[PATCH] net/mlx5: avoid wildcard drop flow in priority discovery

[PATCH] net/mlx5: avoid wildcard drop flow in priority discovery

[Gavin Hu]

From: Wei Yan <yanwei.wy@bytedance.com>

Priority discovery installs temporary drop flows to probe supported flow
priorities. These flows match a wildcard Ethernet pattern, so they can
also match real traffic while discovery is running. On shared devices this
may temporarily drop kernel traffic and cause TCP connection timeouts.

Constrain the probe flows to match both source and destination MAC
addresses as ff:ff:ff:ff:ff:ff. This keeps the rule valid for discovery
while avoiding matches on normal Ethernet traffic.

Fixes: 3eca5f8a610e ("net/mlx5: move flow priority discovery to Verbs file")
Fixes: c5042f93a425 ("net/mlx5: discover max flow priority using DevX")
Cc: stable@dpdk.org

Signed-off-by: Wei Yan <yanwei.wy@bytedance.com>
Signed-off-by: Gavin Hu <gahu@nvidia.com>
---
 drivers/net/mlx5/mlx5_flow_dv.c    | 18 ++++++++++++++++++
 drivers/net/mlx5/mlx5_flow_verbs.c |  8 ++++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/net/mlx5/mlx5_flow_dv.c b/drivers/net/mlx5/mlx5_flow_dv.c
index 58ebcf87eb..9cb7c59b83 100644
--- a/drivers/net/mlx5/mlx5_flow_dv.c
+++ b/drivers/net/mlx5/mlx5_flow_dv.c
@@ -19794,6 +19794,22 @@ mlx5_flow_discover_dr_action_support(struct rte_eth_dev *dev)
 	void *matcher = NULL;
 	void *flow = NULL;
 	int ret = -1;
+	struct rte_flow_item_eth eth;
+	struct rte_flow_item item = {
+		.type = RTE_FLOW_ITEM_TYPE_ETH,
+		.spec = &eth,
+		.mask = &eth,
+	};
+
+	memset(&eth, 0, sizeof(eth));
+	memset(&eth.hdr.dst_addr, 0xff, sizeof(eth.hdr.dst_addr));
+	memset(&eth.hdr.src_addr, 0xff, sizeof(eth.hdr.src_addr));
+	flow_dv_translate_item_eth(mask.buf, &item,
+				   /* inner */ false, /* group */ 0,
+				   MLX5_SET_MATCHER_SW_M);
+	flow_dv_translate_item_eth(value.buf, &item,
+				   /* inner */ false, /* group */ 0,
+				   MLX5_SET_MATCHER_SW_V);
 
 	tbl = mlx5_flow_dv_tbl_resource_get(dev, 0, 0, 0, false, NULL,
 					    0, 0, 0, NULL);
@@ -20683,6 +20699,8 @@ flow_dv_discover_priorities(struct rte_eth_dev *dev,
 	flow.dv.actions[0] = action;
 	flow.dv.actions_n = 1;
 	memset(&eth, 0, sizeof(eth));
+	memset(&eth.hdr.dst_addr, 0xff, sizeof(eth.hdr.dst_addr));
+	memset(&eth.hdr.src_addr, 0xff, sizeof(eth.hdr.src_addr));
 	flow_dv_translate_item_eth(matcher.mask.buf, &item,
 				   /* inner */ false, /* group */ 0,
 				   MLX5_SET_MATCHER_SW_M);
diff --git a/drivers/net/mlx5/mlx5_flow_verbs.c b/drivers/net/mlx5/mlx5_flow_verbs.c
index bb240d38d9..f92258cb5a 100644
--- a/drivers/net/mlx5/mlx5_flow_verbs.c
+++ b/drivers/net/mlx5/mlx5_flow_verbs.c
@@ -65,6 +65,14 @@ flow_verbs_discover_priorities(struct rte_eth_dev *dev,
 		.eth = {
 			.type = IBV_FLOW_SPEC_ETH,
 			.size = sizeof(struct ibv_flow_spec_eth),
+			.val = {
+				.dst_mac = "\xff\xff\xff\xff\xff\xff",
+				.src_mac = "\xff\xff\xff\xff\xff\xff",
+			},
+			.mask = {
+				.dst_mac = "\xff\xff\xff\xff\xff\xff",
+				.src_mac = "\xff\xff\xff\xff\xff\xff",
+			},
 		},
 		.drop = {
 			.size = sizeof(struct ibv_flow_spec_action_drop),
-- 
2.27.0

