Re: [RFC v2 02/13] vdpa net: move iova tree creation from init to start

[Jason Wang]

On Fri, Jan 13, 2023 at 1:24 AM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> Only create iova_tree if and when it is needed.
>
> The cleanup keeps being responsability of last VQ but this change allows
> to merge both cleanup functions.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>  net/vhost-vdpa.c | 101 +++++++++++++++++++++++++++++++++--------------
>  1 file changed, 71 insertions(+), 30 deletions(-)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index de5ed8ff22..75cca497c8 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -178,13 +178,9 @@ err_init:
>  static void vhost_vdpa_cleanup(NetClientState *nc)
>  {
>      VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> -    struct vhost_dev *dev = &s->vhost_net->dev;
>
>      qemu_vfree(s->cvq_cmd_out_buffer);
>      qemu_vfree(s->status);
> -    if (dev->vq_index + dev->nvqs == dev->vq_index_end) {
> -        g_clear_pointer(&s->vhost_vdpa.iova_tree, vhost_iova_tree_delete);
> -    }
>      if (s->vhost_net) {
>          vhost_net_cleanup(s->vhost_net);
>          g_free(s->vhost_net);
> @@ -234,10 +230,64 @@ static ssize_t vhost_vdpa_receive(NetClientState *nc, 
> const uint8_t *buf,
>      return size;
>  }
>
> +/** From any vdpa net client, get the netclient of first queue pair */
> +static VhostVDPAState *vhost_vdpa_net_first_nc_vdpa(VhostVDPAState *s)
> +{
> +    NICState *nic = qemu_get_nic(s->nc.peer);
> +    NetClientState *nc0 = qemu_get_peer(nic->ncs, 0);
> +
> +    return DO_UPCAST(VhostVDPAState, nc, nc0);
> +}
> +
> +static void vhost_vdpa_net_data_start_first(VhostVDPAState *s)
> +{
> +    struct vhost_vdpa *v = &s->vhost_vdpa;
> +
> +    if (v->shadow_vqs_enabled) {
> +        v->iova_tree = vhost_iova_tree_new(v->iova_range.first,
> +                                           v->iova_range.last);
> +    }
> +}
> +
> +static int vhost_vdpa_net_data_start(NetClientState *nc)
> +{
> +    VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> +    struct vhost_vdpa *v = &s->vhost_vdpa;
> +
> +    assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
> +
> +    if (v->index == 0) {
> +        vhost_vdpa_net_data_start_first(s);
> +        return 0;
> +    }
> +
> +    if (v->shadow_vqs_enabled) {
> +        VhostVDPAState *s0 = vhost_vdpa_net_first_nc_vdpa(s);
> +        v->iova_tree = s0->vhost_vdpa.iova_tree;
> +    }

It looks to me the logic here is somehow the same as
vhost_vdpa_net_cvq_start(), can we unify the them?

