[RFC net-next 3/4] devlink: Add runtime parameter boot defaults

[Mark Bloch <mbloch@nvidia.com>]

Add support for setting devlink device parameters from the devlink=
kernel command line parameter.

The supported syntax is:

  devlink=[<handle>]:param:<name>:<value>

Parameter values are parsed according to the registered devlink
parameter type and are applied in runtime configuration mode. Driverinit
and permanent configuration modes are intentionally not part of the
boot-default syntax.

Add a helper that finds a parameter by name, verifies runtime mode
support, converts the string value, runs the parameter validator and
invokes the existing set callback.

Signed-off-by: Mark Bloch <mbloch@nvidia.com>
---
 .../admin-guide/kernel-parameters.txt         |   2 +
 .../networking/devlink/devlink-defaults.rst   |  18 ++-
 net/devlink/core.c                            | 110 ++++++++++++------
 net/devlink/devl_internal.h                   |   3 +
 net/devlink/param.c                           |  70 +++++++++++
 5 files changed, 165 insertions(+), 38 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 150202882870..761ae45b8607 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1293,9 +1293,11 @@ Kernel parameters
 
 			Currently supported settings:
 			esw:mode:{ legacy | switchdev | switchdev_inactive }
+			param:<name>:<value>
 
 			Examples:
 			devlink=[pci/0000:08:00.0]:esw:mode:switchdev
+			devlink=[pci/0000:08:00.0]:param:flow_steering_mode:smfs
 			devlink=[pci/0000:08:00.0,pci/0000:08:00.1]:esw:mode:legacy
 			devlink=[pci/0000:08:00.0]:esw:mode:switchdev,[pci/0000:08:00.1]:esw:mode:switchdev_inactive
 
diff --git a/Documentation/networking/devlink/devlink-defaults.rst b/Documentation/networking/devlink/devlink-defaults.rst
index 7d6ccaddca86..0d4036e59e88 100644
--- a/Documentation/networking/devlink/devlink-defaults.rst
+++ b/Documentation/networking/devlink/devlink-defaults.rst
@@ -55,13 +55,16 @@ The following syntax rules apply:
 * Defaults for the same handle are applied in command-line order.
 * The same ``esw`` attribute may be specified only once for a given devlink
   handle.
+* The same ``param`` name may be specified only once for a given devlink
+  handle.
 * Duplicate entries for the same handle are rejected and all devlink defaults
   are ignored.
+* Parameter names and values must not contain ``:`` or ``,``.
 
 Supported defaults
 ==================
 
-The supported command is ``esw``:
+The supported commands are ``esw`` and ``param``:
 
 .. list-table::
    :widths: 10 25 35
@@ -73,11 +76,16 @@ The supported command is ``esw``:
    * - ``esw``
      - ``mode:<mode>``
      - ``legacy``, ``switchdev``, ``switchdev_inactive``
+   * - ``param``
+     - ``<name>:<value>``
+     - ``<value>`` is parsed according to the registered devlink parameter
+       type. Only runtime devlink parameters are supported.
 
 The ``esw:mode`` default corresponds to the userspace command::
 
   devlink dev eswitch set <handle> mode <value>
 
+The ``param`` default applies the named devlink parameter in runtime mode.
 
 Examples
 ========
@@ -90,6 +98,10 @@ Set two PCI devlink instances to legacy mode::
 
   devlink=[pci/0000:08:00.0,pci/0000:08:00.1]:esw:mode:legacy
 
+Set a runtime devlink device parameter::
+
+  devlink=[pci/0000:08:00.0]:param:flow_steering_mode:smfs
+
 Set different modes for different PCI devlink instances::
 
   devlink=[pci/0000:08:00.0]:esw:mode:switchdev,[pci/0000:08:00.1]:esw:mode:switchdev_inactive
@@ -97,3 +109,7 @@ Set different modes for different PCI devlink instances::
 The following is invalid because the same handle receives ``esw:mode`` twice::
 
   devlink=[pci/0000:08:00.0]:esw:mode:legacy,[pci/0000:08:00.0]:esw:mode:switchdev
+
+The following is invalid because the same handle receives ``param:x`` twice::
+
+  devlink=[pci/0]:param:x:1,[pci/0]:param:x:2
diff --git a/net/devlink/core.c b/net/devlink/core.c
index 4b404135181c..22990793ab8c 100644
--- a/net/devlink/core.c
+++ b/net/devlink/core.c
@@ -50,6 +50,13 @@ struct devlink_default_node {
 	struct list_head cmd_list;
 };
 
