[PATCH net-next 1/5] net/mlx5e: remove channel count limit for XOR8 RSS hash
From: Tariq Toukan <tariqt@nvidia.com>
Date: 2026-05-11 17:28:16
Also in:
linux-rdma, lkml
Subsystem:
mellanox ethernet driver (mlx5e), mellanox mlx5 core vpi driver, networking drivers, the rest · Maintainers:
Saeed Mahameed, Tariq Toukan, Mark Bloch, Leon Romanovsky, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Yael Chemla <redacted>
mlx5e_ethtool_set_channels() and mlx5e_rxfh_hfunc_check() rejected
channel counts that would produce an indirection table larger than 256
entries when the XOR8 hash function was active. This check was
introduced in commit 49e6c9387051 ("net/mlx5e: RSS, Block XOR hash
with over 128 channels").
XOR8 yields an 8-bit hash, so in practice only up to 256 entries in the
indirection table can be reached due to limited entropy. However, this
does not provide a strong justification for prohibiting larger
indirection tables. Remove the limitation.
Signed-off-by: Yael Chemla <redacted>
Reviewed-by: Nimrod Oren <redacted>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
.../net/ethernet/mellanox/mlx5/core/en/rqt.c | 7 ---
.../net/ethernet/mellanox/mlx5/core/en/rqt.h | 1 -
.../ethernet/mellanox/mlx5/core/en_ethtool.c | 48 -------------------
3 files changed, 56 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/rqt.c b/drivers/net/ethernet/mellanox/mlx5/core/en/rqt.c
index 8d9a3b5ec973..bcafb4bf9415 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/rqt.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/rqt.c@@ -179,13 +179,6 @@ u32 mlx5e_rqt_size(struct mlx5_core_dev *mdev, unsigned int num_channels) return min_t(u32, rqt_size, max_cap_rqt_size); } -#define MLX5E_MAX_RQT_SIZE_ALLOWED_WITH_XOR8_HASH 256 - -unsigned int mlx5e_rqt_max_num_channels_allowed_for_xor8(void) -{ - return MLX5E_MAX_RQT_SIZE_ALLOWED_WITH_XOR8_HASH / MLX5E_UNIFORM_SPREAD_RQT_FACTOR; -} - void mlx5e_rqt_destroy(struct mlx5e_rqt *rqt) { mlx5_core_destroy_rqt(rqt->mdev, rqt->rqtn);
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/rqt.h b/drivers/net/ethernet/mellanox/mlx5/core/en/rqt.h
index 2f9e04a8418f..e0bc30308c77 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/rqt.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/rqt.h@@ -38,7 +38,6 @@ static inline u32 mlx5e_rqt_get_rqtn(struct mlx5e_rqt *rqt) } u32 mlx5e_rqt_size(struct mlx5_core_dev *mdev, unsigned int num_channels); -unsigned int mlx5e_rqt_max_num_channels_allowed_for_xor8(void); int mlx5e_rqt_redirect_direct(struct mlx5e_rqt *rqt, u32 rqn, u32 *vhca_id); int mlx5e_rqt_redirect_indir(struct mlx5e_rqt *rqt, u32 *rqns, u32 *vhca_ids, unsigned int num_rqns,
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
index bb61e2179078..a6da0219723c 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c@@ -511,17 +511,6 @@ int mlx5e_ethtool_set_channels(struct mlx5e_priv *priv, mutex_lock(&priv->state_lock); - if (mlx5e_rx_res_get_current_hash(priv->rx_res).hfunc == ETH_RSS_HASH_XOR) { - unsigned int xor8_max_channels = mlx5e_rqt_max_num_channels_allowed_for_xor8(); - - if (count > xor8_max_channels) { - err = -EINVAL; - netdev_err(priv->netdev, "%s: Requested number of channels (%d) exceeds the maximum allowed by the XOR8 RSS hfunc (%d)\n", - __func__, count, xor8_max_channels); - goto out; - } - } - /* If RXFH is configured, changing the channels number is allowed only if * it does not require resizing the RSS table. This is because the previous * configuration may no longer be compatible with the new RSS table.
@@ -1501,29 +1490,6 @@ static int mlx5e_get_rxfh(struct net_device *netdev, struct ethtool_rxfh_param * return 0; } -static int mlx5e_rxfh_hfunc_check(struct mlx5e_priv *priv, - const struct ethtool_rxfh_param *rxfh, - struct netlink_ext_ack *extack) -{ - unsigned int count; - - count = priv->channels.params.num_channels; - - if (rxfh->hfunc == ETH_RSS_HASH_XOR) { - unsigned int xor8_max_channels = mlx5e_rqt_max_num_channels_allowed_for_xor8(); - - if (count > xor8_max_channels) { - NL_SET_ERR_MSG_FMT_MOD( - extack, - "Number of channels (%u) exceeds the max for XOR8 RSS (%u)", - count, xor8_max_channels); - return -EINVAL; - } - } - - return 0; -} - static int mlx5e_set_rxfh(struct net_device *dev, struct ethtool_rxfh_param *rxfh, struct netlink_ext_ack *extack)
@@ -1535,16 +1501,11 @@ static int mlx5e_set_rxfh(struct net_device *dev, mutex_lock(&priv->state_lock); - err = mlx5e_rxfh_hfunc_check(priv, rxfh, extack); - if (err) - goto unlock; - err = mlx5e_rx_res_rss_set_rxfh(priv->rx_res, rxfh->rss_context, rxfh->indir, rxfh->key, hfunc == ETH_RSS_HASH_NO_CHANGE ? NULL : &hfunc, rxfh->input_xfrm == RXH_XFRM_NO_CHANGE ? NULL : &symmetric); -unlock: mutex_unlock(&priv->state_lock); return err; }
@@ -1561,10 +1522,6 @@ static int mlx5e_create_rxfh_context(struct net_device *dev, mutex_lock(&priv->state_lock); - err = mlx5e_rxfh_hfunc_check(priv, rxfh, extack); - if (err) - goto unlock; - err = mlx5e_rx_res_rss_init(priv->rx_res, rxfh->rss_context, priv->channels.params.num_channels); if (err)
@@ -1601,16 +1558,11 @@ static int mlx5e_modify_rxfh_context(struct net_device *dev, mutex_lock(&priv->state_lock); - err = mlx5e_rxfh_hfunc_check(priv, rxfh, extack); - if (err) - goto unlock; - err = mlx5e_rx_res_rss_set_rxfh(priv->rx_res, rxfh->rss_context, rxfh->indir, rxfh->key, hfunc == ETH_RSS_HASH_NO_CHANGE ? NULL : &hfunc, rxfh->input_xfrm == RXH_XFRM_NO_CHANGE ? NULL : &symmetric); -unlock: mutex_unlock(&priv->state_lock); return err; }
--
2.44.0