Linux Ethernet Bridging - May 2023 - [Bridge] [RFC PATCH net-next 3/5] flow_offload: Reject matching on layer 2 miss

tl;dr
====
This patchset adds a single bit to the skb to indicate that a packet
encountered a layer 2 miss in the bridge and extends flower to match on
this metadata. This is required for non-DF (Designated Forwarder)
filtering in EVPN multi-homing which prevents decapsulated BUM packets
from being forwarded multiple times to the same multi-homed host.

Background
=========
In a typical EVPN multi-homing setup each host is multi-homed using a
set of links called ES (Ethernet Segment, i.e., LAG) to multiple leaf
switches in a rack. These switches act as VTEPs and are not directly
connected (as opposed to MLAG), but can communicate with each other (as
well as with VTEPs in remote racks) via spine switches over L3.

When a host sends a BUM packet over ES1 to VTEP1, the VTEP will flood it
to other VTEPs in the network, including those connected to the host
over ES1. The receiving VTEPs must drop the packet and not forward it
back to the host. This is called "split-horizon filtering" (SPH) [1].

FRR configures SPH filtering using two tc filters. The first, an ingress
filter that matches on packets received from VTEP1 and marks them using
a fwmark (firewall mark). The second, an egress filter configured on the
LAG interface connected to the host that matches on the fwmark and drops
the packets. Example:

 # tc filter add dev vxlan0 ingress pref 1 proto all flower enc_src_ip $VTEP1_IP
action skbedit mark 101
 # tc filter add dev bond0 egress pref 1 handle 101 fw action drop

Motivation
=========
For each ES, only one VTEP is elected by the control plane as the DF.
The DF is responsible for forwarding decapsulated BUM traffic to the
host over the ES. The non-DF VTEPs must drop such traffic as otherwise
the host will receive multiple copies of BUM traffic. This is called
"non-DF filtering" [2].

Filtering of multicast and broadcast traffic can be achieved using the
following flower filter:

 # tc filter add dev bond0 egress pref 1 proto all flower indev vxlan0 dst_mac
01:00:00:00:00:00/01:00:00:00:00:00 action drop

Unlike broadcast and multicast traffic, it is not currently possible to
filter unknown unicast traffic. The classification into unknown unicast
is performed by the bridge driver, but is not visible to other layers.

Implementation
=============
The proposed solution is to add a single bit to the skb that is set by
the bridge for packets that encountered an FDB/MDB miss. The flower
classifier is extended to be able to match on this new metadata bit in a
similar fashion to existing metadata options such as 'indev'.

A bit that is set for every flooded packet would also work, but it does
not allow us to differentiate between registered and unregistered
multicast traffic which might be useful in the future.

A relatively generic name is chosen for this bit - 'l2_miss' - to allow
its use to be extended to other layer 2 devices such as VXLAN, should a
use case arise.

With the above, the control plane can implement a non-DF filter using
the following tc filters:

 # tc filter add dev bond0 egress pref 1 proto all flower indev vxlan0 dst_mac
01:00:00:00:00:00/01:00:00:00:00:00 action drop
 # tc filter add dev bond0 egress pref 2 proto all flower indev vxlan0 l2_miss
true action drop

The first drops broadcast and multicast traffic and the second drops
unknown unicast traffic.

Testing
======
A test exercising the different permutations of the 'l2_miss' bit is
added in patch #5.

Patchset overview
================
Patch #1 adds the new bit to the skb and sets it in the bridge driver
for packets that encountered a miss. The new bit is added in an existing
hole in the skb in order not to inflate this data structure.

Patch #2 extends the flower classifier to be able to match on the new
layer 2 miss metadata.

Patch #3 rejects matching on the new metadata in drivers that already
support the 'FLOW_DISSECTOR_KEY_META' key.

Patch #4 extends mlxsw to be able to match on layer 2 miss.

Patch #5 adds a selftest.

iproute2 patches can be found here [3].

[1] https://datatracker.ietf.org/doc/html/rfc7432#section-8.3
[2] https://datatracker.ietf.org/doc/html/rfc7432#section-8.5
[3] https://github.com/idosch/iproute2/tree/submit/non_df_filter_v1

Ido Schimmel (5):
  skbuff: bridge: Add layer 2 miss indication
  net/sched: flower: Allow matching on layer 2 miss
  flow_offload: Reject matching on layer 2 miss
  mlxsw: spectrum_flower: Add ability to match on layer 2 miss
  selftests: forwarding: Add layer 2 miss test cases

