ethtool: rss: report which fields are configured for hashing

Implement ETHTOOL_GRXFH over Netlink. The number of flow types is
reasonable (around 20) so report all of them at once for simplicity.

Do not maintain the flow ID mapping with ioctl at the uAPI level.
This gives us a chance to clean up the confusion that come from
RxNFC vs RxFH (flow direction vs hashing) in the ioctl.
Try to align with the names used in ethtool CLI, they seem to have
stood the test of time just fine. One annoyance is that we still
call L4 ports the weird names, but I guess they also apply to IPSec
(where they cover the SPI) so it is what it is.

 $ ynl --family ethtool --dump rss-get
 {
    "header": {
	"dev-index": 1,
	"dev-name": "enp1s0"
    },
    "hfunc": 1,
    "hkey": b"...",
    "indir": [0, 1, ...],
    "flow-hash": {
        "ether": {"l2da"},
	"ah-esp4": {"ip-src", "ip-dst"},
        "ah-esp6": {"ip-src", "ip-dst"},
        "ah4": {"ip-src", "ip-dst"},
        "ah6": {"ip-src", "ip-dst"},
        "esp4": {"ip-src", "ip-dst"},
        "esp6": {"ip-src", "ip-dst"},
        "ip4": {"ip-src", "ip-dst"},
        "ip6": {"ip-src", "ip-dst"},
        "sctp4": {"ip-src", "ip-dst"},
        "sctp6": {"ip-src", "ip-dst"},
        "udp4": {"ip-src", "ip-dst"},
        "udp6": {"ip-src", "ip-dst"}
        "tcp4": {"l4-b-0-1", "l4-b-2-3", "ip-src", "ip-dst"},
        "tcp6": {"l4-b-0-1", "l4-b-2-3", "ip-src", "ip-dst"},
    },
 }

Link: https://patch.msgid.link/20250708220640.2738464-5-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 95 insertions, 10 deletions

diff --git a/net/ethtool/rss.c b/net/ethtool/rss.c
index 37a7b20fcd07..41ab9fc67652 100644
--- a/net/ethtool/rss.c
+++ b/net/ethtool/rss.c
@@ -12,6 +12,7 @@ struct rss_req_info {
 
 struct rss_reply_data {
 	struct ethnl_reply_data		base;
+	bool				has_flow_hash;
 	bool				no_key_fields;
 	u32				indir_size;
 	u32				hkey_size;
@@ -19,6 +20,37 @@ struct rss_reply_data {
 	u32				input_xfrm;
 	u32				*indir_table;
 	u8				*hkey;
+	int				flow_hash[__ETHTOOL_A_FLOW_CNT];
+};
+
+static const u8 ethtool_rxfh_ft_nl2ioctl[] = {
+	[ETHTOOL_A_FLOW_ETHER]		= ETHER_FLOW,
+	[ETHTOOL_A_FLOW_IP4]		= IPV4_FLOW,
+	[ETHTOOL_A_FLOW_IP6]		= IPV6_FLOW,
+	[ETHTOOL_A_FLOW_TCP4]		= TCP_V4_FLOW,
+	[ETHTOOL_A_FLOW_UDP4]		= UDP_V4_FLOW,
+	[ETHTOOL_A_FLOW_SCTP4]		= SCTP_V4_FLOW,
+	[ETHTOOL_A_FLOW_AH_ESP4]	= AH_ESP_V4_FLOW,
+	[ETHTOOL_A_FLOW_TCP6]		= TCP_V6_FLOW,
+	[ETHTOOL_A_FLOW_UDP6]		= UDP_V6_FLOW,
+	[ETHTOOL_A_FLOW_SCTP6]		= SCTP_V6_FLOW,
+	[ETHTOOL_A_FLOW_AH_ESP6]	= AH_ESP_V6_FLOW,
+	[ETHTOOL_A_FLOW_AH4]		= AH_V4_FLOW,
+	[ETHTOOL_A_FLOW_ESP4]		= ESP_V4_FLOW,
+	[ETHTOOL_A_FLOW_AH6]		= AH_V6_FLOW,
+	[ETHTOOL_A_FLOW_ESP6]		= ESP_V6_FLOW,
+	[ETHTOOL_A_FLOW_GTPU4]		= GTPU_V4_FLOW,
+	[ETHTOOL_A_FLOW_GTPU6]		= GTPU_V6_FLOW,
+	[ETHTOOL_A_FLOW_GTPC4]		= GTPC_V4_FLOW,
+	[ETHTOOL_A_FLOW_GTPC6]		= GTPC_V6_FLOW,
+	[ETHTOOL_A_FLOW_GTPC_TEID4]	= GTPC_TEID_V4_FLOW,
+	[ETHTOOL_A_FLOW_GTPC_TEID6]	= GTPC_TEID_V6_FLOW,
+	[ETHTOOL_A_FLOW_GTPU_EH4]	= GTPU_EH_V4_FLOW,
+	[ETHTOOL_A_FLOW_GTPU_EH6]	= GTPU_EH_V6_FLOW,
+	[ETHTOOL_A_FLOW_GTPU_UL4]	= GTPU_UL_V4_FLOW,
+	[ETHTOOL_A_FLOW_GTPU_UL6]	= GTPU_UL_V6_FLOW,
+	[ETHTOOL_A_FLOW_GTPU_DL4]	= GTPU_DL_V4_FLOW,
+	[ETHTOOL_A_FLOW_GTPU_DL6]	= GTPU_DL_V6_FLOW,
 };
 
