vhost: add packed ring batch enqueue
[dpdk.git] / lib / librte_vhost / virtio_net.c
index 2b7ffcf..4ddf265 100644 (file)
@@ -37,45 +37,6 @@ 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 void *
-alloc_copy_ind_table(struct virtio_net *dev, struct vhost_virtqueue *vq,
-               uint64_t desc_addr, uint64_t desc_len)
-{
-       void *idesc;
-       uint64_t src, dst;
-       uint64_t len, remain = desc_len;
-
-       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(void *idesc)
-{
-       rte_free(idesc);
-}
-
 static __rte_always_inline void
 do_flush_shadow_used_ring_split(struct virtio_net *dev,
                        struct vhost_virtqueue *vq,
@@ -122,7 +83,7 @@ flush_shadow_used_ring_split(struct virtio_net *dev, struct vhost_virtqueue *vq)
 
 static __rte_always_inline void
 update_shadow_used_ring_split(struct vhost_virtqueue *vq,
-                        uint16_t desc_idx, uint16_t len)
+                        uint16_t desc_idx, uint32_t len)
 {
        uint16_t i = vq->shadow_used_idx++;
 
@@ -136,6 +97,8 @@ flush_shadow_used_ring_packed(struct virtio_net *dev,
 {
        int i;
        uint16_t used_idx = vq->last_used_idx;
+       uint16_t head_idx = vq->last_used_idx;
+       uint16_t head_flags = 0;
 
        /* Split loop in two to save memory barriers */
        for (i = 0; i < vq->shadow_used_idx; i++) {
@@ -147,8 +110,6 @@ flush_shadow_used_ring_packed(struct virtio_net *dev,
                        used_idx -= vq->size;
        }
 
-       rte_smp_wmb();
-
        for (i = 0; i < vq->shadow_used_idx; i++) {
                uint16_t flags;
 
@@ -165,28 +126,36 @@ flush_shadow_used_ring_packed(struct virtio_net *dev,
                        flags &= ~VRING_DESC_F_AVAIL;
                }
 
-               vq->desc_packed[vq->last_used_idx].flags = flags;
+               if (i > 0) {
+                       vq->desc_packed[vq->last_used_idx].flags = flags;
 
-               vhost_log_cache_used_vring(dev, vq,
+                       vhost_log_cache_used_vring(dev, vq,
                                        vq->last_used_idx *
                                        sizeof(struct vring_packed_desc),
                                        sizeof(struct vring_packed_desc));
-
-               vq->last_used_idx += vq->shadow_used_packed[i].count;
-               if (vq->last_used_idx >= vq->size) {
-                       vq->used_wrap_counter ^= 1;
-                       vq->last_used_idx -= vq->size;
+               } else {
+                       head_idx = vq->last_used_idx;
+                       head_flags = flags;
                }
+
+               vq_inc_last_used_packed(vq, vq->shadow_used_packed[i].count);
        }
 
-       rte_smp_wmb();
+       __atomic_store_n(&vq->desc_packed[head_idx].flags, head_flags,
+                        __ATOMIC_RELEASE);
+
+       vhost_log_cache_used_vring(dev, vq,
+                               head_idx *
+                               sizeof(struct vring_packed_desc),
+                               sizeof(struct vring_packed_desc));
+
        vq->shadow_used_idx = 0;
        vhost_log_cache_sync(dev, vq);
 }
 
 static __rte_always_inline void
 update_shadow_used_ring_packed(struct vhost_virtqueue *vq,
-                        uint16_t desc_idx, uint16_t len, uint16_t count)
+                        uint16_t desc_idx, uint32_t len, uint16_t count)
 {
        uint16_t i = vq->shadow_used_idx++;
 
@@ -204,7 +173,8 @@ 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_cache_write(dev, vq, elem[i].log_addr, elem[i].len);
+               vhost_log_cache_write_iova(dev, vq, elem[i].log_addr,
+                                          elem[i].len);
                PRINT_PACKET(dev, (uintptr_t)elem[i].dst, elem[i].len, 0);
        }
 
@@ -244,15 +214,15 @@ virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
 
                switch (csum_l4) {
                case PKT_TX_TCP_CKSUM:
-                       net_hdr->csum_offset = (offsetof(struct tcp_hdr,
+                       net_hdr->csum_offset = (offsetof(struct rte_tcp_hdr,
                                                cksum));
                        break;
                case PKT_TX_UDP_CKSUM:
-                       net_hdr->csum_offset = (offsetof(struct udp_hdr,
+                       net_hdr->csum_offset = (offsetof(struct rte_udp_hdr,
                                                dgram_cksum));
                        break;
                case PKT_TX_SCTP_CKSUM:
-                       net_hdr->csum_offset = (offsetof(struct sctp_hdr,
+                       net_hdr->csum_offset = (offsetof(struct rte_sctp_hdr,
                                                cksum));
                        break;
                }
@@ -264,9 +234,9 @@ virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
 
