ethtool: netlink: add ETHTOOL_MSG_MSE_GET and wire up PHY MSE access

Introduce the userspace entry point for PHY MSE diagnostics via
ethtool netlink. This exposes the core API added previously and
returns both capability information and one or more snapshots.

Userspace sends ETHTOOL_MSG_MSE_GET. The reply carries:
- ETHTOOL_A_MSE_CAPABILITIES: scale limits and timing information
- ETHTOOL_A_MSE_CHANNEL_* nests: one or more snapshots (per-channel
if available, otherwise WORST, otherwise LINK)

Link down returns -ENETDOWN.

Changes:
- YAML: add attribute sets (mse, mse-capabilities, mse-snapshot)
and the mse-get operation
- UAPI (generated): add ETHTOOL_A_MSE_* enums and message IDs,
ETHTOOL_MSG_MSE_GET/REPLY
- ethtool core: add net/ethtool/mse.c implementing the request,
register genl op, and hook into ethnl dispatch
- docs: document MSE_GET in ethtool-netlink.rst

The include/uapi/linux/ethtool_netlink_generated.h is generated
from Documentation/netlink/specs/ethtool.yaml.

Signed-off-by: Oleksij Rempel <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/netlink/specs/ethtool.yaml

···
         type: uint
         enum: pse-event
         doc: List of events reported by the PSE controller
+  -
+    name: mse-capabilities
+    doc: MSE capabilities attribute set
+    attr-cnt-name: --ethtool-a-mse-capabilities-cnt
+    attributes:
+      -
+        name: max-average-mse
+        type: uint
+      -
+        name: max-peak-mse
+        type: uint
+      -
+        name: refresh-rate-ps
+        type: uint
+      -
+        name: num-symbols
+        type: uint
+  -
+    name: mse-snapshot
+    doc: MSE snapshot attribute set
+    attr-cnt-name: --ethtool-a-mse-snapshot-cnt
+    attributes:
+      -
+        name: average-mse
+        type: uint
+      -
+        name: peak-mse
+        type: uint
+      -
+        name: worst-peak-mse
+        type: uint
+  -
+    name: mse
+    attr-cnt-name: --ethtool-a-mse-cnt
+    attributes:
+      -
+        name: header
+        type: nest
+        nested-attributes: header
+      -
+        name: capabilities
+        type: nest
+        nested-attributes: mse-capabilities
+      -
+        name: channel-a
+        type: nest
+        nested-attributes: mse-snapshot
+      -
+        name: channel-b
+        type: nest
+        nested-attributes: mse-snapshot
+      -
+        name: channel-c
+        type: nest
+        nested-attributes: mse-snapshot
+      -
+        name: channel-d
+        type: nest
+        nested-attributes: mse-snapshot
+      -
+        name: worst-channel
+        type: nest
+        nested-attributes: mse-snapshot
+      -
+        name: link
+        type: nest
+        nested-attributes: mse-snapshot
 
 operations:
   enum-model: directional
···
         attributes:
           - header
           - context
+    -
+      name: mse-get
+      doc: Get PHY MSE measurement data and capabilities.
+      attribute-set: mse
+      do: &mse-get-op
+        request:
+          attributes:
+            - header
+        reply:
+          attributes:
+            - header
+            - capabilities
+            - channel-a
+            - channel-b
+            - channel-c
+            - channel-d
+            - worst-channel
+            - link
+      dump: *mse-get-op
 
 mcast-groups:
   list:

Documentation/networking/ethtool-netlink.rst

···
   ``ETHTOOL_MSG_RSS_SET``               set RSS settings
   ``ETHTOOL_MSG_RSS_CREATE_ACT``        create an additional RSS context
   ``ETHTOOL_MSG_RSS_DELETE_ACT``        delete an additional RSS context
+  ``ETHTOOL_MSG_MSE_GET``               get MSE diagnostic data
   ===================================== =================================
 
 Kernel to userspace:
···
   ``ETHTOOL_MSG_RSS_CREATE_ACT_REPLY``     create an additional RSS context
   ``ETHTOOL_MSG_RSS_CREATE_NTF``           additional RSS context created
   ``ETHTOOL_MSG_RSS_DELETE_NTF``           additional RSS context deleted
+  ``ETHTOOL_MSG_MSE_GET_REPLY``            MSE diagnostic data
   ======================================== =================================
 
