[dpdk-dev] [PATCH v7 2/4] vhost: add support for packed ring in async vhost

[Jiang, Cheng1]

Hi Jiayu,

> -----Original Message-----
> From: Hu, Jiayu <jiayu.hu at intel.com>
> Sent: Thursday, April 15, 2021 10:03 AM
> To: Jiang, Cheng1 <cheng1.jiang at intel.com>; maxime.coquelin at redhat.com;
> Xia, Chenbo <chenbo.xia at intel.com>
> Cc: dev at dpdk.org; Yang, YvonneX <yvonnex.yang at intel.com>; Wang, Yinan
> <yinan.wang at intel.com>; Liu, Yong <yong.liu at intel.com>
> Subject: RE: [PATCH v7 2/4] vhost: add support for packed ring in async vhost
> 
> Hi Cheng,
> 
> > -----Original Message-----
> > From: Jiang, Cheng1 <cheng1.jiang at intel.com>
> > Sent: Wednesday, April 14, 2021 2:14 PM
> > To: maxime.coquelin at redhat.com; Xia, Chenbo <chenbo.xia at intel.com>
> > Cc: dev at dpdk.org; Hu, Jiayu <jiayu.hu at intel.com>; Yang, YvonneX
> > <yvonnex.yang at intel.com>; Wang, Yinan <yinan.wang at intel.com>; Liu,
> > Yong <yong.liu at intel.com>; Jiang, Cheng1 <cheng1.jiang at intel.com>
> > Subject: [PATCH v7 2/4] vhost: add support for packed ring in async
> > vhost
> >
> > For now async vhost data path only supports split ring. This patch
> > enables packed ring in async vhost data path to make async vhost
> > compatible with virtio 1.1 spec.
> >
> > Signed-off-by: Cheng Jiang <Cheng1.jiang at intel.com>
> > ---
> >  lib/librte_vhost/rte_vhost_async.h |   1 +
> >  lib/librte_vhost/vhost.c           |  49 ++--
> >  lib/librte_vhost/vhost.h           |  15 +-
> >  lib/librte_vhost/virtio_net.c      | 432 +++++++++++++++++++++++++++--
> >  4 files changed, 456 insertions(+), 41 deletions(-)
> >
> > diff --git a/lib/librte_vhost/rte_vhost_async.h
> > b/lib/librte_vhost/rte_vhost_async.h
> > index c855ff875..6faa31f5a 100644
> > --- a/lib/librte_vhost/rte_vhost_async.h
> > +++ b/lib/librte_vhost/rte_vhost_async.h
> > @@ -89,6 +89,7 @@ struct rte_vhost_async_channel_ops {  struct
> > async_inflight_info {  struct rte_mbuf *mbuf;  uint16_t descs; /* num
> > of descs inflight */
> > +uint16_t nr_buffers; /* num of buffers inflight for packed ring */
> >  };
> >
> >  /**
> > diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c index
> > a70fe01d8..f509186c6 100644
> > --- a/lib/librte_vhost/vhost.c
> > +++ b/lib/librte_vhost/vhost.c
> > @@ -338,19 +338,22 @@ cleanup_device(struct virtio_net *dev, int
> > destroy)  }
> >
> >  static void
> > -vhost_free_async_mem(struct vhost_virtqueue *vq)
> > +vhost_free_async_mem(struct virtio_net *dev, struct vhost_virtqueue
> > +*vq)
> >  {
