net-shapers: implement NL get operation

Introduce the basic infrastructure to implement the net-shaper
core functionality. Each network devices carries a net-shaper cache,
the NL get() operation fetches the data from such cache.

The cache is initially empty, will be fill by the set()/group()
operation implemented later and is destroyed at device cleanup time.

The net_shaper_fill_handle(), net_shaper_ctx_init(), and
net_shaper_generic_pre() implementations handle generic index type
attributes, despite the current caller always pass a constant value
to avoid more noise in later patches using them with different
attributes.

Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Link: https://patch.msgid.link/ddd10fd645a9367803ad02fca4a5664ea5ace170.1728460186.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/networking/kapi.rst

@@ -104,6 +104,9 @@ Driver Support
 .. kernel-doc:: include/linux/netdevice.h
    :internal:
 
+.. kernel-doc:: include/net/net_shaper.h
+   :internal:
+
 PHY Support
 -----------
 

include/linux/netdevice.h

@@ -1603,6 +1603,14 @@ struct net_device_ops {
 	int			(*ndo_hwtstamp_set)(struct net_device *dev,
 						    struct kernel_hwtstamp_config *kernel_config,
 						    struct netlink_ext_ack *extack);
+
+#if IS_ENABLED(CONFIG_NET_SHAPER)
+	/**
+	 * @net_shaper_ops: Device shaping offload operations
+	 * see include/net/net_shapers.h
+	 */
+	const struct net_shaper_ops *net_shaper_ops;
+#endif
 };
 
 /**
@@ -2406,6 +2414,19 @@ struct net_device {
 
 	u64			max_pacing_offload_horizon;
 
+	/**
+	 * @lock: protects @net_shaper_hierarchy, feel free to use for other
+	 * netdev-scope protection. Ordering: take after rtnl_lock.
+	 */
+	struct mutex		lock;
+
+#if IS_ENABLED(CONFIG_NET_SHAPER)
+	/**
+	 * @net_shaper_hierarchy: data tracking the current shaper status
+	 *  see include/net/net_shapers.h
+	 */
+	struct net_shaper_hierarchy *net_shaper_hierarchy;
+#endif
 	u8			priv[] ____cacheline_aligned
 				       __counted_by(priv_len);
 } ____cacheline_aligned;

include/net/net_shaper.h

@@ -0,0 +1,120 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _NET_SHAPER_H_
+#define _NET_SHAPER_H_
+
+#include <linux/types.h>
+
+#include <uapi/linux/net_shaper.h>
+
+struct net_device;
+struct devlink;
+struct netlink_ext_ack;
+
+enum net_shaper_binding_type {
+	NET_SHAPER_BINDING_TYPE_NETDEV,
+	/* NET_SHAPER_BINDING_TYPE_DEVLINK_PORT */
+};
+
+struct net_shaper_binding {
+	enum net_shaper_binding_type type;
+	union {
+		struct net_device *netdev;
+		struct devlink *devlink;
+	};
+};
+
+struct net_shaper_handle {
+	enum net_shaper_scope scope;
+	u32 id;
+};
+
+/**
+ * struct net_shaper - represents a shaping node on the NIC H/W
+ * zeroed field are considered not set.
+ * @parent: Unique identifier for the shaper parent, usually implied
+ * @handle: Unique identifier for this shaper
+ * @metric: Specify if the rate limits refers to PPS or BPS
+ * @bw_min: Minimum guaranteed rate for this shaper
+ * @bw_max: Maximum peak rate allowed for this shaper
+ * @burst: Maximum burst for the peek rate of this shaper
+ * @priority: Scheduling priority for this shaper
+ * @weight: Scheduling weight for this shaper
+ */
+struct net_shaper {
+	struct net_shaper_handle parent;
+	struct net_shaper_handle handle;
+	enum net_shaper_metric metric;
+	u64 bw_min;
+	u64 bw_max;
+	u64 burst;
+	u32 priority;
+	u32 weight;
+
+	/* private: */
+	u32 leaves; /* accounted only for NODE scope */
+	struct rcu_head rcu;
+};
+
+/**
+ * struct net_shaper_ops - Operations on device H/W shapers
+ *
+ * The operations applies to either net_device and devlink objects.
+ * The initial shaping configuration at device initialization is empty:
+ * does not constraint the rate in any way.
+ * The network core keeps track of the applied user-configuration in
+ * the net_device or devlink structure.
+ * The operations are serialized via a per device lock.
+ *
+ * Device not supporting any kind of nesting should not provide the
+ * group operation.
+ *
+ * Each shaper is uniquely identified within the device with a 'handle'
+ * comprising the shaper scope and a scope-specific id.
+ */
+struct net_shaper_ops {
+	/**
+	 * @group: create the specified shapers scheduling group
+	 *
+	 * Nest the @leaves shapers identified under the * @node shaper.
+	 * All the shapers belong to the device specified by @binding.
+	 * The @leaves arrays size is specified by @leaves_count.
+	 * Create either the @leaves and the @node shaper; or if they already
+	 * exists, links them together in the desired way.
+	 * @leaves scope must be NET_SHAPER_SCOPE_QUEUE.
+	 */
+	int (*group)(struct net_shaper_binding *binding, int leaves_count,
+		     const struct net_shaper *leaves,
+		     const struct net_shaper *node,
+		     struct netlink_ext_ack *extack);
+
+	/**
+	 * @set: Updates the specified shaper
+	 *
+	 * Updates or creates the @shaper on the device specified by @binding.
+	 */
+	int (*set)(struct net_shaper_binding *binding,
+		   const struct net_shaper *shaper,
+		   struct netlink_ext_ack *extack);
+
+	/**
+	 * @delete: Removes the specified shaper
+	 *
+	 * Removes the shaper configuration as identified by the given @handle
+	 * on the device specified by @binding, restoring the default behavior.
+	 */
+	int (*delete)(struct net_shaper_binding *binding,
+		      const struct net_shaper_handle *handle,
+		      struct netlink_ext_ack *extack);
+
+	/**
+	 * @capabilities: get the shaper features supported by the device
+	 *
+	 * Fills the bitmask @cap with the supported capabilities for the
+	 * specified @scope and device specified by @binding.
+	 */
+	void (*capabilities)(struct net_shaper_binding *binding,
+			     enum net_shaper_scope scope, unsigned long *cap);
+};
+
+#endif

