[PATCH net-next 0/7] Support for nexthop group statistics

[PATCH net-next 0/7] Support for nexthop group statistics

[Petr Machata]

ECMP is a fundamental component in L3 designs. However, it's fragile. Many
factors influence whether an ECMP group will operate as intended: hash
policy (i.e. the set of fields that contribute to ECMP hash calculation),
neighbor validity, hash seed (which might lead to polarization) or the type
of ECMP group used (hash-threshold or resilient).

At the same time, collection of statistics that would help an operator
determine that the group performs as desired, is difficult.

A solution that we present in this patchset is to add counters to next hop
group entries. For SW-datapath deployments, this will on its own allow
collection and evaluation of relevant statistics. For HW-datapath
deployments, we further add a way to request that HW counters be installed
for a given group, in-kernel interfaces to collect the HW statistics, and
netlink interfaces to query them.

For example:

    # ip nexthop replace id 4000 group 4001/4002 hw_stats on

    # ip -s -d nexthop show id 4000
    id 4000 group 4001/4002 scope global proto unspec offload hw_stats on used on
      stats:
        id 4001 packets 5002 packets_hw 5000
        id 4002 packets 4999 packets_hw 4999

The point of the patchset is visibility of ECMP balance, and that is
influenced by packet headers, not their payload. Correspondingly, we only
include packet counters in the statistics, not byte counters.

We also decided to model HW statistics as a nexthop group attribute, not an
arbitrary nexthop one. The latter would count any traffic going through a
given nexthop, regardless of which ECMP group it is in, or any at all. The
reason is again hat the point of the patchset is ECMP balance visibility,
not arbitrary inspection of how busy a particular nexthop is.
Implementation of individual-nexthop statistics is certainly possible, and
could well follow the general approach we are taking in this patchset.
For resilient groups, per-bucket statistics could be done in a similar
manner as well.

This patchset contains the core code. mlxsw support will be sent in a
follow-up patch set.

This patchset progresses as follows:

- Patches #1 and #2 add support for a new next-hop object attribute,
  NHA_OP_FLAGS. That is meant to carry various op-specific signaling, in
  particular whether SW- and HW-collected nexthop stats should be part of
  the get or dump response. The idea is to avoid wasting message space, and
  time for collection of HW statistics, when the values are not needed.

- Patches #3 and #4 add SW-datapath stats and corresponding UAPI.

- Patches #5, #6 and #7 add support fro HW-datapath stats and UAPI.
  Individual drivers still need to contribute the appropriate HW-specific
  support code.

Ido Schimmel (5):
  net: nexthop: Add nexthop group entry stats
  net: nexthop: Expose nexthop group stats to user space
  net: nexthop: Add hardware statistics notifications
  net: nexthop: Add ability to enable / disable hardware statistics
  net: nexthop: Expose nexthop group HW stats to user space

Petr Machata (2):
  net: nexthop: Adjust netlink policy parsing for a new attribute
  net: nexthop: Add NHA_OP_FLAGS

 include/net/nexthop.h        |  29 ++++
 include/uapi/linux/nexthop.h |  47 ++++++
 net/ipv4/nexthop.c           | 314 ++++++++++++++++++++++++++++++-----
 3 files changed, 350 insertions(+), 40 deletions(-)

-- 
2.43.0

[PATCH net-next 1/7] net: nexthop: Adjust netlink policy parsing for a new attribute

[Petr Machata]

A following patch will introduce a new attribute, op-specific flags to
adjust the behavior of an operation. Different operations will recognize
different flags.

- To make the differentiation possible, stop sharing the policies for get
  and del operations.

- To allow querying for presence of the attribute, have all the attribute
  arrays sized to NHA_MAX, regardless of what is permitted by policy, and
  pass the corresponding value to nlmsg_parse() as well.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
---
 net/ipv4/nexthop.c | 58 ++++++++++++++++++++++------------------------
 1 file changed, 28 insertions(+), 30 deletions(-)

diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 70509da4f080..bcd4df2f1cad 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -43,6 +43,10 @@ static const struct nla_policy rtm_nh_policy_get[] = {
 	[NHA_ID]		= { .type = NLA_U32 },
 };
 
+static const struct nla_policy rtm_nh_policy_del[] = {
+	[NHA_ID]		= { .type = NLA_U32 },
+};
+
 static const struct nla_policy rtm_nh_policy_dump[] = {
 	[NHA_OIF]		= { .type = NLA_U32 },
 	[NHA_GROUPS]		= { .type = NLA_FLAG },
@@ -2966,9 +2970,9 @@ static int rtm_new_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 	return err;
 }
 
-static int __nh_valid_get_del_req(const struct nlmsghdr *nlh,
-				  struct nlattr **tb, u32 *id,
-				  struct netlink_ext_ack *extack)
+static int nh_valid_get_del_req(const struct nlmsghdr *nlh,
+				struct nlattr **tb, u32 *id,
+				struct netlink_ext_ack *extack)
 {
 	struct nhmsg *nhm = nlmsg_data(nlh);
 
@@ -2991,26 +2995,12 @@ static int __nh_valid_get_del_req(const struct nlmsghdr *nlh,
 	return 0;
 }
 
-static int nh_valid_get_del_req(const struct nlmsghdr *nlh, u32 *id,
-				struct netlink_ext_ack *extack)
-{
-	struct nlattr *tb[ARRAY_SIZE(rtm_nh_policy_get)];
-	int err;
-
-	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb,
-			  ARRAY_SIZE(rtm_nh_policy_get) - 1,
-			  rtm_nh_policy_get, extack);
-	if (err < 0)
-		return err;
-
-	return __nh_valid_get_del_req(nlh, tb, id, extack);
-}
-
 /* rtnl */
 static int rtm_del_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 			   struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(skb->sk);
+	struct nlattr *tb[NHA_MAX + 1];
 	struct nl_info nlinfo = {
 		.nlh = nlh,
 		.nl_net = net,
@@ -3020,7 +3010,12 @@ static int rtm_del_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 	int err;
 	u32 id;
 
-	err = nh_valid_get_del_req(nlh, &id, extack);
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
+			  rtm_nh_policy_del, extack);
+	if (err < 0)
+		return err;
+
+	err = nh_valid_get_del_req(nlh, tb, &id, extack);
 	if (err)
 		return err;
 
@@ -3038,12 +3033,18 @@ static int rtm_get_nexthop(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 			   struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(in_skb->sk);
+	struct nlattr *tb[NHA_MAX + 1];
 	struct sk_buff *skb = NULL;
 	struct nexthop *nh;
 	int err;
 	u32 id;
 
-	err = nh_valid_get_del_req(nlh, &id, extack);
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
+			  rtm_nh_policy_get, extack);
+	if (err < 0)
+		return err;
+
+	err = nh_valid_get_del_req(nlh, tb, &id, extack);
 	if (err)
 		return err;
 
@@ -3157,11 +3158,10 @@ static int nh_valid_dump_req(const struct nlmsghdr *nlh,
 			     struct nh_dump_filter *filter,
 			     struct netlink_callback *cb)
 {
-	struct nlattr *tb[ARRAY_SIZE(rtm_nh_policy_dump)];
+	struct nlattr *tb[NHA_MAX + 1];
 	int err;
 
-	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb,
-			  ARRAY_SIZE(rtm_nh_policy_dump) - 1,
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
 			  rtm_nh_policy_dump, cb->extack);
 	if (err < 0)
 		return err;
@@ -3300,11 +3300,10 @@ static int nh_valid_dump_bucket_req(const struct nlmsghdr *nlh,
 				    struct netlink_callback *cb)
 {
 	struct nlattr *res_tb[ARRAY_SIZE(rtm_nh_res_bucket_policy_dump)];
-	struct nlattr *tb[ARRAY_SIZE(rtm_nh_policy_dump_bucket)];
+	struct nlattr *tb[NHA_MAX + 1];
 	int err;
 