 #define RSS_REQINFO(__req_base) \
@@ -49,6 +81,37 @@ rss_parse_request(struct ethnl_req_info *req_info, struct nlattr **tb,
 	return 0;
 }
 
+static void
+rss_prepare_flow_hash(const struct rss_req_info *req, struct net_device *dev,
+		      struct rss_reply_data *data, const struct genl_info *info)
+{
+	int i;
+
+	data->has_flow_hash = false;
+
+	if (!dev->ethtool_ops->get_rxfh_fields)
+		return;
+	if (req->rss_context && !dev->ethtool_ops->rxfh_per_ctx_fields)
+		return;
+
+	mutex_lock(&dev->ethtool->rss_lock);
+	for (i = 1; i < __ETHTOOL_A_FLOW_CNT; i++) {
+		struct ethtool_rxfh_fields fields = {
+			.flow_type	= ethtool_rxfh_ft_nl2ioctl[i],
+			.rss_context	= req->rss_context,
+		};
+
+		if (dev->ethtool_ops->get_rxfh_fields(dev, &fields)) {
+			data->flow_hash[i] = -1; /* Unsupported */
+			continue;
+		}
+
+		data->flow_hash[i] = fields.data;
+		data->has_flow_hash = true;
+	}
+	mutex_unlock(&dev->ethtool->rss_lock);
+}
+
 static int
 rss_prepare_get(const struct rss_req_info *request, struct net_device *dev,
 		struct rss_reply_data *data, const struct genl_info *info)
@@ -153,6 +216,8 @@ static int
 rss_prepare(const struct rss_req_info *request, struct net_device *dev,
 	    struct rss_reply_data *data, const struct genl_info *info)
 {
+	rss_prepare_flow_hash(request, dev, data, info);
+
 	if (request->rss_context)
 		return rss_prepare_ctx(request, dev, data, info);
 	return rss_prepare_get(request, dev, data, info);
@@ -190,7 +255,10 @@ rss_reply_size(const struct ethnl_req_info *req_base,
 	      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 */
+	      nla_total_size(data->hkey_size) + /* _RSS_HKEY */
+	      nla_total_size(0) +		/* _RSS_FLOW_HASH */
+		nla_total_size(sizeof(u32)) * ETHTOOL_A_FLOW_MAX +
+	      0;
 
 	return len;
 }
@@ -211,17 +279,34 @@ rss_fill_reply(struct sk_buff *skb, const struct ethnl_req_info *req_base,
 		     sizeof(u32) * data->indir_size, data->indir_table)))
 		return -EMSGSIZE;
 
-	if (data->no_key_fields)
-		return 0;
-
-	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->hkey_size &&
-	     nla_put(skb, ETHTOOL_A_RSS_HKEY, data->hkey_size, data->hkey)))
+	if (!data->no_key_fields &&
+	    ((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->hkey_size &&
+	      nla_put(skb, ETHTOOL_A_RSS_HKEY, data->hkey_size, data->hkey))))
 		return -EMSGSIZE;
 
+	if (data->has_flow_hash) {
+		struct nlattr *nest;
+		int i;
+
+		nest = nla_nest_start(skb, ETHTOOL_A_RSS_FLOW_HASH);
+		if (!nest)
+			return -EMSGSIZE;
+
+		for (i = 1; i < __ETHTOOL_A_FLOW_CNT; i++) {
+			if (data->flow_hash[i] >= 0 &&
+			    nla_put_uint(skb, i, data->flow_hash[i])) {
+				nla_nest_cancel(skb, nest);
+				return -EMSGSIZE;
+			}
+		}
+
+		nla_nest_end(skb, nest);
+	}
+
 	return 0;
 }