net: rtnetlink: Add UAPI for obtaining L3 offload xstats

Add a new IFLA_STATS_LINK_OFFLOAD_XSTATS child attribute,
IFLA_OFFLOAD_XSTATS_L3_STATS, to carry statistics for traffic that takes
place in a HW router.

The offloaded HW stats are designed to allow per-netdevice enablement and
disablement. Additionally, as a netdevice is configured, it may become or
cease being suitable for binding of a HW counter. Both of these aspects
need to be communicated to the userspace. To that end, add another child
attribute, IFLA_OFFLOAD_XSTATS_HW_S_INFO:

    - attr nest IFLA_OFFLOAD_XSTATS_HW_S_INFO
	- attr nest IFLA_OFFLOAD_XSTATS_L3_STATS
 	    - attr IFLA_OFFLOAD_XSTATS_HW_S_INFO_REQUEST
	      - {0,1} as u8
 	    - attr IFLA_OFFLOAD_XSTATS_HW_S_INFO_USED
	      - {0,1} as u8

Thus this one attribute is a nest that can be used to carry information
about various types of HW statistics, and indexing is very simply done by
wrapping the information for a given statistics suite into the attribute
that carries the suite is the RTM_GETSTATS query. At the same time, because
_HW_S_INFO is nested directly below IFLA_STATS_LINK_OFFLOAD_XSTATS, it is
possible through filtering to request only the metadata about individual
statistics suites, without having to hit the HW to get the actual counters.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: pmachata

include/uapi/linux/if_link.h

@@ -1249,10 +1249,21 @@ enum {
 enum {
 	IFLA_OFFLOAD_XSTATS_UNSPEC,
 	IFLA_OFFLOAD_XSTATS_CPU_HIT, /* struct rtnl_link_stats64 */
+	IFLA_OFFLOAD_XSTATS_HW_S_INFO,	/* HW stats info. A nest */
+	IFLA_OFFLOAD_XSTATS_L3_STATS,	/* struct rtnl_hw_stats64 */
 	__IFLA_OFFLOAD_XSTATS_MAX
 };
 #define IFLA_OFFLOAD_XSTATS_MAX (__IFLA_OFFLOAD_XSTATS_MAX - 1)
 
+enum {
+	IFLA_OFFLOAD_XSTATS_HW_S_INFO_UNSPEC,
+	IFLA_OFFLOAD_XSTATS_HW_S_INFO_REQUEST,		/* u8 */
+	IFLA_OFFLOAD_XSTATS_HW_S_INFO_USED,		/* u8 */
+	__IFLA_OFFLOAD_XSTATS_HW_S_INFO_MAX,
+};
+#define IFLA_OFFLOAD_XSTATS_HW_S_INFO_MAX \
+	(__IFLA_OFFLOAD_XSTATS_HW_S_INFO_MAX - 1)
+
 /* XDP section */
 
 #define XDP_FLAGS_UPDATE_IF_NOEXIST	(1U << 0)

net/core/rtnetlink.c

@@ -5091,10 +5091,110 @@ rtnl_offload_xstats_fill_ndo(struct net_device *dev, int attr_id,
 	return 0;
 }
 
+static unsigned int
+rtnl_offload_xstats_get_size_stats(const struct net_device *dev,
+				   enum netdev_offload_xstats_type type)
+{
+	bool enabled = netdev_offload_xstats_enabled(dev, type);
+
+	return enabled ? sizeof(struct rtnl_hw_stats64) : 0;
+}
+
+struct rtnl_offload_xstats_request_used {
+	bool request;
+	bool used;
+};
+
+static int
+rtnl_offload_xstats_get_stats(struct net_device *dev,
+			      enum netdev_offload_xstats_type type,
+			      struct rtnl_offload_xstats_request_used *ru,
+			      struct rtnl_hw_stats64 *stats,
+			      struct netlink_ext_ack *extack)
+{
+	bool request;
+	bool used;
+	int err;
+
+	request = netdev_offload_xstats_enabled(dev, type);
+	if (!request) {
+		used = false;
+		goto out;
+	}
+
+	err = netdev_offload_xstats_get(dev, type, stats, &used, extack);
+	if (err)
+		return err;
+
+out:
+	if (ru) {
+		ru->request = request;
+		ru->used = used;
+	}
+	return 0;
+}
+
+static int
+rtnl_offload_xstats_fill_hw_s_info_one(struct sk_buff *skb, int attr_id,
+				       struct rtnl_offload_xstats_request_used *ru)
+{
+	struct nlattr *nest;
+
+	nest = nla_nest_start(skb, attr_id);
+	if (!nest)
+		return -EMSGSIZE;
+
+	if (nla_put_u8(skb, IFLA_OFFLOAD_XSTATS_HW_S_INFO_REQUEST, ru->request))
+		goto nla_put_failure;
+
+	if (nla_put_u8(skb, IFLA_OFFLOAD_XSTATS_HW_S_INFO_USED, ru->used))
+		goto nla_put_failure;
+
+	nla_nest_end(skb, nest);
+	return 0;
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+	return -EMSGSIZE;
+}
+
+static int
+rtnl_offload_xstats_fill_hw_s_info(struct sk_buff *skb, struct net_device *dev,
+				   struct netlink_ext_ack *extack)
+{
+	enum netdev_offload_xstats_type t_l3 = NETDEV_OFFLOAD_XSTATS_TYPE_L3;
+	struct rtnl_offload_xstats_request_used ru_l3;
+	struct nlattr *nest;
+	int err;
+
+	err = rtnl_offload_xstats_get_stats(dev, t_l3, &ru_l3, NULL, extack);
+	if (err)
+		return err;
+
+	nest = nla_nest_start(skb, IFLA_OFFLOAD_XSTATS_HW_S_INFO);
+	if (!nest)
+		return -EMSGSIZE;
+
+	if (rtnl_offload_xstats_fill_hw_s_info_one(skb,
+						   IFLA_OFFLOAD_XSTATS_L3_STATS,
+						   &ru_l3))
+		goto nla_put_failure;
+
+	nla_nest_end(skb, nest);
+	return 0;
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+	return -EMSGSIZE;
+}
+
 static int rtnl_offload_xstats_fill(struct sk_buff *skb, struct net_device *dev,
 				    int *prividx, u32 off_filter_mask,
 				    struct netlink_ext_ack *extack)
 {
+	enum netdev_offload_xstats_type t_l3 = NETDEV_OFFLOAD_XSTATS_TYPE_L3;
+	int attr_id_hw_s_info = IFLA_OFFLOAD_XSTATS_HW_S_INFO;
+	int attr_id_l3_stats = IFLA_OFFLOAD_XSTATS_L3_STATS;
 	int attr_id_cpu_hit = IFLA_OFFLOAD_XSTATS_CPU_HIT;
 	bool have_data = false;
 	int err;
@@ -5111,16 +5211,76 @@ static int rtnl_offload_xstats_fill(struct sk_buff *skb, struct net_device *dev,
 		}
 	}
 