-	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb,
-			  ARRAY_SIZE(rtm_nh_policy_dump_bucket) - 1,
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
 			  rtm_nh_policy_dump_bucket, NULL);
 	if (err < 0)
 		return err;
@@ -3474,16 +3473,15 @@ static int nh_valid_get_bucket_req(const struct nlmsghdr *nlh,
 				   u32 *id, u16 *bucket_index,
 				   struct netlink_ext_ack *extack)
 {
-	struct nlattr *tb[ARRAY_SIZE(rtm_nh_policy_get_bucket)];
+	struct nlattr *tb[NHA_MAX + 1];
 	int err;
 
-	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb,
-			  ARRAY_SIZE(rtm_nh_policy_get_bucket) - 1,
+	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
 			  rtm_nh_policy_get_bucket, extack);
 	if (err < 0)
 		return err;
 
-	err = __nh_valid_get_del_req(nlh, tb, id, extack);
+	err = nh_valid_get_del_req(nlh, tb, id, extack);
 	if (err)
 		return err;
 
-- 
2.43.0

[PATCH net-next 2/7] net: nexthop: Add NHA_OP_FLAGS

[Petr Machata]

In order to add per-nexthop statistics, but still not increase netlink
message size for consumers that do not care about them, there needs to be a
toggle through which the user indicates their desire to get the statistics.
To that end, add a new attribute, NHA_OP_FLAGS. The idea is to be able to
use the attribute for carrying of arbitrary operation-specific flags, i.e.
not make it specific for get / dump.

Add the new attribute to get and dump policies, but do not actually allow
any flags yet -- those will come later as the flags themselves are defined.
Add the necessary parsing code.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
---
 include/uapi/linux/nexthop.h |  3 +++
 net/ipv4/nexthop.c           | 24 ++++++++++++++++++++----
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/nexthop.h b/include/uapi/linux/nexthop.h
index d8ffa8c9ca78..0d7969911fd2 100644
--- a/include/uapi/linux/nexthop.h
+++ b/include/uapi/linux/nexthop.h
@@ -60,6 +60,9 @@ enum {
 	/* nested; nexthop bucket attributes */
 	NHA_RES_BUCKET,
 
+	/* bitfield32; operation-specific flags */
+	NHA_OP_FLAGS,
+
 	__NHA_MAX,
 };
 
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index bcd4df2f1cad..e41e4ac69aee 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -41,6 +41,7 @@ static const struct nla_policy rtm_nh_policy_new[] = {
 
 static const struct nla_policy rtm_nh_policy_get[] = {
 	[NHA_ID]		= { .type = NLA_U32 },
+	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(0),
 };
 
 static const struct nla_policy rtm_nh_policy_del[] = {
@@ -52,6 +53,7 @@ static const struct nla_policy rtm_nh_policy_dump[] = {
 	[NHA_GROUPS]		= { .type = NLA_FLAG },
 	[NHA_MASTER]		= { .type = NLA_U32 },
 	[NHA_FDB]		= { .type = NLA_FLAG },
+	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(0),
 };
 
 static const struct nla_policy rtm_nh_res_policy_new[] = {
@@ -2971,7 +2973,7 @@ static int rtm_new_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 }
 
 static int nh_valid_get_del_req(const struct nlmsghdr *nlh,
-				struct nlattr **tb, u32 *id,
+				struct nlattr **tb, u32 *id, u32 *op_flags,
 				struct netlink_ext_ack *extack)
 {
 	struct nhmsg *nhm = nlmsg_data(nlh);
@@ -2992,6 +2994,11 @@ static int nh_valid_get_del_req(const struct nlmsghdr *nlh,
 		return -EINVAL;
 	}
 
+	if (tb[NHA_OP_FLAGS])
+		*op_flags = nla_get_bitfield32(tb[NHA_OP_FLAGS]).value;
+	else
+		*op_flags = 0;
+
 	return 0;
 }
 
@@ -3007,6 +3014,7 @@ static int rtm_del_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 		.portid = NETLINK_CB(skb).portid,
 	};
 	struct nexthop *nh;
+	u32 op_flags;
 	int err;
 	u32 id;
 
@@ -3015,7 +3023,7 @@ static int rtm_del_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (err < 0)
 		return err;
 
-	err = nh_valid_get_del_req(nlh, tb, &id, extack);
+	err = nh_valid_get_del_req(nlh, tb, &id, &op_flags, extack);
 	if (err)
 		return err;
 
@@ -3036,6 +3044,7 @@ static int rtm_get_nexthop(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 	struct nlattr *tb[NHA_MAX + 1];
 	struct sk_buff *skb = NULL;
 	struct nexthop *nh;
+	u32 op_flags;
 	int err;
 	u32 id;
 
@@ -3044,7 +3053,7 @@ static int rtm_get_nexthop(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 	if (err < 0)
 		return err;
 
-	err = nh_valid_get_del_req(nlh, tb, &id, extack);
+	err = nh_valid_get_del_req(nlh, tb, &id, &op_flags, extack);
 	if (err)
 		return err;
 
@@ -3080,6 +3089,7 @@ struct nh_dump_filter {
 	bool group_filter;
 	bool fdb_filter;
 	u32 res_bucket_nh_id;
+	u32 op_flags;
 };
 
 static bool nh_dump_filtered(struct nexthop *nh,
@@ -3151,6 +3161,11 @@ static int __nh_valid_dump_req(const struct nlmsghdr *nlh, struct nlattr **tb,
 		return -EINVAL;
 	}
 
+	if (tb[NHA_OP_FLAGS])
+		filter->op_flags = nla_get_bitfield32(tb[NHA_OP_FLAGS]).value;
+	else
+		filter->op_flags = 0;
+
 	return 0;
 }
 
@@ -3474,6 +3489,7 @@ static int nh_valid_get_bucket_req(const struct nlmsghdr *nlh,
 				   struct netlink_ext_ack *extack)
 {
 	struct nlattr *tb[NHA_MAX + 1];
+	u32 op_flags;
 	int err;
 
 	err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
@@ -3481,7 +3497,7 @@ static int nh_valid_get_bucket_req(const struct nlmsghdr *nlh,
 	if (err < 0)
 		return err;
 
-	err = nh_valid_get_del_req(nlh, tb, id, extack);
+	err = nh_valid_get_del_req(nlh, tb, id, &op_flags, extack);
 	if (err)
 		return err;
 
-- 
2.43.0

[PATCH net-next 3/7] net: nexthop: Add nexthop group entry stats

[Petr Machata]

From: Ido Schimmel <idosch@nvidia.com>

Add nexthop group entry stats to count the number of packets forwarded
via each nexthop in the group. The stats will be exposed to user space
for better data path observability in the next patch.

The per-CPU stats pointer is placed at the beginning of 'struct
nh_grp_entry', so that all the fields accessed for the data path reside
on the same cache line:

struct nh_grp_entry {
        struct nexthop *           nh;                   /*     0     8 */
        struct nh_grp_entry_stats * stats;               /*     8     8 */
        u8                         weight;               /*    16     1 */

        /* XXX 7 bytes hole, try to pack */

        union {
                struct {
                        atomic_t   upper_bound;          /*    24     4 */
                } hthr;                                  /*    24     4 */
                struct {
                        struct list_head uw_nh_entry;    /*    24    16 */
                        u16        count_buckets;        /*    40     2 */
                        u16        wants_buckets;        /*    42     2 */
                } res;                                   /*    24    24 */
        };                                               /*    24    24 */
        struct list_head           nh_list;              /*    48    16 */
        /* --- cacheline 1 boundary (64 bytes) --- */
        struct nexthop *           nh_parent;            /*    64     8 */

        /* size: 72, cachelines: 2, members: 6 */
        /* sum members: 65, holes: 1, sum holes: 7 */
        /* last cacheline: 8 bytes */
};

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
---
 include/net/nexthop.h |  6 ++++++
 net/ipv4/nexthop.c    | 24 ++++++++++++++++++++----
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index 77e99cba60ad..4bf1875445d8 100644
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -95,8 +95,14 @@ struct nh_res_table {
 	struct nh_res_bucket	nh_buckets[] __counted_by(num_nh_buckets);
 };
 
