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net/mlx5e: remove channel count limit for XOR8 RSS hash

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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 49e6c93870 ("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 <ychemla@nvidia.com>
Reviewed-by: Nimrod Oren <noren@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20260511172719.330490-2-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Yael Chemla 2026-05-11 20:27:15 +03:00 committed by Jakub Kicinski
parent 6bbc313bcb
commit f7c35c6685
3 changed files with 0 additions and 56 deletions
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7
drivers/net/ethernet/mellanox/mlx5/core/en/rqt.c
View File

@ -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);

1
drivers/net/ethernet/mellanox/mlx5/core/en/rqt.h
View File

@ -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,

48
drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
View File

@ -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;
}