        /* IP cksum verification cannot be bypassed, then calculate here */
        if (m_buf->ol_flags & PKT_TX_IP_CKSUM) {
-               struct ipv4_hdr *ipv4_hdr;
+               struct rte_ipv4_hdr *ipv4_hdr;
 
-               ipv4_hdr = rte_pktmbuf_mtod_offset(m_buf, struct ipv4_hdr *,
+               ipv4_hdr = rte_pktmbuf_mtod_offset(m_buf, struct rte_ipv4_hdr *,
                                                   m_buf->l2_len);
                ipv4_hdr->hdr_checksum = rte_ipv4_cksum(ipv4_hdr);
        }
@@ -312,6 +282,8 @@ map_one_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
                if (unlikely(!desc_addr))
                        return -1;
 
+               rte_prefetch0((void *)(uintptr_t)desc_addr);
+
                buf_vec[vec_id].buf_iova = desc_iova;
                buf_vec[vec_id].buf_addr = desc_addr;
                buf_vec[vec_id].buf_len  = desc_chunck_len;
@@ -329,19 +301,28 @@ static __rte_always_inline int
 fill_vec_buf_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
                         uint32_t avail_idx, uint16_t *vec_idx,
                         struct buf_vector *buf_vec, uint16_t *desc_chain_head,
-                        uint16_t *desc_chain_len, uint8_t perm)
+                        uint32_t *desc_chain_len, uint8_t perm)
 {
        uint16_t idx = vq->avail->ring[avail_idx & (vq->size - 1)];
        uint16_t vec_id = *vec_idx;
        uint32_t len    = 0;
        uint64_t dlen;
+       uint32_t nr_descs = vq->size;
+       uint32_t cnt    = 0;
        struct vring_desc *descs = vq->desc;
        struct vring_desc *idesc = NULL;
 
+       if (unlikely(idx >= vq->size))
+               return -1;
+
        *desc_chain_head = idx;
 
        if (vq->desc[idx].flags & VRING_DESC_F_INDIRECT) {
                dlen = vq->desc[idx].len;
+               nr_descs = dlen / sizeof(struct vring_desc);
+               if (unlikely(nr_descs > vq->size))
+                       return -1;
+
                descs = (struct vring_desc *)(uintptr_t)
                        vhost_iova_to_vva(dev, vq, vq->desc[idx].addr,
                                                &dlen,
@@ -354,7 +335,7 @@ fill_vec_buf_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
                         * The indirect desc table is not contiguous
                         * in process VA space, we have to copy it.
                         */
-                       idesc = alloc_copy_ind_table(dev, vq,
+                       idesc = vhost_alloc_copy_ind_table(dev, vq,
                                        vq->desc[idx].addr, vq->desc[idx].len);
                        if (unlikely(!idesc))
                                return -1;
@@ -366,7 +347,7 @@ fill_vec_buf_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
        }
 
        while (1) {
-               if (unlikely(idx >= vq->size)) {
+               if (unlikely(idx >= nr_descs || cnt++ >= nr_descs)) {
                        free_ind_table(idesc);
                        return -1;
                }
@@ -409,19 +390,26 @@ reserve_avail_buf_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
        uint16_t max_tries, tries = 0;
 
        uint16_t head_idx = 0;
-       uint16_t len = 0;
+       uint32_t len = 0;
 
        *num_buffers = 0;
        cur_idx  = vq->last_avail_idx;
 
        if (rxvq_is_mergeable(dev))
-               max_tries = vq->size;
+               max_tries = vq->size - 1;
        else
                max_tries = 1;
 
        while (size > 0) {
                if (unlikely(cur_idx == avail_head))
                        return -1;
+               /*
+                * if we tried all available ring items, and still
+                * can't get enough buf, it means something abnormal
+                * happened.
+                */
+               if (unlikely(++tries > max_tries))
+                       return -1;
 
                if (unlikely(fill_vec_buf_split(dev, vq, cur_idx,
                                                &vec_idx, buf_vec,
@@ -433,16 +421,7 @@ reserve_avail_buf_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
                size -= len;
 
                cur_idx++;
-               tries++;
                *num_buffers += 1;
-
-               /*
-                * if we tried all available ring items, and still
-                * can't get enough buf, it means something abnormal
-                * happened.
-                */
-               if (unlikely(tries > max_tries))
-                       return -1;
        }
 
        *nr_vec = vec_idx;
@@ -454,7 +433,7 @@ static __rte_always_inline int
 fill_vec_buf_packed_indirect(struct virtio_net *dev,
                        struct vhost_virtqueue *vq,
                        struct vring_packed_desc *desc, uint16_t *vec_idx,
-                       struct buf_vector *buf_vec, uint16_t *len, uint8_t perm)
+                       struct buf_vector *buf_vec, uint32_t *len, uint8_t perm)
 {
        uint16_t i;
        uint32_t nr_descs;
@@ -473,7 +452,8 @@ fill_vec_buf_packed_indirect(struct virtio_net *dev,
                 * The indirect desc table is not contiguous
                 * in process VA space, we have to copy it.
                 */
-               idescs = alloc_copy_ind_table(dev, vq, desc->addr, desc->len);
+               idescs = vhost_alloc_copy_ind_table(dev,
+                               vq, desc->addr, desc->len);
                if (unlikely(!idescs))
                        return -1;
 
