vhost: improve prefetching in enqueue path
[dpdk.git] / lib / librte_vhost / virtio_net.c
index 4f7217f..82d5d9e 100644 (file)
@@ -15,6 +15,8 @@
 #include <rte_udp.h>
 #include <rte_sctp.h>
 #include <rte_arp.h>
+#include <rte_spinlock.h>
+#include <rte_malloc.h>
 
 #include "iotlb.h"
 #include "vhost.h"
 
 #define MAX_BATCH_LEN 256
 
+static  __rte_always_inline bool
+rxvq_is_mergeable(struct virtio_net *dev)
+{
+       return dev->features & (1ULL << VIRTIO_NET_F_MRG_RXBUF);
+}
+
 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;
 }
 
+static __rte_always_inline struct vring_desc *
+alloc_copy_ind_table(struct virtio_net *dev, struct vhost_virtqueue *vq,
+                                        struct vring_desc *desc)
+{
+       struct vring_desc *idesc;
+       uint64_t src, dst;
+       uint64_t len, remain = desc->len;
+       uint64_t desc_addr = desc->addr;
+
+       idesc = rte_malloc(__func__, desc->len, 0);
+       if (unlikely(!idesc))
+               return 0;
+
+       dst = (uint64_t)(uintptr_t)idesc;
+
+       while (remain) {
+               len = remain;
+               src = vhost_iova_to_vva(dev, vq, desc_addr, &len,
+                               VHOST_ACCESS_RO);
+               if (unlikely(!src || !len)) {
+                       rte_free(idesc);
+                       return 0;
+               }
+
+               rte_memcpy((void *)(uintptr_t)dst, (void *)(uintptr_t)src, len);
+
+               remain -= len;
+               dst += len;
+               desc_addr += len;
+       }
+
+       return idesc;
+}
+
+static __rte_always_inline void
+free_ind_table(struct vring_desc *idesc)
+{
+       rte_free(idesc);
+}
+
 static __rte_always_inline void
 do_flush_shadow_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq,
                          uint16_t to, uint16_t from, uint16_t size)
@@ -36,7 +84,7 @@ do_flush_shadow_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq,
        rte_memcpy(&vq->used->ring[to],
                        &vq->shadow_used_ring[from],
                        size * sizeof(struct vring_used_elem));
-       vhost_log_used_vring(dev, vq,
+       vhost_log_cache_used_vring(dev, vq,
                        offsetof(struct vring_used, ring[to]),
                        size * sizeof(struct vring_used_elem));
 }
@@ -64,6 +112,8 @@ flush_shadow_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq)
 
        rte_smp_wmb();
 
+       vhost_log_cache_sync(dev, vq);
+
        *(volatile uint16_t *)&vq->used->idx += vq->shadow_used_idx;
        vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
                sizeof(vq->used->idx));
@@ -88,7 +138,7 @@ do_data_copy_enqueue(struct virtio_net *dev, struct vhost_virtqueue *vq)
 
        for (i = 0; i < count; i++) {
                rte_memcpy(elem[i].dst, elem[i].src, elem[i].len);
-               vhost_log_write(dev, elem[i].log_addr, elem[i].len);
+               vhost_log_cache_write(dev, vq, elem[i].log_addr, elem[i].len);
                PRINT_PACKET(dev, (uintptr_t)elem[i].dst, elem[i].len, 0);
        }
 }
@@ -110,7 +160,7 @@ do_data_copy_dequeue(struct vhost_virtqueue *vq)
                (var) = (val);                  \
 } while (0)
 
-static void
+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 & PKT_TX_L4_MASK;
@@ -159,6 +209,11 @@ virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
                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 & PKT_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);
@@ -166,260 +221,83 @@ virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
        }
 }
 
