From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH net-next 1/3] virtio_net: set multicast filter list to host
Date: Tue, 10 Dec 2013 17:24:29 +0200
Message-ID: <20131210152429.GB25293@redhat.com>
References: <20131209161632.5ac96e5a@nehalam.linuxnetplumber.net>
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Cc: netdev@vger.kernel.org, David Miller <davem@davemloft.net>,
	virtualization@lists.linux-foundation.org
To: Stephen Hemminger <stephen@networkplumber.org>
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On Mon, Dec 09, 2013 at 04:16:32PM -0800, Stephen Hemminger wrote:
> The virtio_net driver never sends the multicast 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 outgoing scatter list.
> 
> 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
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

Question is, can we detect a broken driver in the host somehow?
If not we'll need a feature bit for hosts to actually do
MC filtering.

> --- a/drivers/net/virtio_net.c	2013-12-09 16:12:03.897891975 -0800
> +++ b/drivers/net/virtio_net.c	2013-12-09 16:12:36.353164803 -0800
> @@ -893,7 +893,7 @@ static bool virtnet_send_command(struct
>  	sg_init_one(&hdr, &ctrl, sizeof(ctrl));
>  	sgs[out_num++] = &hdr;
>  
> -	if (out)
> +	for (; out; out = sg_next(out))
>  		sgs[out_num++] = out;
>  	if (in)
>  		sgs[out_num + in_num++] = in;