@@ -510,7 +490,7 @@ static __rte_always_inline int
 fill_vec_buf_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
                                uint16_t avail_idx, uint16_t *desc_count,
                                struct buf_vector *buf_vec, uint16_t *vec_idx,
-                               uint16_t *buf_id, uint16_t *len, uint8_t perm)
+                               uint16_t *buf_id, uint32_t *len, uint8_t perm)
 {
        bool wrap_counter = vq->avail_wrap_counter;
        struct vring_packed_desc *descs = vq->desc_packed;
@@ -519,15 +499,24 @@ fill_vec_buf_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
        if (avail_idx < vq->last_avail_idx)
                wrap_counter ^= 1;
 
+       /*
+        * Perform a load-acquire barrier in desc_is_avail to
+        * enforce the ordering between desc flags and desc
+        * content.
+        */
        if (unlikely(!desc_is_avail(&descs[avail_idx], wrap_counter)))
                return -1;
 
        *desc_count = 0;
+       *len = 0;
 
        while (1) {
                if (unlikely(vec_id >= BUF_VECTOR_MAX))
                        return -1;
 
+               if (unlikely(*desc_count >= vq->size))
+                       return -1;
+
                *desc_count += 1;
                *buf_id = descs[avail_idx].id;
 
@@ -575,23 +564,31 @@ reserve_avail_buf_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
        uint16_t max_tries, tries = 0;
 
        uint16_t buf_id = 0;
-       uint16_t len = 0;
+       uint32_t len = 0;
        uint16_t desc_count;
 
        *num_buffers = 0;
        avail_idx = vq->last_avail_idx;
 
        if (rxvq_is_mergeable(dev))
-               max_tries = vq->size;
+               max_tries = vq->size - 1;
        else
                max_tries = 1;
 
        while (size > 0) {
+               /*
+                * if we tried all available ring items, and still
+                * can't get enough buf, it means something abnormal
+                * happened.
+                */
+               if (unlikely(++tries > max_tries))
+                       return -1;
+
                if (unlikely(fill_vec_buf_packed(dev, vq,
                                                avail_idx, &desc_count,
                                                buf_vec, &vec_idx,
                                                &buf_id, &len,
-                                               VHOST_ACCESS_RO) < 0))
+                                               VHOST_ACCESS_RW) < 0))
                        return -1;
 
                len = RTE_MIN(len, size);
@@ -603,16 +600,7 @@ reserve_avail_buf_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        avail_idx -= vq->size;
 
                *nr_descs += desc_count;
-               tries++;
                *num_buffers += 1;
-
-               /*
-                * if we tried all available ring items, and still
-                * can't get enough buf, it means something abnormal
-                * happened.
-                */
-               if (unlikely(tries > max_tries))
-                       return -1;
        }
 
        *nr_vec = vec_idx;
@@ -620,6 +608,36 @@ reserve_avail_buf_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
        return 0;
 }
 
+static __rte_noinline void
+copy_vnet_hdr_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
+               struct buf_vector *buf_vec,
+               struct virtio_net_hdr_mrg_rxbuf *hdr)
+{
+       uint64_t len;
+       uint64_t remain = dev->vhost_hlen;
+       uint64_t src = (uint64_t)(uintptr_t)hdr, dst;
+       uint64_t iova = buf_vec->buf_iova;
+
+       while (remain) {
+               len = RTE_MIN(remain,
+                               buf_vec->buf_len);
+               dst = buf_vec->buf_addr;
+               rte_memcpy((void *)(uintptr_t)dst,
+                               (void *)(uintptr_t)src,
+                               len);
+
+               PRINT_PACKET(dev, (uintptr_t)dst,
+                               (uint32_t)len, 0);
+               vhost_log_cache_write_iova(dev, vq,
+                               iova, len);
+
+               remain -= len;
+               iova += len;
+               src += len;
+               buf_vec++;
+       }
+}
+
 static __rte_always_inline int
 copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
                            struct rte_mbuf *m, struct buf_vector *buf_vec,
@@ -645,9 +663,6 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
        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;
@@ -690,10 +705,6 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        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;
                }
@@ -713,33 +724,11 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
                                                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++;
-                               }
+                               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(dev, vq,
+                               vhost_log_cache_write_iova(dev, vq,
                                                buf_vec[0].buf_iova,
                                                dev->vhost_hlen);
                        }
@@ -747,15 +736,16 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        hdr_addr = 0;
                }
 
-               cpy_len = RTE_MIN(buf_len, mbuf_avail);
+               cpy_len = RTE_MIN(buf_avail, mbuf_avail);
 
