[next-queue,RFC,2/4] ethtool: Add support for configuring frame preemption via netlink

diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
index 2881af4..21afba1 100644
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -40,6 +40,8 @@  enum {
 	ETHTOOL_MSG_EEE_SET,
 	ETHTOOL_MSG_TSINFO_GET,
 	ETHTOOL_MSG_CABLE_TEST_ACT,
+	ETHTOOL_MSG_PREEMPT_GET,
+	ETHTOOL_MSG_PREEMPT_SET,
 
 	/* add new constants above here */
 	__ETHTOOL_MSG_USER_CNT,
@@ -76,6 +78,8 @@  enum {
 	ETHTOOL_MSG_EEE_NTF,
 	ETHTOOL_MSG_TSINFO_GET_REPLY,
 	ETHTOOL_MSG_CABLE_TEST_NTF,
+	ETHTOOL_MSG_PREEMPT_GET_REPLY,
+	ETHTOOL_MSG_PREEMPT_NTF,
 
 	/* add new constants above here */
 	__ETHTOOL_MSG_KERNEL_CNT,
@@ -476,6 +480,21 @@  enum {
 	ETHTOOL_A_CABLE_TEST_NTF_MAX = (__ETHTOOL_A_CABLE_TEST_NTF_CNT - 1)
 };
 
+/* FRAME PREEMPTION */
+enum {
+	ETHTOOL_A_PREEMPT_UNSPEC,
+	ETHTOOL_A_PREEMPT_HEADER,			/* nest - _A_HEADER_* */
+	ETHTOOL_A_PREEMPT_SUPPORTED,			/* u8 */
+	ETHTOOL_A_PREEMPT_ACTIVE,			/* u8 */
+	ETHTOOL_A_PREEMPT_MIN_FRAG_SIZE,		/* u32 */
+	ETHTOOL_A_PREEMPT_QUEUES_SUPPORTED,		/* u32 */
+	ETHTOOL_A_PREEMPT_QUEUES_PREEMPTIBLE,		/* u32 */
+
+	/* add new constants above here */
+	__ETHTOOL_A_PREEMPT_CNT,
+	ETHTOOL_A_PREEMPT_MAX = (__ETHTOOL_A_PREEMPT_CNT - 1)
+};
+
 /* generic netlink info */
 #define ETHTOOL_GENL_NAME "ethtool"
 #define ETHTOOL_GENL_VERSION 1
diff --git a/net/ethtool/Makefile b/net/ethtool/Makefile
index 0c2b94f..11661d1 100644
--- a/net/ethtool/Makefile
+++ b/net/ethtool/Makefile
@@ -6,4 +6,5 @@  obj-$(CONFIG_ETHTOOL_NETLINK)	+= ethtool_nl.o
 
 ethtool_nl-y	:= netlink.o bitset.o strset.o linkinfo.o linkmodes.o \
 		   linkstate.o debug.o wol.o features.o privflags.o rings.o \
-		   channels.o coalesce.o pause.o eee.o tsinfo.o cabletest.o
+		   channels.o coalesce.o pause.o eee.o tsinfo.o cabletest.o \
+		   preempt.o
diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index 87bc02d..308653f 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -231,6 +231,7 @@  ethnl_default_requests[__ETHTOOL_MSG_USER_CNT] = {
 	[ETHTOOL_MSG_PAUSE_GET]		= &ethnl_pause_request_ops,
 	[ETHTOOL_MSG_EEE_GET]		= &ethnl_eee_request_ops,
 	[ETHTOOL_MSG_TSINFO_GET]	= &ethnl_tsinfo_request_ops,
+	[ETHTOOL_MSG_PREEMPT_GET]	= &ethnl_preempt_request_ops,
 };
 
 static struct ethnl_dump_ctx *ethnl_dump_context(struct netlink_callback *cb)
@@ -550,6 +551,7 @@  ethnl_default_notify_ops[ETHTOOL_MSG_KERNEL_MAX + 1] = {
 	[ETHTOOL_MSG_COALESCE_NTF]	= &ethnl_coalesce_request_ops,
 	[ETHTOOL_MSG_PAUSE_NTF]		= &ethnl_pause_request_ops,
 	[ETHTOOL_MSG_EEE_NTF]		= &ethnl_eee_request_ops,
+	[ETHTOOL_MSG_PREEMPT_NTF]	= &ethnl_preempt_request_ops,
 };
 
