netlink: spec: add shaper introspection support

Allow the user-space to fine-grain query the shaping features
supported by the NIC on each domain.

Reviewed-by: Jiri Pirko <[e-mail]>
Reviewed-by: Jakub Kicinski <[e-mail]>
Signed-off-by: Paolo Abeni <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/netlink/specs/net_shaper.yaml

···
 
   The user can query the running configuration via the @get operation.
 
+  Different devices can provide different feature sets, e.g. with no
+  support for complex scheduling hierarchy, or for some shaping
+  parameters. The user can introspect the HW capabilities via the
+  @cap-get operation.
+
 definitions:
   -
     type: enum
···
         name: priority
       -
         name: weight
+  -
+    name: caps
+    attributes:
+      -
+        name: ifindex
+        type: u32
+        doc: Interface index queried for shapers capabilities.
+      -
+        name: scope
+        type: u32
+        enum: scope
+        doc: The scope to which the queried capabilities apply.
+      -
+        name: support-metric-bps
+        type: flag
+        doc: The device accepts 'bps' metric for bw-min, bw-max and burst.
+      -
+        name: support-metric-pps
+        type: flag
+        doc: The device accepts 'pps' metric for bw-min, bw-max and burst.
+      -
+        name: support-nesting
+        type: flag
+        doc: |
+          The device supports nesting shaper belonging to this scope
+          below 'node' scoped shapers. Only 'queue' and 'node'
+          scope can have flag 'support-nesting'.
+      -
+        name: support-bw-min
+        type: flag
+        doc: The device supports a minimum guaranteed B/W.
+      -
+        name: support-bw-max
+        type: flag
+        doc: The device supports maximum B/W shaping.
+      -
+        name: support-burst
+        type: flag
+        doc: The device supports a maximum burst size.
+      -
+        name: support-priority
+        type: flag
+        doc: The device supports priority scheduling.
+      -
+        name: support-weight
+        type: flag
+        doc: The device supports weighted round robin scheduling.
 
 operations:
   list:
···
             - leaves
         reply:
           attributes: *ns-binding
+
+    -
+      name: cap-get
+      doc: |
+        Get the shaper capabilities supported by the given device
+        for the specified scope.
+      attribute-set: caps
+
+      do:
+        pre: net-shaper-nl-cap-pre-doit
+        post: net-shaper-nl-cap-post-doit
+        request:
+          attributes:
+            - ifindex
+            - scope
+        reply:
+          attributes: &cap-attrs
+            - ifindex
+            - scope
+            - support-metric-bps
+            - support-metric-pps
+            - support-nesting
+            - support-bw-min
+            - support-bw-max
+            - support-burst
+            - support-priority
+            - support-weight
+
+      dump:
+        pre: net-shaper-nl-cap-pre-dumpit
+        post: net-shaper-nl-cap-post-dumpit
+        request:
+          attributes:
+            - ifindex
+        reply:
+          attributes: *cap-attrs

include/uapi/linux/net_shaper.h

···
 };
 
 enum {
+	NET_SHAPER_A_CAPS_IFINDEX = 1,
+	NET_SHAPER_A_CAPS_SCOPE,
+	NET_SHAPER_A_CAPS_SUPPORT_METRIC_BPS,
+	NET_SHAPER_A_CAPS_SUPPORT_METRIC_PPS,
+	NET_SHAPER_A_CAPS_SUPPORT_NESTING,
+	NET_SHAPER_A_CAPS_SUPPORT_BW_MIN,
+	NET_SHAPER_A_CAPS_SUPPORT_BW_MAX,
+	NET_SHAPER_A_CAPS_SUPPORT_BURST,
+	NET_SHAPER_A_CAPS_SUPPORT_PRIORITY,
+	NET_SHAPER_A_CAPS_SUPPORT_WEIGHT,
+
+	__NET_SHAPER_A_CAPS_MAX,
+	NET_SHAPER_A_CAPS_MAX = (__NET_SHAPER_A_CAPS_MAX - 1)
+};
+
+enum {
 	NET_SHAPER_CMD_GET = 1,
 	NET_SHAPER_CMD_SET,
 	NET_SHAPER_CMD_DELETE,
 	NET_SHAPER_CMD_GROUP,
+	NET_SHAPER_CMD_CAP_GET,
 
