Merge branch 'bpf-xsk-selftests'

Merge branch 'bpf-xsk-selftests'

Weqaar Janjua says:

====================
This patch set adds AF_XDP selftests based on veth to selftests/bpf.

 # Topology:
 # ---------
 #                 -----------
 #               _ | Process | _
 #              /  -----------  \
 #             /        |        \
 #            /         |         \
 #      -----------     |     -----------
 #      | Thread1 |     |     | Thread2 |
 #      -----------     |     -----------
 #           |          |          |
 #      -----------     |     -----------
 #      |  xskX   |     |     |  xskY   |
 #      -----------     |     -----------
 #           |          |          |
 #      -----------     |     ----------
 #      |  vethX  | --------- |  vethY |
 #      -----------   peer    ----------
 #           |          |          |
 #      namespaceX      |     namespaceY

These selftests test AF_XDP SKB and Native/DRV modes using veth Virtual
Ethernet interfaces.

The test program contains two threads, each thread is single socket with
a unique UMEM. It validates in-order packet delivery and packet content
by sending packets to each other.

Prerequisites setup by script test_xsk.sh:

   Set up veth interfaces as per the topology shown ^^:
   * setup two veth interfaces and one namespace
   ** veth<xxxx> in root namespace
   ** veth<yyyy> in af_xdp<xxxx> namespace
   ** namespace af_xdp<xxxx>
   * create a spec file veth.spec that includes this run-time configuration
   *** xxxx and yyyy are randomly generated 4 digit numbers used to avoid
       conflict with any existing interface

   Adds xsk framework test to validate veth xdp DRV and SKB modes.

The following tests are provided:

1. AF_XDP SKB mode
   Generic mode XDP is driver independent, used when the driver does
   not have support for XDP. Works on any netdevice using sockets and
   generic XDP path. XDP hook from netif_receive_skb().
   a. nopoll - soft-irq processing
   b. poll - using poll() syscall
   c. Socket Teardown
      Create a Tx and a Rx socket, Tx from one socket, Rx on another.
      Destroy both sockets, then repeat multiple times. Only nopoll mode
	  is used
   d. Bi-directional Sockets
      Configure sockets as bi-directional tx/rx sockets, sets up fill
	  and completion rings on each socket, tx/rx in both directions.
	  Only nopoll mode is used

2. AF_XDP DRV/Native mode
   Works on any netdevice with XDP_REDIRECT support, driver dependent.
   Processes packets before SKB allocation. Provides better performance
   than SKB. Driver hook available just after DMA of buffer descriptor.
   a. nopoll
   b. poll
   c. Socket Teardown
   d. Bi-directional Sockets
   * Only copy mode is supported because veth does not currently support
     zero-copy mode

Total tests: 8

Flow:
* Single process spawns two threads: Tx and Rx
* Each of these two threads attach to a veth interface within their
  assigned namespaces
* Each thread creates one AF_XDP socket connected to a unique umem
  for each veth interface
* Tx thread transmits 10k packets from veth<xxxx> to veth<yyyy>
* Rx thread verifies if all 10k packets were received and delivered
  in-order, and have the right content

v2 changes:
* Move selftests/xsk to selftests/bpf
* Remove Makefiles under selftests/xsk, and utilize selftests/bpf/Makefile
v3 changes:
* merge all test scripts test_xsk_*.sh into test_xsk.sh
v4 changes:
* merge xsk_env.sh into xsk_prereqs.sh
* test_xsk.sh add cliarg -c for color-coded output
* test_xsk.sh PREREQUISITES disables IPv6 on veth interfaces
* test_xsk.sh PREREQUISITES adds xsk framework test
* test_xsk.sh is independently executable
* xdpxceiver.c Tx/Rx validates only IPv4 packets with TOS 0x9, ignores
  others
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>