Re: [PATCH 2/5] vdpa: Add vhost_vdpa_net_load_mq

[Jason Wang]

在 2022/8/20 01:13, Eugenio Pérez 写道:
> Same way as with the MAC, restore the expected number of queues at
> device's start.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>   net/vhost-vdpa.c | 33 +++++++++++++++++++++++++++++++++
>   1 file changed, 33 insertions(+)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 1e0dbfcced..96fd3bc835 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -391,6 +391,35 @@ static int vhost_vdpa_net_load_mac(VhostVDPAState *s,
>       return 0;
>   }
>   
> +static int vhost_vdpa_net_load_mq(VhostVDPAState *s,
> +                                  const VirtIONet *n)
> +{
> +    uint64_t features = n->parent_obj.guest_features;
> +    ssize_t dev_written;
> +    void *cursor = s->cvq_cmd_out_buffer;
> +    if (!(features & BIT_ULL(VIRTIO_NET_F_MQ))) {
> +        return 0;
> +    }
> +
> +    *(struct virtio_net_ctrl_hdr *)cursor = (struct virtio_net_ctrl_hdr) {
> +        .class = VIRTIO_NET_CTRL_MQ,
> +        .cmd = VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET,
> +    };
> +    cursor += sizeof(struct virtio_net_ctrl_hdr);
> +    *(struct virtio_net_ctrl_mq *)cursor = (struct virtio_net_ctrl_mq) {
> +        .virtqueue_pairs = cpu_to_le16(n->curr_queue_pairs),
> +    };


Such casting is not elegant, let's just prepare buffer and then do the 
copy inside vhost_vdpa_net_cvq_add()?


> +    cursor += sizeof(struct virtio_net_ctrl_mq);
> +
> +    dev_written = vhost_vdpa_net_cvq_add(s, cursor - s->cvq_cmd_out_buffer,
> +                                             sizeof(virtio_net_ctrl_ack));
> +    if (unlikely(dev_written < 0)) {
> +        return dev_written;
> +    }
> +
> +    return *((virtio_net_ctrl_ack *)s->cvq_cmd_in_buffer) != VIRTIO_NET_OK;


So I think we should have a dedicated buffer just for ack, then there's 
no need for such casting.

Thanks


> +}
> +
>   static int vhost_vdpa_net_load(NetClientState *nc)
>   {
>       VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> @@ -409,6 +438,10 @@ static int vhost_vdpa_net_load(NetClientState *nc)
>       if (unlikely(r < 0)) {
>           return r;
>       }
> +    r = vhost_vdpa_net_load_mq(s, n);
> +    if (unlikely(r)) {
> +        return r;
> +    }
>   
>       return 0;
>   }