                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_cache_write(dev, vq, buf_iova + buf_offset,
-                                       cpy_len);
+                       vhost_log_cache_write_iova(dev, vq,
+                                                  buf_iova + buf_offset,
+                                                  cpy_len);
                        PRINT_PACKET(dev, (uintptr_t)(buf_addr + buf_offset),
                                cpy_len, 0);
                } else {
@@ -780,7 +770,61 @@ out:
        return error;
 }
 
-static __rte_always_inline uint32_t
+static __rte_always_inline int
+vhost_enqueue_single_packed(struct virtio_net *dev,
+                           struct vhost_virtqueue *vq,
+                           struct rte_mbuf *pkt,
+                           struct buf_vector *buf_vec,
+                           uint16_t *nr_descs)
+{
+       uint16_t nr_vec = 0;
+       uint16_t avail_idx = vq->last_avail_idx;
+       uint16_t max_tries, tries = 0;
+       uint16_t buf_id = 0;
+       uint32_t len = 0;
+       uint16_t desc_count;
+       uint32_t size = pkt->pkt_len + dev->vhost_hlen;
+       uint16_t num_buffers = 0;
+
+       if (rxvq_is_mergeable(dev))
+               max_tries = vq->size - 1;
+       else
+               max_tries = 1;
+
+       while (size > 0) {
+               /*
+                * if we tried all available ring items, and still
+                * can't get enough buf, it means something abnormal
+                * happened.
+                */
+               if (unlikely(++tries > max_tries))
+                       return -1;
+
+               if (unlikely(fill_vec_buf_packed(dev, vq,
+                                               avail_idx, &desc_count,
+                                               buf_vec, &nr_vec,
+                                               &buf_id, &len,
+                                               VHOST_ACCESS_RW) < 0))
+                       return -1;
+
+               len = RTE_MIN(len, size);
+               size -= len;
+
+               num_buffers += 1;
+
+               *nr_descs += desc_count;
+               avail_idx += desc_count;
+               if (avail_idx >= vq->size)
+                       avail_idx -= vq->size;
+       }
+
+       if (copy_mbuf_to_desc(dev, vq, pkt, buf_vec, nr_vec, num_buffers) < 0)
+               return -1;
+
+       return 0;
+}
+
+static __rte_noinline uint32_t
 virtio_dev_rx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
        struct rte_mbuf **pkts, uint32_t count)
 {
@@ -789,9 +833,16 @@ virtio_dev_rx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
        struct buf_vector buf_vec[BUF_VECTOR_MAX];
        uint16_t avail_head;
 
-       rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);
        avail_head = *((volatile uint16_t *)&vq->avail->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;
@@ -806,8 +857,6 @@ virtio_dev_rx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        break;
                }
 
-               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);
@@ -832,7 +881,103 @@ virtio_dev_rx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
        return pkt_idx;
 }
 
-static __rte_always_inline uint32_t
+static __rte_unused int
+virtio_dev_rx_batch_packed(struct virtio_net *dev,
+                          struct vhost_virtqueue *vq,
+                          struct rte_mbuf **pkts)
+{
+       bool wrap_counter = vq->avail_wrap_counter;
+       struct vring_packed_desc *descs = vq->desc_packed;
+       uint16_t avail_idx = vq->last_avail_idx;
+       uint64_t desc_addrs[PACKED_BATCH_SIZE];
+       struct virtio_net_hdr_mrg_rxbuf *hdrs[PACKED_BATCH_SIZE];
+       uint32_t buf_offset = dev->vhost_hlen;
+       uint64_t lens[PACKED_BATCH_SIZE];
+       uint16_t i;
+
+       if (unlikely(avail_idx & PACKED_BATCH_MASK))
+               return -1;
+
+       if (unlikely((avail_idx + PACKED_BATCH_SIZE) > vq->size))
+               return -1;
+
+       vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
+               if (unlikely(pkts[i]->next != NULL))
+                       return -1;
+               if (unlikely(!desc_is_avail(&descs[avail_idx + i],
+                                           wrap_counter)))
+                       return -1;
+       }
+
+       rte_smp_rmb();
+
+       vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
+               lens[i] = descs[avail_idx + i].len;
+
+       vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
+               if (unlikely(pkts[i]->pkt_len > (lens[i] - buf_offset)))
+                       return -1;
+       }
+
+       vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
+               desc_addrs[i] = vhost_iova_to_vva(dev, vq,
+                                                 descs[avail_idx + i].addr,
+                                                 &lens[i],
+                                                 VHOST_ACCESS_RW);
+
+       vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
+               if (unlikely(lens[i] != descs[avail_idx + i].len))
+                       return -1;
+       }
+
+       vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
+               rte_prefetch0((void *)(uintptr_t)desc_addrs[i]);
+               hdrs[i] = (struct virtio_net_hdr_mrg_rxbuf *)
+                                       (uintptr_t)desc_addrs[i];
+               lens[i] = pkts[i]->pkt_len + dev->vhost_hlen;
+       }
+
+       vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
+               virtio_enqueue_offload(pkts[i], &hdrs[i]->hdr);
+
+       vq_inc_last_avail_packed(vq, PACKED_BATCH_SIZE);
+
+       vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
+               rte_memcpy((void *)(uintptr_t)(desc_addrs[i] + buf_offset),
+                          rte_pktmbuf_mtod_offset(pkts[i], void *, 0),
+                          pkts[i]->pkt_len);
+       }
+
+       return 0;
+}
+
+static __rte_unused int16_t
+virtio_dev_rx_single_packed(struct virtio_net *dev,
+                           struct vhost_virtqueue *vq,
+                           struct rte_mbuf *pkt)
+{
+       struct buf_vector buf_vec[BUF_VECTOR_MAX];
+       uint16_t nr_descs = 0;
+
+       rte_smp_rmb();
+       if (unlikely(vhost_enqueue_single_packed(dev, vq, pkt, buf_vec,
+                                                &nr_descs) < 0)) {
+               VHOST_LOG_DEBUG(VHOST_DATA,
+                               "(%d) failed to get enough desc from vring\n",
+                               dev->vid);
+               return -1;
+       }
+
+       VHOST_LOG_DEBUG(VHOST_DATA, "(%d) current index %d | end index %d\n",
+                       dev->vid, vq->last_avail_idx,
+                       vq->last_avail_idx + nr_descs);
+
+       vq_inc_last_avail_packed(vq, nr_descs);
+
+       return 0;
+}
+
+static __rte_noinline uint32_t
 virtio_dev_rx_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
        struct rte_mbuf **pkts, uint32_t count)
 {
@@ -855,8 +1000,6 @@ virtio_dev_rx_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        break;
                }
 
