netdev - [PATCH net-next 06/11] ethtool: rss: support setting hkey via Netlink

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Message-ID: <20250711015303.3688717-7-kuba@kernel.org>
Date: Thu, 10 Jul 2025 18:52:58 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	andrew+netdev@...n.ch,
	horms@...nel.org,
	donald.hunter@...il.com,
	shuah@...nel.org,
	kory.maincent@...tlin.com,
	maxime.chevallier@...tlin.com,
	sdf@...ichev.me,
	ecree.xilinx@...il.com,
	gal@...dia.com,
	Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net-next 06/11] ethtool: rss: support setting hkey via Netlink

Support setting RSS hashing key via ethtool Netlink.
Use the Netlink policy to make sure user doesn't pass
an empty key, "resetting" the key is not a thing.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 Documentation/netlink/specs/ethtool.yaml     |  1 +
 Documentation/networking/ethtool-netlink.rst |  1 +
 net/ethtool/rss.c                            | 42 +++++++++++++++++++-
 3 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/Documentation/netlink/specs/ethtool.yaml b/Documentation/netlink/specs/ethtool.yaml
index 0d02d8342e4c..aa55fc9068e1 100644
--- a/Documentation/netlink/specs/ethtool.yaml
+++ b/Documentation/netlink/specs/ethtool.yaml
@@ -2656,6 +2656,7 @@ c-version-name: ethtool-genl-version
             - context
             - hfunc
             - indir
+            - hkey
     -
       name: rss-ntf
       doc: |
diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
index f6e4439caa94..1830354495ae 100644
--- a/Documentation/networking/ethtool-netlink.rst
+++ b/Documentation/networking/ethtool-netlink.rst
@@ -2001,6 +2001,7 @@ RSS_SET
   ``ETHTOOL_A_RSS_CONTEXT``            u32     context number
   ``ETHTOOL_A_RSS_HFUNC``              u32     RSS hash func
   ``ETHTOOL_A_RSS_INDIR``              binary  Indir table bytes
+  ``ETHTOOL_A_RSS_HKEY``               binary  Hash key bytes
 =====================================  ======  ==============================
 
 ``ETHTOOL_A_RSS_INDIR`` is the minimal RSS table the user expects. Kernel and
diff --git a/net/ethtool/rss.c b/net/ethtool/rss.c
index a11428889419..20c7122fdc99 100644
--- a/net/ethtool/rss.c
+++ b/net/ethtool/rss.c
@@ -475,6 +475,7 @@ const struct nla_policy ethnl_rss_set_policy[ETHTOOL_A_RSS_START_CONTEXT + 1] =
 	[ETHTOOL_A_RSS_CONTEXT] = { .type = NLA_U32, },
 	[ETHTOOL_A_RSS_HFUNC] = NLA_POLICY_MIN(NLA_U32, 1),
 	[ETHTOOL_A_RSS_INDIR] = { .type = NLA_BINARY, },
+	[ETHTOOL_A_RSS_HKEY] = NLA_POLICY_MIN(NLA_BINARY, 1),
 };
 
 static int
@@ -488,8 +489,10 @@ ethnl_rss_set_validate(struct ethnl_req_info *req_info, struct genl_info *info)
 	if (request->rss_context && !ops->create_rxfh_context)
 		bad_attr = bad_attr ?: tb[ETHTOOL_A_RSS_CONTEXT];
 
-	if (request->rss_context && !ops->rxfh_per_ctx_key)
+	if (request->rss_context && !ops->rxfh_per_ctx_key) {
 		bad_attr = bad_attr ?: tb[ETHTOOL_A_RSS_HFUNC];
+		bad_attr = bad_attr ?: tb[ETHTOOL_A_RSS_HKEY];
+	}
 
 	if (bad_attr) {
 		NL_SET_BAD_ATTR(info->extack, bad_attr);
@@ -579,6 +582,33 @@ rss_set_prep_indir(struct net_device *dev, struct genl_info *info,
 	return err;
 }
 
+static int
+rss_set_prep_hkey(struct net_device *dev, struct genl_info *info,
+		  struct rss_reply_data *data, struct ethtool_rxfh_param *rxfh,
+		  bool *mod)
+{
+	struct nlattr **tb = info->attrs;
+
+	if (!tb[ETHTOOL_A_RSS_HKEY])
+		return 0;
+
+	if (nla_len(tb[ETHTOOL_A_RSS_HKEY]) != data->hkey_size) {
+		NL_SET_BAD_ATTR(info->extack, tb[ETHTOOL_A_RSS_HKEY]);
+		return -EINVAL;
+	}
+
+	rxfh->key_size = data->hkey_size;
+	rxfh->key = kzalloc(data->hkey_size, GFP_KERNEL);
+	if (!rxfh->key)
+		return -ENOMEM;
+
+	nla_memcpy(rxfh->key, tb[ETHTOOL_A_RSS_HKEY], rxfh->key_size);
+
+	*mod |= memcmp(rxfh->key, data->hkey, data->hkey_size);
+
+	return 0;
+}
+
 static void
 rss_set_ctx_update(struct ethtool_rxfh_context *ctx, struct nlattr **tb,
 		   struct rss_reply_data *data, struct ethtool_rxfh_param *rxfh)
@@ -590,6 +620,11 @@ rss_set_ctx_update(struct ethtool_rxfh_context *ctx, struct nlattr **tb,
 			ethtool_rxfh_context_indir(ctx)[i] = rxfh->indir[i];
 		ctx->indir_configured = !!nla_len(tb[ETHTOOL_A_RSS_INDIR]);
 	}
+	if (rxfh->key) {
+		memcpy(ethtool_rxfh_context_key(ctx), rxfh->key,
+		       data->hkey_size);
+		ctx->key_configured = !!rxfh->key_size;
+	}
 	if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE)
 		ctx->hfunc = rxfh->hfunc;
 }
@@ -628,6 +663,10 @@ ethnl_rss_set(struct ethnl_req_info *req_info, struct genl_info *info)
 	if (rxfh.hfunc == data.hfunc)
 		rxfh.hfunc = ETH_RSS_HASH_NO_CHANGE;
 
+	ret = rss_set_prep_hkey(dev, info, &data, &rxfh, &mod);
+	if (ret)
+		goto exit_clean_data;
+
 	rxfh.input_xfrm = RXH_XFRM_NO_CHANGE;
 
 	mutex_lock(&dev->ethtool->rss_lock);
@@ -657,6 +696,7 @@ ethnl_rss_set(struct ethnl_req_info *req_info, struct genl_info *info)
 
 exit_unlock:
 	mutex_unlock(&dev->ethtool->rss_lock);
+	kfree(rxfh.key);
 	kfree(rxfh.indir);
 exit_clean_data:
 	rss_cleanup_data(&data.base);
-- 
2.50.1