-static __rte_always_inline int
-copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
-                 struct vring_desc *descs, struct rte_mbuf *m,
-                 uint16_t desc_idx, uint32_t size)
-{
-       uint32_t desc_avail, desc_offset;
-       uint32_t mbuf_avail, mbuf_offset;
-       uint32_t cpy_len;
-       struct vring_desc *desc;
-       uint64_t desc_addr;
-       /* A counter to avoid desc dead loop chain */
-       uint16_t nr_desc = 1;
-       struct batch_copy_elem *batch_copy = vq->batch_copy_elems;
-       uint16_t copy_nb = vq->batch_copy_nb_elems;
-       int error = 0;
-
-       desc = &descs[desc_idx];
-       desc_addr = vhost_iova_to_vva(dev, vq, desc->addr,
-                                       desc->len, VHOST_ACCESS_RW);
-       /*
-        * Checking of 'desc_addr' placed outside of 'unlikely' macro to avoid
-        * performance issue with some versions of gcc (4.8.4 and 5.3.0) which
-        * otherwise stores offset on the stack instead of in a register.
-        */
-       if (unlikely(desc->len < dev->vhost_hlen) || !desc_addr) {
-               error = -1;
-               goto out;
-       }
-
-       rte_prefetch0((void *)(uintptr_t)desc_addr);
-
-       virtio_enqueue_offload(m, (struct virtio_net_hdr *)(uintptr_t)desc_addr);
-       vhost_log_write(dev, desc->addr, dev->vhost_hlen);
-       PRINT_PACKET(dev, (uintptr_t)desc_addr, dev->vhost_hlen, 0);
-
-       desc_offset = dev->vhost_hlen;
-       desc_avail  = desc->len - dev->vhost_hlen;
-
-       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 */
-                               error = -1;
-                               goto out;
-                       }
-                       if (unlikely(desc->next >= size || ++nr_desc > size)) {
-                               error = -1;
-                               goto out;
-                       }
-
-                       desc = &descs[desc->next];
-                       desc_addr = vhost_iova_to_vva(dev, vq, desc->addr,
-                                                       desc->len,
-                                                       VHOST_ACCESS_RW);
-                       if (unlikely(!desc_addr)) {
-                               error = -1;
-                               goto out;
-                       }
-
-                       desc_offset = 0;
-                       desc_avail  = desc->len;
-               }
-
-               cpy_len = RTE_MIN(desc_avail, mbuf_avail);
-               if (likely(cpy_len > MAX_BATCH_LEN || copy_nb >= vq->size)) {
-                       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);
-               } else {
-                       batch_copy[copy_nb].dst =
-                               (void *)((uintptr_t)(desc_addr + desc_offset));
-                       batch_copy[copy_nb].src =
-                               rte_pktmbuf_mtod_offset(m, void *, mbuf_offset);
-                       batch_copy[copy_nb].log_addr = desc->addr + desc_offset;
-                       batch_copy[copy_nb].len = cpy_len;
-                       copy_nb++;
-               }
-
-               mbuf_avail  -= cpy_len;
-               mbuf_offset += cpy_len;
-               desc_avail  -= cpy_len;
-               desc_offset += cpy_len;
-       }
-
-out:
-       vq->batch_copy_nb_elems = copy_nb;
-
-       return error;
-}
-
-/**
- * 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 successfully
- * added to the RX queue. This function works when the mbuf is scattered, but
- * it doesn't support the mergeable feature.
- */
-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;
-       uint16_t avail_idx, free_entries, start_idx;
-       uint16_t desc_indexes[MAX_PKT_BURST];
-       struct vring_desc *descs;
-       uint16_t used_idx;
-       uint32_t i, sz;
-
-       LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
-       if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->nr_vring))) {
-               RTE_LOG(ERR, VHOST_DATA, "(%d) %s: invalid virtqueue idx %d.\n",
-                       dev->vid, __func__, queue_id);
-               return 0;
-       }
-
-       vq = dev->virtqueue[queue_id];
-       if (unlikely(vq->enabled == 0))
-               return 0;
-
-       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)) {
-                       count = 0;
-                       goto out;
-               }
-       }
-
-       avail_idx = *((volatile uint16_t *)&vq->avail->idx);
-       start_idx = vq->last_used_idx;
-       free_entries = avail_idx - start_idx;
-       count = RTE_MIN(count, free_entries);
-       count = RTE_MIN(count, (uint32_t)MAX_PKT_BURST);
-       if (count == 0)
-               goto out;
-
-       LOG_DEBUG(VHOST_DATA, "(%d) start_idx %d | end_idx %d\n",
-               dev->vid, start_idx, start_idx + count);
-
-       vq->batch_copy_nb_elems = 0;
-
-       /* Retrieve all of the desc indexes first to avoid caching issues. */
-       rte_prefetch0(&vq->avail->ring[start_idx & (vq->size - 1)]);
-       for (i = 0; i < count; i++) {
-               used_idx = (start_idx + i) & (vq->size - 1);
-               desc_indexes[i] = vq->avail->ring[used_idx];
-               vq->used->ring[used_idx].id = desc_indexes[i];
-               vq->used->ring[used_idx].len = pkts[i]->pkt_len +
-                                              dev->vhost_hlen;
-               vhost_log_used_vring(dev, vq,
-                       offsetof(struct vring_used, ring[used_idx]),
-                       sizeof(vq->used->ring[used_idx]));
-       }
-
-       rte_prefetch0(&vq->desc[desc_indexes[0]]);
-       for (i = 0; i < count; i++) {
-               uint16_t desc_idx = desc_indexes[i];
-               int err;
-
-               if (vq->desc[desc_idx].flags & VRING_DESC_F_INDIRECT) {
-                       descs = (struct vring_desc *)(uintptr_t)
-                               vhost_iova_to_vva(dev,
-                                               vq, vq->desc[desc_idx].addr,
-                                               vq->desc[desc_idx].len,
-                                               VHOST_ACCESS_RO);
-                       if (unlikely(!descs)) {
-                               count = i;
-                               break;
-                       }
-
-                       desc_idx = 0;
-                       sz = vq->desc[desc_idx].len / sizeof(*descs);
-               } else {
-                       descs = vq->desc;
-                       sz = vq->size;
-               }
-
-               err = copy_mbuf_to_desc(dev, vq, descs, pkts[i], desc_idx, sz);
-               if (unlikely(err)) {
-                       count = i;
-                       break;
-               }
-
-               if (i + 1 < count)
-                       rte_prefetch0(&vq->desc[desc_indexes[i+1]]);
-       }
-
-       do_data_copy_enqueue(dev, vq);
-
-       rte_smp_wmb();
-
-       *(volatile uint16_t *)&vq->used->idx += count;
-       vq->last_used_idx += count;
-       vhost_log_used_vring(dev, vq,
-               offsetof(struct vring_used, idx),
-               sizeof(vq->used->idx));
-
-       vhost_vring_call(vq);
-out:
-       if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
-               vhost_user_iotlb_rd_unlock(vq);
-
-       return count;
-}
-
 static __rte_always_inline int
 fill_vec_buf(struct virtio_net *dev, struct vhost_virtqueue *vq,
                         uint32_t avail_idx, uint32_t *vec_idx,
                         struct buf_vector *buf_vec, uint16_t *desc_chain_head,
-                        uint16_t *desc_chain_len)
+                        uint16_t *desc_chain_len, uint8_t perm)
 {
        uint16_t idx = vq->avail->ring[avail_idx & (vq->size - 1)];
        uint32_t vec_id = *vec_idx;
        uint32_t len    = 0;
+       uint64_t dlen, desc_avail, desc_iova;
        struct vring_desc *descs = vq->desc;
+       struct vring_desc *idesc = NULL;
 
