Re: [RFC PATCH v2 0/5] Add bridge VLAN support

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 08/05/2024 10:38 pm, Leigh Brown wrote:
> Hello all,
>
> I realised over the weekend that there is a valid use case for providing
> a VIF to a domain that has access to multiple VLANs, e.g. a router. Yes,
> you can create a VIF per VLAN, but if you start having several VLANs (as
> I do), it would be nicer to create a single interface that has access to
> all the relevant VLANs (e.g. enX0.10, enX0.20, etc.).
>
> So, version 2 changes the name and type of the parameter from an integer
> called `vid' to a string called `vlan'. The vlan parameter is then
> parsed by the vif-bridge script (actually, the functions called by it in
> xen-network-common.sh).
>
> As it quite a common practice to allocate VLANs in round numbers, I also
> implemented the ability to specify contiguous or non-contiguous ranges.
> You can specify whether a VLAN is tagged or untagged, and which VLAN is
> the PVID (only one PVID is allowed).  For example,
>
> vif = [ 'mac=xx:xx:xx:xx:xx:xx, bridge=br0, vlan=10p/20-29' ]
>
> will setup the VIF so that 10 is the PVID and VLAN IDs 20 through 29
> are permitted with tags. Another example:
>
> vif = [ 'mac=xx:xx:xx:xx:xx:xx, bridge=br0, vlan=1p/10+10x9' ]
>
> will setup the bridge to set 1 as the PVID and permit access with
> tags for VLAN IDs 10, 20, 30, 40, 50, 60, 70, 80 and 90.
>
> This patch set enables this capability as follows:
>
> 1. Adds `vlan' as a new member of the libxl_device_nic structure;
> 2. Adds support to read and write the vlan parameter from the xenstore;
> 3. Adds `vlan' as a new keyword for the vif configuration option;
> 4. Adds support to assign the bridge VLANs in the Linux hotplug scripts;
> 5. Updated xl-network-configuration(5) manpage and example configs.
>
> Original blurb below:
>
> For many years I have been configuring VLANs on my Linux Dom0 by
> creating VLAN interfaces for each VLAN I wanted to connect a domain
> to and then a corresponding bridge. So I would tend to have things
> like:
>
> enp0s0    -> br0     -> vif1, vif2
> enp0s0.10 -> br0vl10 -> vif3, vif4
> enp0s0.20 -> br0vl20 -> vif5
> dummy0    -> br1     -> vif6
>
> I recently discovered that iproute2 supports creating bridge VLANs that
> allows you to assign a VLAN to each of the interfaces associated to a
> bridge. This allows a greatly simplified configuration where a single
> bridge can support all the domains, and the iproute2 bridge command can
> assign each VIF to the required VLAN.  This looks like this:
>
> # bridge vlan
> port              vlan-id  
> enp0s0            1 PVID Egress Untagged
>                   10
>                   20
> br0               1 PVID Egress Untagged
> vif1.0            1 PVID Egress Untagged
> vif2.0            1 PVID Egress Untagged
> vif3.0            10 PVID Egress Untagged
> vif4.0            10 PVID Egress Untagged
> vif5.0            20 PVID Egress Untagged
> vif6.0            30 PVID Egress Untagged
>
> This patch set enables this capability as follows:
>
> 1. Adds `vid' as a new member of the libxl_device_nic structure;
> 2. Adds support to read and write vid from the xenstore;
> 3. Adds `vid' as a new keyword for the vif configuration option;
> 4. Adds support for assign the bridge VLAN in the Linux hotplug scripts.
>
> I don't believe NetBSD or FreeBSD support this capability, but if they
> do please point me in the direction of some documentation and/or examples.
>
> NB: I'm not very familiar with Xen code base so may have missed
> something important, although I have tested it and it is working well
> for me.
>
> Cheers,
>
> Leigh.
>
>
> Leigh Brown (5):
>   tools/libs/light: Add vlan field to libxl_device_nic
>   tools/xl: add vlan keyword to vif option
>   tools/hotplug/Linux: Add bridge VLAN support
>   docs/man: document VIF vlan keyword
>   tools/examples: Example Linux bridge VLAN config
>
>  docs/man/xl-network-configuration.5.pod.in    |  38 ++++++
>  tools/examples/linux-bridge-vlan/README       |  68 +++++++++++
>  tools/examples/linux-bridge-vlan/br0.netdev   |   7 ++
>  tools/examples/linux-bridge-vlan/br0.network  |   8 ++
>  .../examples/linux-bridge-vlan/enp0s0.network |  16 +++
>  tools/hotplug/Linux/xen-network-common.sh     | 111 ++++++++++++++++++
>  tools/libs/light/libxl_nic.c                  |  10 ++
>  tools/libs/light/libxl_types.idl              |   1 +
>  tools/xl/xl_parse.c                           |   2 +
>  9 files changed, 261 insertions(+)
>  create mode 100644 tools/examples/linux-bridge-vlan/README
>  create mode 100644 tools/examples/linux-bridge-vlan/br0.netdev
>  create mode 100644 tools/examples/linux-bridge-vlan/br0.network
>  create mode 100644 tools/examples/linux-bridge-vlan/enp0s0.network
>

This is past the last-post date, so Oleksii will need to decide whether
he's happy to make an exception for it.

Anthony is OoO for a month now, so if this is to get in for 4.19, then
it will need reviewing by others.  I've CC'd a few plausible candidates...

~Andrew