[PATCH net-next 6/6] selftests: drv-net: add netkit devmem TX test

[Bobby Eshleman]

From: Bobby Eshleman <bobbyeshle...@meta.com>

Extend the netkit devmem selftest with a TX test case. The TX path uses
the primary RX redirect BPF program to redirect traffic from the primary
netkit ingress to the physical NIC via bpf_redirect_neigh().

The actual TX path looks like the following:

 TX Path
 -------

 Netkit Guest (netns)     Netkit Host          Physical NIC          Remote
      |                       |                     |                    |
      |--- TCP send --------->|                     |                    |
                              |--- BPF redirect --->|                    |
                                                    |---- transmit ----->|
                                                   dmabuf

Signed-off-by: Bobby Eshleman <bobbyeshle...@meta.com>
---
 .../testing/selftests/drivers/net/hw/nk_devmem.py  | 23 ++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/hw/nk_devmem.py 
b/tools/testing/selftests/drivers/net/hw/nk_devmem.py
index 0a66ff85db9d..0e3c5aab6423 100755
--- a/tools/testing/selftests/drivers/net/hw/nk_devmem.py
+++ b/tools/testing/selftests/drivers/net/hw/nk_devmem.py
@@ -89,14 +89,33 @@ def test_devmem(cfg) -> None:
     ksft_eq(ncdevmem_rx.ret, 0)
 
 
+def test_devmem_tx(cfg) -> None:
+    """Test devmem TX: send from netkit guest, receive on remote."""
+    configure_nic(cfg)
+
+    socat = f"socat -U - TCP6-LISTEN:{cfg.port},reuseaddr"
+    tx_cmd = (f"ip netns exec {cfg.netns.name} bash -c"
+              f" 'echo test_devmem_tx | {cfg.bin_local}"
+              f" -f {cfg._nk_guest_ifname} -s {cfg.remote_addr_v['6']}"
+              f" -p {cfg.port} -t 0 -q 1 -n'")
+
+    with bkg(socat, host=cfg.remote, exit_wait=True) as receiver:
+        wait_port_listen(cfg.port, proto="tcp", host=cfg.remote)
+        cmd(tx_cmd, shell=True)
+
+    ksft_eq(receiver.ret, 0)
+    ksft_eq(receiver.stdout.strip(), "test_devmem_tx")
+
+
 def main() -> None:
     """Run netkit devmem tests."""
-    with NetDrvContEnv(__file__, rxqueues=2) as cfg:
+    with NetDrvContEnv(__file__, rxqueues=2,
+                       primary_rx_redirect=True) as cfg:
         cfg.bin_local = path.abspath(
             path.dirname(__file__) + "/ncdevmem"
         )
         cfg.port = rand_port()
-        ksft_run([test_devmem], args=(cfg,))
+        ksft_run([test_devmem, test_devmem_tx], args=(cfg,))
     ksft_exit()
 
 

-- 
2.52.0