 ``GET`` requests are sent by userspace applications to retrieve device
···
   ======================================== ======  ============================
 
 For a description of each attribute, see ``TSCONFIG_GET``.
+
+MSE_GET
+=======
+
+Retrieves detailed Mean Square Error (MSE) diagnostic information from the PHY.
+
+Request Contents:
+
+  ====================================  ======  ============================
+  ``ETHTOOL_A_MSE_HEADER``              nested  request header
+  ====================================  ======  ============================
+
+Kernel Response Contents:
+
+  ====================================  ======  ================================
+  ``ETHTOOL_A_MSE_HEADER``              nested  reply header
+  ``ETHTOOL_A_MSE_CAPABILITIES``        nested  capability/scale info for MSE
+                                                measurements
+  ``ETHTOOL_A_MSE_CHANNEL_A``           nested  snapshot for Channel A
+  ``ETHTOOL_A_MSE_CHANNEL_B``           nested  snapshot for Channel B
+  ``ETHTOOL_A_MSE_CHANNEL_C``           nested  snapshot for Channel C
+  ``ETHTOOL_A_MSE_CHANNEL_D``           nested  snapshot for Channel D
+  ``ETHTOOL_A_MSE_WORST_CHANNEL``       nested  snapshot for worst channel
+  ``ETHTOOL_A_MSE_LINK``                nested  snapshot for link-wide aggregate
+  ====================================  ======  ================================
+
+MSE Capabilities
+----------------
+
+This nested attribute reports the capability / scaling properties used to
+interpret snapshot values.
+
+  ============================================== ======  =========================
+  ``ETHTOOL_A_MSE_CAPABILITIES_MAX_AVERAGE_MSE`` uint    max avg_mse scale
+  ``ETHTOOL_A_MSE_CAPABILITIES_MAX_PEAK_MSE``    uint    max peak_mse scale
+  ``ETHTOOL_A_MSE_CAPABILITIES_REFRESH_RATE_PS`` uint    sample rate (picoseconds)
+  ``ETHTOOL_A_MSE_CAPABILITIES_NUM_SYMBOLS``     uint    symbols per HW sample
+  ============================================== ======  =========================
+
+The max-average/peak fields are included only if the corresponding metric
+is supported by the PHY. Their absence indicates that the metric is not
+available.
+
+See ``struct phy_mse_capability`` kernel documentation in
+``include/linux/phy.h``.
+
+MSE Snapshot
+------------
+
+Each per-channel nest contains an atomic snapshot of MSE values for that
+selector (channel A/B/C/D, worst channel, or link).
+
+  ==========================================  ======  ===================
+  ``ETHTOOL_A_MSE_SNAPSHOT_AVERAGE_MSE``      uint    average MSE value
+  ``ETHTOOL_A_MSE_SNAPSHOT_PEAK_MSE``         uint    current peak MSE
+  ``ETHTOOL_A_MSE_SNAPSHOT_WORST_PEAK_MSE``   uint    worst-case peak MSE
+  ==========================================  ======  ===================
+
+Within each channel nest, only the metrics supported by the PHY will be present.
+
+See ``struct phy_mse_snapshot`` kernel documentation in
+``include/linux/phy.h``.
 
 Request translation
 ===================

include/uapi/linux/ethtool_netlink_generated.h

···
 };
 
