netdev - Re: [PATCH net-next 0/7] nfp: flower vxlan tunnel offload

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Date:   Tue, 26 Sep 2017 12:15:09 +0200
From:   Jiri Benc <jbenc@...hat.com>
To:     Simon Horman <simon.horman@...ronome.com>
Cc:     Or Gerlitz <gerlitz.or@...il.com>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Linux Netdev List <netdev@...r.kernel.org>,
        oss-drivers@...ronome.com, John Hurley <john.hurley@...ronome.com>,
        Paolo Abeni <pabeni@...hat.com>, Eli Cohen <eli@...lanox.com>,
        Paul Blakey <paulb@...lanox.com>
Subject: Re: [PATCH net-next 0/7] nfp: flower vxlan tunnel offload

On Mon, 25 Sep 2017 19:04:53 +0200, Simon Horman wrote:
> The MAC addresses are extracted from the netdevs already loaded in the
> kernel and are monitored for any changes. The IP addresses are slightly
> different in that they are extracted from the rules themselves. We make the
> assumption that, if a packet is decapsulated at the end point and a match
> is attempted on the IP address,

You lost me here, I'm afraid. What do you mean by "match"?

> that this IP address should be recognised
> in the kernel. That being the case, the same traffic pattern should be
> witnessed if the skip_hw flag is applied.

Just to be really sure that this works correctly, can you confirm that
this will match the packet:

ip link add vxlan0 type vxlan dstport 4789 dev eth0 external
ip link set dev vxlan0 up
tc qdisc add dev vxlan0 ingress
ethtool -K eth0 hw-tc-offload on
tc filter add dev vxlan0 protocol ip parent ffff: flower enc_key_id 102 \
   enc_dst_port 4789 src_ip 3.4.5.6 skip_sw action [...]

while this one will NOT match:

ip link add vxlan0 type vxlan dstport 4789 dev eth0 external
ip link set dev vxlan0 up
tc qdisc add dev eth0 ingress
ethtool -K eth0 hw-tc-offload on
tc filter add dev eth0 protocol ip parent ffff: flower enc_key_id 102 \
   enc_dst_port 4789 src_ip 3.4.5.6 skip_sw action [...]

We found that with mlx5, the second one actually matches, too. Which is
a very serious bug. (Adding Paolo who found this. And adding a few more
Mellanox guys to be aware of the bug.)

 Jiri