> > -if (vq->async_pkts_info)
> > -rte_free(vq->async_pkts_info);
> > -if (vq->async_descs_split)
> > +rte_free(vq->async_pkts_info);
> > +
> > +if (vq_is_packed(dev)) {
> > +rte_free(vq->async_buffers_packed);
> > +vq->async_buffers_packed = NULL;
> > +} else {
> >  rte_free(vq->async_descs_split);
> > -if (vq->it_pool)
> > -rte_free(vq->it_pool);
> > -if (vq->vec_pool)
> > -rte_free(vq->vec_pool);
> > +vq->async_descs_split = NULL;
> > +}
> > +
> > +rte_free(vq->it_pool);
> > +rte_free(vq->vec_pool);
> >
> >  vq->async_pkts_info = NULL;
> > -vq->async_descs_split = NULL;
> >  vq->it_pool = NULL;
> >  vq->vec_pool = NULL;
> >  }
> > @@ -360,10 +363,10 @@ free_vq(struct virtio_net *dev, struct
> > vhost_virtqueue *vq)  {  if (vq_is_packed(dev))
> > rte_free(vq->shadow_used_packed); -else {
> > +else
> >  rte_free(vq->shadow_used_split);
> > -vhost_free_async_mem(vq);
> > -}
> > +
> > +vhost_free_async_mem(dev, vq);
> >  rte_free(vq->batch_copy_elems);
> >  if (vq->iotlb_pool)
> >  rte_mempool_free(vq->iotlb_pool);
> > @@ -1626,10 +1629,9 @@ int rte_vhost_async_channel_register(int vid,
> > uint16_t queue_id,  if (unlikely(vq == NULL || !dev->async_copy))
> > return -1;
> >
> > -/* packed queue is not supported */
> > -if (unlikely(vq_is_packed(dev) || !f.async_inorder)) {
> > +if (unlikely(!f.async_inorder)) {
> >  VHOST_LOG_CONFIG(ERR,
> > -"async copy is not supported on packed queue or non-inorder mode "
> > +"async copy is not supported on non-inorder mode "
> >  "(vid %d, qid: %d)\n", vid, queue_id);  return -1;  } @@ -1667,12
> > +1669,19 @@ int rte_vhost_async_channel_register(int vid, uint16_t
> > queue_id,  vq->vec_pool = rte_malloc_socket(NULL,
> VHOST_MAX_ASYNC_VEC
> > * sizeof(struct iovec),  RTE_CACHE_LINE_SIZE, node);
> > -vq->async_descs_split = rte_malloc_socket(NULL,
> > +if (vq_is_packed(dev)) {
> > +vq->async_buffers_packed = rte_malloc_socket(NULL, size *
> > +vq->sizeof(struct vring_used_elem_packed),
> > +RTE_CACHE_LINE_SIZE, node);
> > +} else {
> > +vq->async_descs_split = rte_malloc_socket(NULL,
> >  vq->size * sizeof(struct vring_used_elem),  RTE_CACHE_LINE_SIZE,
> > node); -if (!vq->async_descs_split || !vq->async_pkts_info ||
> > -!vq->it_pool || !vq->vec_pool) { -vhost_free_async_mem(vq);
> > +}
> > +
> > +if (!vq->async_buffers_packed || !vq->async_descs_split ||
> async_buffers_packed and async_descs_split are two members of a union.
> Like the way processed in vhost_free_async_mem(), do you think it's better
> to check if they are NULL in if-else respectively?