-               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);
@@ -868,11 +1011,7 @@ virtio_dev_rx_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        break;
                }
 
-               vq->last_avail_idx += nr_descs;
-               if (vq->last_avail_idx >= vq->size) {
-                       vq->last_avail_idx -= vq->size;
-                       vq->avail_wrap_counter ^= 1;
-               }
+               vq_inc_last_avail_packed(vq, nr_descs);
        }
 
        do_data_copy_enqueue(dev, vq);
@@ -890,6 +1029,7 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
        struct rte_mbuf **pkts, uint32_t count)
 {
        struct vhost_virtqueue *vq;
+       uint32_t nb_tx = 0;
 
        VHOST_LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
        if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->nr_vring))) {
@@ -917,9 +1057,9 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
                goto out;
 
        if (vq_is_packed(dev))
-               count = virtio_dev_rx_packed(dev, vq, pkts, count);
+               nb_tx = virtio_dev_rx_packed(dev, vq, pkts, count);
        else
-               count = virtio_dev_rx_split(dev, vq, pkts, count);
+               nb_tx = virtio_dev_rx_split(dev, vq, pkts, count);
 
 out:
        if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
@@ -928,7 +1068,7 @@ out:
 out_access_unlock:
        rte_spinlock_unlock(&vq->access_lock);
 
-       return count;
+       return nb_tx;
 }
 
 uint16_t
@@ -967,38 +1107,39 @@ virtio_net_with_host_offload(struct virtio_net *dev)
 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;
+       struct rte_ipv4_hdr *ipv4_hdr;
+       struct rte_ipv6_hdr *ipv6_hdr;
        void *l3_hdr = NULL;
-       struct ether_hdr *eth_hdr;
+       struct rte_ether_hdr *eth_hdr;
        uint16_t ethertype;
 
-       eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
+       eth_hdr = rte_pktmbuf_mtod(m, struct rte_ether_hdr *);
 
-       m->l2_len = sizeof(struct ether_hdr);
+       m->l2_len = sizeof(struct rte_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);
+       if (ethertype == RTE_ETHER_TYPE_VLAN) {
+               struct rte_vlan_hdr *vlan_hdr =
+                       (struct rte_vlan_hdr *)(eth_hdr + 1);
 
-               m->l2_len += sizeof(struct vlan_hdr);
+               m->l2_len += sizeof(struct rte_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:
+       case RTE_ETHER_TYPE_IPV4:
                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:
+       case RTE_ETHER_TYPE_IPV6:
                ipv6_hdr = l3_hdr;
                *l4_proto = ipv6_hdr->proto;
-               m->l3_len = sizeof(struct ipv6_hdr);
+               m->l3_len = sizeof(struct rte_ipv6_hdr);
                *l4_hdr = (char *)l3_hdr + m->l3_len;
                m->ol_flags |= PKT_TX_IPV6;
                break;
@@ -1015,7 +1156,7 @@ 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;
+       struct rte_tcp_hdr *tcp_hdr = NULL;
 