Re: [PATCH] net/mlx5: avoid wildcard drop flow in priority discovery

[Thomas Monjalon]

13/07/2026 06:18, Gavin Hu:
> From: Wei Yan <yanwei.wy@bytedance.com>
> 
> Priority discovery installs temporary drop flows to probe supported flow
> priorities. These flows match a wildcard Ethernet pattern, so they can
> also match real traffic while discovery is running. On shared devices this
> may temporarily drop kernel traffic and cause TCP connection timeouts.
> 
> Constrain the probe flows to match both source and destination MAC
> addresses as ff:ff:ff:ff:ff:ff. This keeps the rule valid for discovery
> while avoiding matches on normal Ethernet traffic.

It does not compile in all conditions.
Please check CI results.

[PATCH v2] net/mlx5: avoid wildcard drop flow in priority discovery

[Gavin Hu]

From: Wei Yan <yanwei.wy@bytedance.com>

Priority discovery installs temporary drop flows to probe supported flow
priorities. These flows match a wildcard Ethernet pattern, so they can
also match real traffic while discovery is running. On shared devices this
may temporarily drop kernel traffic and cause TCP connection timeouts.

Constrain the probe flows to match both source and destination MAC
addresses as ff:ff:ff:ff:ff:ff. This keeps the rule valid for discovery
while avoiding matches on normal Ethernet traffic.

Fixes: 3eca5f8a610e ("net/mlx5: move flow priority discovery to Verbs file")
Fixes: c5042f93a425 ("net/mlx5: discover max flow priority using DevX")
Cc: stable@dpdk.org

Signed-off-by: Wei Yan <yanwei.wy@bytedance.com>
Signed-off-by: Gavin Hu <gahu@nvidia.com>
---
+v2:
+* Fixed the compiling issue by some compilers in mlx5_flow_verbs.c.

 drivers/net/mlx5/mlx5_flow_dv.c    | 18 ++++++++++++++++++
 drivers/net/mlx5/mlx5_flow_verbs.c |  8 ++++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/net/mlx5/mlx5_flow_dv.c b/drivers/net/mlx5/mlx5_flow_dv.c
index 58ebcf87eb..9cb7c59b83 100644
--- a/drivers/net/mlx5/mlx5_flow_dv.c
+++ b/drivers/net/mlx5/mlx5_flow_dv.c
@@ -19794,6 +19794,22 @@ mlx5_flow_discover_dr_action_support(struct rte_eth_dev *dev)
 	void *matcher = NULL;
 	void *flow = NULL;
 	int ret = -1;
+	struct rte_flow_item_eth eth;
+	struct rte_flow_item item = {
+		.type = RTE_FLOW_ITEM_TYPE_ETH,
+		.spec = &eth,
+		.mask = &eth,
+	};
+
+	memset(&eth, 0, sizeof(eth));
+	memset(&eth.hdr.dst_addr, 0xff, sizeof(eth.hdr.dst_addr));
+	memset(&eth.hdr.src_addr, 0xff, sizeof(eth.hdr.src_addr));
+	flow_dv_translate_item_eth(mask.buf, &item,
+				   /* inner */ false, /* group */ 0,
+				   MLX5_SET_MATCHER_SW_M);
+	flow_dv_translate_item_eth(value.buf, &item,
+				   /* inner */ false, /* group */ 0,
+				   MLX5_SET_MATCHER_SW_V);
 