+struct nh_grp_entry_stats {
+	u64 packets;
+	struct u64_stats_sync syncp;
+};
+
 struct nh_grp_entry {
 	struct nexthop	*nh;
+	struct nh_grp_entry_stats __percpu	*stats;
 	u8		weight;
 
 	union {
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index e41e4ac69aee..29d0ed049b91 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -480,6 +480,7 @@ static void nexthop_free_group(struct nexthop *nh)
 		struct nh_grp_entry *nhge = &nhg->nh_entries[i];
 
 		WARN_ON(!list_empty(&nhge->nh_list));
+		free_percpu(nhge->stats);
 		nexthop_put(nhge->nh);
 	}
 
@@ -1182,6 +1183,7 @@ static struct nexthop *nexthop_select_path_fdb(struct nh_group *nhg, int hash)
 		if (hash > atomic_read(&nhge->hthr.upper_bound))
 			continue;
 
+		this_cpu_inc(nhge->stats->packets);
 		return nhge->nh;
 	}
 
@@ -1191,7 +1193,7 @@ static struct nexthop *nexthop_select_path_fdb(struct nh_group *nhg, int hash)
 
 static struct nexthop *nexthop_select_path_hthr(struct nh_group *nhg, int hash)
 {
-	struct nexthop *rc = NULL;
+	struct nh_grp_entry *nhge0 = NULL;
 	int i;
 
 	if (nhg->fdb_nh)
@@ -1206,16 +1208,20 @@ static struct nexthop *nexthop_select_path_hthr(struct nh_group *nhg, int hash)
 		if (!nexthop_is_good_nh(nhge->nh))
 			continue;
 
-		if (!rc)
-			rc = nhge->nh;
+		if (!nhge0)
+			nhge0 = nhge;
 
 		if (hash > atomic_read(&nhge->hthr.upper_bound))
 			continue;
 
+		this_cpu_inc(nhge->stats->packets);
 		return nhge->nh;
 	}
 
-	return rc ? : nhg->nh_entries[0].nh;
+	if (!nhge0)
+		nhge0 = &nhg->nh_entries[0];
+	this_cpu_inc(nhge0->stats->packets);
+	return nhge0->nh;
 }
 
 static struct nexthop *nexthop_select_path_res(struct nh_group *nhg, int hash)
@@ -1231,6 +1237,7 @@ static struct nexthop *nexthop_select_path_res(struct nh_group *nhg, int hash)
 	bucket = &res_table->nh_buckets[bucket_index];
 	nh_res_bucket_set_busy(bucket);
 	nhge = rcu_dereference(bucket->nh_entry);
+	this_cpu_inc(nhge->stats->packets);
 	return nhge->nh;
 }
 
@@ -1804,6 +1811,7 @@ static void remove_nh_grp_entry(struct net *net, struct nh_grp_entry *nhge,
 			newg->has_v4 = true;
 
 		list_del(&nhges[i].nh_list);
+		new_nhges[j].stats = nhges[i].stats;
 		new_nhges[j].nh_parent = nhges[i].nh_parent;
 		new_nhges[j].nh = nhges[i].nh;
 		new_nhges[j].weight = nhges[i].weight;
@@ -1819,6 +1827,7 @@ static void remove_nh_grp_entry(struct net *net, struct nh_grp_entry *nhge,
 	rcu_assign_pointer(nhp->nh_grp, newg);
 
 	list_del(&nhge->nh_list);
+	free_percpu(nhge->stats);
 	nexthop_put(nhge->nh);
 
 	/* Removal of a NH from a resilient group is notified through
@@ -2483,6 +2492,12 @@ static struct nexthop *nexthop_create_group(struct net *net,
 		if (nhi->family == AF_INET)
 			nhg->has_v4 = true;
 
+		nhg->nh_entries[i].stats =
+			netdev_alloc_pcpu_stats(struct nh_grp_entry_stats);
+		if (!nhg->nh_entries[i].stats) {
+			nexthop_put(nhe);
+			goto out_no_nh;
+		}
 		nhg->nh_entries[i].nh = nhe;
 		nhg->nh_entries[i].weight = entry[i].weight + 1;
 		list_add(&nhg->nh_entries[i].nh_list, &nhe->grp_list);
@@ -2522,6 +2537,7 @@ static struct nexthop *nexthop_create_group(struct net *net,
 out_no_nh:
 	for (i--; i >= 0; --i) {
 		list_del(&nhg->nh_entries[i].nh_list);
+		free_percpu(nhg->nh_entries[i].stats);
 		nexthop_put(nhg->nh_entries[i].nh);
 	}
 
-- 
2.43.0

[PATCH net-next 4/7] net: nexthop: Expose nexthop group stats to user space

[Petr Machata]

From: Ido Schimmel <idosch@nvidia.com>

Add netlink support for reading NH group stats.

This data is only for statistics of the traffic in the SW datapath. HW
nexthop group statistics will be added in the following patches.

Emission of the stats is keyed to a new op_stats flag to avoid cluttering
the netlink message with stats if the user doesn't need them:
NHA_OP_FLAG_DUMP_STATS.

Co-developed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
---
 include/uapi/linux/nexthop.h | 32 +++++++++++++
 net/ipv4/nexthop.c           | 91 ++++++++++++++++++++++++++++++++----
 2 files changed, 115 insertions(+), 8 deletions(-)

diff --git a/include/uapi/linux/nexthop.h b/include/uapi/linux/nexthop.h
index 0d7969911fd2..b19871b7e7f5 100644
--- a/include/uapi/linux/nexthop.h
+++ b/include/uapi/linux/nexthop.h
@@ -30,6 +30,8 @@ enum {
 
 #define NEXTHOP_GRP_TYPE_MAX (__NEXTHOP_GRP_TYPE_MAX - 1)
 
+#define NHA_OP_FLAG_DUMP_STATS		BIT(0)
+
 enum {
 	NHA_UNSPEC,
 	NHA_ID,		/* u32; id for nexthop. id == 0 means auto-assign */
@@ -63,6 +65,9 @@ enum {
 	/* bitfield32; operation-specific flags */
 	NHA_OP_FLAGS,
 
+	/* nested; nexthop group stats */
+	NHA_GROUP_STATS,
+
 	__NHA_MAX,
 };
 
@@ -104,4 +109,31 @@ enum {
 
 #define NHA_RES_BUCKET_MAX	(__NHA_RES_BUCKET_MAX - 1)
 
+enum {
+	NHA_GROUP_STATS_UNSPEC,
+
+	/* nested; nexthop group entry stats */
+	NHA_GROUP_STATS_ENTRY,
+
+	__NHA_GROUP_STATS_MAX,
+};
+
+#define NHA_GROUP_STATS_MAX	(__NHA_GROUP_STATS_MAX - 1)
+
+enum {
+	NHA_GROUP_STATS_ENTRY_UNSPEC,
+	/* Pad attribute for 64-bit alignment */
+	NHA_GROUP_STATS_ENTRY_PAD = NHA_GROUP_STATS_ENTRY_UNSPEC,
+
+	/* u32; nexthop id of the nexthop group entry */
+	NHA_GROUP_STATS_ENTRY_ID,
+
+	/* u64; number of packets forwarded via the nexthop group entry */
+	NHA_GROUP_STATS_ENTRY_PACKETS,
+
+	__NHA_GROUP_STATS_ENTRY_MAX,
+};
+
+#define NHA_GROUP_STATS_ENTRY_MAX	(__NHA_GROUP_STATS_ENTRY_MAX - 1)
+
 #endif
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 29d0ed049b91..9c7ec9f15f55 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -41,7 +41,7 @@ static const struct nla_policy rtm_nh_policy_new[] = {
 
 static const struct nla_policy rtm_nh_policy_get[] = {
 	[NHA_ID]		= { .type = NLA_U32 },
-	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(0),
+	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(NHA_OP_FLAG_DUMP_STATS),
 };
 
 static const struct nla_policy rtm_nh_policy_del[] = {
@@ -53,7 +53,7 @@ static const struct nla_policy rtm_nh_policy_dump[] = {
 	[NHA_GROUPS]		= { .type = NLA_FLAG },
 	[NHA_MASTER]		= { .type = NLA_U32 },
 	[NHA_FDB]		= { .type = NLA_FLAG },
-	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(0),
+	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(NHA_OP_FLAG_DUMP_STATS),
 };
 
 static const struct nla_policy rtm_nh_res_policy_new[] = {
@@ -661,8 +661,78 @@ static int nla_put_nh_group_res(struct sk_buff *skb, struct nh_group *nhg)
 	return -EMSGSIZE;
 }
 