+struct devlink_default_attr_spec {
+	const char *name;
+	enum devlink_attr attr;
+	int (*value_parse)(const char *value,
+			   struct devlink_default_attr_item *attr_item);
+};
+
 struct devlink_default_cmd_spec {
 	const char *name;
 	enum devlink_command cmd;
@@ -73,13 +80,6 @@ devlink_default_attr_free(struct devlink_default_attr_item *attr)
 	kfree(attr->value.param.value);
 }
 
-struct devlink_default_attr_spec {
-	const char *name;
-	enum devlink_attr attr;
-	int (*value_parse)(const char *value,
-			   struct devlink_default_attr_item *attr_item);
-};
-
 static int __init
 devlink_default_attr_parse(char *str,
 			   const struct devlink_default_attr_spec *attrs,
@@ -153,6 +153,33 @@ devlink_default_esw_attr_parse(char *str,
 					  attr_item);
 }
 
+static int __init
+devlink_default_param_attr_parse(char *str,
+				 struct devlink_default_attr_item *attr_item)
+{
+	char *name;
+	char *value;
+
+	attr_item->attr = DEVLINK_ATTR_PARAM;
+
+	name = strsep(&str, ":");
+	value = strsep(&str, ":");
+	if (!name || !*name || !value || !*value || str)
+		return -EINVAL;
+
+	attr_item->value.param.name = kstrdup(name, GFP_KERNEL);
+	if (!attr_item->value.param.name)
+		return -ENOMEM;
+	attr_item->value.param.value = kstrdup(value, GFP_KERNEL);
+	if (!attr_item->value.param.value) {
+		kfree(attr_item->value.param.name);
+		attr_item->value.param.name = NULL;
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
 static int
 devlink_default_eswitch_apply(struct devlink *devlink,
 			      const struct devlink_default_attr_item *attr)
@@ -171,6 +198,17 @@ devlink_default_eswitch_apply(struct devlink *devlink,
 	}
 }
 
+static int
+devlink_default_param_apply(struct devlink *devlink,
+			    const struct devlink_default_attr_item *attr)
+{
+	if (attr->attr != DEVLINK_ATTR_PARAM)
+		return -EOPNOTSUPP;
+
+	return devlink_param_set_from_string(devlink, attr->value.param.name,
+					     attr->value.param.value);
+}
+
 static const struct devlink_default_cmd_spec devlink_default_cmds[] __initconst = {
 	{
 		.name = "esw",
@@ -178,52 +216,46 @@ static const struct devlink_default_cmd_spec devlink_default_cmds[] __initconst
 		.run = devlink_default_eswitch_apply,
 		.attr_parse = devlink_default_esw_attr_parse,
 	},
+	{
+		.name = "param",
+		.cmd = DEVLINK_CMD_PARAM_SET,
+		.run = devlink_default_param_apply,
+		.attr_parse = devlink_default_param_attr_parse,
+	},
 };
 
-static const struct devlink_default_cmd_spec *__init
-devlink_default_cmd_spec_find(const char *name)
-{
-	size_t i;
-
-	for (i = 0; i < ARRAY_SIZE(devlink_default_cmds); i++) {
-		if (!strcmp(name, devlink_default_cmds[i].name))
-			return &devlink_default_cmds[i];
-	}
-
-	return NULL;
-}
-
 static int __init
 devlink_default_cmd_parse(char *str,
 			  struct devlink_default_cmd_item *cmd_item)
 {
-	const struct devlink_default_cmd_spec *spec;
 	struct devlink_default_attr_item attr_item = {};
 	char *cmd_name;
 	int err;
+	size_t i;
 
 	cmd_name = strsep(&str, ":");
 	if (!cmd_name || !*cmd_name || !str || !*str)
 		return -EINVAL;
 
-	spec = devlink_default_cmd_spec_find(cmd_name);
-	if (!spec)
-		return -EINVAL;
-
-	err = spec->attr_parse(str, &attr_item);
-	if (err) {
-		devlink_default_attr_free(&attr_item);
-		return err;
-	}
-	if (cmd_item) {
-		cmd_item->cmd = spec->cmd;
-		cmd_item->run = spec->run;
-		cmd_item->attr = attr_item;
-	} else {
-		devlink_default_attr_free(&attr_item);
+	for (i = 0; i < ARRAY_SIZE(devlink_default_cmds); i++) {
+		if (!strcmp(cmd_name, devlink_default_cmds[i].name)) {
+			err = devlink_default_cmds[i].attr_parse(str, &attr_item);
+			if (err) {
+				devlink_default_attr_free(&attr_item);
+				return err;
+			}
+			if (cmd_item) {
+				cmd_item->cmd = devlink_default_cmds[i].cmd;
+				cmd_item->run = devlink_default_cmds[i].run;
+				cmd_item->attr = attr_item;
+			} else {
+				devlink_default_attr_free(&attr_item);
+			}
+			return 0;
+		}
 	}
 