net/core/dev.c

@@ -11147,6 +11147,8 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
 	hash_init(dev->qdisc_hash);
 #endif
 
+	mutex_init(&dev->lock);
+
 	dev->priv_flags = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
 	setup(dev);
 
@@ -11217,6 +11219,8 @@ void free_netdev(struct net_device *dev)
 		return;
 	}
 
+	mutex_destroy(&dev->lock);
+
 	kfree(dev->ethtool);
 	netif_free_tx_queues(dev);
 	netif_free_rx_queues(dev);
@@ -11426,6 +11430,8 @@ void unregister_netdevice_many_notify(struct list_head *head,
 
 		mutex_destroy(&dev->ethtool->rss_lock);
 
+		net_shaper_flush_netdev(dev);
+
 		if (skb)
 			rtmsg_ifinfo_send(skb, dev, GFP_KERNEL, portid, nlh);
 

net/core/dev.h

@@ -35,6 +35,12 @@ void dev_addr_flush(struct net_device *dev);
 int dev_addr_init(struct net_device *dev);
 void dev_addr_check(struct net_device *dev);
 
+#if IS_ENABLED(CONFIG_NET_SHAPER)
+void net_shaper_flush_netdev(struct net_device *dev);
+#else
+static inline void net_shaper_flush_netdev(struct net_device *dev) {}
+#endif
+
 /* sysctls not referred to from outside net/core/ */
 extern int		netdev_unregister_timeout_secs;
 extern int		weight_p;

net/shaper/shaper.c

@@ -1,30 +1,333 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <linux/bits.h>
+#include <linux/bitfield.h>
+#include <linux/idr.h>
 #include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/netlink.h>
 #include <linux/skbuff.h>
+#include <linux/xarray.h>
+#include <net/devlink.h>
+#include <net/net_shaper.h>
 
 #include "shaper_nl_gen.h"
 
