[PATCH net v3 0/2] Fix ntuple rules targeting default RSS

[PATCH net v3 0/2] Fix ntuple rules targeting default RSS

[Gal Pressman]

This series addresses a regression in ethtool flow steering where rules
targeting the default RSS context (context 0) were incorrectly rejected.

The default RSS context always exists but is not stored in the rss_ctx
xarray like additional contexts. The current validation logic was
checking for the existence of context 0 in this array, causing valid
flow steering rules to be rejected.

This prevented configurations such as:
- High priority rules directing specific traffic to the default context
- Low priority catch-all rules directing remaining traffic to additional
  contexts

Patch 1 fixes the validation logic to skip the existence check for
context 0.

Patch 2 adds a selftest that verifies this behavior.

Changelog -
v2->v3: https://lore.kernel.org/all/20250609120250.1630125-1-gal@nvidia.com/
* Reworded commit message.
* Fix pylint warning.

v1->v2: https://lore.kernel.org/all/20250225071348.509432-1-gal@nvidia.com/
* Reworded commit message.
* Added a selftest.

Gal Pressman (2):
  net: ethtool: Don't check if RSS context exists in case of context 0
  selftests: drv-net: rss_ctx: Add test for ntuple rules targeting
    default RSS context

 net/ethtool/ioctl.c                           |  3 +-
 .../selftests/drivers/net/hw/rss_ctx.py       | 59 ++++++++++++++++++-
 2 files changed, 60 insertions(+), 2 deletions(-)

-- 
2.40.1

[PATCH net v3 1/2] net: ethtool: Don't check if RSS context exists in case of context 0

[Gal Pressman]

Context 0 (default context) always exists, there is no need to check
whether it exists or not when adding a flow steering rule.

The existing check fails when creating a flow steering rule for context
0 as it is not stored in the rss_ctx xarray.

For example:
$ ethtool --config-ntuple eth2 flow-type tcp4 dst-ip 194.237.147.23 dst-port 19983 context 0 loc 618
rmgr: Cannot insert RX class rule: Invalid argument
Cannot insert classification rule

An example usecase for this could be:
- 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 is a user-visible regression that was caught in our testing
environment, it was not reported by a user yet.

Fixes: de7f7582dff2 ("net: ethtool: prevent flow steering to RSS contexts which don't exist")
Cc: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Nimrod Oren <noren@nvidia.com>
Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Joe Damato <jdamato@fastly.com>
---
 net/ethtool/ioctl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 39ec920f5de7..71c828d0bf31 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -1083,7 +1083,8 @@ static noinline_for_stack int ethtool_set_rxnfc(struct net_device *dev,
 		    ethtool_get_flow_spec_ring(info.fs.ring_cookie))
 			return -EINVAL;
 
-		if (!xa_load(&dev->ethtool->rss_ctx, info.rss_context))
+		if (info.rss_context &&
+		    !xa_load(&dev->ethtool->rss_ctx, info.rss_context))
 			return -EINVAL;
 	}
 
-- 
2.40.1

[PATCH net v3 2/2] selftests: drv-net: rss_ctx: Add test for ntuple rules targeting default RSS context

[Gal Pressman]

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.

Cc: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Nimrod Oren <noren@nvidia.com>
Signed-off-by: Gal Pressman <gal@nvidia.com>
---
 .../selftests/drivers/net/hw/rss_ctx.py       | 59 ++++++++++++++++++-
 1 file changed, 58 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/drivers/net/hw/rss_ctx.py b/tools/testing/selftests/drivers/net/hw/rss_ctx.py
index ca60ae325c22..7bb552f8b182 100755
--- a/tools/testing/selftests/drivers/net/hw/rss_ctx.py
+++ b/tools/testing/selftests/drivers/net/hw/rss_ctx.py
@@ -747,6 +747,62 @@ 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.context_cnt = None
@@ -760,7 +816,8 @@ 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()
 
-- 
2.40.1

Re: [PATCH net v3 1/2] net: ethtool: Don't check if RSS context exists in case of context 0

[Edward Cree]

On 12/06/2025 08:19, Gal Pressman wrote:
> Context 0 (default context) always exists, there is no need to check
> whether it exists or not when adding a flow steering rule.
> 
> The existing check fails when creating a flow steering rule for context
> 0 as it is not stored in the rss_ctx xarray.
> 
> For example:
> $ ethtool --config-ntuple eth2 flow-type tcp4 dst-ip 194.237.147.23 dst-port 19983 context 0 loc 618
> rmgr: Cannot insert RX class rule: Invalid argument
> Cannot insert classification rule
> 
> An example usecase for this could be:
> - 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 is a user-visible regression that was caught in our testing
> environment, it was not reported by a user yet.
> 
> Fixes: de7f7582dff2 ("net: ethtool: prevent flow steering to RSS contexts which don't exist")
> Cc: Jakub Kicinski <kuba@kernel.org>
> Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
> Reviewed-by: Nimrod Oren <noren@nvidia.com>
> Signed-off-by: Gal Pressman <gal@nvidia.com>
> Reviewed-by: Joe Damato <jdamato@fastly.com>

Reviewed-by: Edward Cree <ecree.xilinx@gmail.com>

Re: [PATCH net v3 0/2] Fix ntuple rules targeting default RSS

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 12 Jun 2025 10:19:56 +0300 you wrote:
> This series addresses a regression in ethtool flow steering where rules
> targeting the default RSS context (context 0) were incorrectly rejected.
> 
> The default RSS context always exists but is not stored in the rss_ctx
> xarray like additional contexts. The current validation logic was
> checking for the existence of context 0 in this array, causing valid
> flow steering rules to be rejected.
> 
> [...]

Here is the summary with links:
  - [net,v3,1/2] net: ethtool: Don't check if RSS context exists in case of context 0
    https://git.kernel.org/netdev/net/c/d78ebc772c7c
  - [net,v3,2/2] selftests: drv-net: rss_ctx: Add test for ntuple rules targeting default RSS context
    https://git.kernel.org/netdev/net/c/56c5d291e885

You are awesome, thank you!
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