-static int nla_put_nh_group(struct sk_buff *skb, struct nh_group *nhg)
+static void nh_grp_entry_stats_read(struct nh_grp_entry *nhge,
+				    struct nh_grp_entry_stats *stats)
 {
+	int i;
+
+	memset(stats, 0, sizeof(*stats));
+	for_each_possible_cpu(i) {
+		struct nh_grp_entry_stats *cpu_stats;
+		unsigned int start;
+		u64 packets;
+
+		cpu_stats = per_cpu_ptr(nhge->stats, i);
+		do {
+			start = u64_stats_fetch_begin(&cpu_stats->syncp);
+			packets = cpu_stats->packets;
+		} while (u64_stats_fetch_retry(&cpu_stats->syncp, start));
+
+		stats->packets += packets;
+	}
+}
+
+static int nla_put_nh_group_stats_entry(struct sk_buff *skb,
+					struct nh_grp_entry *nhge)
+{
+	struct nh_grp_entry_stats stats;
+	struct nlattr *nest;
+
+	nh_grp_entry_stats_read(nhge, &stats);
+
+	nest = nla_nest_start(skb, NHA_GROUP_STATS_ENTRY);
+	if (!nest)
+		return -EMSGSIZE;
+
+	if (nla_put_u32(skb, NHA_GROUP_STATS_ENTRY_ID, nhge->nh->id) ||
+	    nla_put_u64_64bit(skb, NHA_GROUP_STATS_ENTRY_PACKETS, stats.packets,
+			      NHA_GROUP_STATS_ENTRY_PAD))
+		goto nla_put_failure;
+
+	nla_nest_end(skb, nest);
+	return 0;
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+	return -EMSGSIZE;
+}
+
+static int nla_put_nh_group_stats(struct sk_buff *skb, struct nexthop *nh)
+{
+	struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
+	struct nlattr *nest;
+	int i;
+
+	nest = nla_nest_start(skb, NHA_GROUP_STATS);
+	if (!nest)
+		return -EMSGSIZE;
+
+	for (i = 0; i < nhg->num_nh; i++)
+		if (nla_put_nh_group_stats_entry(skb, &nhg->nh_entries[i]))
+			goto nla_put_failure;
+
+	nla_nest_end(skb, nest);
+	return 0;
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+	return -EMSGSIZE;
+}
+
+static int nla_put_nh_group(struct sk_buff *skb, struct nexthop *nh,
+			    u32 op_flags)
+{
+	struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 	struct nexthop_grp *p;
 	size_t len = nhg->num_nh * sizeof(*p);
 	struct nlattr *nla;
@@ -691,6 +761,10 @@ static int nla_put_nh_group(struct sk_buff *skb, struct nh_group *nhg)
 	if (nhg->resilient && nla_put_nh_group_res(skb, nhg))
 		goto nla_put_failure;
 
+	if (op_flags & NHA_OP_FLAG_DUMP_STATS &&
+	    nla_put_nh_group_stats(skb, nh))
+		goto nla_put_failure;
+
 	return 0;
 
 nla_put_failure:
@@ -698,7 +772,8 @@ static int nla_put_nh_group(struct sk_buff *skb, struct nh_group *nhg)
 }
 
 static int nh_fill_node(struct sk_buff *skb, struct nexthop *nh,
-			int event, u32 portid, u32 seq, unsigned int nlflags)
+			int event, u32 portid, u32 seq, unsigned int nlflags,
+			u32 op_flags)
 {
 	struct fib6_nh *fib6_nh;
 	struct fib_nh *fib_nh;
@@ -725,7 +800,7 @@ static int nh_fill_node(struct sk_buff *skb, struct nexthop *nh,
 
 		if (nhg->fdb_nh && nla_put_flag(skb, NHA_FDB))
 			goto nla_put_failure;
-		if (nla_put_nh_group(skb, nhg))
+		if (nla_put_nh_group(skb, nh, op_flags))
 			goto nla_put_failure;
 		goto out;
 	}
@@ -856,7 +931,7 @@ static void nexthop_notify(int event, struct nexthop *nh, struct nl_info *info)
 	if (!skb)
 		goto errout;
 
-	err = nh_fill_node(skb, nh, event, info->portid, seq, nlflags);
+	err = nh_fill_node(skb, nh, event, info->portid, seq, nlflags, 0);
 	if (err < 0) {
 		/* -EMSGSIZE implies BUG in nh_nlmsg_size() */
 		WARN_ON(err == -EMSGSIZE);
@@ -3084,7 +3159,7 @@ static int rtm_get_nexthop(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 		goto errout_free;
 
 	err = nh_fill_node(skb, nh, RTM_NEWNEXTHOP, NETLINK_CB(in_skb).portid,
-			   nlh->nlmsg_seq, 0);
+			   nlh->nlmsg_seq, 0, op_flags);
 	if (err < 0) {
 		WARN_ON(err == -EMSGSIZE);
 		goto errout_free;
@@ -3254,7 +3329,7 @@ static int rtm_dump_nexthop_cb(struct sk_buff *skb, struct netlink_callback *cb,
 
 	return nh_fill_node(skb, nh, RTM_NEWNEXTHOP,
 			    NETLINK_CB(cb->skb).portid,
-			    cb->nlh->nlmsg_seq, NLM_F_MULTI);
+			    cb->nlh->nlmsg_seq, NLM_F_MULTI, filter->op_flags);
 }
 
 /* rtnl */
-- 
2.43.0

[PATCH net-next 5/7] net: nexthop: Add hardware statistics notifications

[Petr Machata]

From: Ido Schimmel <idosch@nvidia.com>

Add hw_stats field to several notifier structures to communicate to the
drivers that HW statistics should be configured for nexthops within a given
group.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
---
 include/net/nexthop.h | 3 +++
 net/ipv4/nexthop.c    | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index 4bf1875445d8..a8dad8f48ca8 100644
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -130,6 +130,7 @@ struct nh_group {
 	bool			resilient;
 	bool			fdb_nh;
 	bool			has_v4;
+	bool			hw_stats;
 
 	struct nh_res_table __rcu *res_table;
 	struct nh_grp_entry	nh_entries[] __counted_by(num_nh);
@@ -193,6 +194,7 @@ struct nh_notifier_grp_entry_info {
 struct nh_notifier_grp_info {
 	u16 num_nh;
 	bool is_fdb;
+	bool hw_stats;
 	struct nh_notifier_grp_entry_info nh_entries[] __counted_by(num_nh);
 };
 
@@ -206,6 +208,7 @@ struct nh_notifier_res_bucket_info {
 
 struct nh_notifier_res_table_info {
 	u16 num_nh_buckets;
+	bool hw_stats;
 	struct nh_notifier_single_info nhs[] __counted_by(num_nh_buckets);
 };
 
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 9c7ec9f15f55..0e983be431d6 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -137,6 +137,7 @@ static int nh_notifier_mpath_info_init(struct nh_notifier_info *info,
 
 	info->nh_grp->num_nh = num_nh;
 	info->nh_grp->is_fdb = nhg->fdb_nh;
+	info->nh_grp->hw_stats = nhg->hw_stats;
 
 	for (i = 0; i < num_nh; i++) {
 		struct nh_grp_entry *nhge = &nhg->nh_entries[i];
@@ -168,6 +169,7 @@ static int nh_notifier_res_table_info_init(struct nh_notifier_info *info,
 		return -ENOMEM;
 
 	info->nh_res_table->num_nh_buckets = num_nh_buckets;
+	info->nh_res_table->hw_stats = nhg->hw_stats;
 
 	for (i = 0; i < num_nh_buckets; i++) {
 		struct nh_res_bucket *bucket = &res_table->nh_buckets[i];
-- 
2.43.0