        if (hdr->flags == 0 && hdr->gso_type == VIRTIO_NET_HDR_GSO_NONE)
                return;
@@ -1024,15 +1165,15 @@ vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
        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)):
+                       case (offsetof(struct rte_tcp_hdr, cksum)):
                                if (l4_proto == IPPROTO_TCP)
                                        m->ol_flags |= PKT_TX_TCP_CKSUM;
                                break;
-                       case (offsetof(struct udp_hdr, dgram_cksum)):
+                       case (offsetof(struct rte_udp_hdr, dgram_cksum)):
                                if (l4_proto == IPPROTO_UDP)
                                        m->ol_flags |= PKT_TX_UDP_CKSUM;
                                break;
-                       case (offsetof(struct sctp_hdr, cksum)):
+                       case (offsetof(struct rte_sctp_hdr, cksum)):
                                if (l4_proto == IPPROTO_SCTP)
                                        m->ol_flags |= PKT_TX_SCTP_CKSUM;
                                break;
@@ -1054,7 +1195,7 @@ vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
                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);
+                       m->l4_len = sizeof(struct rte_udp_hdr);
                        break;
                default:
                        RTE_LOG(WARNING, VHOST_DATA,
@@ -1064,10 +1205,25 @@ vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
        }
 }
 
-static __rte_always_inline void
-put_zmbuf(struct zcopy_mbuf *zmbuf)
+static __rte_noinline void
+copy_vnet_hdr_from_desc(struct virtio_net_hdr *hdr,
+               struct buf_vector *buf_vec)
 {
-       zmbuf->in_use = 0;
+       uint64_t len;
+       uint64_t remain = sizeof(struct virtio_net_hdr);
+       uint64_t src;
+       uint64_t dst = (uint64_t)(uintptr_t)hdr;
+
+       while (remain) {
+               len = RTE_MIN(remain, buf_vec->buf_len);
+               src = buf_vec->buf_addr;
+               rte_memcpy((void *)(uintptr_t)dst,
+                               (void *)(uintptr_t)src, len);
+
+               remain -= len;
+               dst += len;
+               buf_vec++;
+       }
 }
 
 static __rte_always_inline int
@@ -1096,36 +1252,16 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
                goto out;
        }
 
-       if (likely(nr_vec > 1))
-               rte_prefetch0((void *)(uintptr_t)buf_vec[1].buf_addr);
-
        if (virtio_net_with_host_offload(dev)) {
                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++;
-                       }
-
+                       copy_vnet_hdr_from_desc(&tmp_hdr, buf_vec);
                        hdr = &tmp_hdr;
                } else {
                        hdr = (struct virtio_net_hdr *)((uintptr_t)buf_addr);
-                       rte_prefetch0(hdr);
                }
        }
 
@@ -1155,9 +1291,6 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
                buf_avail = buf_vec[vec_idx].buf_len - dev->vhost_hlen;
        }
 
-       rte_prefetch0((void *)(uintptr_t)
-                       (buf_addr + buf_offset));
-
        PRINT_PACKET(dev,
                        (uintptr_t)(buf_addr + buf_offset),
                        (uint32_t)buf_avail, 0);
@@ -1223,14 +1356,6 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        buf_iova = buf_vec[vec_idx].buf_iova;
                        buf_len = buf_vec[vec_idx].buf_len;
 
-                       /*
-                        * 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);
-
                        buf_offset = 0;
                        buf_avail  = buf_len;
 
@@ -1306,35 +1431,94 @@ again:
        return NULL;
 }
 
-static __rte_always_inline bool
-mbuf_is_consumed(struct rte_mbuf *m)
+static void
+virtio_dev_extbuf_free(void *addr __rte_unused, void *opaque)
+{
+       rte_free(opaque);
+}
+
+static int
+virtio_dev_extbuf_alloc(struct rte_mbuf *pkt, uint32_t size)
 {
-       while (m) {
-               if (rte_mbuf_refcnt_read(m) > 1)
-                       return false;
-               m = m->next;
+       struct rte_mbuf_ext_shared_info *shinfo = NULL;
+       uint32_t total_len = RTE_PKTMBUF_HEADROOM + size;
+       uint16_t buf_len;
+       rte_iova_t iova;
+       void *buf;
+
+       /* Try to use pkt buffer to store shinfo to reduce the amount of memory
+        * required, otherwise store shinfo in the new buffer.
+        */
+       if (rte_pktmbuf_tailroom(pkt) >= sizeof(*shinfo))
+               shinfo = rte_pktmbuf_mtod(pkt,
+                                         struct rte_mbuf_ext_shared_info *);
+       else {
+               total_len += sizeof(*shinfo) + sizeof(uintptr_t);
+               total_len = RTE_ALIGN_CEIL(total_len, sizeof(uintptr_t));
+       }
+
+       if (unlikely(total_len > UINT16_MAX))
+               return -ENOSPC;
+
+       buf_len = total_len;
+       buf = rte_malloc(NULL, buf_len, RTE_CACHE_LINE_SIZE);
+       if (unlikely(buf == NULL))
+               return -ENOMEM;
+
+       /* Initialize shinfo */
+       if (shinfo) {
+               shinfo->free_cb = virtio_dev_extbuf_free;
+               shinfo->fcb_opaque = buf;
+               rte_mbuf_ext_refcnt_set(shinfo, 1);
+       } else {
+               shinfo = rte_pktmbuf_ext_shinfo_init_helper(buf, &buf_len,
+                                             virtio_dev_extbuf_free, buf);
+               if (unlikely(shinfo == NULL)) {
+                       rte_free(buf);
+                       RTE_LOG(ERR, VHOST_DATA, "Failed to init shinfo\n");
+                       return -1;
+               }
        }
 
