Re: [PATCH v5 06/10] vdpa: Make vhost_vdpa_net_cvq_map_elem accept any out sg

[Jason Wang]

在 2022/8/3 01:57, 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>
> ---
> v5: Accept out sg instead of dev_buffers[]
> ---
>   net/vhost-vdpa.c | 13 +++++++------
>   1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 33bf3d6409..2421bca347 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -302,16 +302,16 @@ 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
>    */
> -static bool vhost_vdpa_net_cvq_map_elem(VhostVDPAState *s,
> -                                        VirtQueueElement *elem,
> -                                        size_t *out_len)
> +static bool vhost_vdpa_net_cvq_map_sg(VhostVDPAState *s,
> +                                      const struct iovec *out, size_t out_num,
> +                                      size_t *out_len)


This still looks not genreal as there's no guarantee that we won't have 
command-in-specific-data. One example is that Ali is working on the 
virtio-net statistics fetching from the control virtqueue.

So it looks to me we'd better have a general bounce_map here that accepts:

1) out_sg and out_num
2) in_sg and in_num

In this level, we'd better not have any special care about the in as the 
ack. And we need do bouncing:

1) for out buffer, during map
2) for in buffer during unmap

Thanks


>   {
>       size_t in_copied;
>       bool ok;
>   
> -    ok = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, elem->out_sg, elem->out_num,
> +    ok = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, out, out_num,
>                                   vhost_vdpa_net_cvq_cmd_len(),
>                                   s->cvq_cmd_out_buffer, out_len, false);
>       if (unlikely(!ok)) {
> @@ -435,7 +435,8 @@ static int 
> vhost_vdpa_net_handle_ctrl_avail(VhostShadowVirtqueue *svq,
>       };
>       bool ok;
>   
> -    ok = vhost_vdpa_net_cvq_map_elem(s, elem, &dev_buffers[0].iov_len);
> +    ok = vhost_vdpa_net_cvq_map_sg(s, elem->out_sg, elem->out_num,
> +                                   &dev_buffers[0].iov_len);
>       if (unlikely(!ok)) {
>           goto out;
>       }