        *desc_chain_head = idx;
 
        if (vq->desc[idx].flags & VRING_DESC_F_INDIRECT) {
+               dlen = vq->desc[idx].len;
                descs = (struct vring_desc *)(uintptr_t)
                        vhost_iova_to_vva(dev, vq, vq->desc[idx].addr,
-                                               vq->desc[idx].len,
+                                               &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 = alloc_copy_ind_table(dev, vq, &vq->desc[idx]);
+                       if (unlikely(!idesc))
+                               return -1;
+
+                       descs = idesc;
+               }
+
                idx = 0;
        }
 
        while (1) {
-               if (unlikely(vec_id >= BUF_VECTOR_MAX || idx >= vq->size))
+               if (unlikely(idx >= vq->size)) {
+                       free_ind_table(idesc);
                        return -1;
+               }
+
 
                len += descs[idx].len;
-               buf_vec[vec_id].buf_addr = descs[idx].addr;
-               buf_vec[vec_id].buf_len  = descs[idx].len;
-               buf_vec[vec_id].desc_idx = idx;
-               vec_id++;
+               desc_avail = descs[idx].len;
+               desc_iova = descs[idx].addr;
+
+               while (desc_avail) {
+                       uint64_t desc_addr;
+                       uint64_t desc_chunck_len = desc_avail;
+
+                       if (unlikely(vec_id >= BUF_VECTOR_MAX)) {
+                               free_ind_table(idesc);
+                               return -1;
+                       }
+
+                       desc_addr = vhost_iova_to_vva(dev, vq,
+                                       desc_iova,
+                                       &desc_chunck_len,
+                                       perm);
+                       if (unlikely(!desc_addr)) {
+                               free_ind_table(idesc);
+                               return -1;
+                       }
+
+                       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;
+                       buf_vec[vec_id].desc_idx = idx;
+
+                       desc_avail -= desc_chunck_len;
+                       desc_iova += desc_chunck_len;
+                       vec_id++;
+               }
 
                if ((descs[idx].flags & VRING_DESC_F_NEXT) == 0)
                        break;
@@ -430,6 +308,9 @@ fill_vec_buf(struct virtio_net *dev, struct vhost_virtqueue *vq,
        *desc_chain_len = len;
        *vec_idx = vec_id;
 
+       if (unlikely(!!idesc))
+               free_ind_table(idesc);
+
        return 0;
 }
 
@@ -437,13 +318,14 @@ fill_vec_buf(struct virtio_net *dev, struct vhost_virtqueue *vq,
  * Returns -1 on fail, 0 on success
  */
 static inline int
-reserve_avail_buf_mergeable(struct virtio_net *dev, struct vhost_virtqueue *vq,
+reserve_avail_buf(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 *num_buffers, uint16_t avail_head,
+                               uint16_t *nr_vec)
 {
        uint16_t cur_idx;
        uint32_t vec_idx = 0;
-       uint16_t tries = 0;
+       uint16_t max_tries, tries = 0;
 
        uint16_t head_idx = 0;
        uint16_t len = 0;
@@ -451,12 +333,18 @@ reserve_avail_buf_mergeable(struct virtio_net *dev, struct vhost_virtqueue *vq,
        *num_buffers = 0;
        cur_idx  = vq->last_avail_idx;
 
+       if (rxvq_is_mergeable(dev))
+               max_tries = vq->size;
+       else
+               max_tries = 1;
+
        while (size > 0) {
                if (unlikely(cur_idx == avail_head))
                        return -1;
 
                if (unlikely(fill_vec_buf(dev, vq, cur_idx, &vec_idx, buf_vec,
-                                               &head_idx, &len) < 0))
+                                               &head_idx, &len,
+                                               VHOST_ACCESS_RW) < 0))
                        return -1;
                len = RTE_MIN(len, size);
                update_shadow_used_ring(vq, head_idx, len);
@@ -471,27 +359,29 @@ reserve_avail_buf_mergeable(struct virtio_net *dev, struct vhost_virtqueue *vq,
                 * can't get enough buf, it means something abnormal
                 * happened.
                 */
-               if (unlikely(tries >= vq->size))
+               if (unlikely(tries > max_tries))
                        return -1;
        }
 
+       *nr_vec = vec_idx;
+
        return 0;
 }
 
 static __rte_always_inline int
-copy_mbuf_to_desc_mergeable(struct virtio_net *dev, struct vhost_virtqueue *vq,
+copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
                            struct rte_mbuf *m, struct buf_vector *buf_vec,
-                           uint16_t num_buffers)
+                           uint16_t nr_vec, uint16_t num_buffers)
 {
        uint32_t vec_idx = 0;
-       uint64_t desc_addr;
        uint32_t mbuf_offset, mbuf_avail;
-       uint32_t desc_offset, desc_avail;
+       uint32_t buf_offset, buf_avail;
+       uint64_t buf_addr, buf_iova, buf_len;
        uint32_t cpy_len;
-       uint64_t hdr_addr, hdr_phys_addr;
+       uint64_t hdr_addr;
        struct rte_mbuf *hdr_mbuf;
        struct batch_copy_elem *batch_copy = vq->batch_copy_elems;
-       uint16_t copy_nb = vq->batch_copy_nb_elems;
+       struct virtio_net_hdr_mrg_rxbuf tmp_hdr, *hdr = NULL;
        int error = 0;
 
        if (unlikely(m == NULL)) {
@@ -499,45 +389,61 @@ copy_mbuf_to_desc_mergeable(struct virtio_net *dev, struct vhost_virtqueue *vq,
                goto out;
        }
 