+#include "../core/dev.h"
+
+#define NET_SHAPER_SCOPE_SHIFT	26
+#define NET_SHAPER_ID_MASK	GENMASK(NET_SHAPER_SCOPE_SHIFT - 1, 0)
+#define NET_SHAPER_SCOPE_MASK	GENMASK(31, NET_SHAPER_SCOPE_SHIFT)
+
+#define NET_SHAPER_ID_UNSPEC NET_SHAPER_ID_MASK
+
+struct net_shaper_hierarchy {
+	struct xarray shapers;
+};
+
+struct net_shaper_nl_ctx {
+	struct net_shaper_binding binding;
+	netdevice_tracker dev_tracker;
+	unsigned long start_index;
+};
+
+static struct net_shaper_binding *net_shaper_binding_from_ctx(void *ctx)
+{
+	return &((struct net_shaper_nl_ctx *)ctx)->binding;
+}
+
+static struct net_shaper_hierarchy *
+net_shaper_hierarchy(struct net_shaper_binding *binding)
+{
+	/* Pairs with WRITE_ONCE() in net_shaper_hierarchy_setup. */
+	if (binding->type == NET_SHAPER_BINDING_TYPE_NETDEV)
+		return READ_ONCE(binding->netdev->net_shaper_hierarchy);
+
+	/* No other type supported yet. */
+	return NULL;
+}
+
+static int net_shaper_fill_binding(struct sk_buff *msg,
+				   const struct net_shaper_binding *binding,
+				   u32 type)
+{
+	/* Should never happen, as currently only NETDEV is supported. */
+	if (WARN_ON_ONCE(binding->type != NET_SHAPER_BINDING_TYPE_NETDEV))
+		return -EINVAL;
+
+	if (nla_put_u32(msg, type, binding->netdev->ifindex))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+static int net_shaper_fill_handle(struct sk_buff *msg,
+				  const struct net_shaper_handle *handle,
+				  u32 type)
+{
+	struct nlattr *handle_attr;
+
+	if (handle->scope == NET_SHAPER_SCOPE_UNSPEC)
+		return 0;
+
+	handle_attr = nla_nest_start(msg, type);
+	if (!handle_attr)
+		return -EMSGSIZE;
+
+	if (nla_put_u32(msg, NET_SHAPER_A_HANDLE_SCOPE, handle->scope) ||
+	    (handle->scope >= NET_SHAPER_SCOPE_QUEUE &&
+	     nla_put_u32(msg, NET_SHAPER_A_HANDLE_ID, handle->id)))
+		goto handle_nest_cancel;
+
+	nla_nest_end(msg, handle_attr);
+	return 0;
+
+handle_nest_cancel:
+	nla_nest_cancel(msg, handle_attr);
+	return -EMSGSIZE;
+}
+
+static int
+net_shaper_fill_one(struct sk_buff *msg,
+		    const struct net_shaper_binding *binding,
+		    const struct net_shaper *shaper,
+		    const struct genl_info *info)
+{
+	void *hdr;
+
+	hdr = genlmsg_iput(msg, info);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	if (net_shaper_fill_binding(msg, binding, NET_SHAPER_A_IFINDEX) ||
+	    net_shaper_fill_handle(msg, &shaper->parent,
+				   NET_SHAPER_A_PARENT) ||
+	    net_shaper_fill_handle(msg, &shaper->handle,
+				   NET_SHAPER_A_HANDLE) ||
+	    ((shaper->bw_min || shaper->bw_max || shaper->burst) &&
+	     nla_put_u32(msg, NET_SHAPER_A_METRIC, shaper->metric)) ||
+	    (shaper->bw_min &&
+	     nla_put_uint(msg, NET_SHAPER_A_BW_MIN, shaper->bw_min)) ||
+	    (shaper->bw_max &&
+	     nla_put_uint(msg, NET_SHAPER_A_BW_MAX, shaper->bw_max)) ||
+	    (shaper->burst &&
+	     nla_put_uint(msg, NET_SHAPER_A_BURST, shaper->burst)) ||
+	    (shaper->priority &&
+	     nla_put_u32(msg, NET_SHAPER_A_PRIORITY, shaper->priority)) ||
+	    (shaper->weight &&
+	     nla_put_u32(msg, NET_SHAPER_A_WEIGHT, shaper->weight)))
+		goto nla_put_failure;
+
+	genlmsg_end(msg, hdr);
+
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	return -EMSGSIZE;
