Re: [PATCH net-next v5 2/9] virtio_net: virtnet_send_command supports command-specific-result

From: Jason Wang <jasowang@redhat.com>
To: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
	 Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	 "Michael S. Tsirkin" <mst@redhat.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	 Jesper Dangaard Brouer <hawk@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	 Stanislav Fomichev <sdf@google.com>,
	Amritha Nambiar <amritha.nambiar@intel.com>,
	 Larysa Zaremba <larysa.zaremba@intel.com>,
	Sridhar Samudrala <sridhar.samudrala@intel.com>,
	 Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
	virtualization@lists.linux.dev,  bpf@vger.kernel.org
Subject: Re: [PATCH net-next v5 2/9] virtio_net: virtnet_send_command supports command-specific-result
Date: Wed, 10 Apr 2024 14:09:11 +0800	[thread overview]
Message-ID: <CACGkMEt_RYQMLpZOYe6MhhxeH8xpzKUJE-UCthBCr+7JgD6V1g@mail.gmail.com> (raw)
In-Reply-To: <20240318110602.37166-3-xuanzhuo@linux.alibaba.com>

On Mon, Mar 18, 2024 at 7:06 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
>
> As the spec https://github.com/oasis-tcs/virtio-spec/commit/42f389989823039724f95bbbd243291ab0064f82
>
> The virtnet cvq supports to get result from the device.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
>  drivers/net/virtio_net.c | 47 +++++++++++++++++++++++-----------------
>  1 file changed, 27 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index d7ce4a1011ea..af512d85cd5b 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2512,10 +2512,11 @@ static int virtnet_tx_resize(struct virtnet_info *vi,
>   * never fail unless improperly formatted.
>   */
>  static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
> -                                struct scatterlist *out)
> +                                struct scatterlist *out,
> +                                struct scatterlist *in)
>  {
> -       struct scatterlist *sgs[4], hdr, stat;
> -       unsigned out_num = 0, tmp;
> +       struct scatterlist *sgs[5], hdr, stat;
> +       u32 out_num = 0, tmp, in_num = 0;
>         int ret;
>
>         /* Caller should know better */
> @@ -2533,10 +2534,13 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
>
>         /* Add return status. */
>         sg_init_one(&stat, &vi->ctrl->status, sizeof(vi->ctrl->status));
> -       sgs[out_num] = &stat;
> +       sgs[out_num + in_num++] = &stat;
>
> -       BUG_ON(out_num + 1 > ARRAY_SIZE(sgs));
> -       ret = virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC);
> +       if (in)
> +               sgs[out_num + in_num++] = in;
> +
> +       BUG_ON(out_num + in_num > ARRAY_SIZE(sgs));
> +       ret = virtqueue_add_sgs(vi->cvq, sgs, out_num, in_num, vi, GFP_ATOMIC);
>         if (ret < 0) {
>                 dev_warn(&vi->vdev->dev,
>                          "Failed to add sgs for command vq: %d\n.", ret);
> @@ -2578,7 +2582,8 @@ static int virtnet_set_mac_address(struct net_device *dev, void *p)
>         if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
>                 sg_init_one(&sg, addr->sa_data, dev->addr_len);
>                 if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
> -                                         VIRTIO_NET_CTRL_MAC_ADDR_SET, &sg)) {
> +                                         VIRTIO_NET_CTRL_MAC_ADDR_SET,
> +                                         &sg, NULL)) {
>                         dev_warn(&vdev->dev,
>                                  "Failed to set mac address by vq command.\n");
>                         ret = -EINVAL;
> @@ -2647,7 +2652,7 @@ static void virtnet_ack_link_announce(struct virtnet_info *vi)
>  {
>         rtnl_lock();
>         if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_ANNOUNCE,
> -                                 VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL))
> +                                 VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL, NULL))

Nit: It might be better to introduce a virtnet_send_command_reply()
and let virtnet_send_command() call it as in=NULL to simplify the
changes.

Others look good.

Thanks