Sure, make sense to me. I'll fix them together with other async mem check.

> 
> > +!vq->async_pkts_info || !vq->it_pool || !vq->vec_pool) {
> > +vhost_free_async_mem(dev, vq);
> >  VHOST_LOG_CONFIG(ERR,
> >  "async register failed: cannot allocate memory for vq data "
> >  "(vid %d, qid: %d)\n", vid, queue_id); @@ -1728,7 +1737,7 @@ int
> > rte_vhost_async_channel_unregister(int vid, uint16_t queue_id)  goto
> > out;  }
> >
> > -vhost_free_async_mem(vq);
> > +vhost_free_async_mem(dev, vq);
> >
> >  vq->async_ops.transfer_data = NULL;
> >  vq->async_ops.check_completed_copies = NULL; diff --git
> > a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h index
> > f628714c2..673335217 100644
> > --- a/lib/librte_vhost/vhost.h
> > +++ b/lib/librte_vhost/vhost.h
> > @@ -201,9 +201,18 @@ struct vhost_virtqueue {  uint16_tasync_pkts_idx;
> > uint16_tasync_pkts_inflight_n;  uint16_tasync_last_pkts_n; -struct
> > vring_used_elem  *async_descs_split; -uint16_t async_desc_idx;
> > -uint16_t last_async_desc_idx;
> > +union {
> > +struct vring_used_elem  *async_descs_split; struct
> > +vring_used_elem_packed *async_buffers_packed; }; union { uint16_t
> > +async_desc_idx; uint16_t async_packed_buffer_idx; }; union { uint16_t
> > +last_async_desc_idx; uint16_t last_async_buffer_idx; };
> >
> >  /* vq async features */
> >  boolasync_inorder;
> > diff --git a/lib/librte_vhost/virtio_net.c
> > b/lib/librte_vhost/virtio_net.c index 438bdafd1..54e11e3a5 100644
> > --- a/lib/librte_vhost/virtio_net.c
> > +++ b/lib/librte_vhost/virtio_net.c
> > @@ -363,14 +363,14 @@
> > vhost_shadow_dequeue_single_packed_inorder(struct vhost_virtqueue
> *vq,
> > }
> >
> >  static __rte_always_inline void
> > -vhost_shadow_enqueue_single_packed(struct virtio_net *dev,
> > -   struct vhost_virtqueue *vq,
> > -   uint32_t len[],
> > -   uint16_t id[],
> > -   uint16_t count[],
> > +vhost_shadow_enqueue_packed(struct vhost_virtqueue *vq,
> > +   uint32_t *len,
> > +   uint16_t *id,
> > +   uint16_t *count,
> >     uint16_t num_buffers)
> >  {
> >  uint16_t i;
> > +
> >  for (i = 0; i < num_buffers; i++) {
> >  /* enqueue shadow flush action aligned with batch num */  if
> > (!vq->shadow_used_idx) @@ -382,6 +382,17 @@
> > vhost_shadow_enqueue_single_packed(struct
> > virtio_net *dev,
> >  vq->shadow_aligned_idx += count[i];
> >  vq->shadow_used_idx++;
> >  }
> > +}
> > +
> > +static __rte_always_inline void
> > +vhost_shadow_enqueue_single_packed(struct virtio_net *dev,
> > +   struct vhost_virtqueue *vq,
> > +   uint32_t *len,
> > +   uint16_t *id,
> > +   uint16_t *count,
> > +   uint16_t num_buffers)
> > +{
> > +vhost_shadow_enqueue_packed(vq, len, id, count, num_buffers);
> >
> >  if (vq->shadow_aligned_idx >= PACKED_BATCH_SIZE) {
> > do_data_copy_enqueue(dev, vq); @@ -1474,6 +1485,23 @@
> > store_dma_desc_info_split(struct vring_used_elem *s_ring, struct
> > vring_used_elem  }  }
> >
> > +static __rte_always_inline void
> > +store_dma_desc_info_packed(struct vring_used_elem_packed *s_ring,
> > +struct vring_used_elem_packed *d_ring, uint16_t ring_size, uint16_t
> > +s_idx, uint16_t d_idx, uint16_t
> > count)
> > +{
> > +uint16_t elem_size = sizeof(struct vring_used_elem_packed);
> > +
> > +if (d_idx + count <= ring_size) {
> > +rte_memcpy(d_ring + d_idx, s_ring + s_idx, count *
> > elem_size);
> > +} else {
> > +uint16_t size = ring_size - d_idx;
> > +
> > +rte_memcpy(d_ring + d_idx, s_ring + s_idx, size * elem_size);
> > +rte_memcpy(d_ring, s_ring + s_idx + 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, @@ -1641,6 +1669,330 @@
> > virtio_dev_rx_async_submit_split(struct
> > virtio_net *dev,
> >  return pkt_idx;
> >  }
> >
> > +static __rte_always_inline void
> > +vhost_update_used_packed(struct vhost_virtqueue *vq, struct
> > +vring_used_elem_packed *shadow_ring, uint16_t count) { int i;
> > +uint16_t used_idx = vq->last_used_idx; uint16_t head_idx =
> > +vq->last_used_idx; uint16_t head_flags = 0;
> > +
> > +if (count == 0)
> > +return;
> > +
> > +/* Split loop in two to save memory barriers */ for (i = 0; i <
> > +count; i++) {
> > +vq->desc_packed[used_idx].id = shadow_ring[i].id;
> > +vq->desc_packed[used_idx].len = shadow_ring[i].len;
> > +
> > +used_idx += shadow_ring[i].count;
> > +if (used_idx >= vq->size)
> > +used_idx -= vq->size;
> > +}
> > +
> > +/* The ordering for storing desc flags needs to be enforced. */
> > +rte_atomic_thread_fence(__ATOMIC_RELEASE);
> > +
> > +for (i = 0; i < count; i++) {
> > +uint16_t flags;
> > +
> > +if (vq->shadow_used_packed[i].len)
> > +flags = VRING_DESC_F_WRITE;
> > +else
> > +flags = 0;
> > +
> > +if (vq->used_wrap_counter) {
> > +flags |= VRING_DESC_F_USED;
> > +flags |= VRING_DESC_F_AVAIL;
> > +} else {
> > +flags &= ~VRING_DESC_F_USED;
> > +flags &= ~VRING_DESC_F_AVAIL;
> > +}
> > +
> > +if (i > 0) {
> > +vq->desc_packed[vq->last_used_idx].flags = flags;
> > +
> No need a blank line above.

Sure, thanks.