 /* default notification handler */
@@ -642,6 +644,7 @@  static const ethnl_notify_handler_t ethnl_notify_handlers[] = {
 	[ETHTOOL_MSG_COALESCE_NTF]	= ethnl_default_notify,
 	[ETHTOOL_MSG_PAUSE_NTF]		= ethnl_default_notify,
 	[ETHTOOL_MSG_EEE_NTF]		= ethnl_default_notify,
+	[ETHTOOL_MSG_PREEMPT_NTF]	= ethnl_default_notify,
 };
 
 void ethtool_notify(struct net_device *dev, unsigned int cmd, const void *data)
@@ -844,6 +847,18 @@  static const struct genl_ops ethtool_genl_ops[] = {
 		.flags	= GENL_UNS_ADMIN_PERM,
 		.doit	= ethnl_act_cable_test,
 	},
+	{
+		.cmd	= ETHTOOL_MSG_PREEMPT_GET,
+		.doit	= ethnl_default_doit,
+		.start	= ethnl_default_start,
+		.dumpit	= ethnl_default_dumpit,
+		.done	= ethnl_default_done,
+	},
+	{
+		.cmd	= ETHTOOL_MSG_PREEMPT_SET,
+		.flags	= GENL_UNS_ADMIN_PERM,
+		.doit	= ethnl_set_preempt,
+	},
 };
 
 static const struct genl_multicast_group ethtool_nl_mcgrps[] = {
diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
index b0eb5d9..d22dac6 100644
--- a/net/ethtool/netlink.h
+++ b/net/ethtool/netlink.h
@@ -347,6 +347,7 @@  extern const struct ethnl_request_ops ethnl_coalesce_request_ops;
 extern const struct ethnl_request_ops ethnl_pause_request_ops;
 extern const struct ethnl_request_ops ethnl_eee_request_ops;
 extern const struct ethnl_request_ops ethnl_tsinfo_request_ops;
+extern const struct ethnl_request_ops ethnl_preempt_request_ops;
 
 int ethnl_set_linkinfo(struct sk_buff *skb, struct genl_info *info);
 int ethnl_set_linkmodes(struct sk_buff *skb, struct genl_info *info);
@@ -360,5 +361,6 @@  int ethnl_set_coalesce(struct sk_buff *skb, struct genl_info *info);
 int ethnl_set_pause(struct sk_buff *skb, struct genl_info *info);
 int ethnl_set_eee(struct sk_buff *skb, struct genl_info *info);
 int ethnl_act_cable_test(struct sk_buff *skb, struct genl_info *info);
+int ethnl_set_preempt(struct sk_buff *skb, struct genl_info *info);
 