-       desc_addr = vhost_iova_to_vva(dev, vq, buf_vec[vec_idx].buf_addr,
-                                               buf_vec[vec_idx].buf_len,
-                                               VHOST_ACCESS_RW);
-       if (buf_vec[vec_idx].buf_len < dev->vhost_hlen || !desc_addr) {
+       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 (nr_vec > 1)
+               rte_prefetch0((void *)(uintptr_t)buf_vec[1].buf_addr);
+
+       if (unlikely(buf_len < dev->vhost_hlen && nr_vec <= 1)) {
                error = -1;
                goto out;
        }
 
        hdr_mbuf = m;
-       hdr_addr = desc_addr;
-       hdr_phys_addr = buf_vec[vec_idx].buf_addr;
-       rte_prefetch0((void *)(uintptr_t)hdr_addr);
+       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;
 
-       LOG_DEBUG(VHOST_DATA, "(%d) RX: num merge buffers %d\n",
+       VHOST_LOG_DEBUG(VHOST_DATA, "(%d) RX: num merge buffers %d\n",
                dev->vid, num_buffers);
 
-       desc_avail  = buf_vec[vec_idx].buf_len - dev->vhost_hlen;
-       desc_offset = dev->vhost_hlen;
+       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 desc buf, get the next one */
-               if (desc_avail == 0) {
+               /* done with current buf, get the next one */
+               if (buf_avail == 0) {
                        vec_idx++;
-                       desc_addr =
-                               vhost_iova_to_vva(dev, vq,
-                                       buf_vec[vec_idx].buf_addr,
-                                       buf_vec[vec_idx].buf_len,
-                                       VHOST_ACCESS_RW);
-                       if (unlikely(!desc_addr)) {
+                       if (unlikely(vec_idx >= nr_vec)) {
                                error = -1;
                                goto out;
                        }
 
-                       /* Prefetch buffer address. */
-                       rte_prefetch0((void *)(uintptr_t)desc_addr);
-                       desc_offset = 0;
-                       desc_avail  = buf_vec[vec_idx].buf_len;
+                       buf_addr = buf_vec[vec_idx].buf_addr;
+                       buf_iova = buf_vec[vec_idx].buf_iova;
+                       buf_len = buf_vec[vec_idx].buf_len;
+
+                       /* Prefetch next buffer address. */
+                       if (vec_idx + 1 < nr_vec)
+                               rte_prefetch0((void *)(uintptr_t)
+                                               buf_vec[vec_idx + 1].buf_addr);
+                       buf_offset = 0;
+                       buf_avail  = buf_len;
                }
 
                /* done with current mbuf, get the next one */
@@ -549,57 +455,81 @@ copy_mbuf_to_desc_mergeable(struct virtio_net *dev, struct vhost_virtqueue *vq,
                }
 
                if (hdr_addr) {
-                       struct virtio_net_hdr_mrg_rxbuf *hdr;
-
-                       hdr = (struct virtio_net_hdr_mrg_rxbuf *)(uintptr_t)
-                               hdr_addr;
                        virtio_enqueue_offload(hdr_mbuf, &hdr->hdr);
-                       ASSIGN_UNLESS_EQUAL(hdr->num_buffers, num_buffers);
-
-                       vhost_log_write(dev, hdr_phys_addr, dev->vhost_hlen);
-                       PRINT_PACKET(dev, (uintptr_t)hdr_addr,
-                                    dev->vhost_hlen, 0);
+                       if (rxvq_is_mergeable(dev))
+                               ASSIGN_UNLESS_EQUAL(hdr->num_buffers,
+                                               num_buffers);
+
+                       if (unlikely(hdr == &tmp_hdr)) {
+                               uint64_t len;
+                               uint64_t remain = dev->vhost_hlen;
+                               uint64_t src = (uint64_t)(uintptr_t)hdr, dst;
+                               uint64_t iova = buf_vec[0].buf_iova;
+                               uint16_t hdr_vec_idx = 0;
+
+                               while (remain) {
+                                       len = remain;
+                                       dst = buf_vec[hdr_vec_idx].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(dev, vq,
+                                                       iova, len);
+
+                                       remain -= len;
+                                       iova += len;
+                                       src += len;
+                                       hdr_vec_idx++;
+                               }
+                       } else {
+                               PRINT_PACKET(dev, (uintptr_t)hdr_addr,
+                                               dev->vhost_hlen, 0);
+                               vhost_log_cache_write(dev, vq,
+                                               buf_vec[0].buf_iova,
+                                               dev->vhost_hlen);
+                       }
 
                        hdr_addr = 0;
                }
 
-               cpy_len = RTE_MIN(desc_avail, mbuf_avail);
+               cpy_len = RTE_MIN(buf_len, mbuf_avail);
 
