[dpdk-dev] Query on Filtering Support in DPDK

[Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>]

Hi,

We are working towards adding h/w based filtering support in cxgbe PMD.

Chelsio T5 supports carrying out filtering in hardware which supports 3
actions to carry out on a packet which hit a filter viz.

1. Action Pass - Packets hitting a filter rule can be directed to a
   particular RXQ.

2. Action Drop - Packets hitting a filter rule are dropped in h/w.

3. Action Switch - Packets hitting a filter rule can be switched in h/w
   from one port to another, without involvement of host.  Also, the
   action Switch also supports rewrite of src-mac/dst-mac headers as
   well as rewrite of vlan headers.  It also supports rewrite of IP
   headers and thereby, supports NAT (Network Address Translation)
   in h/w.

Also, each filter rule can optionally support specifying a mask value
i.e. it's possible to create a filter rule for an entire subnet of IP
addresses or a range of tcp/udp ports, etc.

We went through the existing filtering support (ethertype_filter,
syn_filter, ntuple_filter, flow_director) and have some questions on how
to accommodate the various h/w filtering features supported by Chelsio T5
by extending DPDK filtering support.

Some of the features that we would like to accommodate in DPDK filtering
are:

1. Add a new action 'switch' that will:
   * Allow re-direction to different ports in hardware.

   Also, for such a rule, additionally support below:

   * Allow source mac/destination mac and vlan header re-writing to be
     done by the hardware.

   * Allow re-write of TCP/IP headers to perform NAT in hardware.

2. Add ability to mask individual fields at a particular layer for each
   filter in flow_director. For example, mask all ip packets coming from
   a particular subnet mask and particular range of l4 ports for each
   filter rule.

We would like to get some suggestions on how to proceed with adding the
above features.

Thanks,
Rahul