Re: [PATCH v4 3/7] vdpa: Make vhost_vdpa_net_cvq_map_elem accept any out sg

[Jason Wang <jasowang@redhat.com>]

在 2022/7/22 19:12, Eugenio Pérez 写道:
> So its generic enough to accept any out sg buffer and we can inject
> NIC state messages.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>   net/vhost-vdpa.c | 29 +++++++++++++++--------------
>   1 file changed, 15 insertions(+), 14 deletions(-)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 1b82ac2e07..bbe1830824 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -302,35 +302,36 @@ dma_map_err:
>   }
>   
>   /**
> - * Copy the guest element into a dedicated buffer suitable to be sent to NIC
> + * Maps out sg and in buffer into dedicated buffers suitable to be sent to NIC
>    *
> - * @iov: [0] is the out buffer, [1] is the in one
> + * @dev_iov: [0] is the out buffer, [1] is the in one


This still has assumption on the layout. I wonder if it's better to 
simply use in_sg and out_sg.

Thanks


>    */
> -static bool vhost_vdpa_net_cvq_map_elem(VhostVDPAState *s,
> -                                        VirtQueueElement *elem,
> -                                        struct iovec *iov)
> +static bool vhost_vdpa_net_cvq_map_sg(VhostVDPAState *s,
> +                                      const struct iovec *out, size_t out_num,
> +                                      struct iovec *dev_iov)
>   {
>       size_t in_copied;
>       bool ok;
>   
> -    iov[0].iov_base = s->cvq_cmd_out_buffer;
> -    ok = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, elem->out_sg, elem->out_num,
> -                                vhost_vdpa_net_cvq_cmd_len(), iov[0].iov_base,
> -                                &iov[0].iov_len, false);
> +    dev_iov[0].iov_base = s->cvq_cmd_out_buffer;
> +    ok = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, out, out_num,
> +                                vhost_vdpa_net_cvq_cmd_len(),
> +                                dev_iov[0].iov_base, &dev_iov[0].iov_len,
> +                                false);
>       if (unlikely(!ok)) {
>           return false;
>       }
>   
> -    iov[1].iov_base = s->cvq_cmd_in_buffer;
> +    dev_iov[1].iov_base = s->cvq_cmd_in_buffer;
>       ok = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, NULL, 0,
> -                                sizeof(virtio_net_ctrl_ack), iov[1].iov_base,
> -                                &in_copied, true);
> +                                sizeof(virtio_net_ctrl_ack),
> +                                dev_iov[1].iov_base, &in_copied, true);
>       if (unlikely(!ok)) {
>           vhost_vdpa_cvq_unmap_buf(&s->vhost_vdpa, s->cvq_cmd_out_buffer);
>           return false;
>       }
>   
> -    iov[1].iov_len = sizeof(virtio_net_ctrl_ack);
> +    dev_iov[1].iov_len = sizeof(virtio_net_ctrl_ack);
>       return true;
>   }
>   
> @@ -434,7 +435,7 @@ static int vhost_vdpa_net_handle_ctrl_avail(VhostShadowVirtqueue *svq,
>       };
>       bool ok;
>   
> -    ok = vhost_vdpa_net_cvq_map_elem(s, elem, dev_buffers);
> +    ok = vhost_vdpa_net_cvq_map_sg(s, elem->out_sg, elem->out_num, dev_buffers);
>       if (unlikely(!ok)) {
>           goto out;
>       }