 enum {
+	ETHTOOL_A_MSE_CAPABILITIES_MAX_AVERAGE_MSE = 1,
+	ETHTOOL_A_MSE_CAPABILITIES_MAX_PEAK_MSE,
+	ETHTOOL_A_MSE_CAPABILITIES_REFRESH_RATE_PS,
+	ETHTOOL_A_MSE_CAPABILITIES_NUM_SYMBOLS,
+
+	__ETHTOOL_A_MSE_CAPABILITIES_CNT,
+	ETHTOOL_A_MSE_CAPABILITIES_MAX = (__ETHTOOL_A_MSE_CAPABILITIES_CNT - 1)
+};
+
+enum {
+	ETHTOOL_A_MSE_SNAPSHOT_AVERAGE_MSE = 1,
+	ETHTOOL_A_MSE_SNAPSHOT_PEAK_MSE,
+	ETHTOOL_A_MSE_SNAPSHOT_WORST_PEAK_MSE,
+
+	__ETHTOOL_A_MSE_SNAPSHOT_CNT,
+	ETHTOOL_A_MSE_SNAPSHOT_MAX = (__ETHTOOL_A_MSE_SNAPSHOT_CNT - 1)
+};
+
+enum {
+	ETHTOOL_A_MSE_HEADER = 1,
+	ETHTOOL_A_MSE_CAPABILITIES,
+	ETHTOOL_A_MSE_CHANNEL_A,
+	ETHTOOL_A_MSE_CHANNEL_B,
+	ETHTOOL_A_MSE_CHANNEL_C,
+	ETHTOOL_A_MSE_CHANNEL_D,
+	ETHTOOL_A_MSE_WORST_CHANNEL,
+	ETHTOOL_A_MSE_LINK,
+
+	__ETHTOOL_A_MSE_CNT,
+	ETHTOOL_A_MSE_MAX = (__ETHTOOL_A_MSE_CNT - 1)
+};
+
+enum {
 	ETHTOOL_MSG_USER_NONE = 0,
 	ETHTOOL_MSG_STRSET_GET = 1,
 	ETHTOOL_MSG_LINKINFO_GET,
···
 	ETHTOOL_MSG_RSS_SET,
 	ETHTOOL_MSG_RSS_CREATE_ACT,
 	ETHTOOL_MSG_RSS_DELETE_ACT,
+	ETHTOOL_MSG_MSE_GET,
 
 	__ETHTOOL_MSG_USER_CNT,
 	ETHTOOL_MSG_USER_MAX = (__ETHTOOL_MSG_USER_CNT - 1)
···
 	ETHTOOL_MSG_RSS_CREATE_ACT_REPLY,
 	ETHTOOL_MSG_RSS_CREATE_NTF,
 	ETHTOOL_MSG_RSS_DELETE_NTF,
+	ETHTOOL_MSG_MSE_GET_REPLY,
 
 	__ETHTOOL_MSG_KERNEL_CNT,
 	ETHTOOL_MSG_KERNEL_MAX = (__ETHTOOL_MSG_KERNEL_CNT - 1)

net/ethtool/Makefile

···
 		   channels.o coalesce.o pause.o eee.o tsinfo.o cabletest.o \
 		   tunnels.o fec.o eeprom.o stats.o phc_vclocks.o mm.o \
 		   module.o cmis_fw_update.o cmis_cdb.o pse-pd.o plca.o \
-		   phy.o tsconfig.o
+		   phy.o tsconfig.o mse.o

