selftests: drv-net: rss_ctx: Add test for ntuple rules targeting default RSS context

JIRA: https://issues.redhat.com/browse/RHEL-89014

Conflicts:
 A small conflict occurred due to unrelated changes.

commit 56c5d29
Author: Gal Pressman <gal@nvidia.com>
Date:   Thu Jun 12 10:19:58 2025 +0300

    selftests: drv-net: rss_ctx: Add test for ntuple rules targeting default RSS context

    Add test_rss_default_context_rule() to verify that ntuple rules can
    correctly direct traffic to the default RSS context (context 0).

    The test creates two ntuple rules with explicit location priorities:
    - A high-priority rule (loc 0) directing specific port traffic to
      context 0.
    - A low-priority rule (loc 1) directing all other TCP traffic to context
      1.

    This validates that:
    1. Rules targeting the default context function properly.
    2. Traffic steering works as expected when mixing default and
       additional RSS contexts.

    The test was written by AI, and reviewed by humans.

    Reviewed-by: Nimrod Oren <noren@nvidia.com>
    Signed-off-by: Gal Pressman <gal@nvidia.com>
    Link: https://patch.msgid.link/20250612071958.1696361-3-gal@nvidia.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Mohammad Heib <mheib@redhat.com>

Author: mohammadheib

tools/testing/selftests/drivers/net/hw/rss_ctx.py

@@ -739,6 +739,62 @@ def test_rss_ntuple_addition(cfg):
                                                           'noise' : (0,) })
 
 
+def test_rss_default_context_rule(cfg):
+    """
+    Allocate a port, direct this port to context 0, then create a new RSS
+    context and steer all TCP traffic to it (context 1).  Verify that:
+      * Traffic to the specific port continues to use queues of the main
+        context (0/1).
+      * Traffic to any other TCP port is redirected to the new context
+        (queues 2/3).
+    """
+
+    require_ntuple(cfg)
+
+    queue_cnt = len(_get_rx_cnts(cfg))
+    if queue_cnt < 4:
+        try:
+            ksft_pr(f"Increasing queue count {queue_cnt} -> 4")
+            ethtool(f"-L {cfg.ifname} combined 4")
+            defer(ethtool, f"-L {cfg.ifname} combined {queue_cnt}")
+        except Exception as exc:
+            raise KsftSkipEx("Not enough queues for the test") from exc
+
+    # Use queues 0 and 1 for the main context
+    ethtool(f"-X {cfg.ifname} equal 2")
+    defer(ethtool, f"-X {cfg.ifname} default")
+
+    # Create a new RSS context that uses queues 2 and 3
+    ctx_id = ethtool_create(cfg, "-X", "context new start 2 equal 2")
+    defer(ethtool, f"-X {cfg.ifname} context {ctx_id} delete")
+
+    # Generic low-priority rule: redirect all TCP traffic to the new context.
+    # Give it an explicit higher location number (lower priority).
+    flow_generic = f"flow-type tcp{cfg.addr_ipver} dst-ip {cfg.addr} context {ctx_id} loc 1"
+    ethtool(f"-N {cfg.ifname} {flow_generic}")
+    defer(ethtool, f"-N {cfg.ifname} delete 1")
+
+    # Specific high-priority rule for a random port that should stay on context 0.
+    # Assign loc 0 so it is evaluated before the generic rule.
+    port_main = rand_port()
+    flow_main = f"flow-type tcp{cfg.addr_ipver} dst-ip {cfg.addr} dst-port {port_main} context 0 loc 0"
+    ethtool(f"-N {cfg.ifname} {flow_main}")
+    defer(ethtool, f"-N {cfg.ifname} delete 0")
+
+    _ntuple_rule_check(cfg, 1, ctx_id)
+
+    # Verify that traffic matching the specific rule still goes to queues 0/1
+    _send_traffic_check(cfg, port_main, "context 0",
+                        { 'target': (0, 1),
+                          'empty' : (2, 3) })
+
+    # And that traffic for any other port is steered to the new context
+    port_other = rand_port()
+    _send_traffic_check(cfg, port_other, f"context {ctx_id}",
+                        { 'target': (2, 3),
+                          'noise' : (0, 1) })
+
+
 def main() -> None:
     with NetDrvEpEnv(__file__, nsim_test=False) as cfg:
         cfg.ethnl = EthtoolFamily()
@@ -751,7 +807,8 @@ def main() -> None:
                   test_rss_context_overlap, test_rss_context_overlap2,
                   test_rss_context_out_of_order, test_rss_context4_create_with_cfg,
                   test_flow_add_context_missing,
-                  test_delete_rss_context_busy, test_rss_ntuple_addition],
+                  test_delete_rss_context_busy, test_rss_ntuple_addition,
+                  test_rss_default_context_rule],
                  args=(cfg, ))
     ksft_exit()