[PATCH net-next 6/7] net: nexthop: Add ability to enable / disable hardware statistics

[Petr Machata]

From: Ido Schimmel <idosch@nvidia.com>

Add netlink support for enabling collection of HW statistics on nexthop
groups.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
---
 include/net/nexthop.h        |  2 ++
 include/uapi/linux/nexthop.h |  3 +++
 net/ipv4/nexthop.c           | 15 ++++++++++++++-
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index a8dad8f48ca8..20cd337b4a9c 100644
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -47,6 +47,8 @@ struct nh_config {
 	bool		nh_grp_res_has_idle_timer;
 	bool		nh_grp_res_has_unbalanced_timer;
 
+	bool		nh_hw_stats;
+
 	struct nlattr	*nh_encap;
 	u16		nh_encap_type;
 
diff --git a/include/uapi/linux/nexthop.h b/include/uapi/linux/nexthop.h
index b19871b7e7f5..6d5ec1c4bb05 100644
--- a/include/uapi/linux/nexthop.h
+++ b/include/uapi/linux/nexthop.h
@@ -68,6 +68,9 @@ enum {
 	/* nested; nexthop group stats */
 	NHA_GROUP_STATS,
 
+	/* u32; nexthop hardware stats enable */
+	NHA_HW_STATS_ENABLE,
+
 	__NHA_MAX,
 };
 
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 0e983be431d6..2e6889245294 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -37,6 +37,7 @@ static const struct nla_policy rtm_nh_policy_new[] = {
 	[NHA_ENCAP]		= { .type = NLA_NESTED },
 	[NHA_FDB]		= { .type = NLA_FLAG },
 	[NHA_RES_GROUP]		= { .type = NLA_NESTED },
+	[NHA_HW_STATS_ENABLE]	= NLA_POLICY_MAX(NLA_U32, 1),
 };
 
 static const struct nla_policy rtm_nh_policy_get[] = {
@@ -764,7 +765,8 @@ static int nla_put_nh_group(struct sk_buff *skb, struct nexthop *nh,
 		goto nla_put_failure;
 
 	if (op_flags & NHA_OP_FLAG_DUMP_STATS &&
-	    nla_put_nh_group_stats(skb, nh))
+	    (nla_put_u32(skb, NHA_HW_STATS_ENABLE, nhg->hw_stats) ||
+	     nla_put_nh_group_stats(skb, nh)))
 		goto nla_put_failure;
 
 	return 0;
@@ -1188,6 +1190,7 @@ static int nh_check_attr_group(struct net *net,
 		if (!tb[i])
 			continue;
 		switch (i) {
+		case NHA_HW_STATS_ENABLE:
 		case NHA_FDB:
 			continue;
 		case NHA_RES_GROUP:
@@ -2607,6 +2610,9 @@ static struct nexthop *nexthop_create_group(struct net *net,
 	if (cfg->nh_fdb)
 		nhg->fdb_nh = 1;
 
+	if (cfg->nh_hw_stats)
+		nhg->hw_stats = true;
+
 	rcu_assign_pointer(nh->nh_grp, nhg);
 
 	return nh;
@@ -2949,6 +2955,9 @@ static int rtm_to_nh_config(struct net *net, struct sk_buff *skb,
 			err = rtm_to_nh_config_grp_res(tb[NHA_RES_GROUP],
 						       cfg, extack);
 
+		if (tb[NHA_HW_STATS_ENABLE])
+			cfg->nh_hw_stats = nla_get_u32(tb[NHA_HW_STATS_ENABLE]);
+
 		/* no other attributes should be set */
 		goto out;
 	}
@@ -3040,6 +3049,10 @@ static int rtm_to_nh_config(struct net *net, struct sk_buff *skb,
 		goto out;
 	}
 
+	if (tb[NHA_HW_STATS_ENABLE]) {
+		NL_SET_ERR_MSG(extack, "Cannot enable nexthop hardware statistics for non-group nexthops");
+		goto out;
+	}
 
 	err = 0;
 out:
-- 
2.43.0

[PATCH net-next 7/7] net: nexthop: Expose nexthop group HW stats to user space

[Petr Machata]

From: Ido Schimmel <idosch@nvidia.com>

Add netlink support for reading NH group hardware stats.

Stats collection is done through a new notifier,
NEXTHOP_EVENT_HW_STATS_REPORT_DELTA. Drivers that implement HW counters for
a given NH group are thereby asked to collect the stats and report back to
core by calling nh_grp_hw_stats_report_delta(). This is similar to what
netdevice L3 stats do.

Besides exposing number of packets that passed in the HW datapath, also
include information on whether any driver actually realizes the counters.
The core can tell based on whether it got any _report_delta() reports from
the drivers. This allows enabling the statistics at the group at any time,
with drivers opting into supporting them. This is also in line with what
netdevice L3 stats are doing.

So as not to waste time and space, tie the collection and reporting of HW
stats with a new op flag, NHA_OP_FLAG_DUMP_HW_STATS.

Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Co-developed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
---
 include/net/nexthop.h        |  18 +++++
 include/uapi/linux/nexthop.h |   9 +++
 net/ipv4/nexthop.c           | 130 ++++++++++++++++++++++++++++++++---
 3 files changed, 149 insertions(+), 8 deletions(-)

diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index 20cd337b4a9c..235f94ab16a8 100644
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -122,6 +122,7 @@ struct nh_grp_entry {
 
 	struct list_head nh_list;
 	struct nexthop	*nh_parent;  /* nexthop of group with this entry */
+	u64		packets_hw;
 };
 
 struct nh_group {
@@ -166,6 +167,7 @@ enum nexthop_event_type {
 	NEXTHOP_EVENT_REPLACE,
 	NEXTHOP_EVENT_RES_TABLE_PRE_REPLACE,
 	NEXTHOP_EVENT_BUCKET_REPLACE,
+	NEXTHOP_EVENT_HW_STATS_REPORT_DELTA,
 };
 
 enum nh_notifier_info_type {
@@ -173,6 +175,7 @@ enum nh_notifier_info_type {
 	NH_NOTIFIER_INFO_TYPE_GRP,
 	NH_NOTIFIER_INFO_TYPE_RES_TABLE,
 	NH_NOTIFIER_INFO_TYPE_RES_BUCKET,
+	NH_NOTIFIER_INFO_TYPE_GRP_HW_STATS,
 };
 
 struct nh_notifier_single_info {
@@ -214,6 +217,17 @@ struct nh_notifier_res_table_info {
 	struct nh_notifier_single_info nhs[] __counted_by(num_nh_buckets);
 };
 
+struct nh_notifier_grp_hw_stats_entry_info {
+	u32 id;
+	u64 packets;
+};
+
+struct nh_notifier_grp_hw_stats_info {
+	u16 num_nh;
+	bool hw_stats_used;
+	struct nh_notifier_grp_hw_stats_entry_info stats[] __counted_by(num_nh);
+};
+
 struct nh_notifier_info {
 	struct net *net;
 	struct netlink_ext_ack *extack;
@@ -224,6 +238,7 @@ struct nh_notifier_info {
 		struct nh_notifier_grp_info *nh_grp;
 		struct nh_notifier_res_table_info *nh_res_table;
 		struct nh_notifier_res_bucket_info *nh_res_bucket;
+		struct nh_notifier_grp_hw_stats_info *nh_grp_hw_stats;
 	};
 };
 
@@ -236,6 +251,9 @@ void nexthop_bucket_set_hw_flags(struct net *net, u32 id, u16 bucket_index,
 				 bool offload, bool trap);
 void nexthop_res_grp_activity_update(struct net *net, u32 id, u16 num_buckets,
 				     unsigned long *activity);
+void nh_grp_hw_stats_report_delta(struct nh_notifier_grp_hw_stats_info *info,
+				  unsigned int nh_idx,
+				  u64 delta_packets);
 