 	__NET_SHAPER_CMD_MAX,
 	NET_SHAPER_CMD_MAX = (__NET_SHAPER_CMD_MAX - 1)

net/shaper/shaper.c

···
 	return 0;
 }
 
+int net_shaper_nl_cap_pre_doit(const struct genl_split_ops *ops,
+			       struct sk_buff *skb, struct genl_info *info)
+{
+	return -EOPNOTSUPP;
+}
+
+void net_shaper_nl_cap_post_doit(const struct genl_split_ops *ops,
+				 struct sk_buff *skb, struct genl_info *info)
+{
+}
+
+int net_shaper_nl_cap_pre_dumpit(struct netlink_callback *cb)
+{
+	return -EOPNOTSUPP;
+}
+
+int net_shaper_nl_cap_post_dumpit(struct netlink_callback *cb)
+{
+	return -EOPNOTSUPP;
+}
+
 int net_shaper_nl_get_doit(struct sk_buff *skb, struct genl_info *info)
 {
 	struct net_shaper_binding *binding;
···
 free_msg:
 	kfree_skb(msg);
 	goto free_leaves;
+}
+
+int net_shaper_nl_cap_get_doit(struct sk_buff *skb, struct genl_info *info)
+{
+	return 0;
+}
+
+int net_shaper_nl_cap_get_dumpit(struct sk_buff *skb,
+				 struct netlink_callback *cb)
+{
+	return 0;
 }
 
 static void net_shaper_flush(struct net_shaper_binding *binding)

net/shaper/shaper_nl_gen.c

···
 	[NET_SHAPER_A_LEAVES] = NLA_POLICY_NESTED(net_shaper_leaf_info_nl_policy),
 };
 
+/* NET_SHAPER_CMD_CAP_GET - do */
+static const struct nla_policy net_shaper_cap_get_do_nl_policy[NET_SHAPER_A_CAPS_SCOPE + 1] = {
+	[NET_SHAPER_A_CAPS_IFINDEX] = { .type = NLA_U32, },
+	[NET_SHAPER_A_CAPS_SCOPE] = NLA_POLICY_MAX(NLA_U32, 3),
+};
+
+/* NET_SHAPER_CMD_CAP_GET - dump */
+static const struct nla_policy net_shaper_cap_get_dump_nl_policy[NET_SHAPER_A_CAPS_IFINDEX + 1] = {
+	[NET_SHAPER_A_CAPS_IFINDEX] = { .type = NLA_U32, },
+};
+
 /* Ops table for net_shaper */
 static const struct genl_split_ops net_shaper_nl_ops[] = {
 	{
···
 		.policy		= net_shaper_group_nl_policy,
 		.maxattr	= NET_SHAPER_A_LEAVES,
 		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
+	},
+	{
+		.cmd		= NET_SHAPER_CMD_CAP_GET,
+		.pre_doit	= net_shaper_nl_cap_pre_doit,
+		.doit		= net_shaper_nl_cap_get_doit,
+		.post_doit	= net_shaper_nl_cap_post_doit,
+		.policy		= net_shaper_cap_get_do_nl_policy,
+		.maxattr	= NET_SHAPER_A_CAPS_SCOPE,
+		.flags		= GENL_CMD_CAP_DO,
+	},
+	{
+		.cmd		= NET_SHAPER_CMD_CAP_GET,
+		.start		= net_shaper_nl_cap_pre_dumpit,
+		.dumpit		= net_shaper_nl_cap_get_dumpit,
+		.done		= net_shaper_nl_cap_post_dumpit,
+		.policy		= net_shaper_cap_get_dump_nl_policy,
+		.maxattr	= NET_SHAPER_A_CAPS_IFINDEX,
+		.flags		= GENL_CMD_CAP_DUMP,
 	},
 };
 

net/shaper/shaper_nl_gen.h

···
 
 int net_shaper_nl_pre_doit(const struct genl_split_ops *ops,
 			   struct sk_buff *skb, struct genl_info *info);
+int net_shaper_nl_cap_pre_doit(const struct genl_split_ops *ops,
+			       struct sk_buff *skb, struct genl_info *info);
 void
 net_shaper_nl_post_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 			struct genl_info *info);
+void
+net_shaper_nl_cap_post_doit(const struct genl_split_ops *ops,
+			    struct sk_buff *skb, struct genl_info *info);
 int net_shaper_nl_pre_dumpit(struct netlink_callback *cb);
+int net_shaper_nl_cap_pre_dumpit(struct netlink_callback *cb);
 int net_shaper_nl_post_dumpit(struct netlink_callback *cb);
+int net_shaper_nl_cap_post_dumpit(struct netlink_callback *cb);
 
 int net_shaper_nl_get_doit(struct sk_buff *skb, struct genl_info *info);
 int net_shaper_nl_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb);
 int net_shaper_nl_set_doit(struct sk_buff *skb, struct genl_info *info);
 int net_shaper_nl_delete_doit(struct sk_buff *skb, struct genl_info *info);
 int net_shaper_nl_group_doit(struct sk_buff *skb, struct genl_info *info);
+int net_shaper_nl_cap_get_doit(struct sk_buff *skb, struct genl_info *info);
+int net_shaper_nl_cap_get_dumpit(struct sk_buff *skb,
+				 struct netlink_callback *cb);
 
 extern struct genl_family net_shaper_nl_family;