-               if (likely(cpy_len > MAX_BATCH_LEN || copy_nb >= vq->size)) {
-                       rte_memcpy((void *)((uintptr_t)(desc_addr +
-                                                       desc_offset)),
+               if (likely(cpy_len > MAX_BATCH_LEN ||
+                                       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);
-                       vhost_log_write(dev,
-                               buf_vec[vec_idx].buf_addr + desc_offset,
-                               cpy_len);
-                       PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset),
+                       vhost_log_cache_write(dev, vq, buf_iova + buf_offset,
+                                       cpy_len);
+                       PRINT_PACKET(dev, (uintptr_t)(buf_addr + buf_offset),
                                cpy_len, 0);
                } else {
-                       batch_copy[copy_nb].dst =
-                               (void *)((uintptr_t)(desc_addr + desc_offset));
-                       batch_copy[copy_nb].src =
+                       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[copy_nb].log_addr =
-                               buf_vec[vec_idx].buf_addr + desc_offset;
-                       batch_copy[copy_nb].len = cpy_len;
-                       copy_nb++;
+                       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;
-               desc_avail  -= cpy_len;
-               desc_offset += cpy_len;
+               buf_avail  -= cpy_len;
+               buf_offset += cpy_len;
        }
 
 out:
-       vq->batch_copy_nb_elems = copy_nb;
 
        return error;
 }
 
 static __rte_always_inline uint32_t
-virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
+virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
        struct rte_mbuf **pkts, uint32_t count)
 {
        struct vhost_virtqueue *vq;
@@ -608,7 +538,7 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
        struct buf_vector buf_vec[BUF_VECTOR_MAX];
        uint16_t avail_head;
 
-       LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
+       VHOST_LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
        if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->nr_vring))) {
                RTE_LOG(ERR, VHOST_DATA, "(%d) %s: invalid virtqueue idx %d.\n",
                        dev->vid, __func__, queue_id);
@@ -616,8 +546,11 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
        }
 
        vq = dev->virtqueue[queue_id];
+
+       rte_spinlock_lock(&vq->access_lock);
+
        if (unlikely(vq->enabled == 0))
-               return 0;
+               goto out_access_unlock;
 
        if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
                vhost_user_iotlb_rd_lock(vq);
@@ -638,23 +571,27 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
        avail_head = *((volatile uint16_t *)&vq->avail->idx);
        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_mergeable(dev, vq,
+               if (unlikely(reserve_avail_buf(dev, vq,
                                                pkt_len, buf_vec, &num_buffers,
-                                               avail_head) < 0)) {
-                       LOG_DEBUG(VHOST_DATA,
+                                               avail_head, &nr_vec) < 0)) {
+                       VHOST_LOG_DEBUG(VHOST_DATA,
                                "(%d) failed to get enough desc from vring\n",
                                dev->vid);
                        vq->shadow_used_idx -= num_buffers;
                        break;
                }
 
-               LOG_DEBUG(VHOST_DATA, "(%d) current index %d | end index %d\n",
+               rte_prefetch0((void *)(uintptr_t)buf_vec[0].buf_addr);
+
+               VHOST_LOG_DEBUG(VHOST_DATA, "(%d) current index %d | end index %d\n",
                        dev->vid, vq->last_avail_idx,
                        vq->last_avail_idx + num_buffers);
 
-               if (copy_mbuf_to_desc_mergeable(dev, vq, pkts[pkt_idx],
-                                               buf_vec, num_buffers) < 0) {
+               if (copy_mbuf_to_desc(dev, vq, pkts[pkt_idx],
+                                               buf_vec, nr_vec,
+                                               num_buffers) < 0) {
                        vq->shadow_used_idx -= num_buffers;
                        break;
                }
@@ -666,13 +603,16 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
 
        if (likely(vq->shadow_used_idx)) {
                flush_shadow_used_ring(dev, vq);
-               vhost_vring_call(vq);
+               vhost_vring_call(dev, vq);
        }
 
 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 pkt_idx;
 }
 
@@ -685,10 +625,14 @@ rte_vhost_enqueue_burst(int vid, uint16_t queue_id,
        if (!dev)
                return 0;
 
-       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);
+       if (unlikely(!(dev->flags & VIRTIO_DEV_BUILTIN_VIRTIO_NET))) {
+               RTE_LOG(ERR, VHOST_DATA,
+                       "(%d) %s: built-in vhost net backend is disabled.\n",
+                       dev->vid, __func__);
+               return 0;
+       }
+
+       return virtio_dev_rx(dev, queue_id, pkts, count);
 }
 
 static inline bool
@@ -792,6 +736,11 @@ vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
                        m->tso_segsz = hdr->gso_size;
                        m->l4_len = (tcp_hdr->data_off & 0xf0) >> 2;
                        break;
+               case VIRTIO_NET_HDR_GSO_UDP:
+                       m->ol_flags |= PKT_TX_UDP_SEG;
+                       m->tso_segsz = hdr->gso_size;
+                       m->l4_len = sizeof(struct udp_hdr);
+                       break;
                default:
                        RTE_LOG(WARNING, VHOST_DATA,
                                "unsupported gso type %u.\n", hdr->gso_type);
@@ -800,45 +749,6 @@ vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
        }
 }
 
-#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 __rte_always_inline void
 put_zmbuf(struct zcopy_mbuf *zmbuf)
 {
@@ -847,42 +757,61 @@ put_zmbuf(struct zcopy_mbuf *zmbuf)
 
 static __rte_always_inline int
 copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
-                 struct vring_desc *descs, uint16_t max_desc,
-                 struct rte_mbuf *m, uint16_t desc_idx,
-                 struct rte_mempool *mbuf_pool)
+                 struct buf_vector *buf_vec, uint16_t nr_vec,
+                 struct rte_mbuf *m, struct rte_mempool *mbuf_pool)
 {
-       struct vring_desc *desc;
-       uint64_t desc_addr;
-       uint32_t desc_avail, desc_offset;
+       uint32_t buf_avail, buf_offset;
+       uint64_t buf_addr, buf_iova, buf_len;
        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 */
-       uint32_t nr_desc = 1;
+       uint16_t vec_idx = 0;
        struct batch_copy_elem *batch_copy = vq->batch_copy_elems;
-       uint16_t copy_nb = vq->batch_copy_nb_elems;
        int error = 0;
 