net/ethtool/mse.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/ethtool.h>
+#include <linux/phy.h>
+#include <linux/slab.h>
+
+#include "netlink.h"
+#include "common.h"
+
+/* Channels A-D only; WORST and LINK are exclusive alternatives */
+#define PHY_MSE_CHANNEL_COUNT 4
+
+struct mse_req_info {
+	struct ethnl_req_info base;
+};
+
+struct mse_snapshot_entry {
+	struct phy_mse_snapshot snapshot;
+	int channel;
+};
+
+struct mse_reply_data {
+	struct ethnl_reply_data base;
+	struct phy_mse_capability capability;
+	struct mse_snapshot_entry *snapshots;
+	unsigned int num_snapshots;
+};
+
+static struct mse_reply_data *
+mse_repdata(const struct ethnl_reply_data *reply_base)
+{
+	return container_of(reply_base, struct mse_reply_data, base);
+}
+
+const struct nla_policy ethnl_mse_get_policy[] = {
+	[ETHTOOL_A_MSE_HEADER] = NLA_POLICY_NESTED(ethnl_header_policy_phy),
+};
+
+static int get_snapshot_if_supported(struct phy_device *phydev,
+				     struct mse_reply_data *data,
+				     unsigned int *idx, u32 cap_bit,
+				     enum phy_mse_channel channel)
+{
+	int ret;
+
+	if (data->capability.supported_caps & cap_bit) {
+		ret = phydev->drv->get_mse_snapshot(phydev, channel,
+					&data->snapshots[*idx].snapshot);
+		if (ret)
+			return ret;
+		data->snapshots[*idx].channel = channel;
+		(*idx)++;
+	}
+
+	return 0;
+}
+
+static int mse_get_channels(struct phy_device *phydev,
+			    struct mse_reply_data *data)
+{
+	unsigned int i = 0;
+	int ret;
+
+	if (!data->capability.supported_caps)
+		return 0;
+
+	data->snapshots = kcalloc(PHY_MSE_CHANNEL_COUNT,
+				  sizeof(*data->snapshots), GFP_KERNEL);
+	if (!data->snapshots)
+		return -ENOMEM;
+
+	/* Priority 1: Individual channels */
+	ret = get_snapshot_if_supported(phydev, data, &i, PHY_MSE_CAP_CHANNEL_A,
+					PHY_MSE_CHANNEL_A);
+	if (ret)
+		return ret;
+	ret = get_snapshot_if_supported(phydev, data, &i, PHY_MSE_CAP_CHANNEL_B,
+					PHY_MSE_CHANNEL_B);
+	if (ret)
+		return ret;
+	ret = get_snapshot_if_supported(phydev, data, &i, PHY_MSE_CAP_CHANNEL_C,
+					PHY_MSE_CHANNEL_C);
+	if (ret)
+		return ret;
+	ret = get_snapshot_if_supported(phydev, data, &i, PHY_MSE_CAP_CHANNEL_D,
+					PHY_MSE_CHANNEL_D);
+	if (ret)
+		return ret;
+
+	/* If any individual channels were found, we are done. */
+	if (i > 0) {
+		data->num_snapshots = i;
+		return 0;
+	}
+
+	/* Priority 2: Worst channel, if no individual channels supported. */
+	ret = get_snapshot_if_supported(phydev, data, &i,
+					PHY_MSE_CAP_WORST_CHANNEL,
+					PHY_MSE_CHANNEL_WORST);
+	if (ret)
+		return ret;
+
+	/* If worst channel was found, we are done. */
+	if (i > 0) {
+		data->num_snapshots = i;
+		return 0;
+	}
+
+	/* Priority 3: Link-wide, if nothing else is supported. */
+	ret = get_snapshot_if_supported(phydev, data, &i, PHY_MSE_CAP_LINK,
+					PHY_MSE_CHANNEL_LINK);
+	if (ret)
+		return ret;
+
+	data->num_snapshots = i;
+	return 0;
+}
+
+static int mse_prepare_data(const struct ethnl_req_info *req_base,
+			    struct ethnl_reply_data *reply_base,
+			    const struct genl_info *info)
+{
+	struct mse_reply_data *data = mse_repdata(reply_base);
+	struct net_device *dev = reply_base->dev;
+	struct phy_device *phydev;
+	int ret;
+
+	phydev = ethnl_req_get_phydev(req_base, info->attrs,
+				      ETHTOOL_A_MSE_HEADER, info->extack);
+	if (IS_ERR(phydev))
+		return PTR_ERR(phydev);
+	if (!phydev)
+		return -EOPNOTSUPP;
+
+	ret = ethnl_ops_begin(dev);
+	if (ret)
+		return ret;
+
+	mutex_lock(&phydev->lock);
+
+	if (!phydev->drv || !phydev->drv->get_mse_capability ||
+	    !phydev->drv->get_mse_snapshot) {
+		ret = -EOPNOTSUPP;
+		goto out_unlock;
+	}
+	if (!phydev->link) {
+		ret = -ENETDOWN;
+		goto out_unlock;
+	}
+
+	ret = phydev->drv->get_mse_capability(phydev, &data->capability);
+	if (ret)
+		goto out_unlock;
+
+	ret = mse_get_channels(phydev, data);
+
+out_unlock:
+	mutex_unlock(&phydev->lock);
+	ethnl_ops_complete(dev);
+	if (ret)
+		kfree(data->snapshots);
+	return ret;
+}
+
+static void mse_cleanup_data(struct ethnl_reply_data *reply_base)
+{
+	struct mse_reply_data *data = mse_repdata(reply_base);
+
+	kfree(data->snapshots);
+}
+
+static int mse_reply_size(const struct ethnl_req_info *req_base,
+			  const struct ethnl_reply_data *reply_base)
+{
+	const struct mse_reply_data *data = mse_repdata(reply_base);
+	size_t len = 0;
+	unsigned int i;