-	return 0;
+	return -EINVAL;
 }
 
 static int __init
@@ -369,6 +401,10 @@ devlink_default_cmd_equal(const struct devlink_default_cmd_item *a,
 	if (a->cmd != b->cmd || a->attr.attr != b->attr.attr)
 		return false;
 
+	if (a->cmd == DEVLINK_CMD_PARAM_SET)
+		return !strcmp(a->attr.value.param.name,
+			       b->attr.value.param.name);
+
 	return true;
 }
 
diff --git a/net/devlink/devl_internal.h b/net/devlink/devl_internal.h
index e4e48ee2da5a..bde333c22f18 100644
--- a/net/devlink/devl_internal.h
+++ b/net/devlink/devl_internal.h
@@ -212,6 +212,9 @@ static inline int devlink_nl_put_u64(struct sk_buff *msg, int attrtype, u64 val)
 int devlink_nl_put_nested_handle(struct sk_buff *msg, struct net *net,
 				 struct devlink *devlink, int attrtype);
 int devlink_nl_msg_reply_and_new(struct sk_buff **msg, struct genl_info *info);
+int devlink_param_set_from_string(struct devlink *devlink,
+				  const char *param_name,
+				  const char *value_str);
 
 static inline bool devlink_nl_notify_need(struct devlink *devlink)
 {
diff --git a/net/devlink/param.c b/net/devlink/param.c
index cf95268da5b0..d2604fe2eee5 100644
--- a/net/devlink/param.c
+++ b/net/devlink/param.c
@@ -4,6 +4,8 @@
  * Copyright (c) 2016 Jiri Pirko <jiri@mellanox.com>
  */
 
+#include <linux/kstrtox.h>
+
 #include "devl_internal.h"
 
 static const struct devlink_param devlink_param_generic[] = {
@@ -551,6 +553,74 @@ devlink_param_value_get_from_info(const struct devlink_param *param,
 	return 0;
 }
 
+static int
+devlink_param_value_get_from_str(const struct devlink_param *param,
+				 const char *value_str,
+				 union devlink_param_value *value)
+{
+	switch (param->type) {
+	case DEVLINK_PARAM_TYPE_U8:
+		return kstrtou8(value_str, 0, &value->vu8);
+	case DEVLINK_PARAM_TYPE_U16:
+		return kstrtou16(value_str, 0, &value->vu16);
+	case DEVLINK_PARAM_TYPE_U32:
+		return kstrtou32(value_str, 0, &value->vu32);
+	case DEVLINK_PARAM_TYPE_U64:
+		return kstrtou64(value_str, 0, &value->vu64);
+	case DEVLINK_PARAM_TYPE_STRING:
+		if (strscpy(value->vstr, value_str, sizeof(value->vstr)) < 0)
+			return -EINVAL;
+		return 0;
+	case DEVLINK_PARAM_TYPE_BOOL:
+		return kstrtobool(value_str, &value->vbool);
+	}
+
+	return -EINVAL;
+}
+
+int devlink_param_set_from_string(struct devlink *devlink,
+				  const char *param_name,
+				  const char *value_str)
+{
+	struct devlink_param_gset_ctx ctx;
+	struct devlink_param_item *param_item;
+	const struct devlink_param *param;
+	union devlink_param_value value;
+	int err;
+
+	devl_assert_locked(devlink);
+
+	param_item = devlink_param_find_by_name(&devlink->params, param_name);
+	if (!param_item)
+		return -EINVAL;
+	param = param_item->param;
+
+	if (!devlink_param_cmode_is_supported(param,
+					      DEVLINK_PARAM_CMODE_RUNTIME))
+		return -EOPNOTSUPP;
+	if (!param->set)
+		return -EOPNOTSUPP;
+
+	err = devlink_param_value_get_from_str(param, value_str, &value);
+	if (err)
+		return err;
+
+	if (param->validate) {
+		err = param->validate(devlink, param->id, value, NULL);
+		if (err)
+			return err;
+	}
+
+	ctx.val = value;
+	ctx.cmode = DEVLINK_PARAM_CMODE_RUNTIME;
+	err = devlink_param_set(devlink, param, &ctx, NULL);
+	if (err)
+		return err;
+
+	devlink_param_notify(devlink, 0, param_item, DEVLINK_CMD_PARAM_NEW);
+	return 0;
+}
+
 static struct devlink_param_item *
 devlink_param_get_from_info(struct xarray *params, struct genl_info *info)
 {
-- 
2.34.1