 /* caller is holding rcu or rtnl; no reference taken to nexthop */
 struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
diff --git a/include/uapi/linux/nexthop.h b/include/uapi/linux/nexthop.h
index 6d5ec1c4bb05..37ed705fcf6d 100644
--- a/include/uapi/linux/nexthop.h
+++ b/include/uapi/linux/nexthop.h
@@ -31,6 +31,7 @@ enum {
 #define NEXTHOP_GRP_TYPE_MAX (__NEXTHOP_GRP_TYPE_MAX - 1)
 
 #define NHA_OP_FLAG_DUMP_STATS		BIT(0)
+#define NHA_OP_FLAG_DUMP_HW_STATS	BIT(1)
 
 enum {
 	NHA_UNSPEC,
@@ -71,6 +72,9 @@ enum {
 	/* u32; nexthop hardware stats enable */
 	NHA_HW_STATS_ENABLE,
 
+	/* u32; read-only; whether any driver collects HW stats */
+	NHA_HW_STATS_USED,
+
 	__NHA_MAX,
 };
 
@@ -134,6 +138,11 @@ enum {
 	/* u64; number of packets forwarded via the nexthop group entry */
 	NHA_GROUP_STATS_ENTRY_PACKETS,
 
+	/* u64; number of packets forwarded via the nexthop group entry in
+	 * hardware
+	 */
+	NHA_GROUP_STATS_ENTRY_PACKETS_HW,
+
 	__NHA_GROUP_STATS_ENTRY_MAX,
 };
 
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 2e6889245294..ea2fef853337 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -42,7 +42,8 @@ static const struct nla_policy rtm_nh_policy_new[] = {
 
 static const struct nla_policy rtm_nh_policy_get[] = {
 	[NHA_ID]		= { .type = NLA_U32 },
-	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(NHA_OP_FLAG_DUMP_STATS),
+	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(NHA_OP_FLAG_DUMP_STATS |
+							NHA_OP_FLAG_DUMP_HW_STATS),
 };
 
 static const struct nla_policy rtm_nh_policy_del[] = {
@@ -54,7 +55,8 @@ static const struct nla_policy rtm_nh_policy_dump[] = {
 	[NHA_GROUPS]		= { .type = NLA_FLAG },
 	[NHA_MASTER]		= { .type = NLA_U32 },
 	[NHA_FDB]		= { .type = NLA_FLAG },
-	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(NHA_OP_FLAG_DUMP_STATS),
+	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(NHA_OP_FLAG_DUMP_STATS |
+							NHA_OP_FLAG_DUMP_HW_STATS),
 };
 
 static const struct nla_policy rtm_nh_res_policy_new[] = {
@@ -685,8 +687,95 @@ static void nh_grp_entry_stats_read(struct nh_grp_entry *nhge,
 	}
 }
 
+static int nh_notifier_grp_hw_stats_init(struct nh_notifier_info *info,
+					 const struct nexthop *nh)
+{
+	struct nh_group *nhg;
+	int i;
+
+	ASSERT_RTNL();
+	nhg = rtnl_dereference(nh->nh_grp);
+
+	info->id = nh->id;
+	info->type = NH_NOTIFIER_INFO_TYPE_GRP_HW_STATS;
+	info->nh_grp_hw_stats = kzalloc(struct_size(info->nh_grp_hw_stats,
+						    stats, nhg->num_nh),
+					GFP_KERNEL);
+	if (!info->nh_grp_hw_stats)
+		return -ENOMEM;
+
+	info->nh_grp_hw_stats->num_nh = nhg->num_nh;
+	for (i = 0; i < nhg->num_nh; i++) {
+		struct nh_grp_entry *nhge = &nhg->nh_entries[i];
+
+		info->nh_grp_hw_stats->stats[i].id = nhge->nh->id;
+	}
+
+	return 0;
+}
+
+static void nh_notifier_grp_hw_stats_fini(struct nh_notifier_info *info)
+{
+	kfree(info->nh_grp_hw_stats);
+}
+
+void nh_grp_hw_stats_report_delta(struct nh_notifier_grp_hw_stats_info *info,
+				  unsigned int nh_idx,
+				  u64 delta_packets)
+{
+	info->hw_stats_used = true;
+	info->stats[nh_idx].packets += delta_packets;
+}
+EXPORT_SYMBOL(nh_grp_hw_stats_report_delta);
+
+static void nh_grp_hw_stats_apply_update(struct nexthop *nh,
+					 struct nh_notifier_info *info)
+{
+	struct nh_group *nhg;
+	int i;
+
+	ASSERT_RTNL();
+	nhg = rtnl_dereference(nh->nh_grp);
+
+	for (i = 0; i < nhg->num_nh; i++) {
+		struct nh_grp_entry *nhge = &nhg->nh_entries[i];
+
+		nhge->packets_hw += info->nh_grp_hw_stats->stats[i].packets;
+	}
+}
+
+static int nh_grp_hw_stats_update(struct nexthop *nh, bool *hw_stats_used)
+{
+	struct nh_notifier_info info = {
+		.net = nh->net,
+	};
+	struct net *net = nh->net;
+	int err;
+
+	if (nexthop_notifiers_is_empty(net))
+		return 0;
+
+	err = nh_notifier_grp_hw_stats_init(&info, nh);
+	if (err)
+		return err;
+
+	err = blocking_notifier_call_chain(&net->nexthop.notifier_chain,
+					   NEXTHOP_EVENT_HW_STATS_REPORT_DELTA,
+					   &info);
+
+	/* Cache whatever we got, even if there was an error, otherwise the
+	 * successful stats retrievals would get lost.
+	 */
+	nh_grp_hw_stats_apply_update(nh, &info);
+	*hw_stats_used = info.nh_grp_hw_stats->hw_stats_used;
+
+	nh_notifier_grp_hw_stats_fini(&info);
+	return notifier_to_errno(err);
+}
+
 static int nla_put_nh_group_stats_entry(struct sk_buff *skb,
-					struct nh_grp_entry *nhge)
+					struct nh_grp_entry *nhge,
+					u32 op_flags)
 {
 	struct nh_grp_entry_stats stats;
 	struct nlattr *nest;
@@ -698,10 +787,16 @@ static int nla_put_nh_group_stats_entry(struct sk_buff *skb,
 		return -EMSGSIZE;
 
 	if (nla_put_u32(skb, NHA_GROUP_STATS_ENTRY_ID, nhge->nh->id) ||
-	    nla_put_u64_64bit(skb, NHA_GROUP_STATS_ENTRY_PACKETS, stats.packets,
+	    nla_put_u64_64bit(skb, NHA_GROUP_STATS_ENTRY_PACKETS,
+			      stats.packets + nhge->packets_hw,
 			      NHA_GROUP_STATS_ENTRY_PAD))
 		goto nla_put_failure;
 
+	if (op_flags & NHA_OP_FLAG_DUMP_HW_STATS &&
+	    nla_put_u64_64bit(skb, NHA_GROUP_STATS_ENTRY_PACKETS_HW,
+			      nhge->packets_hw, NHA_GROUP_STATS_ENTRY_PAD))
+		goto nla_put_failure;
+
 	nla_nest_end(skb, nest);
 	return 0;
 
@@ -710,26 +805,45 @@ static int nla_put_nh_group_stats_entry(struct sk_buff *skb,
 	return -EMSGSIZE;
 }
 
-static int nla_put_nh_group_stats(struct sk_buff *skb, struct nexthop *nh)
+static int nla_put_nh_group_stats(struct sk_buff *skb, struct nexthop *nh,
+				  u32 op_flags)
 {
 	struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 	struct nlattr *nest;
+	bool hw_stats_used;
+	int err;
 	int i;
 