+
+	/* ETHTOOL_A_MSE_CAPABILITIES */
+	len += nla_total_size(0);
+	if (data->capability.supported_caps & PHY_MSE_CAP_AVG)
+		/* ETHTOOL_A_MSE_CAPABILITIES_MAX_AVERAGE_MSE */
+		len += nla_total_size(sizeof(u64));
+	if (data->capability.supported_caps & (PHY_MSE_CAP_PEAK |
+					       PHY_MSE_CAP_WORST_PEAK))
+		/* ETHTOOL_A_MSE_CAPABILITIES_MAX_PEAK_MSE */
+		len += nla_total_size(sizeof(u64));
+	/* ETHTOOL_A_MSE_CAPABILITIES_REFRESH_RATE_PS */
+	len += nla_total_size(sizeof(u64));
+	/* ETHTOOL_A_MSE_CAPABILITIES_NUM_SYMBOLS */
+	len += nla_total_size(sizeof(u64));
+
+	for (i = 0; i < data->num_snapshots; i++) {
+		size_t snapshot_len = 0;
+
+		/* Per-channel nest (e.g., ETHTOOL_A_MSE_CHANNEL_A / _B / _C /
+		 * _D / _WORST_CHANNEL / _LINK)
+		 */
+		snapshot_len += nla_total_size(0);
+
+		if (data->capability.supported_caps & PHY_MSE_CAP_AVG)
+			snapshot_len += nla_total_size(sizeof(u64));
+		if (data->capability.supported_caps & PHY_MSE_CAP_PEAK)
+			snapshot_len += nla_total_size(sizeof(u64));
+		if (data->capability.supported_caps & PHY_MSE_CAP_WORST_PEAK)
+			snapshot_len += nla_total_size(sizeof(u64));
+
+		len += snapshot_len;
+	}
+
+	return len;
+}
+
+static int mse_channel_to_attr(int ch)
+{
+	switch (ch) {
+	case PHY_MSE_CHANNEL_A:
+		return ETHTOOL_A_MSE_CHANNEL_A;
+	case PHY_MSE_CHANNEL_B:
+		return ETHTOOL_A_MSE_CHANNEL_B;
+	case PHY_MSE_CHANNEL_C:
+		return ETHTOOL_A_MSE_CHANNEL_C;
+	case PHY_MSE_CHANNEL_D:
+		return ETHTOOL_A_MSE_CHANNEL_D;
+	case PHY_MSE_CHANNEL_WORST:
+		return ETHTOOL_A_MSE_WORST_CHANNEL;
+	case PHY_MSE_CHANNEL_LINK:
+		return ETHTOOL_A_MSE_LINK;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mse_fill_reply(struct sk_buff *skb,
+			  const struct ethnl_req_info *req_base,
+			  const struct ethnl_reply_data *reply_base)
+{
+	const struct mse_reply_data *data = mse_repdata(reply_base);
+	struct nlattr *nest;
+	unsigned int i;
+	int ret;
+
+	nest = nla_nest_start(skb, ETHTOOL_A_MSE_CAPABILITIES);
+	if (!nest)
+		return -EMSGSIZE;
+
+	if (data->capability.supported_caps & PHY_MSE_CAP_AVG) {
+		ret = nla_put_uint(skb,
+				   ETHTOOL_A_MSE_CAPABILITIES_MAX_AVERAGE_MSE,
+				   data->capability.max_average_mse);
+		if (ret < 0)
+			goto nla_put_nest_failure;
+	}
+
+	if (data->capability.supported_caps & (PHY_MSE_CAP_PEAK |
+					       PHY_MSE_CAP_WORST_PEAK)) {
+		ret = nla_put_uint(skb, ETHTOOL_A_MSE_CAPABILITIES_MAX_PEAK_MSE,
+				   data->capability.max_peak_mse);
+		if (ret < 0)
+			goto nla_put_nest_failure;
+	}
+
+	ret = nla_put_uint(skb, ETHTOOL_A_MSE_CAPABILITIES_REFRESH_RATE_PS,
+			   data->capability.refresh_rate_ps);
+	if (ret < 0)
+		goto nla_put_nest_failure;
+
+	ret = nla_put_uint(skb, ETHTOOL_A_MSE_CAPABILITIES_NUM_SYMBOLS,
+			   data->capability.num_symbols);
+	if (ret < 0)
+		goto nla_put_nest_failure;
+
+	nla_nest_end(skb, nest);
+
+	for (i = 0; i < data->num_snapshots; i++) {
+		const struct mse_snapshot_entry *s = &data->snapshots[i];
+		int chan_attr;
+
+		chan_attr = mse_channel_to_attr(s->channel);
+		if (chan_attr < 0)
+			return chan_attr;
+
+		nest = nla_nest_start(skb, chan_attr);
+		if (!nest)
+			return -EMSGSIZE;
+
+		if (data->capability.supported_caps & PHY_MSE_CAP_AVG) {
+			ret = nla_put_uint(skb,
+					   ETHTOOL_A_MSE_SNAPSHOT_AVERAGE_MSE,
+					   s->snapshot.average_mse);
+			if (ret)
+				goto nla_put_nest_failure;
+		}
+		if (data->capability.supported_caps & PHY_MSE_CAP_PEAK) {
+			ret = nla_put_uint(skb, ETHTOOL_A_MSE_SNAPSHOT_PEAK_MSE,
+					   s->snapshot.peak_mse);
+			if (ret)
+				goto nla_put_nest_failure;
+		}
+		if (data->capability.supported_caps & PHY_MSE_CAP_WORST_PEAK) {
+			ret = nla_put_uint(skb,
+					   ETHTOOL_A_MSE_SNAPSHOT_WORST_PEAK_MSE,
+					   s->snapshot.worst_peak_mse);
+			if (ret)
+				goto nla_put_nest_failure;
+		}
+
+		nla_nest_end(skb, nest);
+	}
+
+	return 0;
+
+nla_put_nest_failure:
+	nla_nest_cancel(skb, nest);
+	return ret;
+}
+
+const struct ethnl_request_ops ethnl_mse_request_ops = {
+	.request_cmd = ETHTOOL_MSG_MSE_GET,
+	.reply_cmd = ETHTOOL_MSG_MSE_GET_REPLY,
+	.hdr_attr = ETHTOOL_A_MSE_HEADER,
+	.req_info_size = sizeof(struct mse_req_info),
+	.reply_data_size = sizeof(struct mse_reply_data),
+
+	.prepare_data = mse_prepare_data,
+	.cleanup_data = mse_cleanup_data,
+	.reply_size = mse_reply_size,
+	.fill_reply = mse_fill_reply,
+};

