[PATCH net] net/mlx5e: Add mutual exclusion between PSP and PTP TX port timestamping

[PATCH net] net/mlx5e: Add mutual exclusion between PSP and PTP TX port timestamping

[Tariq Toukan]

From: Carolina Jubran <cjubran@nvidia.com>

The WQE flow_table_metadata field is shared by multiple TX offloads:
IPsec, MACsec, PTP timestamping and PSP each write to it.

Commit [1] resolved the conflicts between IPsec/MACsec and PTP
by shifting their markers to bits [8+], leaving PTP's 8-bit metadata
index in bits [7:0] without overlap.
But then PSP support was added in commit [2], which writes a 32-bit
keyid across all bits of flow_table_metadata. Unlike IPsec and MACsec,
PTP timestamping applies independently of encryption -- a PSP-encrypted
packet can also require a HW timestamp. When both write to the same
WQE, the values corrupt each other, leading to wrong PTP timestamp
tracking and potentially wrong PSP encryption keys.

Prevent the conflict at configuration time by blocking:
- Enabling TX-port-TS when PSP has active TX keys.
- Adding PSP TX keys when TX-port-TS is already enabled.

[1] Commit 2ac207381c37 ("net/mlx5e: Prevent WQE metadata conflicts
between timestamping and offloads")
[2] Commit 89ee2d92f66c ("net/mlx5e: Support PSP offload functionality")

Fixes: 89ee2d92f66c ("net/mlx5e: Support PSP offload functionality")
Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 .../ethernet/mellanox/mlx5/core/en_accel/psp.c   | 16 +++++++++++++++-
 .../ethernet/mellanox/mlx5/core/en_accel/psp.h   | 11 +++++++++++
 .../net/ethernet/mellanox/mlx5/core/en_ethtool.c |  8 ++++++++
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.c b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.c
index d9adb993e64d..8d76dd488d77 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.c
@@ -993,6 +993,20 @@ static int mlx5e_psp_assoc_add(struct psp_dev *psd, struct psp_assoc *pas,
 	struct psp_key *nkey;
 	int err;
 
+	/* Mutual exclusion with TX-port-TS (shared WQE metadata). Reserve
+	 * tx_key_cnt under state_lock with the TS check so ethtool cannot
+	 * enable TX-port-TS until key creation completes or fails.
+	 */
+	mutex_lock(&priv->state_lock);
+	if (MLX5E_GET_PFLAG(&priv->channels.params, MLX5E_PFLAG_TX_PORT_TS)) {
+		mutex_unlock(&priv->state_lock);
+		NL_SET_ERR_MSG_MOD(extack,
+				   "TX-port-TS is active, PSP TX keys cannot be added");
+		return -EBUSY;
+	}
+	atomic_inc(&psp->tx_key_cnt);
+	mutex_unlock(&priv->state_lock);
+
 	mdev = priv->mdev;
 	nkey = (struct psp_key *)pas->drv_data;
 
@@ -1001,11 +1015,11 @@ static int mlx5e_psp_assoc_add(struct psp_dev *psd, struct psp_assoc *pas,
 					 MLX5_ACCEL_OBJ_PSP_KEY,
 					 &nkey->id);
 	if (err) {
+		atomic_dec(&psp->tx_key_cnt);
 		mlx5_core_err(mdev, "Failed to create encryption key (err = %d)\n", err);
 		return err;
 	}
 
-	atomic_inc(&psp->tx_key_cnt);
 	return 0;
 }
 
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.h b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.h
index 6b62fef0d9a7..315c4b2101c2 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.h
@@ -30,6 +30,11 @@ struct mlx5e_psp {
 	atomic_t tx_drop;
 };
 