-       desc = &descs[desc_idx];
-       if (unlikely((desc->len < dev->vhost_hlen)) ||
-                       (desc->flags & VRING_DESC_F_INDIRECT)) {
-               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;
 
-       desc_addr = vhost_iova_to_vva(dev,
-                                       vq, desc->addr,
-                                       desc->len,
-                                       VHOST_ACCESS_RO);
-       if (unlikely(!desc_addr)) {
+       if (unlikely(buf_len < dev->vhost_hlen && nr_vec <= 1)) {
                error = -1;
                goto out;
        }
 
+       if (likely(nr_vec > 1))
+               rte_prefetch0((void *)(uintptr_t)buf_vec[1].buf_addr);
+
        if (virtio_net_with_host_offload(dev)) {
-               hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
-               rte_prefetch0(hdr);
+               if (unlikely(buf_len < sizeof(struct virtio_net_hdr))) {
+                       uint64_t len;
+                       uint64_t remain = sizeof(struct virtio_net_hdr);
+                       uint64_t src;
+                       uint64_t dst = (uint64_t)(uintptr_t)&tmp_hdr;
+                       uint16_t hdr_vec_idx = 0;
+
+                       /*
+                        * No luck, the virtio-net header doesn't fit
+                        * in a contiguous virtual area.
+                        */
+                       while (remain) {
+                               len = remain;
+                               src = buf_vec[hdr_vec_idx].buf_addr;
+                               rte_memcpy((void *)(uintptr_t)dst,
+                                                  (void *)(uintptr_t)src, len);
+
+                               remain -= len;
+                               dst += len;
+                               hdr_vec_idx++;
+                       }
+
+                       hdr = &tmp_hdr;
+               } else {
+                       hdr = (struct virtio_net_hdr *)((uintptr_t)buf_addr);
+                       rte_prefetch0(hdr);
+               }
        }
 
        /*
@@ -890,41 +819,40 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
         * for Tx: the first for storing the header, and others
         * for storing the data.
         */
-       if (likely((desc->len == dev->vhost_hlen) &&
-                  (desc->flags & VRING_DESC_F_NEXT) != 0)) {
-               desc = &descs[desc->next];
-               if (unlikely(desc->flags & VRING_DESC_F_INDIRECT)) {
-                       error = -1;
+       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 out;
-               }
-
-               desc_addr = vhost_iova_to_vva(dev,
-                                                       vq, desc->addr,
-                                                       desc->len,
-                                                       VHOST_ACCESS_RO);
-               if (unlikely(!desc_addr)) {
-                       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;
 
-               desc_offset = 0;
-               desc_avail  = desc->len;
-               nr_desc    += 1;
+               buf_offset = 0;
+               buf_avail = buf_len;
        } else {
-               desc_avail  = desc->len - dev->vhost_hlen;
-               desc_offset = dev->vhost_hlen;
+               buf_offset = dev->vhost_hlen;
+               buf_avail = buf_vec[vec_idx].buf_len - dev->vhost_hlen;
        }
 
-       rte_prefetch0((void *)(uintptr_t)(desc_addr + desc_offset));
+       rte_prefetch0((void *)(uintptr_t)
+                       (buf_addr + buf_offset));
 
-       PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset), desc_avail, 0);
+       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;
        while (1) {
                uint64_t hpa;
 
-               cpy_len = RTE_MIN(desc_avail, mbuf_avail);
+               cpy_len = RTE_MIN(buf_avail, mbuf_avail);
 
                /*
                 * A desc buf might across two host physical pages that are
@@ -932,11 +860,11 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
                 * will be copied even though zero copy is enabled.
                 */
                if (unlikely(dev->dequeue_zero_copy && (hpa = gpa_to_hpa(dev,
-                                       desc->addr + desc_offset, cpy_len)))) {
+                                       buf_iova + buf_offset, cpy_len)))) {
                        cur->data_len = cpy_len;
                        cur->data_off = 0;
-                       cur->buf_addr = (void *)(uintptr_t)(desc_addr
-                               + desc_offset);
+                       cur->buf_addr =
+                               (void *)(uintptr_t)(buf_addr + buf_offset);
                        cur->buf_iova = hpa;
 
                        /*
@@ -946,61 +874,53 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        mbuf_avail = cpy_len;
                } else {
                        if (likely(cpy_len > MAX_BATCH_LEN ||
-                                  copy_nb >= vq->size ||
+                                  vq->batch_copy_nb_elems >= vq->size ||
                                   (hdr && cur == m))) {
                                rte_memcpy(rte_pktmbuf_mtod_offset(cur, void *,
                                                                   mbuf_offset),
-                                          (void *)((uintptr_t)(desc_addr +
-                                                               desc_offset)),
+                                          (void *)((uintptr_t)(buf_addr +
+                                                          buf_offset)),
                                           cpy_len);
                        } else {
-                               batch_copy[copy_nb].dst =
+                               batch_copy[vq->batch_copy_nb_elems].dst =
                                        rte_pktmbuf_mtod_offset(cur, void *,
                                                                mbuf_offset);
-                               batch_copy[copy_nb].src =
-                                       (void *)((uintptr_t)(desc_addr +
-                                                            desc_offset));
-                               batch_copy[copy_nb].len = cpy_len;
-                               copy_nb++;
+                               batch_copy[vq->batch_copy_nb_elems].src =
+                                       (void *)((uintptr_t)(buf_addr +
+                                                               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;
-               desc_avail  -= cpy_len;
-               desc_offset += cpy_len;
+               buf_avail -= cpy_len;
+               buf_offset += cpy_len;
 
