Re: [RFC] virtio_net: multicast address list never sent to host

[Amos Kong <akong@redhat.com>]

On Thu, Dec 05, 2013 at 03:20:52PM -0800, Stephen Hemminger wrote:
> 
> The virtio_net driver never sends the second address list to
> the host. This is because send command takes a pointer to scatter list
> to send but only inserts that one entry into the scatter list that
> is sent to the host.
> 
> This bug has been there since:
> commit f565a7c259d71cc186753653d978c646d2354b36
> Author: Alex Williamson <alex.williamson@hp.com>
> Date:   Wed Feb 4 09:02:45 2009 +0000
> 
>     virtio_net: Add a MAC filter table
> 
> 
> I also dropped the in argument since it is never used.

Hi Stephen,

I don't think this patch is necessary, did you touch some real
problem?
 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
>
> --- a/drivers/net/virtio_net.c	2013-12-05 15:11:34.000000000 -0800
> +++ b/drivers/net/virtio_net.c	2013-12-05 15:17:16.211568831 -0800
> @@ -877,16 +877,16 @@ static netdev_tx_t start_xmit(struct sk_
>   * never fail unless improperly formated.
>   */
>  static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
> -				 struct scatterlist *out,
> -				 struct scatterlist *in)
> +				 struct scatterlist *out, unsigned out_cnt)
>  {
>  	struct scatterlist *sgs[4], hdr, stat;

We save scatterlist point in sgs[], one list can have 0, 1 or more than 1 items.

In virtio_rng.c: virtqueue_add_sgs()

   /* Count them first. */
   for (i = total_out = total_in = 0; i < out_sgs; i++) {
           struct scatterlist *sg;
           for (sg = sgs[i]; sg; sg = sg_next(sg))
                   total_out++;
   }

Each item of sgs[] will be visited, all the scatter entries of one scatterlist
will also be visited.

In my testing (w/o this patch), multicast addresses can be sent to qemu.

guest) # ip maddr show
1:      lo
        inet  224.0.0.1
        inet6 ff02::1
        inet6 ff01::1
2:      eth0
        link  33:33:00:00:00:01
        link  01:00:5e:00:00:01
        link  33:33:ff:12:34:56
        link  33:33:00:00:02:02
        link  01:00:5e:00:00:fb
        inet  224.0.0.251
        inet  224.0.0.1
        inet6 ff02::202
        inet6 ff02::1:ff12:3456
        inet6 ff02::1
        inet6 ff01::1

qmp) { 'execute': 'query-rx-filter'}

{
    "return": [
        {
            "promiscuous": false, 
            "name": "vnet0", 
            "main-mac": "52:54:00:12:34:56", 
            "unicast": "normal", 
            "vlan-table": [
            ], 
            "unicast-table": [
            ], 
            "multicast": "normal", 
            "multicast-overflow": false, 
            "unicast-overflow": false, 
            "multicast-table": [
                "01:00:5e:00:00:fb", 
                "33:33:00:00:02:02", 
                "33:33:ff:12:34:56", 
                "01:00:5e:00:00:01", 
                "33:33:00:00:00:01"
            ], 
            "broadcast-allowed": false
        }
    ]
}