+	if (*prividx <= attr_id_hw_s_info &&
+	    (off_filter_mask & IFLA_STATS_FILTER_BIT(attr_id_hw_s_info))) {
+		*prividx = attr_id_hw_s_info;
+
+		err = rtnl_offload_xstats_fill_hw_s_info(skb, dev, extack);
+		if (err)
+			return err;
+
+		have_data = true;
+		*prividx = 0;
+	}
+
+	if (*prividx <= attr_id_l3_stats &&
+	    (off_filter_mask & IFLA_STATS_FILTER_BIT(attr_id_l3_stats))) {
+		unsigned int size_l3;
+		struct nlattr *attr;
+
+		*prividx = attr_id_l3_stats;
+
+		size_l3 = rtnl_offload_xstats_get_size_stats(dev, t_l3);
+		attr = nla_reserve_64bit(skb, attr_id_l3_stats, size_l3,
+					 IFLA_OFFLOAD_XSTATS_UNSPEC);
+		if (!attr)
+			return -EMSGSIZE;
+
+		err = rtnl_offload_xstats_get_stats(dev, t_l3, NULL,
+						    nla_data(attr), extack);
+		if (err)
+			return err;
+
+		have_data = true;
+		*prividx = 0;
+	}
+
 	if (!have_data)
 		return -ENODATA;
 
 	*prividx = 0;
 	return 0;
 }
 
+static unsigned int
+rtnl_offload_xstats_get_size_hw_s_info_one(const struct net_device *dev,
+					   enum netdev_offload_xstats_type type)
+{
+	bool enabled = netdev_offload_xstats_enabled(dev, type);
+
+	return nla_total_size(0) +
+		/* IFLA_OFFLOAD_XSTATS_HW_S_INFO_REQUEST */
+		nla_total_size(sizeof(u8)) +
+		/* IFLA_OFFLOAD_XSTATS_HW_S_INFO_USED */
+		(enabled ? nla_total_size(sizeof(u8)) : 0) +
+		0;
+}
+
+static unsigned int
+rtnl_offload_xstats_get_size_hw_s_info(const struct net_device *dev)
+{
+	enum netdev_offload_xstats_type t_l3 = NETDEV_OFFLOAD_XSTATS_TYPE_L3;
+
+	return nla_total_size(0) +
+		/* IFLA_OFFLOAD_XSTATS_L3_STATS */
+		rtnl_offload_xstats_get_size_hw_s_info_one(dev, t_l3) +
+		0;
+}
+
 static int rtnl_offload_xstats_get_size(const struct net_device *dev,
 					u32 off_filter_mask)
 {
+	enum netdev_offload_xstats_type t_l3 = NETDEV_OFFLOAD_XSTATS_TYPE_L3;
 	int attr_id_cpu_hit = IFLA_OFFLOAD_XSTATS_CPU_HIT;
 	int nla_size = 0;
 	int size;
@@ -5131,6 +5291,16 @@ static int rtnl_offload_xstats_get_size(const struct net_device *dev,
 		nla_size += nla_total_size_64bit(size);
 	}
 
+	if (off_filter_mask &
+	    IFLA_STATS_FILTER_BIT(IFLA_OFFLOAD_XSTATS_HW_S_INFO))
+		nla_size += rtnl_offload_xstats_get_size_hw_s_info(dev);
+
+	if (off_filter_mask &
+	    IFLA_STATS_FILTER_BIT(IFLA_OFFLOAD_XSTATS_L3_STATS)) {
+		size = rtnl_offload_xstats_get_size_stats(dev, t_l3);
+		nla_size += nla_total_size_64bit(size);
+	}
+
 	if (nla_size != 0)
 		nla_size += nla_total_size(0);