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>

2 files changed, 31 insertions, 4 deletions

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 86e5fc64b711..86d47425038b 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -972,18 +972,35 @@ static int ethtool_rxnfc_copy_to_user(void __user *useraddr,
 static noinline_for_stack int ethtool_set_rxnfc(struct net_device *dev,
 						u32 cmd, void __user *useraddr)
 {
+	const struct ethtool_ops *ops = dev->ethtool_ops;
+	struct ethtool_rxfh_param rxfh = {};
 	struct ethtool_rxnfc info;
 	size_t info_size = sizeof(info);
 	int rc;
 
-	if (!dev->ethtool_ops->set_rxnfc)
+	if (!ops->set_rxnfc || !ops->get_rxfh)
 		return -EOPNOTSUPP;
 
 	rc = ethtool_rxnfc_copy_struct(cmd, &info, &info_size, useraddr);
 	if (rc)
 		return rc;
 
-	rc = dev->ethtool_ops->set_rxnfc(dev, &info);
+	rc = ops->get_rxfh(dev, &rxfh);
+	if (rc)
+		return rc;
+
+	/* Sanity check: if symmetric-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) &&
+	    ((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)) ||
+	     (!!(info.data & RXH_L4_B_0_1) ^ !!(info.data & RXH_L4_B_2_3))))
+		return -EINVAL;
+
+	rc = ops->set_rxnfc(dev, &info);
 	if (rc)
 		return rc;
 
@@ -1198,7 +1215,7 @@ static noinline_for_stack int ethtool_get_rxfh(struct net_device *dev,
 	user_key_size = rxfh.key_size;
 
 	/* Check that reserved fields are 0 for now */
-	if (rxfh.rsvd8[0] || rxfh.rsvd8[1] || rxfh.rsvd8[2] || rxfh.rsvd32)
+	if (rxfh.rsvd8[0] || rxfh.rsvd8[1] || rxfh.rsvd32)
 		return -EINVAL;
 	/* Most drivers don't handle rss_context, check it's 0 as well */
 	if (rxfh.rss_context && !ops->cap_rss_ctx_supported)
@@ -1271,11 +1288,15 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 		return -EFAULT;
 
 	/* Check that reserved fields are 0 for now */
-	if (rxfh.rsvd8[0] || rxfh.rsvd8[1] || rxfh.rsvd8[2] || rxfh.rsvd32)
+	if (rxfh.rsvd8[0] || rxfh.rsvd8[1] || rxfh.rsvd32)
 		return -EINVAL;
 	/* Most drivers don't handle rss_context, check it's 0 as well */
 	if (rxfh.rss_context && !ops->cap_rss_ctx_supported)
 		return -EOPNOTSUPP;
+	/* Check input data transformation capabilities */
+	if ((rxfh.input_xfrm & RXH_XFRM_SYM_XOR) &&
+	    !ops->cap_rss_sym_xor_supported)
+		return -EOPNOTSUPP;
 
 	/* If either indir, hash key or function is valid, proceed further.
 	 * Must request at least one change: indir size, hash key or function.
@@ -1341,6 +1362,7 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 
 	rxfh_dev.hfunc = rxfh.hfunc;
 	rxfh_dev.rss_context = rxfh.rss_context;
+	rxfh_dev.input_xfrm = rxfh.input_xfrm;
 
 	ret = ops->set_rxfh(dev, &rxfh_dev, extack);
 	if (ret)
diff --git a/net/ethtool/rss.c b/net/ethtool/rss.c
index efc9f4409e40..71679137eff2 100644
--- a/net/ethtool/rss.c
+++ b/net/ethtool/rss.c
@@ -13,6 +13,7 @@ struct rss_reply_data {
 	u32				indir_size;
 	u32				hkey_size;
 	u32				hfunc;
+	u32				input_xfrm;
 	u32				*indir_table;
 	u8				*hkey;
 };
@@ -97,6 +98,7 @@ rss_prepare_data(const struct ethnl_req_info *req_base,
 		goto out_ops;
 
 	data->hfunc = rxfh.hfunc;
+	data->input_xfrm = rxfh.input_xfrm;
 out_ops:
 	ethnl_ops_complete(dev);
 	return ret;
@@ -110,6 +112,7 @@ rss_reply_size(const struct ethnl_req_info *req_base,
 	int len;
 
 	len = nla_total_size(sizeof(u32)) +	/* _RSS_HFUNC */
+	      nla_total_size(sizeof(u32)) +	/* _RSS_INPUT_XFRM */
 	      nla_total_size(sizeof(u32) * data->indir_size) + /* _RSS_INDIR */
 	      nla_total_size(data->hkey_size);	/* _RSS_HKEY */
 
@@ -124,6 +127,8 @@ rss_fill_reply(struct sk_buff *skb, const struct ethnl_req_info *req_base,
 
 	if ((data->hfunc &&
 	     nla_put_u32(skb, ETHTOOL_A_RSS_HFUNC, data->hfunc)) ||
+	    (data->input_xfrm &&
+	     nla_put_u32(skb, ETHTOOL_A_RSS_INPUT_XFRM, data->input_xfrm)) ||
 	    (data->indir_size &&
 	     nla_put(skb, ETHTOOL_A_RSS_INDIR,
 		     sizeof(u32) * data->indir_size, data->indir_table)) ||