Re: [net-next PATCH v3 7/8] net: ixgbe: add support for tc_u32 offload

On 16-02-17 12:18 AM, John Fastabend wrote:

This adds initial support for offloading the u32 tc classifier. This
initial implementation only implements a few base matches and actions
to illustrate the use of the infrastructure patches.

However it is an interesting subset because it handles the u32 next
hdr logic to correctly map tcp packets from ip headers using the ihl
and protocol fields. After this is accepted we can extend the match
and action fields easily by updating the model header file.

Also only the drop action is supported initially.

Here is a short test script,

  #tc qdisc add dev eth4 ingress
  #tc filter add dev eth4 parent ffff: protocol ip \
	u32 ht 800: order 1 \
	match ip dst 15.0.0.1/32 match ip src 15.0.0.2/32 action drop

Note: i dont see anything that says "hw". Are you delegating ht 0x800
for h/w only? It is the default ht; so may not be the best choice.

<-- hardware has dst/src ip match rule installed -->

  #tc filter del dev eth4 parent ffff: prio 49152

Would be useful to dump the installed rule so user gets to
see kernel-assigned prio 49152. The better way
to do this is use the handle 800::1 as opposed to prio.

  #tc filter add dev eth4 parent ffff: protocol ip prio 99 \
	handle 1: u32 divisor 1
  #tc filter add dev eth4 protocol ip parent ffff: prio 99 \
	u32 ht 800: order 1 link 1: \
	offset at 0 mask 0f00 shift 6 plus 0 eat match ip protocol 6 ff
  #tc filter add dev eth4 parent ffff: protocol ip \
	u32 ht 1: order 3 match tcp src 23 ffff action drop

<-- hardware has tcp src port rule installed -->

  #tc qdisc del dev eth4 parent ffff:

<-- hardware cleaned up -->

All looks cool but I am just worried about the lack of intent that
something needs to go to hw vs sw. Other worry:
What happens when things fail to install in hw?
As it stands right now your assumption is all default rules go to h/w.
And failure to install is not handled.
I know Dave wants to push this in so a followup sets of patches to
address this is fine by me. Otherwise if it is not too much work, please
address this.

cheers,
jamal