 .../marvell/prestera/prestera_flower.c        |   6 +
 .../net/ethernet/mellanox/mlx5/core/en_tc.c   |   6 +
 .../mellanox/mlxsw/core_acl_flex_keys.c       |   1 +
 .../mellanox/mlxsw/core_acl_flex_keys.h       |   3 +-
 .../mellanox/mlxsw/spectrum_acl_flex_keys.c   |   5 +
 .../ethernet/mellanox/mlxsw/spectrum_flower.c |  16 +
 drivers/net/ethernet/mscc/ocelot_flower.c     |  10 +
 include/linux/skbuff.h                        |   4 +
 include/net/flow_dissector.h                  |   2 +
 include/uapi/linux/pkt_cls.h                  |   2 +
 net/bridge/br_device.c                        |   1 +
 net/bridge/br_forward.c                       |   3 +
 net/bridge/br_input.c                         |   1 +
 net/core/flow_dissector.c                     |   3 +
 net/sched/cls_flower.c                        |  14 +-
 .../testing/selftests/net/forwarding/Makefile |   1 +
 .../net/forwarding/tc_flower_l2_miss.sh       | 343 ++++++++++++++++++
 17 files changed, 418 insertions(+), 3 deletions(-)
 create mode 100755 tools/testing/selftests/net/forwarding/tc_flower_l2_miss.sh

-- 
2.40.1

Allow the bridge driver to mark packets that did not match a layer 2
entry during forwarding by adding a 'l2_miss' bit to the skb.

Clear the bit whenever a packet enters the bridge (received from a
bridge port or transmitted via the bridge) and set it if the packet did
not match an FDB/MDB entry.

Subsequent patches will allow the flower classifier to match on this
bit. The motivating use case in non-DF (Designated Forwarder) filtering
where we would like to prevent decapsulated packets from being flooded
to a multi-homed host.

Do not allocate the bit if the kernel was not compiled with bridge
support and place it after the two bit fields in accordance with commit
4c60d04c2888 ("net: skbuff: push nf_trace down the bitfield"). The bit
does not increase the size of the structure as it is placed at an
existing hole. Layout with allmodconfig:

struct sk_buff {
[...]
			__u8       csum_not_inet:1;      /*   132: 3  1 */
			__u8       l2_miss:1;            /*   132: 4  1 */

			/* XXX 3 bits hole, try to pack */
			/* XXX 1 byte hole, try to pack */

			__u16      tc_index;             /*   134     2 */
			u16        alloc_cpu;            /*   136     2 */
[...]
} __attribute__((__aligned__(8)));

Signed-off-by: Ido Schimmel <idosch at nvidia.com>
---
 include/linux/skbuff.h  | 4 ++++
 net/bridge/br_device.c  | 1 +
 net/bridge/br_forward.c | 3 +++
 net/bridge/br_input.c   | 1 +
 4 files changed, 9 insertions(+)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 738776ab8838..c7a84767ed48 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -801,6 +801,7 @@ typedef unsigned char *sk_buff_data_t;
  *	@encap_hdr_csum: software checksum is needed
  *	@csum_valid: checksum is already valid
  *	@csum_not_inet: use CRC32c to resolve CHECKSUM_PARTIAL
+ *	@l2_miss: Packet did not match an L2 entry during forwarding
  *	@csum_complete_sw: checksum was completed by software
  *	@csum_level: indicates the number of consecutive checksums found in
  *		the packet minus one that have been verified as
@@ -991,6 +992,9 @@ struct sk_buff {
 #if IS_ENABLED(CONFIG_IP_SCTP)
 	__u8			csum_not_inet:1;
 #endif
+#if IS_ENABLED(CONFIG_BRIDGE)
+	__u8			l2_miss:1;
+#endif
 
 #ifdef CONFIG_NET_SCHED
 	__u16			tc_index;	/* traffic control index */
diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 8eca8a5c80c6..91dbdae4afd4 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -39,6 +39,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device
*dev)
 	u16 vid = 0;
 
 	memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
+	skb->l2_miss = 0;
 
 	rcu_read_lock();
 	nf_ops = rcu_dereference(nf_br_ops);
diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index 57744704ff69..5893648c4da2 100644
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -203,6 +203,8 @@ void br_flood(struct net_bridge *br, struct sk_buff *skb,
 	struct net_bridge_port *prev = NULL;
 	struct net_bridge_port *p;
 
+	skb->l2_miss = 1;
+
 	list_for_each_entry_rcu(p, &br->port_list, list) {
 		/* Do not flood unicast traffic to ports that turn it off, nor
 		 * other traffic if flood off, except for traffic we originate
@@ -295,6 +297,7 @@ void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 			allow_mode_include = false;
 	} else {
 		p = NULL;
+		skb->l2_miss = 1;
 	}
 
 	while (p || rp) {
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index fc17b9fd93e6..d8ab5890cbe6 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -334,6 +334,7 @@ static rx_handler_result_t br_handle_frame(struct sk_buff
**pskb)
 		return RX_HANDLER_CONSUMED;
 
 	memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
+	skb->l2_miss = 0;
 
 	p = br_port_get_rcu(skb->dev);
 	if (p->flags & BR_VLAN_TUNNEL)
-- 
2.40.1

Add the 'TCA_FLOWER_L2_MISS' netlink attribute that allows user space to
match on packets that encountered a layer 2 miss. The miss indication is
set as metadata in the skb by the bridge driver upon FDB/MDB lookup
miss.

