netdev - Re: [PATCH net-next v2] openvswitch: enable NSH support

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Date:   Fri, 11 Aug 2017 17:54:23 +0800
From:   "Yang, Yi" <yi.y.yang@...el.com>
To:     Jiri Benc <jbenc@...hat.com>
Cc:     netdev@...r.kernel.org, dev@...nvswitch.org
Subject: Re: [PATCH net-next v2] openvswitch: enable NSH support

On Fri, Aug 11, 2017 at 11:44:49AM +0200, Jiri Benc wrote:
> On Fri, 11 Aug 2017 09:24:25 +0000, Yang, Yi Y wrote:
> > So far, we're not clear how we can support MD type 2 better, as I
> > explained before, we need to reuse tun_metadata in struct flow_tnl
> > which is the thing Geneve is using. Geneve predefined 64 keys for
> > this from tun_metadata0 to tun_metadata63, we will reuse it for MD
> > type 2. But you know NSH is not tunnel, so it has to be changed to
> > support both Geneve and NSH. Anyway, they won't be part of
> > ovs_key_nsh.
> 
> Please do not top post.

Sorry for this inconvenience, I'm using outlook. But now I have to use
mutt to address your concern :-)

> 
> The context field does not apply to MD type 2. It looks wrong for the
> context field to be included in netlink attribute for anything other
> than MD type 1. Perhaps it needs to be put into a separate attribute,
> too?
> 
> Note that I'm talking only about the uAPI. Internally, ovs can use
> struct ovs_key_nsh that is MD type 1 only, there's no problem changing
> that later. But for the user space interface, this needs to be clean.
> This can be solved for example this way:
> 
> In include/uapi/linux/openvswitch.h:
> 
> struct ovs_key_nsh_base {
> 	__u8 flags;
> 	__u8 mdtype;
> 	__u8 np;
> 	__u8 pad;
> 	__be32 path_hdr;
> };
> 
> + one more netlink attribute carrying MD type 1 info. Will probably
> require to change OVS_KEY_ATTR_NSH to a nested attribute etc.
> 
> In net/openvswitch/flow.h (or perhaps a different header would be more
> appropriate?):
> 
> struct ovs_key_nsh {
> 	struct ovs_key_nsh_base base;
> 	__be32 context[4];
> };
> 
> Plus needed conversions between OVS_KEY_ATTR_NSH and struct ovs_key_nsh
> when interfacing between the kernel and user space.
> 
> That way, we can have MD type 1 support only for now while still being
> allowed to redesign things in whatever way later.

Yeah, good suggestion, will try to do that way.

> 
>  Jiri