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ethtool: Symmetric OR-XOR RSS hash

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Add an additional type of symmetric RSS hash type: OR-XOR.
The "Symmetric-OR-XOR" algorithm transforms the input as follows:

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

Change 'cap_rss_sym_xor_supported' to 'supported_input_xfrm', a bitmap
of supported RXH_XFRM_* types.

Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Edward Cree <ecree.xilinx@gmail.com>
Link: https://patch.msgid.link/20250224174416.499070-2-gal@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Gal Pressman 2025-02-24 19:44:13 +02:00 committed by Jakub Kicinski
parent ad530283d3
commit ecdff89338
7 changed files with 24 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/networking/ethtool-netlink.rst
View File

@ -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
============

15
Documentation/networking/scaling.rst
View File

@ -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

2
drivers/net/ethernet/intel/iavf/iavf_ethtool.c
View File

@ -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,

2
drivers/net/ethernet/intel/ice/ice_ethtool.c
View File

@ -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,

5
include/linux/ethtool.h
View File

@ -763,13 +763,12 @@ struct kernel_ethtool_ts_info {
/**
* struct ethtool_ops - optional netdev operations
* @supported_input_xfrm: supported types of input xfrm from %RXH_XFRM_*.
* @cap_link_lanes_supported: indicates if the driver supports lanes
* parameter.
* @cap_rss_ctx_supported: indicates if the driver supports RSS
* contexts via legacy API, drivers implementing @create_rxfh_context
* do not have to set this bit.
* @cap_rss_sym_xor_supported: indicates if the driver supports symmetric-xor
* RSS.
* @rxfh_per_ctx_key: device supports setting different RSS key for each
* additional context. Netlink API should report hfunc, key, and input_xfrm
* for every context, not just context 0.
@ -995,9 +994,9 @@ struct kernel_ethtool_ts_info {
* of the generic netdev features interface.
*/
struct ethtool_ops {
u32 supported_input_xfrm:8;
u32 cap_link_lanes_supported:1;
u32 cap_rss_ctx_supported:1;
u32 cap_rss_sym_xor_supported:1;
u32 rxfh_per_ctx_key:1;
u32 cap_rss_rxnfc_adds:1;
u32 rxfh_indir_space;

4
include/uapi/linux/ethtool.h
View File

@ -2289,6 +2289,10 @@ static inline int ethtool_validate_duplex(__u8 duplex)
* be exploited to reduce the RSS queue spread.
*/
#define RXH_XFRM_SYM_XOR (1 << 0)
/* Similar to SYM_XOR, except that one copy of the XOR'ed fields is replaced by
* an OR of the same fields
*/
#define RXH_XFRM_SYM_OR_XOR (1 << 1)
#define RXH_XFRM_NO_CHANGE 0xff
/* L2-L4 network traffic flow types */

8
net/ethtool/ioctl.c
View File

@ -1011,11 +1011,11 @@ static noinline_for_stack int ethtool_set_rxnfc(struct net_device *dev,
if (rc)
return rc;
/* Sanity check: if symmetric-xor is set, then:
/* Sanity check: if symmetric-xor/symmetric-or-xor is set, then:
* 1 - no other fields besides IP src/dst and/or L4 src/dst
* 2 - If src is set, dst must also be set
*/
if ((rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
if ((rxfh.input_xfrm & (RXH_XFRM_SYM_XOR | RXH_XFRM_SYM_OR_XOR)) &&
((info.data & ~(RXH_IP_SRC | RXH_IP_DST |
RXH_L4_B_0_1 | RXH_L4_B_2_3)) ||
(!!(info.data & RXH_IP_SRC) ^ !!(info.data & RXH_IP_DST)) ||
@ -1388,11 +1388,11 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
return -EOPNOTSUPP;
/* Check input data transformation capabilities */
if (rxfh.input_xfrm && rxfh.input_xfrm != RXH_XFRM_SYM_XOR &&
rxfh.input_xfrm != RXH_XFRM_SYM_OR_XOR &&
rxfh.input_xfrm != RXH_XFRM_NO_CHANGE)
return -EINVAL;
if (rxfh.input_xfrm != RXH_XFRM_NO_CHANGE &&
(rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
!ops->cap_rss_sym_xor_supported)
rxfh.input_xfrm & ~ops->supported_input_xfrm)
return -EOPNOTSUPP;
create = rxfh.rss_context == ETH_RXFH_CONTEXT_ALLOC;