 	tbl = mlx5_flow_dv_tbl_resource_get(dev, 0, 0, 0, false, NULL,
 					    0, 0, 0, NULL);
@@ -20683,6 +20699,8 @@ flow_dv_discover_priorities(struct rte_eth_dev *dev,
 	flow.dv.actions[0] = action;
 	flow.dv.actions_n = 1;
 	memset(&eth, 0, sizeof(eth));
+	memset(&eth.hdr.dst_addr, 0xff, sizeof(eth.hdr.dst_addr));
+	memset(&eth.hdr.src_addr, 0xff, sizeof(eth.hdr.src_addr));
 	flow_dv_translate_item_eth(matcher.mask.buf, &item,
 				   /* inner */ false, /* group */ 0,
 				   MLX5_SET_MATCHER_SW_M);
diff --git a/drivers/net/mlx5/mlx5_flow_verbs.c b/drivers/net/mlx5/mlx5_flow_verbs.c
index bb240d38d9..eb576f73d4 100644
--- a/drivers/net/mlx5/mlx5_flow_verbs.c
+++ b/drivers/net/mlx5/mlx5_flow_verbs.c
@@ -65,6 +65,14 @@ flow_verbs_discover_priorities(struct rte_eth_dev *dev,
 		.eth = {
 			.type = IBV_FLOW_SPEC_ETH,
 			.size = sizeof(struct ibv_flow_spec_eth),
+			.val = {
+				.dst_mac = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+				.src_mac = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+			},
+			.mask = {
+				.dst_mac = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+				.src_mac = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+			},
 		},
 		.drop = {
 			.size = sizeof(struct ibv_flow_spec_action_drop),
-- 
2.27.0

RE: [PATCH v2] net/mlx5: avoid wildcard drop flow in priority discovery

[Suanming Mou]

> -----Original Message-----
> From: Gavin Hu <gahu@nvidia.com>
> Sent: Tuesday, July 14, 2026 2:08 PM
> To: dev@dpdk.org
> Cc: Wei Yan <yanwei.wy@bytedance.com>; stable@dpdk.org; Dariusz
> Sosnowski <dsosnowski@nvidia.com>; Slava Ovsiienko
> <viacheslavo@nvidia.com>; Bing Zhao <bingz@nvidia.com>; Ori Kam
> <orika@nvidia.com>; Suanming Mou <suanmingm@nvidia.com>; Matan
> Azrad <matan@nvidia.com>; Ophir Munk <ophirmu@nvidia.com>; Dmitry
> Kozlyuk <dmitry.kozliuk@gmail.com>
> Subject: [PATCH v2] net/mlx5: avoid wildcard drop flow in priority discovery
> 
> From: Wei Yan <yanwei.wy@bytedance.com>
> 
> Priority discovery installs temporary drop flows to probe supported flow
> priorities. These flows match a wildcard Ethernet pattern, so they can also
> match real traffic while discovery is running. On shared devices this may
> temporarily drop kernel traffic and cause TCP connection timeouts.
> 
> Constrain the probe flows to match both source and destination MAC
> addresses as ff:ff:ff:ff:ff:ff. This keeps the rule valid for discovery while
> avoiding matches on normal Ethernet traffic.
> 
> Fixes: 3eca5f8a610e ("net/mlx5: move flow priority discovery to Verbs file")
> Fixes: c5042f93a425 ("net/mlx5: discover max flow priority using DevX")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Wei Yan <yanwei.wy@bytedance.com>
> Signed-off-by: Gavin Hu <gahu@nvidia.com>
Acked-by: Suanming Mou <suanmingm@nvidia.com>

Thanks

Re: [PATCH v2] net/mlx5: avoid wildcard drop flow in priority discovery

[Raslan Darawsheh]

Hi,


On 14/07/2026 9:07 AM, Gavin Hu wrote:
> From: Wei Yan <yanwei.wy@bytedance.com>
> 
> Priority discovery installs temporary drop flows to probe supported flow
> priorities. These flows match a wildcard Ethernet pattern, so they can
> also match real traffic while discovery is running. On shared devices this
> may temporarily drop kernel traffic and cause TCP connection timeouts.
> 
> Constrain the probe flows to match both source and destination MAC
> addresses as ff:ff:ff:ff:ff:ff. This keeps the rule valid for discovery
> while avoiding matches on normal Ethernet traffic.
> 
> Fixes: 3eca5f8a610e ("net/mlx5: move flow priority discovery to Verbs file")
> Fixes: c5042f93a425 ("net/mlx5: discover max flow priority using DevX")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Wei Yan <yanwei.wy@bytedance.com>
> Signed-off-by: Gavin Hu <gahu@nvidia.com>
> ---
> +v2:
> +* Fixed the compiling issue by some compilers in mlx5_flow_verbs.c.
> 

Patch applied to next-net-mlx,

Kindest regards
Raslan Darawsheh