+	if (nla_put_u32(skb, NHA_HW_STATS_ENABLE, nhg->hw_stats))
+		goto nla_put_failure;
+
+	if (op_flags & NHA_OP_FLAG_DUMP_HW_STATS &&
+	    nhg->hw_stats) {
+		err = nh_grp_hw_stats_update(nh, &hw_stats_used);
+		if (err)
+			goto hw_stats_update_fail;
+
+		if (nla_put_u32(skb, NHA_HW_STATS_USED, hw_stats_used))
+			goto nla_put_failure;
+	}
+
 	nest = nla_nest_start(skb, NHA_GROUP_STATS);
 	if (!nest)
 		return -EMSGSIZE;
 
 	for (i = 0; i < nhg->num_nh; i++)
-		if (nla_put_nh_group_stats_entry(skb, &nhg->nh_entries[i]))
+		if (nla_put_nh_group_stats_entry(skb, &nhg->nh_entries[i],
+						 op_flags))
 			goto nla_put_failure;
 
 	nla_nest_end(skb, nest);
 	return 0;
 
 nla_put_failure:
+	err = -EMSGSIZE;
+hw_stats_update_fail:
 	nla_nest_cancel(skb, nest);
-	return -EMSGSIZE;
+	return err;
 }
 
 static int nla_put_nh_group(struct sk_buff *skb, struct nexthop *nh,
@@ -766,7 +880,7 @@ static int nla_put_nh_group(struct sk_buff *skb, struct nexthop *nh,
 
 	if (op_flags & NHA_OP_FLAG_DUMP_STATS &&
 	    (nla_put_u32(skb, NHA_HW_STATS_ENABLE, nhg->hw_stats) ||
-	     nla_put_nh_group_stats(skb, nh)))
+	     nla_put_nh_group_stats(skb, nh, op_flags)))
 		goto nla_put_failure;
 
 	return 0;
-- 
2.43.0

Re: [PATCH net-next 2/7] net: nexthop: Add NHA_OP_FLAGS

[Jakub Kicinski]

On Tue, 27 Feb 2024 19:17:27 +0100 Petr Machata wrote:
> +	/* bitfield32; operation-specific flags */
> +	NHA_OP_FLAGS,

>  static const struct nla_policy rtm_nh_policy_get[] = {
>  	[NHA_ID]		= { .type = NLA_U32 },
> +	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(0),

Why bitfiled? You never use the mask.
bitfield gives you the ability to do RMW "atomically" on object fields.
For op flags I don't think it makes much sense.

Re: [PATCH net-next 4/7] net: nexthop: Expose nexthop group stats to user space

[Jakub Kicinski]

On Tue, 27 Feb 2024 19:17:29 +0100 Petr Machata wrote:
> +	NHA_GROUP_STATS_ENTRY_PAD = NHA_GROUP_STATS_ENTRY_UNSPEC,
> +
> +	/* u32; nexthop id of the nexthop group entry */
> +	NHA_GROUP_STATS_ENTRY_ID,
> +
> +	/* u64; number of packets forwarded via the nexthop group entry */
> +	NHA_GROUP_STATS_ENTRY_PACKETS,

auto-int, please - nla_put_uint() etc.
No need for the padding or guessing how big the value needs to be.

Re: [PATCH net-next 7/7] net: nexthop: Expose nexthop group HW stats to user space

[Jakub Kicinski]

On Tue, 27 Feb 2024 19:17:32 +0100 Petr Machata wrote:
> +	if (nla_put_u32(skb, NHA_HW_STATS_ENABLE, nhg->hw_stats))
> +		goto nla_put_failure;
> +
> +	if (op_flags & NHA_OP_FLAG_DUMP_HW_STATS &&
> +	    nhg->hw_stats) {
> +		err = nh_grp_hw_stats_update(nh, &hw_stats_used);
> +		if (err)
> +			goto hw_stats_update_fail;
> +
> +		if (nla_put_u32(skb, NHA_HW_STATS_USED, hw_stats_used))
> +			goto nla_put_failure;

Something's off with the jump targets here.
clang detects nest is not initialized and you'll try to cancel it

> +	}
> +
>  	nest = nla_nest_start(skb, NHA_GROUP_STATS);
>  	if (!nest)
>  		return -EMSGSIZE;
>  
>  	for (i = 0; i < nhg->num_nh; i++)
> -		if (nla_put_nh_group_stats_entry(skb, &nhg->nh_entries[i]))
> +		if (nla_put_nh_group_stats_entry(skb, &nhg->nh_entries[i],
> +						 op_flags))
>  			goto nla_put_failure;
>  
>  	nla_nest_end(skb, nest);
>  	return 0;
>  
>  nla_put_failure:
> +	err = -EMSGSIZE;
> +hw_stats_update_fail:
>  	nla_nest_cancel(skb, nest);
> -	return -EMSGSIZE;
> +	return err;
-- 
pw-bot: cr

Re: [PATCH net-next 7/7] net: nexthop: Expose nexthop group HW stats to user space

[Kees Cook]

On Tue, Feb 27, 2024 at 07:17:32PM +0100, Petr Machata wrote:
> [...]
> diff --git a/include/net/nexthop.h b/include/net/nexthop.h
> index 20cd337b4a9c..235f94ab16a8 100644
> --- a/include/net/nexthop.h
> +++ b/include/net/nexthop.h
> [...]
> @@ -214,6 +217,17 @@ struct nh_notifier_res_table_info {
>  	struct nh_notifier_single_info nhs[] __counted_by(num_nh_buckets);
>  };
>  
> +struct nh_notifier_grp_hw_stats_entry_info {
> +	u32 id;
> +	u64 packets;
> +};
> +
> +struct nh_notifier_grp_hw_stats_info {
> +	u16 num_nh;
> +	bool hw_stats_used;
> +	struct nh_notifier_grp_hw_stats_entry_info stats[] __counted_by(num_nh);
> +};
> +
>  struct nh_notifier_info {
>  	struct net *net;
>  	struct netlink_ext_ack *extack;
> [...]
> @@ -685,8 +687,95 @@ static void nh_grp_entry_stats_read(struct nh_grp_entry *nhge,
>  	}
>  }
>  
> +static int nh_notifier_grp_hw_stats_init(struct nh_notifier_info *info,
> +					 const struct nexthop *nh)
> +{
> +	struct nh_group *nhg;
> +	int i;
> +
> +	ASSERT_RTNL();
> +	nhg = rtnl_dereference(nh->nh_grp);
> +
> +	info->id = nh->id;
> +	info->type = NH_NOTIFIER_INFO_TYPE_GRP_HW_STATS;
> +	info->nh_grp_hw_stats = kzalloc(struct_size(info->nh_grp_hw_stats,
> +						    stats, nhg->num_nh),
> +					GFP_KERNEL);
> +	if (!info->nh_grp_hw_stats)
> +		return -ENOMEM;
> +
> +	info->nh_grp_hw_stats->num_nh = nhg->num_nh;
> +	for (i = 0; i < nhg->num_nh; i++) {
> +		struct nh_grp_entry *nhge = &nhg->nh_entries[i];
> +
> +		info->nh_grp_hw_stats->stats[i].id = nhge->nh->id;
> +	}

The order of operations using __counted_by looks good to me: allocate,
assign counter (num_nh), access flex array (stats).

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH net-next 2/7] net: nexthop: Add NHA_OP_FLAGS

[Petr Machata]

Jakub Kicinski <kuba@kernel.org> writes:

> On Tue, 27 Feb 2024 19:17:27 +0100 Petr Machata wrote:
>> +	/* bitfield32; operation-specific flags */
>> +	NHA_OP_FLAGS,
>
>>  static const struct nla_policy rtm_nh_policy_get[] = {
>>  	[NHA_ID]		= { .type = NLA_U32 },
>> +	[NHA_OP_FLAGS]		= NLA_POLICY_BITFIELD32(0),
>
> Why bitfiled? You never use the mask.
> bitfield gives you the ability to do RMW "atomically" on object fields.
> For op flags I don't think it makes much sense.

Mostly because we get flag validation for free, whereas it would need to
be hand-rolled for u32. But also I don't know what will be useful in the
future. It would be silly to have to add another flags attribute as
bitfield because this time we actually care about toggling single bits
of an object.