> 
> > +} else {
> > +head_idx = vq->last_used_idx;
> > +head_flags = flags;
> > +}
> > +
> > +vq_inc_last_used_packed(vq, shadow_ring[i].count); }
> > +
> > +vq->desc_packed[head_idx].flags = head_flags;
> > +}
> > +
> > +static __rte_always_inline int
> > +vhost_enqueue_async_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_buffers,
> > +    struct vring_packed_desc *async_descs,
> > +    struct iovec *src_iovec, struct iovec *dst_iovec,
> > +    struct rte_vhost_iov_iter *src_it,
> > +    struct rte_vhost_iov_iter *dst_it) { 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 = 0;
> > +uint32_t size = pkt->pkt_len + sizeof(struct
> > virtio_net_hdr_mrg_rxbuf);
> > +uint32_t buffer_len[vq->size];
> > +uint16_t buffer_buf_id[vq->size];
> > +uint16_t buffer_desc_count[vq->size]; *nr_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;
> > +
> > +buffer_len[*nr_buffers] = len;
> > +buffer_buf_id[*nr_buffers] = buf_id;
> > +buffer_desc_count[*nr_buffers] = desc_count; *nr_buffers += 1;
> > +
> > +*nr_descs += desc_count;
> > +avail_idx += desc_count;
> > +if (avail_idx >= vq->size)
> > +avail_idx -= vq->size;
> > +}
> > +
> > +if (async_mbuf_to_desc(dev, vq, pkt, buf_vec, nr_vec, *nr_buffers,
> > src_iovec, dst_iovec,
> > +src_it, dst_it) < 0)
> > +return -1;
> > +/* store descriptors for DMA */
> > +if (avail_idx >= *nr_descs) {
> > +rte_memcpy(async_descs, &vq->desc_packed[vq-
> > >last_avail_idx],
> > +*nr_descs * sizeof(struct vring_packed_desc)); } else { uint16_t
> > +nr_copy = vq->size - vq->last_avail_idx; rte_memcpy(async_descs,
> > +&vq->desc_packed[vq-
> > >last_avail_idx],
> > +nr_copy * sizeof(struct vring_packed_desc)); rte_memcpy(async_descs +
> > +nr_copy, vq->desc_packed, (*nr_descs - nr_copy) * sizeof(struct
> > vring_packed_desc));
> > +}
> > +
> > +vhost_shadow_enqueue_packed(vq, buffer_len, buffer_buf_id,
> > buffer_desc_count, *nr_buffers);
> > +
> > +return 0;
> > +}
> > +
> > +static __rte_always_inline int16_t
> > +virtio_dev_rx_async_single_packed(struct virtio_net *dev, struct
> > vhost_virtqueue *vq,
> > +    struct rte_mbuf *pkt, uint16_t *nr_descs, uint16_t
> > *nr_buffers,
> > +    struct vring_packed_desc *async_descs,
> > +    struct iovec *src_iovec, struct iovec *dst_iovec,
> > +    struct rte_vhost_iov_iter *src_it, struct
> > rte_vhost_iov_iter *dst_it)
> > +{
> > +struct buf_vector buf_vec[BUF_VECTOR_MAX]; *nr_descs = 0;
> *nr_buffers
> > += 0;
> > +
> > +if (unlikely(vhost_enqueue_async_single_packed(dev, vq, pkt,
> > buf_vec, nr_descs, nr_buffers,
> > + async_descs, src_iovec,
> > dst_iovec,
> > + src_it, dst_it) < 0)) {
> > +VHOST_LOG_DATA(DEBUG, "(%d) failed to get enough desc
> > from vring\n", dev->vid);
> > +return -1;
> > +}
> > +
> > +VHOST_LOG_DATA(DEBUG, "(%d) current index %d | end
> > index %d\n",
> > +dev->vid, vq->last_avail_idx, vq->last_avail_idx +
> > *nr_descs);
> > +
> > +return 0;
> > +}
> > +
> > +static __rte_always_inline void
> > +dma_error_handler_packed(struct vhost_virtqueue *vq, struct
> > vring_packed_desc *async_descs,
> > +uint16_t async_descs_idx, uint16_t slot_idx, uint32_t
> > nr_err,
> > +uint32_t *pkt_idx, uint32_t *num_async_pkts,
> > uint32_t *num_done_pkts)
> > +{
> > +uint16_t descs_err = 0;
> > +uint16_t buffers_err = 0;
> > +struct async_inflight_info *pkts_info = vq->async_pkts_info;
> > +
> > +*num_async_pkts -= nr_err;
> > +*pkt_idx -= nr_err;
> > +/* calculate the sum of buffers and descs of DMA-error packets. */
> > +while (nr_err-- > 0) { descs_err += pkts_info[slot_idx %
> > +vq->size].descs;
> I notice there are several parts using "%" to wrap around index, but existed
> code uses "& (vq->size - 1)" instead. I think it's better to keep it consistent.

Unlike split ring, packed ring size is not necessarily a power of 2. So I can't use "& (vq->size - 1) in packed ring.

Thanks,
Cheng

> 
> Thanks,
> Jiayu