-       return true;
+       iova = rte_malloc_virt2iova(buf);
+       rte_pktmbuf_attach_extbuf(pkt, buf, iova, buf_len, shinfo);
+       rte_pktmbuf_reset_headroom(pkt);
+
+       return 0;
 }
 
-static __rte_always_inline void
-restore_mbuf(struct rte_mbuf *m)
+/*
+ * Allocate a host supported pktmbuf.
+ */
+static __rte_always_inline struct rte_mbuf *
+virtio_dev_pktmbuf_alloc(struct virtio_net *dev, struct rte_mempool *mp,
+                        uint32_t data_len)
 {
-       uint32_t mbuf_size, priv_size;
+       struct rte_mbuf *pkt = rte_pktmbuf_alloc(mp);
 
-       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 */
+       if (unlikely(pkt == NULL))
+               return NULL;
 
-               m->buf_addr = (char *)m + mbuf_size;
-               m->buf_iova = rte_mempool_virt2iova(m) + mbuf_size;
-               m = m->next;
-       }
+       if (rte_pktmbuf_tailroom(pkt) >= data_len)
+               return pkt;
+
+       /* attach an external buffer if supported */
+       if (dev->extbuf && !virtio_dev_extbuf_alloc(pkt, data_len))
+               return pkt;
+
+       /* check if chained buffers are allowed */
+       if (!dev->linearbuf)
+               return pkt;
+
+       /* Data doesn't fit into the buffer and the host supports
+        * only linear buffers
+        */
+       rte_pktmbuf_free(pkt);
+
+       return NULL;
 }
 
-static __rte_always_inline uint16_t
+static __rte_noinline uint16_t
 virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
        struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
 {
@@ -1343,7 +1527,6 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 
        if (unlikely(dev->dequeue_zero_copy)) {
                struct zcopy_mbuf *zmbuf, *next;
-               int nr_updated = 0;
 
                for (zmbuf = TAILQ_FIRST(&vq->zmbuf_list);
                     zmbuf != NULL; zmbuf = next) {
@@ -1352,8 +1535,6 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        if (mbuf_is_consumed(zmbuf->mbuf)) {
                                update_shadow_used_ring_split(vq,
                                                zmbuf->desc_idx, 0);
-                               nr_updated += 1;
-
                                TAILQ_REMOVE(&vq->zmbuf_list, zmbuf, next);
                                restore_mbuf(zmbuf->mbuf);
                                rte_pktmbuf_free(zmbuf->mbuf);
@@ -1362,17 +1543,25 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        }
                }
 
-               flush_shadow_used_ring_split(dev, vq);
-               vhost_vring_call_split(dev, vq);
+               if (likely(vq->shadow_used_idx)) {
+                       flush_shadow_used_ring_split(dev, vq);
+                       vhost_vring_call_split(dev, vq);
+               }
        }
 
-       rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);
-
        free_entries = *((volatile uint16_t *)&vq->avail->idx) -
                        vq->last_avail_idx;
        if (free_entries == 0)
                return 0;
 
+       /*
+        * 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)]);
+
        VHOST_LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
 
        count = RTE_MIN(count, MAX_PKT_BURST);
@@ -1382,28 +1571,24 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 
        for (i = 0; i < count; i++) {
                struct buf_vector buf_vec[BUF_VECTOR_MAX];
-               uint16_t head_idx, dummy_len;
+               uint16_t head_idx;
+               uint32_t buf_len;
                uint16_t nr_vec = 0;
                int err;
 
                if (unlikely(fill_vec_buf_split(dev, vq,
                                                vq->last_avail_idx + i,
                                                &nr_vec, buf_vec,
-                                               &head_idx, &dummy_len,
+                                               &head_idx, &buf_len,
                                                VHOST_ACCESS_RO) < 0))
                        break;
 
                if (likely(dev->dequeue_zero_copy == 0))
                        update_shadow_used_ring_split(vq, head_idx, 0);
 
