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

[Luiz Capitulino <lcapitulino@redhat.com>]

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?

> 
> [1] [PATCH] virtio-net: Do not filter VLANs without F_CTRL_VLAN 
> 
> Thanks, Amos
>  
> > > -    info->vlan_table = int_list;
> > >  
> > >      /* enable event notification after query */
> > >      nc->rxfilter_notify_enabled = 1;
> > > diff --git a/qapi-schema.json b/qapi-schema.json
> > > index 7cfb5e5..5b54e94 100644
> > > --- a/qapi-schema.json
> > > +++ b/qapi-schema.json
> > > @@ -4032,6 +4032,8 @@
> > >  #
> > >  # @unicast-overflow: unicast table is overflowed or not
> > >  #
> > > +# @vlan: whether management uses the vlan table
> > > +#
> > 
> > The above description seems a bit confusing to me.  The value
> > we are returning describes whether or not qemu is performing
> > vlan filtering.  I am not sure if it has any bearing on what
> > management may be doing.
> > 
> > I think the idea is that management, in the future, would look at
> > this value and make some decision about applying provided filter
> > to the current host configuration.
> > 
> > >  # @main-mac: the main macaddr string
> > >  #
> > >  # @vlan-table: a list of active vlan id
> > > @@ -4052,6 +4054,7 @@
> > >      'broadcast-allowed':  'bool',
> > >      'multicast-overflow': 'bool',
> > >      'unicast-overflow':   'bool',
> > > +    'vlan':               'bool',
> > 
> > Not terribly descriptive.  May be call it vlan-filter?
> > 
> > Thanks
> > -vlad
> > >      'main-mac':           'str',
> > >      'vlan-table':         ['int'],
> > >      'unicast-table':      ['str'],
> > > diff --git a/qmp-commands.hx b/qmp-commands.hx
> > > index cce6b81..b170c79 100644
> > > --- a/qmp-commands.hx
> > > +++ b/qmp-commands.hx
> > > @@ -3307,6 +3307,7 @@ Each array entry contains the following:
> > >  - "broadcast-allowed": allow to receive broadcast (json-bool)
> > >  - "multicast-overflow": multicast table is overflowed (json-bool)
> > >  - "unicast-overflow": unicast table is overflowed (json-bool)
> > > +- "vlan": management uses the vlan table (json-bool)
> > >  - "main-mac": main macaddr string (json-string)
> > >  - "vlan-table": a json-array of active vlan id
> > >  - "unicast-table": a json-array of unicast macaddr string
> > > @@ -3321,6 +3322,7 @@ Example:
> > >              "name": "vnet0",
> > >              "main-mac": "52:54:00:12:34:56",
> > >              "unicast": "normal",
> > > +            "vlan": true,
> > >              "vlan-table": [
> > >                  4,
> > >                  0
> > > 
>