-               /* This desc reaches to its end, get the next one */
-               if (desc_avail == 0) {
-                       if ((desc->flags & VRING_DESC_F_NEXT) == 0)
+               /* This buf reaches to its end, get the next one */
+               if (buf_avail == 0) {
+                       if (++vec_idx >= nr_vec)
                                break;
 
-                       if (unlikely(desc->next >= max_desc ||
-                                    ++nr_desc > max_desc)) {
-                               error = -1;
-                               goto out;
-                       }
-                       desc = &descs[desc->next];
-                       if (unlikely(desc->flags & VRING_DESC_F_INDIRECT)) {
-                               error = -1;
-                               goto out;
-                       }
-
-                       desc_addr = vhost_iova_to_vva(dev,
-                                                       vq, desc->addr,
-                                                       desc->len,
-                                                       VHOST_ACCESS_RO);
-                       if (unlikely(!desc_addr)) {
-                               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;
 
-                       rte_prefetch0((void *)(uintptr_t)desc_addr);
+                       /*
+                        * Prefecth desc n + 1 buffer while
+                        * desc n buffer is processed.
+                        */
+                       if (vec_idx + 1 < nr_vec)
+                               rte_prefetch0((void *)(uintptr_t)
+                                               buf_vec[vec_idx + 1].buf_addr);
 
-                       desc_offset = 0;
-                       desc_avail  = desc->len;
+                       buf_offset = 0;
+                       buf_avail  = buf_len;
 
-                       PRINT_PACKET(dev, (uintptr_t)desc_addr, desc->len, 0);
+                       PRINT_PACKET(dev, (uintptr_t)buf_addr,
+                                       (uint32_t)buf_avail, 0);
                }
 
                /*
@@ -1036,38 +956,10 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
                vhost_dequeue_offload(hdr, m);
 
 out:
-       vq->batch_copy_nb_elems = copy_nb;
 
        return error;
 }
 
-static __rte_always_inline void
-update_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq,
-                uint32_t used_idx, uint32_t desc_idx)
-{
-       vq->used->ring[used_idx].id  = desc_idx;
-       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]));
-}
-
-static __rte_always_inline void
-update_used_idx(struct virtio_net *dev, struct vhost_virtqueue *vq,
-               uint32_t count)
-{
-       if (unlikely(count == 0))
-               return;
-
-       rte_smp_wmb();
-       rte_smp_rmb();
-
-       vq->used->idx += count;
-       vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
-                       sizeof(vq->used->idx));
-       vhost_vring_call(vq);
-}
-
 static __rte_always_inline struct zcopy_mbuf *
 get_zmbuf(struct vhost_virtqueue *vq)
 {
@@ -1111,6 +1003,22 @@ mbuf_is_consumed(struct rte_mbuf *m)
        return true;
 }
 
+static __rte_always_inline void
+restore_mbuf(struct rte_mbuf *m)
+{
+       uint32_t mbuf_size, priv_size;
+
+       while (m) {
+               priv_size = rte_pktmbuf_priv_size(m->pool);
+               mbuf_size = sizeof(struct rte_mbuf) + priv_size;
+               /* start of buffer is after mbuf structure and priv data */
+
+               m->buf_addr = (char *)m + mbuf_size;
+               m->buf_iova = rte_mempool_virt2iova(m) + mbuf_size;
+               m = m->next;
+       }
+}
+
 uint16_t
 rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
        struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
@@ -1118,16 +1026,20 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
        struct virtio_net *dev;
        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;
 
        dev = get_device(vid);
        if (!dev)
                return 0;
 
+       if (unlikely(!(dev->flags & VIRTIO_DEV_BUILTIN_VIRTIO_NET))) {
+               RTE_LOG(ERR, VHOST_DATA,
+                       "(%d) %s: built-in vhost net backend is disabled.\n",
+                       dev->vid, __func__);
+               return 0;
+       }
+
        if (unlikely(!is_valid_virt_queue_idx(queue_id, 1, dev->nr_vring))) {
                RTE_LOG(ERR, VHOST_DATA, "(%d) %s: invalid virtqueue idx %d.\n",
                        dev->vid, __func__, queue_id);
@@ -1135,10 +1047,15 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
        }
 
        vq = dev->virtqueue[queue_id];
-       if (unlikely(vq->enabled == 0))
+
+       if (unlikely(rte_spinlock_trylock(&vq->access_lock) == 0))
                return 0;
 
+       if (unlikely(vq->enabled == 0))
+               goto out_access_unlock;
+
        vq->batch_copy_nb_elems = 0;
+       vq->shadow_used_idx = 0;
 
        if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
                vhost_user_iotlb_rd_lock(vq);
@@ -1156,21 +1073,24 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
                        next = TAILQ_NEXT(zmbuf, next);
 
                        if (mbuf_is_consumed(zmbuf->mbuf)) {
-                               used_idx = vq->last_used_idx++ & (vq->size - 1);
-                               update_used_ring(dev, vq, used_idx,
-                                                zmbuf->desc_idx);
+                               update_shadow_used_ring(vq, zmbuf->desc_idx, 0);
                                nr_updated += 1;
 
                                TAILQ_REMOVE(&vq->zmbuf_list, zmbuf, next);
+                               restore_mbuf(zmbuf->mbuf);
                                rte_pktmbuf_free(zmbuf->mbuf);
                                put_zmbuf(zmbuf);
                                vq->nr_zmbuf -= 1;
                        }
                }
 
-               update_used_idx(dev, vq, nr_updated);
+               flush_shadow_used_ring(dev, vq);
+               vhost_vring_call(dev, vq);
+               vq->shadow_used_idx = 0;
        }
 
