net: ethtool: add support for symmetric-xor RSS hash

Symmetric RSS hash functions are beneficial in applications that monitor
both Tx and Rx packets of the same flow (IDS, software firewalls, ..etc).
Getting all traffic of the same flow on the same RX queue results in
higher CPU cache efficiency.

A NIC that supports "symmetric-xor" can achieve this RSS hash symmetry
by XORing the source and destination fields and pass the values to the
RSS hash algorithm.

The user may request RSS hash symmetry for a specific algorithm, via:

    # ethtool -X eth0 hfunc <hash_alg> symmetric-xor

or turn symmetry off (asymmetric) by:

    # ethtool -X eth0 hfunc <hash_alg>

The specific fields for each flow type should then be specified as usual
via:
    # ethtool -N|-U eth0 rx-flow-hash <flow_type> s|d|f|n

Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>
Link: https://lore.kernel.org/r/20231213003321.605376-4-ahmed.zaki@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 66fe254c3e51..cfcd952a1d4f 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -615,6 +615,8 @@ struct ethtool_mm_stats {
  *	to allocate a new RSS context; on return this field will
  *	contain the ID of the newly allocated context.
  * @rss_delete: Set to non-ZERO to remove the @rss_context context.
+ * @input_xfrm: Defines how the input data is transformed. Valid values are one
+ *	of %RXH_XFRM_*.
  */
 struct ethtool_rxfh_param {
 	u8	hfunc;
@@ -624,6 +626,7 @@ struct ethtool_rxfh_param {
 	u8	*key;
 	u32	rss_context;
 	u8	rss_delete;
+	u8	input_xfrm;
 };
 
 /**
@@ -632,6 +635,8 @@ struct ethtool_rxfh_param {
  *	parameter.
  * @cap_rss_ctx_supported: indicates if the driver supports RSS
  *	contexts.
+ * @cap_rss_sym_xor_supported: indicates if the driver supports symmetric-xor
+ *	RSS.
  * @supported_coalesce_params: supported types of interrupt coalescing.
  * @supported_ring_params: supported ring params.
  * @get_drvinfo: Report driver/device information. Modern drivers no
@@ -811,6 +816,7 @@ struct ethtool_rxfh_param {
 struct ethtool_ops {
 	u32     cap_link_lanes_supported:1;
 	u32     cap_rss_ctx_supported:1;
+	u32	cap_rss_sym_xor_supported:1;
 	u32	supported_coalesce_params;
 	u32	supported_ring_params;
 	void	(*get_drvinfo)(struct net_device *, struct ethtool_drvinfo *);