintptr_t)desc_addr);
+
+			desc_offset = 0;
+			desc_avail  = desc->len;
+
+			PRINT_PACKET(dev, (uintptr_t)desc_addr, desc->len, 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)) {
+				RTE_LOG(ERR, VHOST_DATA, "Failed to "
+					"allocate memory for mbuf.\n");
+				return -1;
+			}
+
+			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;
+		}
+
+		cpy_len = RTE_MIN(desc_avail, mbuf_avail);
+		rte_memcpy(rte_pktmbuf_mtod_offset(cur, void *, mbuf_offset),
+			(void *)((uintptr_t)(desc_addr + desc_offset)),
+			cpy_len);
+
+		mbuf_avail  -= cpy_len;
+		mbuf_offset += cpy_len;
+		desc_avail  -= cpy_len;
+		desc_offset += cpy_len;
+	}
+
+	prev->data_len = mbuf_offset;
+	m->pkt_len    += mbuf_offset;
+
+	if (hdr->flags != 0 || hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE)
+		vhost_dequeue_offload(hdr, m);
+
+	return 0;
+}
+
+uint16_t
+rte_vhost_dequeue_burst(struct virtio_net *dev, uint16_t queue_id,
+	struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
+{
+	struct rte_mbuf *rarp_mbuf = NULL;
+	struct vhost_virtqueue *vq;
+	uint32_t desc_indexes[MAX_PKT_BURST];
+	uint32_t used_idx;
+	uint32_t i = 0;
+	uint16_t free_entries;
+	uint16_t avail_idx;
+
+	if (unlikely(!is_valid_virt_queue_idx(queue_id, 1, dev->virt_qp_nb))) {
+		RTE_LOG(ERR, VHOST_DATA,
+			"%s (%"PRIu64"): virtqueue idx:%d invalid.\n",
+			__func__, dev->device_fh, queue_id);
+		return 0;
+	}
+
+	vq = dev->virtqueue[queue_id];
+	if (unlikely(vq->enabled == 0))
+		return 0;
+
+	/*
+	 * Construct a RARP broadcast packet, and inject it to the "pkts"
+	 * array, to looks like that guest actually send such packet.
+	 *
+	 * Check user_send_rarp() for more information.
+	 */
+	if (unlikely(rte_atomic16_cmpset((volatile uint16_t *)
+					 &dev->broadcast_rarp.cnt, 1, 0))) {
+		rarp_mbuf = rte_pktmbuf_alloc(mbuf_pool);
+		if (rarp_mbuf == NULL) {
+			RTE_LOG(ERR, VHOST_DATA,
+				"Failed to allocate memory for mbuf.\n");
+			return 0;
+		}
+
+		if (make_rarp_packet(rarp_mbuf, &dev->mac)) {
+			rte_pktmbuf_free(rarp_mbuf);
+			rarp_mbuf = NULL;
+		} else {
+			count -= 1;
+		}
+	}
+
+	avail_idx =  *((volatile uint16_t *)&vq->avail->idx);
+	free_entries = avail_idx - vq->last_used_idx;
+	if (free_entries == 0)
+		goto out;
+
+	LOG_DEBUG(VHOST_DATA, "%s (%"PRIu64")\n", __func__, dev->device_fh);
+
+	/* Prefetch available ring to retrieve head indexes. */
+	used_idx = vq->last_used_idx & (vq->size - 1);
+	rte_prefetch0(&vq->avail->ring[used_idx]);
+
+	count = RTE_MIN(count, MAX_PKT_BURST);
+	count = RTE_MIN(count, free_entries);
+	LOG_DEBUG(VHOST_DATA, "(%"PRIu64") about to dequeue %u buffers\n",
+			dev->device_fh, count);
+
+	/* Retrieve all of the head indexes first to avoid caching issues. */
+	for (i = 0; i < count; i++) {
+		desc_indexes[i] = vq->avail->ring[(vq->last_used_idx + i) &
+					(vq->size - 1)];
+	}
+
+	/* Prefetch descriptor index. */
+	rte_prefetch0(&vq->desc[desc_indexes[0]]);
+	rte_prefetch0(&vq->used->ring[vq->last_used_idx & (vq->size - 1)]);
+
+	for (i = 0; i < count; i++) {
+		int err;
+
+		if (likely(i + 1 < count)) {
+			rte_prefetch0(&vq->desc[desc_indexes[i + 1]]);
+			rte_prefetch0(&vq->used->ring[(used_idx + 1) &
+						      (vq->size - 1)]);
+		}
+
+		pkts[i] = rte_pktmbuf_alloc(mbuf_pool);
+		if (unlikely(pkts[i] == NULL)) {
+			RTE_LOG(ERR, VHOST_DATA,
+				"Failed to allocate memory for mbuf.\n");
+			break;
+		}
+		err = copy_desc_to_mbuf(dev, vq, pkts[i], desc_indexes[i],
+					mbuf_pool);
+		if (unlikely(err)) {
+			rte_pktmbuf_free(pkts[i]);
+			break;
+		}
+
+		used_idx = vq->last_used_idx++ & (vq->size - 1);
+		vq->used->ring[used_idx].id  = desc_indexes[i];
+		vq->used->ring[used_idx].len = 0;
+		vhost_log_used_vring(dev, vq,
+				offsetof(struct vring_used, ring[used_idx]),
+				sizeof(vq->used->ring[used_idx]));
+	}
+
+	rte_smp_wmb();
+	rte_smp_rmb();
+	vq->used->idx += i;
+	vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
+			sizeof(vq->used->idx));
+
+	/* Kick guest if required. */
+	if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+			&& (vq->callfd >= 0))
+		eventfd_write(vq->callfd, (eventfd_t)1);
+
+out:
+	if (unlikely(rarp_mbuf != NULL)) {
+		/*
+		 * Inject it to the head of "pkts" array, so that switch's mac
+		 * learning table will get updated first.
+		 */
+		memmove(&pkts[1], pkts, i * sizeof(struct rte_mbuf *));
+		pkts[0] = rarp_mbuf;
+		i += 1;
+	}
+
+	return i;
+}