Commit 13f7e999 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'symmetric-or-xor-rss-hash' 

Gal Pressman says:

====================
Symmetric OR-XOR RSS hash

Add support for a new type of input_xfrm: Symmetric OR-XOR.
Symmetric OR-XOR performs hash as follows:
(SRC_IP | DST_IP, SRC_IP ^ DST_IP, SRC_PORT | DST_PORT, SRC_PORT ^ DST_PORT)

Configuration is done through ethtool -x/X command.
For mlx5, the default is already symmetric hash, this patch now exposes
this to userspace and allows enabling/disabling of the feature.

v5: https://lore.kernel.org/20250220113435.417487-1-gal@nvidia.com
v4: https://lore.kernel.org/20250216182453.226325-1-gal@nvidia.com
v3: https://lore.kernel.org/20250205135341.542720-1-gal@nvidia.com
v2: https://lore.kernel.org/20250203150039.519301-1-gal@nvidia.com
====================

Link: https://patch.msgid.link/20250224174416.499070-1-gal@nvidia.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents ad530283 da87caba

Documentation/networking/ethtool-netlink.rst

+1 −1
Original line number Diff line number Diff line
@@ -1934,7 +1934,7 @@ ETHTOOL_A_RSS_INDIR attribute returns RSS indirection table where each byte 
indicates queue number.

ETHTOOL_A_RSS_INPUT_XFRM attribute is a bitmap indicating the type of

transformation applied to the input protocol fields before given to the RSS

hfunc. Current supported option is symmetric-xor.

hfunc. Current supported options are symmetric-xor and symmetric-or-xor.



PLCA_GET_CFG

============

Documentation/networking/scaling.rst

+11 −4
Original line number Diff line number Diff line
@@ -49,14 +49,21 @@ destination address) and TCP/UDP (source port, destination port) tuples 
are swapped, the computed hash is the same. This is beneficial in some

applications that monitor TCP/IP flows (IDS, firewalls, ...etc) and need

both directions of the flow to land on the same Rx queue (and CPU). The

"Symmetric-XOR" is a type of RSS algorithms that achieves this hash

symmetry by XORing the input source and destination fields of the IP

and/or L4 protocols. This, however, results in reduced input entropy and

could potentially be exploited. Specifically, the algorithm XORs the input

"Symmetric-XOR" and "Symmetric-OR-XOR" are types of RSS algorithms that

achieve this hash symmetry by XOR/ORing the input source and destination

fields of the IP and/or L4 protocols. This, however, results in reduced

input entropy and could potentially be exploited.



Specifically, the "Symmetric-XOR" algorithm XORs the input

as follows::



    # (SRC_IP ^ DST_IP, SRC_IP ^ DST_IP, SRC_PORT ^ DST_PORT, SRC_PORT ^ DST_PORT)



The "Symmetric-OR-XOR" algorithm, on the other hand, transforms the input as

follows::



    # (SRC_IP | DST_IP, SRC_IP ^ DST_IP, SRC_PORT | DST_PORT, SRC_PORT ^ DST_PORT)



The result is then fed to the underlying RSS algorithm.



Some advanced NICs allow steering packets to queues based on

drivers/net/ethernet/intel/iavf/iavf_ethtool.c

+1 −1
Original line number Diff line number Diff line
@@ -1808,7 +1808,7 @@ static int iavf_set_rxfh(struct net_device *netdev, 
static const struct ethtool_ops iavf_ethtool_ops = {

	.supported_coalesce_params = ETHTOOL_COALESCE_USECS |

				     ETHTOOL_COALESCE_USE_ADAPTIVE,

	.cap_rss_sym_xor_supported = true,

	.supported_input_xfrm	= RXH_XFRM_SYM_XOR,

	.get_drvinfo		= iavf_get_drvinfo,

	.get_link		= ethtool_op_get_link,

	.get_ringparam		= iavf_get_ringparam,

drivers/net/ethernet/intel/ice/ice_ethtool.c

+1 −1
Original line number Diff line number Diff line
@@ -4770,7 +4770,7 @@ static const struct ethtool_ops ice_ethtool_ops = { 
	.supported_coalesce_params = ETHTOOL_COALESCE_USECS |

				     ETHTOOL_COALESCE_USE_ADAPTIVE |

				     ETHTOOL_COALESCE_RX_USECS_HIGH,

	.cap_rss_sym_xor_supported = true,

	.supported_input_xfrm	= RXH_XFRM_SYM_XOR,

	.rxfh_per_ctx_key	= true,

	.get_link_ksettings	= ice_get_link_ksettings,

	.set_link_ksettings	= ice_set_link_ksettings,

drivers/net/ethernet/mellanox/mlx5/core/en/rss.c

+11 −2
Original line number Diff line number Diff line
@@ -161,6 +161,7 @@ static void mlx5e_rss_params_init(struct mlx5e_rss *rss) 
{

	enum mlx5_traffic_types tt;



	rss->hash.symmetric = true;

	rss->hash.hfunc = ETH_RSS_HASH_TOP;

	netdev_rss_key_fill(rss->hash.toeplitz_hash_key,

			    sizeof(rss->hash.toeplitz_hash_key));
@@ -566,7 +567,7 @@ int mlx5e_rss_packet_merge_set_param(struct mlx5e_rss *rss, 
	return final_err;

}



int mlx5e_rss_get_rxfh(struct mlx5e_rss *rss, u32 *indir, u8 *key, u8 *hfunc)

int mlx5e_rss_get_rxfh(struct mlx5e_rss *rss, u32 *indir, u8 *key, u8 *hfunc, bool *symmetric)

{

	if (indir)

		memcpy(indir, rss->indir.table,
@@ -579,11 +580,14 @@ int mlx5e_rss_get_rxfh(struct mlx5e_rss *rss, u32 *indir, u8 *key, u8 *hfunc) 
	if (hfunc)

		*hfunc = rss->hash.hfunc;



	if (symmetric)

		*symmetric = rss->hash.symmetric;



	return 0;

}



int mlx5e_rss_set_rxfh(struct mlx5e_rss *rss, const u32 *indir,

		       const u8 *key, const u8 *hfunc,

		       const u8 *key, const u8 *hfunc, const bool *symmetric,

		       u32 *rqns, u32 *vhca_ids, unsigned int num_rqns)

{

	bool changed_indir = false;
@@ -623,6 +627,11 @@ int mlx5e_rss_set_rxfh(struct mlx5e_rss *rss, const u32 *indir, 
		       rss->indir.actual_table_size * sizeof(*rss->indir.table));

	}



	if (symmetric) {

		rss->hash.symmetric = *symmetric;

		changed_hash = true;

	}



	if (changed_indir && rss->enabled) {

		err = mlx5e_rss_apply(rss, rqns, vhca_ids, num_rqns);

		if (err) {