+}
+
+/* Initialize the context fetching the relevant device and
+ * acquiring a reference to it.
+ */
+static int net_shaper_ctx_setup(const struct genl_info *info, int type,
+				struct net_shaper_nl_ctx *ctx)
+{
+	struct net *ns = genl_info_net(info);
+	struct net_device *dev;
+	int ifindex;
+
+	if (GENL_REQ_ATTR_CHECK(info, type))
+		return -EINVAL;
+
+	ifindex = nla_get_u32(info->attrs[type]);
+	dev = netdev_get_by_index(ns, ifindex, &ctx->dev_tracker, GFP_KERNEL);
+	if (!dev) {
+		NL_SET_BAD_ATTR(info->extack, info->attrs[type]);
+		return -ENOENT;
+	}
+
+	if (!dev->netdev_ops->net_shaper_ops) {
+		NL_SET_BAD_ATTR(info->extack, info->attrs[type]);
+		netdev_put(dev, &ctx->dev_tracker);
+		return -EOPNOTSUPP;
+	}
+
+	ctx->binding.type = NET_SHAPER_BINDING_TYPE_NETDEV;
+	ctx->binding.netdev = dev;
+	return 0;
+}
+
+static void net_shaper_ctx_cleanup(struct net_shaper_nl_ctx *ctx)
+{
+	if (ctx->binding.type == NET_SHAPER_BINDING_TYPE_NETDEV)
+		netdev_put(ctx->binding.netdev, &ctx->dev_tracker);
+}
+
+static u32 net_shaper_handle_to_index(const struct net_shaper_handle *handle)
+{
+	return FIELD_PREP(NET_SHAPER_SCOPE_MASK, handle->scope) |
+		FIELD_PREP(NET_SHAPER_ID_MASK, handle->id);
+}
+
+static struct net_shaper *
+net_shaper_lookup(struct net_shaper_binding *binding,
+		  const struct net_shaper_handle *handle)
+{
+	struct net_shaper_hierarchy *hierarchy = net_shaper_hierarchy(binding);
+	u32 index = net_shaper_handle_to_index(handle);
+
+	return hierarchy ? xa_load(&hierarchy->shapers, index) : NULL;
+}
+
+static int net_shaper_parse_handle(const struct nlattr *attr,
+				   const struct genl_info *info,
+				   struct net_shaper_handle *handle)
+{
+	struct nlattr *tb[NET_SHAPER_A_HANDLE_MAX + 1];
+	struct nlattr *id_attr;
+	u32 id = 0;
+	int ret;
+
+	ret = nla_parse_nested(tb, NET_SHAPER_A_HANDLE_MAX, attr,
+			       net_shaper_handle_nl_policy, info->extack);
+	if (ret < 0)
+		return ret;
+
+	if (NL_REQ_ATTR_CHECK(info->extack, attr, tb,
+			      NET_SHAPER_A_HANDLE_SCOPE))
+		return -EINVAL;
+
+	handle->scope = nla_get_u32(tb[NET_SHAPER_A_HANDLE_SCOPE]);
+
+	/* The default id for NODE scope shapers is an invalid one
+	 * to help the 'group' operation discriminate between new
+	 * NODE shaper creation (ID_UNSPEC) and reuse of existing
+	 * shaper (any other value).
+	 */
+	id_attr = tb[NET_SHAPER_A_HANDLE_ID];
+	if (id_attr)
+		id = nla_get_u32(id_attr);
+	else if (handle->scope == NET_SHAPER_SCOPE_NODE)
+		id = NET_SHAPER_ID_UNSPEC;
+
+	handle->id = id;
+	return 0;
+}
+
+static int net_shaper_generic_pre(struct genl_info *info, int type)
+{
+	struct net_shaper_nl_ctx *ctx = (struct net_shaper_nl_ctx *)info->ctx;
+
+	BUILD_BUG_ON(sizeof(*ctx) > sizeof(info->ctx));
+
+	return net_shaper_ctx_setup(info, type, ctx);
+}
+
 int net_shaper_nl_pre_doit(const struct genl_split_ops *ops,
 			   struct sk_buff *skb, struct genl_info *info)
 {
-	return -EOPNOTSUPP;
+	return net_shaper_generic_pre(info, NET_SHAPER_A_IFINDEX);
+}
+
+static void net_shaper_generic_post(struct genl_info *info)
+{
+	net_shaper_ctx_cleanup((struct net_shaper_nl_ctx *)info->ctx);
 }
 
