In order to improve code efficiency and readability when async packed
ring support is enabled. This patch abstract some functions like
shadow_ring_store and write_back_completed_descs_split. And improve
the efficiency of some pointer offset calculation.

Signed-off-by: Cheng Jiang <cheng1.ji...@intel.com>
---
 lib/librte_vhost/virtio_net.c | 146 +++++++++++++++++++---------------
 1 file changed, 84 insertions(+), 62 deletions(-)

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index ff3987860..c43ab0093 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -1458,6 +1458,29 @@ virtio_dev_rx_async_get_info_idx(uint16_t pkts_idx,
                (vq_size - n_inflight + pkts_idx) & (vq_size - 1);
 }
 
+static __rte_always_inline void
+shadow_ring_store(struct vhost_virtqueue *vq,  void *shadow_ring, void *d_ring,
+               uint16_t s_idx, uint16_t d_idx,
+               uint16_t count, uint16_t elem_size)
+{
+       if (d_idx + count <= vq->size) {
+               rte_memcpy((void *)((uintptr_t)d_ring + d_idx * elem_size),
+                       (void *)((uintptr_t)shadow_ring + s_idx * elem_size),
+                       count * elem_size);
+       } else {
+               uint16_t size = vq->size - d_idx;
+
+               rte_memcpy((void *)((uintptr_t)d_ring + d_idx * elem_size),
+                       (void *)((uintptr_t)shadow_ring + s_idx * elem_size),
+                       size * elem_size);
+
+               rte_memcpy((void *)((uintptr_t)d_ring),
+                       (void *)((uintptr_t)shadow_ring +
+                               (s_idx + size) * elem_size),
+                       (count - size) * elem_size);
+       }
+}
+
 static __rte_noinline uint32_t
 virtio_dev_rx_async_submit_split(struct virtio_net *dev,
        struct vhost_virtqueue *vq, uint16_t queue_id,
@@ -1478,6 +1501,7 @@ virtio_dev_rx_async_submit_split(struct virtio_net *dev,
        struct rte_vhost_iov_iter *dst_it = it_pool + 1;
        uint16_t slot_idx = 0;
        uint16_t segs_await = 0;
+       uint16_t iovec_idx = 0, it_idx = 0;
        struct async_inflight_info *pkts_info = vq->async_pkts_info;
        uint32_t n_pkts = 0, pkt_err = 0;
        uint32_t num_async_pkts = 0, num_done_pkts = 0;
@@ -1513,27 +1537,32 @@ virtio_dev_rx_async_submit_split(struct virtio_net *dev,
 
                if (async_mbuf_to_desc(dev, vq, pkts[pkt_idx],
                                buf_vec, nr_vec, num_buffers,
-                               src_iovec, dst_iovec, src_it, dst_it) < 0) {
+                               &src_iovec[iovec_idx],
+                               &dst_iovec[iovec_idx],
+                               &src_it[it_idx],
+                               &dst_it[it_idx]) < 0) {
                        vq->shadow_used_idx -= num_buffers;
                        break;
                }
 
                slot_idx = (vq->async_pkts_idx + num_async_pkts) &
                        (vq->size - 1);
-               if (src_it->count) {
+               if (src_it[it_idx].count) {
                        uint16_t from, to;
 
-                       async_fill_desc(&tdes[pkt_burst_idx++], src_it, dst_it);
+                       async_fill_desc(&tdes[pkt_burst_idx++],
+                               &src_it[it_idx],
+                               &dst_it[it_idx]);
                        pkts_info[slot_idx].descs = num_buffers;
                        pkts_info[slot_idx].mbuf = pkts[pkt_idx];
                        async_pkts_log[num_async_pkts].pkt_idx = pkt_idx;
                        async_pkts_log[num_async_pkts++].last_avail_idx =
                                vq->last_avail_idx;
-                       src_iovec += src_it->nr_segs;
-                       dst_iovec += dst_it->nr_segs;
-                       src_it += 2;
-                       dst_it += 2;
-                       segs_await += src_it->nr_segs;
+
+                       iovec_idx += src_it[it_idx].nr_segs;
+                       it_idx += 2;
+
+                       segs_await += src_it[it_idx].nr_segs;
 
