[ovs-dev] [RFC OVS 0/2] ovs-tc: support OvS internal port offload

[John Hurley]

Common use-cases in OvS can produce datapath rules that match on OvS
internal ports. For example, when the endpoint IP address of a VXLAN
tunnel is on the OvS bridge itself, datapath rules may take the form:

1. in_port(eth1),actions:set(tunnel(...)),vxlan_sys_4789
2. in_port(br0),eth(src=...,dst=...),actions:eth2

Here, the first rule outputs to the vxlan port which determines the next
hop to be the OvS bridge. The user-space NORMAL rule can then be used
to form rule 2 that forwards the tunnelled packet to a physicaly port.

Currently, rules applied to internal ports are not offloaded to the TC
datapath. This RFC proposes changes to addresses that. It modifies the TC
API in OvS to allow the creation of and interaction with qdiscs at the TC
egress hook. These API changes are then used to offload rules applied to
internal ports as TC egress filters.

The start xmit ndo in OvS internal ports pushes packets into the OvS
kernel datapath with ingress set to the given internal port. This is
essentially what happens when packets RX on other ports that have an OvS
bridge as their master. Therefore, applying flower filters to the egress
path of an internal port is akin to the current practice of adding the
filters to the ingress path of non internal ports.

Once such filters exist in TC, it enables drivers to interpret OvS
internal ports with the potential to offload a representation of them to
harware devices.


An alternative approach to the above it to apply a TC ingress hook in the
OvS kernel datapath internal port functions. This would allow the TC
offload of internal port rules as ingress fitlers rather than egress.


John Hurley (2):
  ovs-tc: allow offloading TC rules to egress qdiscs
  ovs-tc: offload datapath rules matching on internal ports

 lib/dpif.c               | 31 ++++++---------------------
 lib/netdev-linux.c       |  9 ++++----
 lib/netdev-tc-offloads.c | 56 ++++++++++++++++++++++++++++++++----------------
 lib/tc.c                 | 45 +++++++++++++++++++++++++-------------
 lib/tc.h                 | 20 +++++++++++------
 5 files changed, 93 insertions(+), 68 deletions(-)

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2.7.4