 void net_shaper_nl_post_doit(const struct genl_split_ops *ops,
 			     struct sk_buff *skb, struct genl_info *info)
 {
+	net_shaper_generic_post(info);
+}
+
+int net_shaper_nl_pre_dumpit(struct netlink_callback *cb)
+{
+	struct net_shaper_nl_ctx *ctx = (struct net_shaper_nl_ctx *)cb->ctx;
+	const struct genl_info *info = genl_info_dump(cb);
+
+	return net_shaper_ctx_setup(info, NET_SHAPER_A_IFINDEX, ctx);
+}
+
+int net_shaper_nl_post_dumpit(struct netlink_callback *cb)
+{
+	net_shaper_ctx_cleanup((struct net_shaper_nl_ctx *)cb->ctx);
+	return 0;
 }
 
 int net_shaper_nl_get_doit(struct sk_buff *skb, struct genl_info *info)
 {
-	return -EOPNOTSUPP;
+	struct net_shaper_binding *binding;
+	struct net_shaper_handle handle;
+	struct net_shaper *shaper;
+	struct sk_buff *msg;
+	int ret;
+
+	if (GENL_REQ_ATTR_CHECK(info, NET_SHAPER_A_HANDLE))
+		return -EINVAL;
+
+	binding = net_shaper_binding_from_ctx(info->ctx);
+	ret = net_shaper_parse_handle(info->attrs[NET_SHAPER_A_HANDLE], info,
+				      &handle);
+	if (ret < 0)
+		return ret;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	rcu_read_lock();
+	shaper = net_shaper_lookup(binding, &handle);
+	if (!shaper) {
+		NL_SET_BAD_ATTR(info->extack,
+				info->attrs[NET_SHAPER_A_HANDLE]);
+		rcu_read_unlock();
+		ret = -ENOENT;
+		goto free_msg;
+	}
+
+	ret = net_shaper_fill_one(msg, binding, shaper, info);
+	rcu_read_unlock();
+	if (ret)
+		goto free_msg;
+
+	ret = genlmsg_reply(msg, info);
+	if (ret)
+		goto free_msg;
+
+	return 0;
+
+free_msg:
+	nlmsg_free(msg);
+	return ret;
 }
 
 int net_shaper_nl_get_dumpit(struct sk_buff *skb,
 			     struct netlink_callback *cb)
 {
-	return -EOPNOTSUPP;
+	struct net_shaper_nl_ctx *ctx = (struct net_shaper_nl_ctx *)cb->ctx;
+	const struct genl_info *info = genl_info_dump(cb);
+	struct net_shaper_hierarchy *hierarchy;
+	struct net_shaper_binding *binding;
+	struct net_shaper *shaper;
+	int ret = 0;
+
+	/* Don't error out dumps performed before any set operation. */
+	binding = net_shaper_binding_from_ctx(ctx);
+	hierarchy = net_shaper_hierarchy(binding);
+	if (!hierarchy)
+		return 0;
+
+	rcu_read_lock();
+	for (; (shaper = xa_find(&hierarchy->shapers, &ctx->start_index,
+				 U32_MAX, XA_PRESENT)); ctx->start_index++) {
+		ret = net_shaper_fill_one(skb, binding, shaper, info);
+		if (ret)
+			break;
+	}
+	rcu_read_unlock();
+
+	return ret;
 }
 
 int net_shaper_nl_set_doit(struct sk_buff *skb, struct genl_info *info)
@@ -37,14 +340,32 @@ int net_shaper_nl_delete_doit(struct sk_buff *skb, struct genl_info *info)
 	return -EOPNOTSUPP;
 }
 
-int net_shaper_nl_pre_dumpit(struct netlink_callback *cb)
+static void net_shaper_flush(struct net_shaper_binding *binding)
 {
-	return -EOPNOTSUPP;
+	struct net_shaper_hierarchy *hierarchy = net_shaper_hierarchy(binding);
+	struct net_shaper *cur;
+	unsigned long index;
+
+	if (!hierarchy)
+		return;
+
+	xa_lock(&hierarchy->shapers);
+	xa_for_each(&hierarchy->shapers, index, cur) {
+		__xa_erase(&hierarchy->shapers, index);
+		kfree(cur);
+	}
+	xa_unlock(&hierarchy->shapers);
+	kfree(hierarchy);
 }
 
-int net_shaper_nl_post_dumpit(struct netlink_callback *cb)
+void net_shaper_flush_netdev(struct net_device *dev)
 {
-	return -EOPNOTSUPP;
+	struct net_shaper_binding binding = {
+		.type = NET_SHAPER_BINDING_TYPE_NETDEV,
+		.netdev = dev,
+	};
+
+	net_shaper_flush(&binding);
 }
 
 static int __init shaper_init(void)