Re: [PATCH net-next 4/7] net: nexthop: Expose nexthop group stats to user space

[Petr Machata]

Jakub Kicinski <kuba@kernel.org> writes:

> On Tue, 27 Feb 2024 19:17:29 +0100 Petr Machata wrote:
>> +	NHA_GROUP_STATS_ENTRY_PAD = NHA_GROUP_STATS_ENTRY_UNSPEC,
>> +
>> +	/* u32; nexthop id of the nexthop group entry */
>> +	NHA_GROUP_STATS_ENTRY_ID,
>> +
>> +	/* u64; number of packets forwarded via the nexthop group entry */
>> +	NHA_GROUP_STATS_ENTRY_PACKETS,
>
> auto-int, please - nla_put_uint() etc.
> No need for the padding or guessing how big the value needs to be.

OK.

Re: [PATCH net-next 3/7] net: nexthop: Add nexthop group entry stats

[Simon Horman]

On Tue, Feb 27, 2024 at 07:17:28PM +0100, Petr Machata wrote:

...

> @@ -2483,6 +2492,12 @@ static struct nexthop *nexthop_create_group(struct net *net,
>  		if (nhi->family == AF_INET)
>  			nhg->has_v4 = true;
>  
> +		nhg->nh_entries[i].stats =
> +			netdev_alloc_pcpu_stats(struct nh_grp_entry_stats);
> +		if (!nhg->nh_entries[i].stats) {
> +			nexthop_put(nhe);
> +			goto out_no_nh;

Hi Petr and Ido,

Jumping to the out_no_nh label will result in err being returned,
however it appears that err is uninitialised here. Perhaps
it should be set to a negative error value?

Flagged by Smatch.

> +		}
>  		nhg->nh_entries[i].nh = nhe;
>  		nhg->nh_entries[i].weight = entry[i].weight + 1;
>  		list_add(&nhg->nh_entries[i].nh_list, &nhe->grp_list);

...

Re: [PATCH net-next 2/7] net: nexthop: Add NHA_OP_FLAGS

[Jakub Kicinski]

On Wed, 28 Feb 2024 11:50:33 +0100 Petr Machata wrote:
> > Why bitfiled? You never use the mask.
> > bitfield gives you the ability to do RMW "atomically" on object fields.
> > For op flags I don't think it makes much sense.  
> 
> Mostly because we get flag validation for free, whereas it would need to
> be hand-rolled for u32. 

NLA_POLICY_MASK() ?

> But also I don't know what will be useful in the
> future. It would be silly to have to add another flags attribute as
> bitfield because this time we actually care about toggling single bits
> of an object.

IDK how you can do RMW on operation flags, that only makes sense if
you're modifying something. Besides you're not using BITFIELD right,
you're ignoring the mask completely now.

Re: [PATCH net-next 2/7] net: nexthop: Add NHA_OP_FLAGS

[Jakub Kicinski]

On Wed, 28 Feb 2024 06:48:59 -0800 Jakub Kicinski wrote:
> > But also I don't know what will be useful in the
> > future. It would be silly to have to add another flags attribute as
> > bitfield because this time we actually care about toggling single bits
> > of an object.  
> 
> IDK how you can do RMW on operation flags, that only makes sense if
> you're modifying something. Besides you're not using BITFIELD right,
> you're ignoring the mask completely now.

Let me rephrase this a bit since I've had my coffee now :)
BITFILED is designed to do:

	object->flags = object->flags & ~bf->mask | bf->flags;

since there's no object, there's nothing to & the mask with.
Plus if we do have some object flags at some point, chances 
are we'd want the uAPI flags to mirror the recorded object flags
so that we don't have to translate bit positions, so new attr
will be cleaner.

That's just in the way of clarifying my thinking, your call..

Re: [PATCH net-next 3/7] net: nexthop: Add nexthop group entry stats

[Petr Machata]

Simon Horman <horms@kernel.org> writes:

> On Tue, Feb 27, 2024 at 07:17:28PM +0100, Petr Machata wrote:
>
>> @@ -2483,6 +2492,12 @@ static struct nexthop *nexthop_create_group(struct net *net,
>>  		if (nhi->family == AF_INET)
>>  			nhg->has_v4 = true;
>>  
>> +		nhg->nh_entries[i].stats =
>> +			netdev_alloc_pcpu_stats(struct nh_grp_entry_stats);
>> +		if (!nhg->nh_entries[i].stats) {
>> +			nexthop_put(nhe);
>> +			goto out_no_nh;
>
> Hi Petr and Ido,
>
> Jumping to the out_no_nh label will result in err being returned,
> however it appears that err is uninitialised here. Perhaps
> it should be set to a negative error value?
>
> Flagged by Smatch.

Pretty sure. It's missing an err = -ENOMEM.

Re: [PATCH net-next 2/7] net: nexthop: Add NHA_OP_FLAGS

[Petr Machata]

Jakub Kicinski <kuba@kernel.org> writes:

> On Wed, 28 Feb 2024 06:48:59 -0800 Jakub Kicinski wrote:
>> > But also I don't know what will be useful in the
>> > future. It would be silly to have to add another flags attribute as
>> > bitfield because this time we actually care about toggling single bits
>> > of an object.  
>> 
>> IDK how you can do RMW on operation flags, that only makes sense if
>> you're modifying something. Besides you're not using BITFIELD right,
>> you're ignoring the mask completely now.
>
> Let me rephrase this a bit since I've had my coffee now :)
> BITFILED is designed to do:
>
> 	object->flags = object->flags & ~bf->mask | bf->flags;
>
> since there's no object, there's nothing to & the mask with.
> Plus if we do have some object flags at some point, chances 
> are we'd want the uAPI flags to mirror the recorded object flags
> so that we don't have to translate bit positions, so new attr
> will be cleaner.
>
> That's just in the way of clarifying my thinking, your call..

Oh, I see, it wouldn't be useful as an attribute in isolation, and if we
ever introduce flags field for the NH objects, we would want a separate
attribute for it anyway. So whatever new uses the OP_FLAGS attribute
would be put to, we know we won't need the mask.

Um, so as I said, I mostly figured let's use bitfield because of the
validation. I really like how it's all part of the policy and there's no
explicit checking code. So I'd keep it as it is.

Re: [PATCH net-next 2/7] net: nexthop: Add NHA_OP_FLAGS

[Jakub Kicinski]

On Wed, 28 Feb 2024 16:58:24 +0100 Petr Machata wrote:
> Um, so as I said, I mostly figured let's use bitfield because of the
> validation. I really like how it's all part of the policy and there's no
> explicit checking code. So I'd keep it as it is.

FWIW the same validation is possible for bare unsigned types with
NLA_POLICY_MASK().

Re: [PATCH net-next 7/7] net: nexthop: Expose nexthop group HW stats to user space

[Petr Machata]

Jakub Kicinski <kuba@kernel.org> writes:

> On Tue, 27 Feb 2024 19:17:32 +0100 Petr Machata wrote:
>> +	if (nla_put_u32(skb, NHA_HW_STATS_ENABLE, nhg->hw_stats))
>> +		goto nla_put_failure;
>> +
>> +	if (op_flags & NHA_OP_FLAG_DUMP_HW_STATS &&
>> +	    nhg->hw_stats) {
>> +		err = nh_grp_hw_stats_update(nh, &hw_stats_used);
>> +		if (err)
>> +			goto hw_stats_update_fail;
>> +
>> +		if (nla_put_u32(skb, NHA_HW_STATS_USED, hw_stats_used))
>> +			goto nla_put_failure;
>
> Something's off with the jump targets here.
> clang detects nest is not initialized and you'll try to cancel it

Yes, the nest only starts below. Will fix.
>
>> +	}
>> +
>>  	nest = nla_nest_start(skb, NHA_GROUP_STATS);
>>  	if (!nest)
>>  		return -EMSGSIZE;

Re: [PATCH net-next 2/7] net: nexthop: Add NHA_OP_FLAGS

[Petr Machata]

Jakub Kicinski <kuba@kernel.org> writes:

> On Wed, 28 Feb 2024 16:58:24 +0100 Petr Machata wrote:
>> Um, so as I said, I mostly figured let's use bitfield because of the
>> validation. I really like how it's all part of the policy and there's no
>> explicit checking code. So I'd keep it as it is.
>
> FWIW the same validation is possible for bare unsigned types with
> NLA_POLICY_MASK().

Awesome, that's what I need.