> +
> +    return 0;
> +}
> +
> +static void vhost_vdpa_net_client_stop(NetClientState *nc)
> +{
> +    VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> +    struct vhost_dev *dev;
> +
> +    assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
> +
> +    dev = s->vhost_vdpa.dev;
> +    if (dev->vq_index + dev->nvqs == dev->vq_index_end) {
> +        g_clear_pointer(&s->vhost_vdpa.iova_tree, vhost_iova_tree_delete);
> +    }
> +}
> +
>  static NetClientInfo net_vhost_vdpa_info = {
>          .type = NET_CLIENT_DRIVER_VHOST_VDPA,
>          .size = sizeof(VhostVDPAState),
>          .receive = vhost_vdpa_receive,
> +        .start = vhost_vdpa_net_data_start,
> +        .stop = vhost_vdpa_net_client_stop,
>          .cleanup = vhost_vdpa_cleanup,
>          .has_vnet_hdr = vhost_vdpa_has_vnet_hdr,
>          .has_ufo = vhost_vdpa_has_ufo,
> @@ -351,7 +401,7 @@ dma_map_err:
>
>  static int vhost_vdpa_net_cvq_start(NetClientState *nc)
>  {
> -    VhostVDPAState *s;
> +    VhostVDPAState *s, *s0;
>      struct vhost_vdpa *v;
>      uint64_t backend_features;
>      int64_t cvq_group;
> @@ -415,8 +465,6 @@ static int vhost_vdpa_net_cvq_start(NetClientState *nc)
>          return r;
>      }
>
> -    v->iova_tree = vhost_iova_tree_new(v->iova_range.first,
> -                                       v->iova_range.last);
>      v->shadow_vqs_enabled = true;
>      s->vhost_vdpa.address_space_id = VHOST_VDPA_NET_CVQ_ASID;
>
> @@ -425,6 +473,15 @@ out:
>          return 0;
>      }
>
> +    s0 = vhost_vdpa_net_first_nc_vdpa(s);
> +    if (s0->vhost_vdpa.iova_tree) {
> +        /* SVQ is already configured for all virtqueues */
> +        v->iova_tree = s0->vhost_vdpa.iova_tree;
> +    } else {
> +        v->iova_tree = vhost_iova_tree_new(v->iova_range.first,
> +                                           v->iova_range.last);
> +    }
> +
>      r = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, s->cvq_cmd_out_buffer,
>                                 vhost_vdpa_net_cvq_cmd_page_len(), false);
>      if (unlikely(r < 0)) {
> @@ -449,15 +506,9 @@ static void vhost_vdpa_net_cvq_stop(NetClientState *nc)
>      if (s->vhost_vdpa.shadow_vqs_enabled) {
>          vhost_vdpa_cvq_unmap_buf(&s->vhost_vdpa, s->cvq_cmd_out_buffer);
>          vhost_vdpa_cvq_unmap_buf(&s->vhost_vdpa, s->status);
> -        if (!s->always_svq) {
> -            /*
> -             * If only the CVQ is shadowed we can delete this safely.
> -             * If all the VQs are shadows this will be needed by the time the
> -             * device is started again to register SVQ vrings and similar.
> -             */
> -            g_clear_pointer(&s->vhost_vdpa.iova_tree, 
> vhost_iova_tree_delete);
> -        }
>      }
> +
> +    vhost_vdpa_net_client_stop(nc);
>  }
>
>  static ssize_t vhost_vdpa_net_cvq_add(VhostVDPAState *s, size_t out_len,
> @@ -667,8 +718,7 @@ static NetClientState *net_vhost_vdpa_init(NetClientState 
> *peer,
>                                         int nvqs,
>                                         bool is_datapath,
>                                         bool svq,
> -                                       struct vhost_vdpa_iova_range 
> iova_range,
> -                                       VhostIOVATree *iova_tree)
> +                                       struct vhost_vdpa_iova_range 
> iova_range)
>  {
>      NetClientState *nc = NULL;
>      VhostVDPAState *s;
> @@ -690,7 +740,6 @@ static NetClientState *net_vhost_vdpa_init(NetClientState 
> *peer,
>      s->vhost_vdpa.shadow_vqs_enabled = svq;
>      s->vhost_vdpa.iova_range = iova_range;
>      s->vhost_vdpa.shadow_data = svq;
> -    s->vhost_vdpa.iova_tree = iova_tree;
>      if (!is_datapath) {
>          s->cvq_cmd_out_buffer = qemu_memalign(qemu_real_host_page_size(),
>                                              
> vhost_vdpa_net_cvq_cmd_page_len());
> @@ -760,7 +809,6 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char 
> *name,
>      uint64_t features;
>      int vdpa_device_fd;
>      g_autofree NetClientState **ncs = NULL;
> -    g_autoptr(VhostIOVATree) iova_tree = NULL;
>      struct vhost_vdpa_iova_range iova_range;
>      NetClientState *nc;
>      int queue_pairs, r, i = 0, has_cvq = 0;
> @@ -812,12 +860,8 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char 
> *name,
>          goto err;
>      }
>
> -    if (opts->x_svq) {
> -        if (!vhost_vdpa_net_valid_svq_features(features, errp)) {
> -            goto err_svq;
> -        }
> -
> -        iova_tree = vhost_iova_tree_new(iova_range.first, iova_range.last);
> +    if (opts->x_svq && !vhost_vdpa_net_valid_svq_features(features, errp)) {
> +        goto err;
>      }
>
>      ncs = g_malloc0(sizeof(*ncs) * queue_pairs);
> @@ -825,7 +869,7 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char 
> *name,
>      for (i = 0; i < queue_pairs; i++) {
>          ncs[i] = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
>                                       vdpa_device_fd, i, 2, true, opts->x_svq,
> -                                     iova_range, iova_tree);
> +                                     iova_range);
>          if (!ncs[i])
>              goto err;
>      }
> @@ -833,13 +877,11 @@ int net_init_vhost_vdpa(const Netdev *netdev, const 
> char *name,
>      if (has_cvq) {
>          nc = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
>                                   vdpa_device_fd, i, 1, false,
> -                                 opts->x_svq, iova_range, iova_tree);
> +                                 opts->x_svq, iova_range);
>          if (!nc)
>              goto err;
>      }
>
> -    /* iova_tree ownership belongs to last NetClientState */
> -    g_steal_pointer(&iova_tree);
>      return 0;
>
>  err:
> @@ -849,7 +891,6 @@ err:
>          }
>      }
>
> -err_svq:
>      qemu_close(vdpa_device_fd);
>
>      return -1;
> --
> 2.31.1
>