+       rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);
+
        /*
         * Construct a RARP broadcast packet, and inject it to the "pkts"
         * array, to looks like that guest actually send such packet.
@@ -1191,19 +1111,13 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
                        rte_atomic16_cmpset((volatile uint16_t *)
                                &dev->broadcast_rarp.cnt, 1, 0))) {
 
-               rarp_mbuf = rte_pktmbuf_alloc(mbuf_pool);
+               rarp_mbuf = rte_net_make_rarp_packet(mbuf_pool, &dev->mac);
                if (rarp_mbuf == NULL) {
                        RTE_LOG(ERR, VHOST_DATA,
-                               "Failed to allocate memory for mbuf.\n");
+                               "Failed to make RARP packet.\n");
                        return 0;
                }
-
-               if (make_rarp_packet(rarp_mbuf, &dev->mac)) {
-                       rte_pktmbuf_free(rarp_mbuf);
-                       rarp_mbuf = NULL;
-               } else {
-                       count -= 1;
-               }
+               count -= 1;
        }
 
        free_entries = *((volatile uint16_t *)&vq->avail->idx) -
@@ -1211,56 +1125,30 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
        if (free_entries == 0)
                goto out;
 
-       LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
-
-       /* Prefetch available and used ring */
-       avail_idx = vq->last_avail_idx & (vq->size - 1);
-       used_idx  = vq->last_used_idx  & (vq->size - 1);
-       rte_prefetch0(&vq->avail->ring[avail_idx]);
-       rte_prefetch0(&vq->used->ring[used_idx]);
+       VHOST_LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
 
        count = RTE_MIN(count, MAX_PKT_BURST);
        count = RTE_MIN(count, free_entries);
-       LOG_DEBUG(VHOST_DATA, "(%d) about to dequeue %u buffers\n",
+       VHOST_LOG_DEBUG(VHOST_DATA, "(%d) about to dequeue %u buffers\n",
                        dev->vid, count);
 
-       /* Retrieve all of the head indexes first to avoid caching issues. */
-       for (i = 0; i < count; i++) {
-               avail_idx = (vq->last_avail_idx + i) & (vq->size - 1);
-               used_idx  = (vq->last_used_idx  + i) & (vq->size - 1);
-               desc_indexes[i] = vq->avail->ring[avail_idx];
-
-               if (likely(dev->dequeue_zero_copy == 0))
-                       update_used_ring(dev, vq, used_idx, desc_indexes[i]);
-       }
-
-       /* Prefetch descriptor index. */
-       rte_prefetch0(&vq->desc[desc_indexes[0]]);
        for (i = 0; i < count; i++) {
-               struct vring_desc *desc;
-               uint16_t sz, idx;
+               struct buf_vector buf_vec[BUF_VECTOR_MAX];
+               uint16_t head_idx, dummy_len;
+               uint32_t nr_vec = 0;
                int err;
 
-               if (likely(i + 1 < count))
-                       rte_prefetch0(&vq->desc[desc_indexes[i + 1]]);
+               if (unlikely(fill_vec_buf(dev, vq,
+                                               vq->last_avail_idx + i,
+                                               &nr_vec, buf_vec,
+                                               &head_idx, &dummy_len,
+                                               VHOST_ACCESS_RO) < 0))
+                       break;
 
-               if (vq->desc[desc_indexes[i]].flags & VRING_DESC_F_INDIRECT) {
-                       desc = (struct vring_desc *)(uintptr_t)
-                               vhost_iova_to_vva(dev, vq,
-                                               vq->desc[desc_indexes[i]].addr,
-                                               sizeof(*desc),
-                                               VHOST_ACCESS_RO);
-                       if (unlikely(!desc))
-                               break;
+               if (likely(dev->dequeue_zero_copy == 0))
+                       update_shadow_used_ring(vq, head_idx, 0);
 
-                       rte_prefetch0(desc);
-                       sz = vq->desc[desc_indexes[i]].len / sizeof(*desc);
-                       idx = 0;
-               } else {
-                       desc = vq->desc;
-                       sz = vq->size;
-                       idx = desc_indexes[i];
-               }
+               rte_prefetch0((void *)(uintptr_t)buf_vec[0].buf_addr);
 
                pkts[i] = rte_pktmbuf_alloc(mbuf_pool);
                if (unlikely(pkts[i] == NULL)) {
@@ -1269,8 +1157,8 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
                        break;
                }
 
-               err = copy_desc_to_mbuf(dev, vq, desc, sz, pkts[i], idx,
-                                       mbuf_pool);
+               err = copy_desc_to_mbuf(dev, vq, buf_vec, nr_vec, pkts[i],
+                               mbuf_pool);
                if (unlikely(err)) {
                        rte_pktmbuf_free(pkts[i]);
                        break;
@@ -1285,7 +1173,7 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
                                break;
                        }
                        zmbuf->mbuf = pkts[i];
-                       zmbuf->desc_idx = desc_indexes[i];
+                       zmbuf->desc_idx = head_idx;
 
                        /*
                         * Pin lock the mbuf; we will check later to see
@@ -1303,14 +1191,19 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
 
        if (likely(dev->dequeue_zero_copy == 0)) {
                do_data_copy_dequeue(vq);
-               vq->last_used_idx += i;
-               update_used_idx(dev, vq, i);
+               if (unlikely(i < count))
+                       vq->shadow_used_idx = i;
+               flush_shadow_used_ring(dev, vq);
+               vhost_vring_call(dev, vq);
        }
 
 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 (unlikely(rarp_mbuf != NULL)) {
                /*
                 * Inject it to the head of "pkts" array, so that switch's mac