 #endif /* _NET_ETHTOOL_NETLINK_H */
diff --git a/net/ethtool/preempt.c b/net/ethtool/preempt.c
new file mode 100644
index 0000000..9c8df6f
--- /dev/null
+++ b/net/ethtool/preempt.c
@@ -0,0 +1,181 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "netlink.h"
+#include "common.h"
+
+struct preempt_req_info {
+	struct ethnl_req_info		base;
+};
+
+struct preempt_reply_data {
+	struct ethnl_reply_data		base;
+	struct ethtool_fp		fp;
+};
+
+#define PREEMPT_REPDATA(__reply_base) \
+	container_of(__reply_base, struct preempt_reply_data, base)
+
+static const struct nla_policy
+preempt_get_policy[ETHTOOL_A_PREEMPT_MAX + 1] = {
+	[ETHTOOL_A_PREEMPT_UNSPEC]		= { .type = NLA_REJECT },
+	[ETHTOOL_A_PREEMPT_HEADER]		= { .type = NLA_NESTED },
+	[ETHTOOL_A_PREEMPT_SUPPORTED]		= { .type = NLA_REJECT },
+	[ETHTOOL_A_PREEMPT_ACTIVE]		= { .type = NLA_REJECT },
+	[ETHTOOL_A_PREEMPT_MIN_FRAG_SIZE]	= { .type = NLA_REJECT },
+	[ETHTOOL_A_PREEMPT_QUEUES_SUPPORTED]	= { .type = NLA_REJECT },
+	[ETHTOOL_A_PREEMPT_QUEUES_PREEMPTIBLE]	= { .type = NLA_REJECT },
+};
+
+static int preempt_prepare_data(const struct ethnl_req_info *req_base,
+				struct ethnl_reply_data *reply_base,
+				struct genl_info *info)
+{
+	struct preempt_reply_data *data = PREEMPT_REPDATA(reply_base);
+	struct net_device *dev = reply_base->dev;
+	int ret;
+
+	if (!dev->ethtool_ops->get_preempt)
+		return -EOPNOTSUPP;
+
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		return ret;
+
+	ret = dev->ethtool_ops->get_preempt(dev, &data->fp);
+	ethnl_ops_complete(dev);
+
+	return ret;
+}
+
+static int preempt_reply_size(const struct ethnl_req_info *req_base,
+			      const struct ethnl_reply_data *reply_base)
+{
+	int len = 0;
+
+	len += nla_total_size(sizeof(u8)); /* _PREEMPT_SUPPORTED */
+	len += nla_total_size(sizeof(u8)); /* _PREEMPT_ACTIVE */
+	len += nla_total_size(sizeof(u32)); /* _PREEMPT_QUEUES_SUPPORTED */
+	len += nla_total_size(sizeof(u32)); /* _PREEMPT_QUEUES_PREEMPTIBLE */
+	len += nla_total_size(sizeof(u32)); /* _PREEMPT_MIN_FRAG_SIZE */
+
+	return len;
+}
+
+static int preempt_fill_reply(struct sk_buff *skb,
+			      const struct ethnl_req_info *req_base,
+			      const struct ethnl_reply_data *reply_base)
+{
+	const struct preempt_reply_data *data = PREEMPT_REPDATA(reply_base);
+	const struct ethtool_fp *preempt = &data->fp;
+
+	if (nla_put_u32(skb, ETHTOOL_A_PREEMPT_QUEUES_SUPPORTED,
+			  preempt->supported_queues_mask))
+		return -EMSGSIZE;
+
+	if (nla_put_u32(skb, ETHTOOL_A_PREEMPT_QUEUES_PREEMPTIBLE,
+			  preempt->preemptible_queues_mask))
+		return -EMSGSIZE;
+
+	if (nla_put_u8(skb, ETHTOOL_A_PREEMPT_ACTIVE, preempt->fp_enabled))
+		return -EMSGSIZE;
+
+	if (nla_put_u8(skb, ETHTOOL_A_PREEMPT_SUPPORTED,
+		       preempt->fp_supported))
+		return -EMSGSIZE;
+
+	if (nla_put_u32(skb, ETHTOOL_A_PREEMPT_MIN_FRAG_SIZE,
+			preempt->min_frag_size))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+const struct ethnl_request_ops ethnl_preempt_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_PREEMPT_GET,
+	.reply_cmd		= ETHTOOL_MSG_PREEMPT_GET_REPLY,
+	.hdr_attr		= ETHTOOL_A_PREEMPT_HEADER,
+	.max_attr		= ETHTOOL_A_PREEMPT_MAX,
+	.req_info_size		= sizeof(struct preempt_req_info),
+	.reply_data_size	= sizeof(struct preempt_reply_data),
+	.request_policy		= preempt_get_policy,
+
+	.prepare_data		= preempt_prepare_data,
+	.reply_size		= preempt_reply_size,
+	.fill_reply		= preempt_fill_reply,
+};
+
+static const struct nla_policy
+preempt_set_policy[ETHTOOL_A_PREEMPT_MAX + 1] = {
+	[ETHTOOL_A_PREEMPT_UNSPEC]			= { .type = NLA_REJECT },
+	[ETHTOOL_A_PREEMPT_HEADER]			= { .type = NLA_NESTED },
+	[ETHTOOL_A_PREEMPT_SUPPORTED]			= { .type = NLA_REJECT },
+	[ETHTOOL_A_PREEMPT_ACTIVE]			= { .type = NLA_U8 },
+	[ETHTOOL_A_PREEMPT_MIN_FRAG_SIZE]		= { .type = NLA_U32 },
+	[ETHTOOL_A_PREEMPT_QUEUES_SUPPORTED]		= { .type = NLA_REJECT },
+	[ETHTOOL_A_PREEMPT_QUEUES_PREEMPTIBLE]		= { .type = NLA_U32 },
+};
+
+int ethnl_set_preempt(struct sk_buff *skb, struct genl_info *info)
+{
+	struct nlattr *tb[ETHTOOL_A_LINKINFO_MAX + 1];
+	struct ethtool_fp preempt = {};
+	struct ethnl_req_info req_info = {};
+	struct net_device *dev;
+	bool mod = false;
+	int ret;
+
+	ret = nlmsg_parse(info->nlhdr, GENL_HDRLEN, tb,
+			  ETHTOOL_A_PREEMPT_MAX, preempt_set_policy,
+			  info->extack);
+	if (ret < 0)
+		return ret;
+
+	ret = ethnl_parse_header_dev_get(&req_info,
+					 tb[ETHTOOL_A_PREEMPT_HEADER],
+					 genl_info_net(info), info->extack,
+					 true);
+	if (ret < 0)
+		return ret;
+	dev = req_info.dev;
+	ret = -EOPNOTSUPP;
+	if (!dev->ethtool_ops->get_preempt ||
+	    !dev->ethtool_ops->set_preempt)
+		goto out_dev;
+
+	rtnl_lock();
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		goto out_rtnl;
+
+	ret = dev->ethtool_ops->get_preempt(dev, &preempt);
+	if (ret < 0) {
+		if (info)
+			GENL_SET_ERR_MSG(info, "failed to retrieve frame preemption settings");
+		goto out_ops;
+	}
+
+	ethnl_update_u8(&preempt.fp_enabled,
+			tb[ETHTOOL_A_PREEMPT_ACTIVE], &mod);
+	ethnl_update_u32(&preempt.min_frag_size,
+			 tb[ETHTOOL_A_PREEMPT_MIN_FRAG_SIZE], &mod);
+	ethnl_update_u32(&preempt.preemptible_queues_mask,
+			 tb[ETHTOOL_A_PREEMPT_QUEUES_PREEMPTIBLE], &mod);
+
+	ret = 0;
+	if (!mod)
+		goto out_ops;
+
+	ret = dev->ethtool_ops->set_preempt(dev, &preempt);
+	if (ret < 0)
+		GENL_SET_ERR_MSG(info, "frame preemption settings update failed");
+	else
+		ethtool_notify(dev, ETHTOOL_MSG_PREEMPT_NTF, NULL);
+
+out_ops:
+	ethnl_ops_complete(dev);
+out_rtnl:
+	rtnl_unlock();
+out_dev:
+	dev_put(dev);
+	return ret;
+}