                        /**
                         * recover shadow used ring and keep DMA-occupied
@@ -1541,23 +1570,12 @@ virtio_dev_rx_async_submit_split(struct virtio_net *dev,
                         */
                        from = vq->shadow_used_idx - num_buffers;
                        to = vq->async_desc_idx & (vq->size - 1);
-                       if (num_buffers + to <= vq->size) {
-                               rte_memcpy(&vq->async_descs_split[to],
-                                               &vq->shadow_used_split[from],
-                                               num_buffers *
-                                               sizeof(struct vring_used_elem));
-                       } else {
-                               int size = vq->size - to;
-
-                               rte_memcpy(&vq->async_descs_split[to],
-                                               &vq->shadow_used_split[from],
-                                               size *
-                                               sizeof(struct vring_used_elem));
-                               rte_memcpy(vq->async_descs_split,
-                                               &vq->shadow_used_split[from +
-                                               size], (num_buffers - size) *
-                                          sizeof(struct vring_used_elem));
-                       }
+
+                       shadow_ring_store(vq, vq->shadow_used_split,
+                                       vq->async_descs_split,
+                                       from, to, num_buffers,
+                                       sizeof(struct vring_used_elem));
+
                        vq->async_desc_idx += num_buffers;
                        vq->shadow_used_idx -= num_buffers;
                } else
@@ -1575,10 +1593,9 @@ virtio_dev_rx_async_submit_split(struct virtio_net *dev,
                        BUF_VECTOR_MAX))) {
                        n_pkts = vq->async_ops.transfer_data(dev->vid,
                                        queue_id, tdes, 0, pkt_burst_idx);
-                       src_iovec = vec_pool;
-                       dst_iovec = vec_pool + (VHOST_MAX_ASYNC_VEC >> 1);
-                       src_it = it_pool;
-                       dst_it = it_pool + 1;
+                       iovec_idx = 0;
+                       it_idx = 0;
+
                        segs_await = 0;
                        vq->async_pkts_inflight_n += n_pkts;
 
@@ -1639,6 +1656,43 @@ virtio_dev_rx_async_submit_split(struct virtio_net *dev,
        return pkt_idx;
 }
 
+static __rte_always_inline void
+write_back_completed_descs_split(struct vhost_virtqueue *vq, uint16_t n_descs)
+{
+       uint16_t nr_left = n_descs;
+       uint16_t nr_copy;
+       uint16_t to, from;
+
+       do {
+               from = vq->last_async_desc_idx & (vq->size - 1);
+               nr_copy = nr_left + from <= vq->size ? nr_left :
+                       vq->size - from;
+               to = vq->last_used_idx & (vq->size - 1);
+
+               if (to + nr_copy <= vq->size) {
+                       rte_memcpy(&vq->used->ring[to],
+                                       &vq->async_descs_split[from],
+                                       nr_copy *
+                                       sizeof(struct vring_used_elem));
+               } else {
+                       uint16_t size = vq->size - to;
+
+                       rte_memcpy(&vq->used->ring[to],
+                                       &vq->async_descs_split[from],
+                                       size *
+                                       sizeof(struct vring_used_elem));
+                       rte_memcpy(vq->used->ring,
+                                       &vq->async_descs_split[from +
+                                       size], (nr_copy - size) *
+                                       sizeof(struct vring_used_elem));
+               }
+
+               vq->last_async_desc_idx += nr_copy;
+               vq->last_used_idx += nr_copy;
+               nr_left -= nr_copy;
+       } while (nr_left > 0);
+}
+
 uint16_t rte_vhost_poll_enqueue_completed(int vid, uint16_t queue_id,
                struct rte_mbuf **pkts, uint16_t count)
 {
@@ -1695,39 +1749,7 @@ uint16_t rte_vhost_poll_enqueue_completed(int vid, 
uint16_t queue_id,
        vq->async_pkts_inflight_n -= n_pkts_put;
 
        if (likely(vq->enabled && vq->access_ok)) {
-               uint16_t nr_left = n_descs;
-               uint16_t nr_copy;
-               uint16_t to;
-
-               /* write back completed descriptors to used ring */
-               do {
-                       from = vq->last_async_desc_idx & (vq->size - 1);
-                       nr_copy = nr_left + from <= vq->size ? nr_left :
-                               vq->size - from;
-                       to = vq->last_used_idx & (vq->size - 1);
-
-                       if (to + nr_copy <= vq->size) {
-                               rte_memcpy(&vq->used->ring[to],
-                                               &vq->async_descs_split[from],
-                                               nr_copy *
-                                               sizeof(struct vring_used_elem));
-                       } else {
-                               uint16_t size = vq->size - to;
-
-                               rte_memcpy(&vq->used->ring[to],
-                                               &vq->async_descs_split[from],
-                                               size *
-                                               sizeof(struct vring_used_elem));
-                               rte_memcpy(vq->used->ring,
-                                               &vq->async_descs_split[from +
-                                               size], (nr_copy - size) *
-                                               sizeof(struct vring_used_elem));
-                       }
-
-                       vq->last_async_desc_idx += nr_copy;
-                       vq->last_used_idx += nr_copy;
-                       nr_left -= nr_copy;
-               } while (nr_left > 0);
+               write_back_completed_descs_split(vq, n_descs);
 
                __atomic_add_fetch(&vq->used->idx, n_descs, __ATOMIC_RELEASE);
                vhost_vring_call_split(dev, vq);
-- 
2.29.2

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