Re: [Qemu-devel] [PATCH v2] virtio-net: add a field to indicate if vlan table is used

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Mar 03, 2014 at 01:46:34PM +0800, Amos Kong wrote:
> On Fri, Feb 28, 2014 at 01:29:59PM -0500, Luiz Capitulino wrote:
> > On Fri, 21 Feb 2014 18:01:40 +0800
> > Amos Kong <akong@redhat.com> wrote:
> > 
> > > On Thu, Feb 20, 2014 at 12:46:14PM -0500, Vlad Yasevich wrote:
> > > > On 02/20/2014 11:38 AM, Amos Kong wrote:
> > > > > Stefan Fritsch just fixed a virtio-net driver bug [1], virtio-net won't
> > > > > filter out VLAN-tagged packets if VIRTIO_NET_F_CTRL_VLAN isn't negotiated.
> > > > > 
> > > > > This patch added a new field to @RxFilterInfo to indicate if management
> > > > > uses the vlan table.
> > > > > 
> > > > > [1] http://lists.nongnu.org/archive/html/qemu-devel/2014-02/msg02604.html
> > > > > 
> > > > > Signed-off-by: Amos Kong <akong@redhat.com>
> > > > > ---
> > > > > V2: don't make vlan-table optional, add a flag to indicate
> > > > >     if vlan table is used by management
> > > > > ---
> > > > >  hw/net/virtio-net.c | 38 +++++++++++++++++++++++++-------------
> > > > >  qapi-schema.json    |  3 +++
> > > > >  qmp-commands.hx     |  2 ++
> > > > >  3 files changed, 30 insertions(+), 13 deletions(-)
> > > > > 
> > > > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> > > > > index 3626608..f591f4e 100644
> > > > > --- a/hw/net/virtio-net.c
> > > > > +++ b/hw/net/virtio-net.c
> > > > > @@ -222,13 +222,33 @@ static char *mac_strdup_printf(const uint8_t *mac)
> > > > >                              mac[1], mac[2], mac[3], mac[4], mac[5]);
> > > > >  }
> > > > >  
> > > > > +static intList *get_vlan_table(VirtIONet *n)
> > > > > +{
> > > > > +    intList *list, *entry;
> > > > > +    int i, j;
> > > > > +
> > > > > +    list = NULL;
> > > > > +    for (i = 0; i < MAX_VLAN >> 5; i++) {
> > > > > +        for (j = 0; n->vlans[i] && j < 0x1f; j++) {
> > > > > +            if (n->vlans[i] & (1U << j)) {
> > > > > +                entry = g_malloc0(sizeof(*entry));
> > > > > +                entry->value = (i << 5) + j;
> > > > > +                entry->next = list;
> > > > > +                list = entry;
> > > > > +            }
> > > > > +        }
> > > > > +    }
> > > > > +
> > > > > +    return list;
> > > > > +}
> > > > > +
> > > > >  static RxFilterInfo *virtio_net_query_rxfilter(NetClientState *nc)
> > > > >  {
> > > > >      VirtIONet *n = qemu_get_nic_opaque(nc);
> > > > > +    VirtIODevice *vdev = VIRTIO_DEVICE(n);
> > > > >      RxFilterInfo *info;
> > > > >      strList *str_list, *entry;
> > > > > -    intList *int_list, *int_entry;
> > > > > -    int i, j;
> > > > > +    int i;
> > > > >  
> > > > >      info = g_malloc0(sizeof(*info));
> > > > >      info->name = g_strdup(nc->name);
> > > > > @@ -273,19 +293,11 @@ static RxFilterInfo *virtio_net_query_rxfilter(NetClientState *nc)
> > > > >          str_list = entry;
> > > > >      }
> > > > >      info->multicast_table = str_list;
> > > > > +    info->vlan_table = get_vlan_table(n);
> > > > >  
> > > > > -    int_list = NULL;
> > > > > -    for (i = 0; i < MAX_VLAN >> 5; i++) {
> > > > > -        for (j = 0; n->vlans[i] && j < 0x1f; j++) {
> > > > > -            if (n->vlans[i] & (1U << j)) {
> > > > > -                int_entry = g_malloc0(sizeof(*int_entry));
> > > > > -                int_entry->value = (i << 5) + j;
> > > > > -                int_entry->next = int_list;
> > > > > -                int_list = int_entry;
> > > > > -            }
> > > > > -        }
> > > > > +    if ((1 << VIRTIO_NET_F_CTRL_VLAN) & vdev->guest_features) {
> > > > > +        info->vlan = true;
> > > > >      }
> > > > 
> > > > So, in the case that vlan filtering is not supported in the guest
> > > > we get:
> > > >              "vlan": false,
> > > >              "vlan-table": [
> > > >                  0,
> > > >                  1,
> > > >                  2,
> > > >                  ...
> > > >                  4095
> > > >             ]
> > > > since virtio_net now initializes the table to all 1s.
> > > > Seems a bit awkward.  We are providing a lot of data that
> > > > is simply going to be ignored.
> > > 
> > > In Stefan's patch [1], qemu fills all vlan ids to 1, then all the
> > > packets will come to guest.
> > > 
> > > For the host device, it also should not filter out any vlan-tagged
> > > packets when VIRTIO_NET_F_CTRL_VLAN is not negotiated. We should also
> > > fill vlan ids of host device to 1, then vlan-filter of host device
> > > will not perform.
> > > 
> > > If so, we don't need my patch, just pass [0,1,2,...4095] to management
> > > as past. The new field in RxFilterInfo isn't necessary.
> > 
> > What's the conclusion here?
>  
> NAK my patch, it's unnecessary.

I don't agree.
libvirt does not yet look at the filter info, so let's do the
job properly.
https://lists.gnu.org/archive/html/qemu-devel/2014-02/msg02604.html


> > > [1] [PATCH] virtio-net: Do not filter VLANs without F_CTRL_VLAN 
> > > 
> > > Thanks, Amos