net/ethtool/netlink.c

···
 	[ETHTOOL_MSG_TSCONFIG_GET]	= &ethnl_tsconfig_request_ops,
 	[ETHTOOL_MSG_TSCONFIG_SET]	= &ethnl_tsconfig_request_ops,
 	[ETHTOOL_MSG_PHY_GET]		= &ethnl_phy_request_ops,
+	[ETHTOOL_MSG_MSE_GET]		= &ethnl_mse_request_ops,
 };
 
 static struct ethnl_dump_ctx *ethnl_dump_context(struct netlink_callback *cb)
···
 		.doit	= ethnl_rss_delete_doit,
 		.policy	= ethnl_rss_delete_policy,
 		.maxattr = ARRAY_SIZE(ethnl_rss_delete_policy) - 1,
+	},
+	{
+		.cmd	= ETHTOOL_MSG_MSE_GET,
+		.doit	= ethnl_default_doit,
+		.start	= ethnl_perphy_start,
+		.dumpit	= ethnl_perphy_dumpit,
+		.done	= ethnl_perphy_done,
+		.policy = ethnl_mse_get_policy,
+		.maxattr = ARRAY_SIZE(ethnl_mse_get_policy) - 1,
 	},
 };
 

net/ethtool/netlink.h

···
 extern const struct ethnl_request_ops ethnl_mm_request_ops;
 extern const struct ethnl_request_ops ethnl_phy_request_ops;
 extern const struct ethnl_request_ops ethnl_tsconfig_request_ops;
+extern const struct ethnl_request_ops ethnl_mse_request_ops;
 
 extern const struct nla_policy ethnl_header_policy[ETHTOOL_A_HEADER_FLAGS + 1];
 extern const struct nla_policy ethnl_header_policy_stats[ETHTOOL_A_HEADER_FLAGS + 1];
···
 extern const struct nla_policy ethnl_phy_get_policy[ETHTOOL_A_PHY_HEADER + 1];
 extern const struct nla_policy ethnl_tsconfig_get_policy[ETHTOOL_A_TSCONFIG_HEADER + 1];
 extern const struct nla_policy ethnl_tsconfig_set_policy[ETHTOOL_A_TSCONFIG_MAX + 1];
+extern const struct nla_policy ethnl_mse_get_policy[ETHTOOL_A_MSE_HEADER + 1];
 
 int ethnl_set_features(struct sk_buff *skb, struct genl_info *info);
 int ethnl_act_cable_test(struct sk_buff *skb, struct genl_info *info);