Thanks, Amos


>  	struct virtio_net_ctrl_hdr ctrl;
>  	virtio_net_ctrl_ack status = ~0;
> -	unsigned out_num = 0, in_num = 0, tmp;
> +	unsigned out_num = 0, tmp;
>  
>  	/* Caller should know better */
>  	BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));
> +	BUG_ON(out_cnt > 2);
>  
>  	ctrl.class = class;
>  	ctrl.cmd = cmd;
> @@ -894,17 +894,14 @@ static bool virtnet_send_command(struct
>  	sg_init_one(&hdr, &ctrl, sizeof(ctrl));
>  	sgs[out_num++] = &hdr;
>  
> -	if (out)
> -		sgs[out_num++] = out;
> -	if (in)
> -		sgs[out_num + in_num++] = in;
> +	while (out_cnt-- > 0)
> +		sgs[out_num++] = out++;
>  
>  	/* Add return status. */
>  	sg_init_one(&stat, &status, sizeof(status));
> -	sgs[out_num + in_num++] = &stat;
> +	sgs[out_num] = &stat;
>  
> -	BUG_ON(out_num + in_num > ARRAY_SIZE(sgs));
> -	BUG_ON(virtqueue_add_sgs(vi->cvq, sgs, out_num, in_num, vi, GFP_ATOMIC)
> +	BUG_ON(virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC)
>  	       < 0);
>  
>  	if (unlikely(!virtqueue_kick(vi->cvq)))
> @@ -936,7 +933,7 @@ static int virtnet_set_mac_address(struc
>  		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, NULL)) {
> +					  &sg, 1)) {
>  			dev_warn(&vdev->dev,
>  				 "Failed to set mac address by vq command.\n");
>  			return -EINVAL;
> @@ -1009,7 +1006,7 @@ static void virtnet_ack_link_announce(st
>  {
>  	rtnl_lock();
>  	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_ANNOUNCE,
> -				  VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL, NULL))
> +				  VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL, 0))
>  		dev_warn(&vi->dev->dev, "Failed to ack link announce.\n");
>  	rtnl_unlock();
>  }
> @@ -1027,7 +1024,7 @@ static int virtnet_set_queues(struct vir
>  	sg_init_one(&sg, &s, sizeof(s));
>  
>  	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MQ,
> -				  VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET, &sg, NULL)) {
> +				  VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET, &sg, 1)) {
>  		dev_warn(&dev->dev, "Fail to set num of queue pairs to %d\n",
>  			 queue_pairs);
>  		return -EINVAL;
> @@ -1078,7 +1075,7 @@ static void virtnet_set_rx_mode(struct n
>  
>  	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
>  				  VIRTIO_NET_CTRL_RX_PROMISC,
> -				  sg, NULL))
> +				  sg, 1))
>  		dev_warn(&dev->dev, "Failed to %sable promisc mode.\n",
>  			 promisc ? "en" : "dis");
>  
> @@ -1086,7 +1083,7 @@ static void virtnet_set_rx_mode(struct n
>  
>  	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
>  				  VIRTIO_NET_CTRL_RX_ALLMULTI,
> -				  sg, NULL))
> +				  sg, 1))
>  		dev_warn(&dev->dev, "Failed to %sable allmulti mode.\n",
>  			 allmulti ? "en" : "dis");
>  
> @@ -1123,7 +1120,7 @@ static void virtnet_set_rx_mode(struct n
>  
>  	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
>  				  VIRTIO_NET_CTRL_MAC_TABLE_SET,
> -				  sg, NULL))
> +				  sg, 2))
>  		dev_warn(&dev->dev, "Failed to set MAC filter table.\n");
>  
>  	kfree(buf);
> @@ -1138,7 +1135,7 @@ static int virtnet_vlan_rx_add_vid(struc
>  	sg_init_one(&sg, &vid, sizeof(vid));
>  
>  	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
> -				  VIRTIO_NET_CTRL_VLAN_ADD, &sg, NULL))
> +				  VIRTIO_NET_CTRL_VLAN_ADD, &sg, 1))
>  		dev_warn(&dev->dev, "Failed to add VLAN ID %d.\n", vid);
>  	return 0;
>  }
> @@ -1152,7 +1149,7 @@ static int virtnet_vlan_rx_kill_vid(stru
>  	sg_init_one(&sg, &vid, sizeof(vid));
>  
>  	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
> -				  VIRTIO_NET_CTRL_VLAN_DEL, &sg, NULL))
> +				  VIRTIO_NET_CTRL_VLAN_DEL, &sg, 1))
>  		dev_warn(&dev->dev, "Failed to kill VLAN ID %d.\n", vid);
>  	return 0;
>  }