-               rte_prefetch0((void *)(uintptr_t)buf_vec[0].buf_addr);
-
-               pkts[i] = rte_pktmbuf_alloc(mbuf_pool);
-               if (unlikely(pkts[i] == NULL)) {
-                       RTE_LOG(ERR, VHOST_DATA,
-                               "Failed to allocate memory for mbuf.\n");
+               pkts[i] = virtio_dev_pktmbuf_alloc(dev, mbuf_pool, buf_len);
+               if (unlikely(pkts[i] == NULL))
                        break;
-               }
 
                err = copy_desc_to_mbuf(dev, vq, buf_vec, nr_vec, pkts[i],
                                mbuf_pool);
@@ -1441,21 +1626,21 @@ virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
                do_data_copy_dequeue(vq);
                if (unlikely(i < count))
                        vq->shadow_used_idx = i;
-               flush_shadow_used_ring_split(dev, vq);
-               vhost_vring_call_split(dev, vq);
+               if (likely(vq->shadow_used_idx)) {
+                       flush_shadow_used_ring_split(dev, vq);
+                       vhost_vring_call_split(dev, vq);
+               }
        }
 
        return i;
 }
 
-static __rte_always_inline uint16_t
+static __rte_noinline uint16_t
 virtio_dev_tx_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
        struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
 {
        uint16_t i;
 
-       rte_prefetch0(&vq->desc_packed[vq->last_avail_idx]);
-
        if (unlikely(dev->dequeue_zero_copy)) {
                struct zcopy_mbuf *zmbuf, *next;
 
@@ -1477,8 +1662,10 @@ virtio_dev_tx_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        }
                }
 
-               flush_shadow_used_ring_packed(dev, vq);
-               vhost_vring_call_packed(dev, vq);
+               if (likely(vq->shadow_used_idx)) {
+                       flush_shadow_used_ring_packed(dev, vq);
+                       vhost_vring_call_packed(dev, vq);
+               }
        }
 
        VHOST_LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
@@ -1489,29 +1676,25 @@ virtio_dev_tx_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
 
        for (i = 0; i < count; i++) {
                struct buf_vector buf_vec[BUF_VECTOR_MAX];
-               uint16_t buf_id, dummy_len;
+               uint16_t buf_id;
+               uint32_t buf_len;
                uint16_t desc_count, nr_vec = 0;
                int err;
 
                if (unlikely(fill_vec_buf_packed(dev, vq,
                                                vq->last_avail_idx, &desc_count,
                                                buf_vec, &nr_vec,
-                                               &buf_id, &dummy_len,
-                                               VHOST_ACCESS_RW) < 0))
+                                               &buf_id, &buf_len,
+                                               VHOST_ACCESS_RO) < 0))
                        break;
 
                if (likely(dev->dequeue_zero_copy == 0))
                        update_shadow_used_ring_packed(vq, buf_id, 0,
                                        desc_count);
 
-               rte_prefetch0((void *)(uintptr_t)buf_vec[0].buf_addr);
-
-               pkts[i] = rte_pktmbuf_alloc(mbuf_pool);
-               if (unlikely(pkts[i] == NULL)) {
-                       RTE_LOG(ERR, VHOST_DATA,
-                               "Failed to allocate memory for mbuf.\n");
+               pkts[i] = virtio_dev_pktmbuf_alloc(dev, mbuf_pool, buf_len);
+               if (unlikely(pkts[i] == NULL))
                        break;
-               }
 
                err = copy_desc_to_mbuf(dev, vq, buf_vec, nr_vec, pkts[i],
                                mbuf_pool);
@@ -1544,19 +1727,17 @@ virtio_dev_tx_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
                        TAILQ_INSERT_TAIL(&vq->zmbuf_list, zmbuf, next);
                }
 
-               vq->last_avail_idx += desc_count;
-               if (vq->last_avail_idx >= vq->size) {
-                       vq->last_avail_idx -= vq->size;
-                       vq->avail_wrap_counter ^= 1;
-               }
+               vq_inc_last_avail_packed(vq, desc_count);
        }
 
        if (likely(dev->dequeue_zero_copy == 0)) {
                do_data_copy_dequeue(vq);
                if (unlikely(i < count))
                        vq->shadow_used_idx = i;
-               flush_shadow_used_ring_packed(dev, vq);
-               vhost_vring_call_packed(dev, vq);
+               if (likely(vq->shadow_used_idx)) {
+                       flush_shadow_used_ring_packed(dev, vq);
+                       vhost_vring_call_packed(dev, vq);
+               }
        }
 
        return i;
@@ -1592,15 +1773,19 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
        if (unlikely(rte_spinlock_trylock(&vq->access_lock) == 0))
                return 0;
 
-       if (unlikely(vq->enabled == 0))
+       if (unlikely(vq->enabled == 0)) {
+               count = 0;
                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))
+               if (unlikely(vring_translate(dev, vq) < 0)) {
+                       count = 0;
                        goto out;
+               }
 
        /*
         * Construct a RARP broadcast packet, and inject it to the "pkts"
@@ -1625,7 +1810,8 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
                if (rarp_mbuf == NULL) {
                        RTE_LOG(ERR, VHOST_DATA,
                                "Failed to make RARP packet.\n");
-                       return 0;
+                       count = 0;
+                       goto out;
                }
                count -= 1;
        }