+static inline bool mlx5e_psp_tx_keys_active(const struct mlx5e_priv *priv)
+{
+	return priv->psp && atomic_read(&priv->psp->tx_key_cnt);
+}
+
 static inline bool mlx5_is_psp_device(struct mlx5_core_dev *mdev)
 {
 	if (!MLX5_CAP_GEN(mdev, psp))
@@ -52,6 +57,11 @@ void mlx5e_psp_unregister(struct mlx5e_priv *priv);
 int mlx5e_psp_init(struct mlx5e_priv *priv);
 void mlx5e_psp_cleanup(struct mlx5e_priv *priv);
 #else
+static inline bool mlx5e_psp_tx_keys_active(const struct mlx5e_priv *priv)
+{
+	return false;
+}
+
 static inline int mlx5_accel_psp_fs_init_rx_tables(struct mlx5e_priv *priv)
 {
 	return 0;
@@ -74,4 +84,5 @@ static inline void mlx5e_psp_unregister(struct mlx5e_priv *priv) { }
 static inline int mlx5e_psp_init(struct mlx5e_priv *priv) { return 0; }
 static inline void mlx5e_psp_cleanup(struct mlx5e_priv *priv) { }
 #endif /* CONFIG_MLX5_EN_PSP */
+
 #endif /* __MLX5E_ACCEL_PSP_H__ */
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
index 112926d07634..98941088d100 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
@@ -42,6 +42,7 @@
 #include "en/ptp.h"
 #include "lib/clock.h"
 #include "en/fs_ethtool.h"
+#include "en_accel/psp.h"
 
 #define LANES_UNKNOWN		 0
 
@@ -2387,6 +2388,13 @@ static int set_pflag_tx_port_ts(struct net_device *netdev, bool enable)
 			   __func__);
 		return -EINVAL;
 	}
+
+	if (enable && mlx5e_psp_tx_keys_active(priv)) {
+		netdev_err(priv->netdev,
+			   "%s: PSP TX keys are active, TX-port-TS cannot be enabled\n",
+			   __func__);
+		return -EBUSY;
+	}
 	MLX5E_SET_PFLAG(&new_params, MLX5E_PFLAG_TX_PORT_TS, enable);
 	/* No need to verify SQ stop room as
 	 * ptpsq.txqsq.stop_room <= generic_sq->stop_room, and both

base-commit: 3bd438a58e910db5dc369aa25dfed1fc95f1b596
-- 
2.44.0

Re: [PATCH net] net/mlx5e: Add mutual exclusion between PSP and PTP TX port timestamping

[Jakub Kicinski]

On Wed, 29 Jul 2026 09:51:37 +0300 Tariq Toukan wrote:
> The WQE flow_table_metadata field is shared by multiple TX offloads:
> IPsec, MACsec, PTP timestamping and PSP each write to it.
> 
> Commit [1] resolved the conflicts between IPsec/MACsec and PTP
> by shifting their markers to bits [8+], leaving PTP's 8-bit metadata
> index in bits [7:0] without overlap.
> But then PSP support was added in commit [2], which writes a 32-bit
> keyid across all bits of flow_table_metadata. Unlike IPsec and MACsec,
> PTP timestamping applies independently of encryption -- a PSP-encrypted
> packet can also require a HW timestamp. When both write to the same
> WQE, the values corrupt each other, leading to wrong PTP timestamp
> tracking and potentially wrong PSP encryption keys.

Is the concern about Tx? (please clarify)
If so, Tx HW timestamps are never guaranteed, why can't we just
skip timestamping for PSP packets? Only TCP supports PSP, and
upstream TCP and HW timestamps are pretty much mutually exclusive.

> Prevent the conflict at configuration time by blocking:
> - Enabling TX-port-TS when PSP has active TX keys.
> - Adding PSP TX keys when TX-port-TS is already enabled.

Why catch PSP at the Tx key programming? PSP docs very explicitly
require drivers to _not_ enable the feature by default. And tx
keys can't be added if it's disabled. So it would make much more
sense to catch the enable / config callback of PSP?
-- 
pw-bot: cr