Signed-off-by: Ido Schimmel <idosch at nvidia.com>
---
 include/net/flow_dissector.h |  2 ++
 include/uapi/linux/pkt_cls.h |  2 ++
 net/core/flow_dissector.c    |  3 +++
 net/sched/cls_flower.c       | 14 ++++++++++++--
 4 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 85b2281576ed..8b41668c77fc 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -243,10 +243,12 @@ struct flow_dissector_key_ip {
  * struct flow_dissector_key_meta:
  * @ingress_ifindex: ingress ifindex
  * @ingress_iftype: ingress interface type
+ * @l2_miss: packet did not match an L2 entry during forwarding
  */
 struct flow_dissector_key_meta {
 	int ingress_ifindex;
 	u16 ingress_iftype;
+	u8 l2_miss;
 };
 
 /**
diff --git a/include/uapi/linux/pkt_cls.h b/include/uapi/linux/pkt_cls.h
index 648a82f32666..00933dda7b10 100644
--- a/include/uapi/linux/pkt_cls.h
+++ b/include/uapi/linux/pkt_cls.h
@@ -594,6 +594,8 @@ enum {
 
 	TCA_FLOWER_KEY_L2TPV3_SID,	/* be32 */
 
+	TCA_FLOWER_L2_MISS,		/* u8 */
+
 	__TCA_FLOWER_MAX,
 };
 
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 25fb0bbc310f..3776c7bdd228 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -241,6 +241,9 @@ void skb_flow_dissect_meta(const struct sk_buff *skb,
 					 FLOW_DISSECTOR_KEY_META,
 					 target_container);
 	meta->ingress_ifindex = skb->skb_iif;
+#if IS_ENABLED(CONFIG_BRIDGE)
+	meta->l2_miss = skb->l2_miss;
+#endif
 }
 EXPORT_SYMBOL(skb_flow_dissect_meta);
 
diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 9dbc43388e57..4eb06c6367fc 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -615,7 +615,8 @@ static void *fl_get(struct tcf_proto *tp, u32 handle)
 }
 
 static const struct nla_policy fl_policy[TCA_FLOWER_MAX + 1] = {
-	[TCA_FLOWER_UNSPEC]		= { .type = NLA_UNSPEC },
+	[TCA_FLOWER_UNSPEC]		= { .strict_start_type +						TCA_FLOWER_L2_MISS },
 	[TCA_FLOWER_CLASSID]		= { .type = NLA_U32 },
 	[TCA_FLOWER_INDEV]		= { .type = NLA_STRING,
 					    .len = IFNAMSIZ },
@@ -720,7 +721,7 @@ static const struct nla_policy fl_policy[TCA_FLOWER_MAX + 1]
= {
 	[TCA_FLOWER_KEY_PPPOE_SID]	= { .type = NLA_U16 },
 	[TCA_FLOWER_KEY_PPP_PROTO]	= { .type = NLA_U16 },
 	[TCA_FLOWER_KEY_L2TPV3_SID]	= { .type = NLA_U32 },
-
+	[TCA_FLOWER_L2_MISS]		= NLA_POLICY_MAX(NLA_U8, 1),
 };
 
 static const struct nla_policy
@@ -1668,6 +1669,10 @@ static int fl_set_key(struct net *net, struct nlattr
**tb,
 		mask->meta.ingress_ifindex = 0xffffffff;
 	}
 
+	fl_set_key_val(tb, &key->meta.l2_miss, TCA_FLOWER_L2_MISS,
+		       &mask->meta.l2_miss, TCA_FLOWER_UNSPEC,
+		       sizeof(key->meta.l2_miss));
+
 	fl_set_key_val(tb, key->eth.dst, TCA_FLOWER_KEY_ETH_DST,
 		       mask->eth.dst, TCA_FLOWER_KEY_ETH_DST_MASK,
 		       sizeof(key->eth.dst));
@@ -3074,6 +3079,11 @@ static int fl_dump_key(struct sk_buff *skb, struct net
*net,
 			goto nla_put_failure;
 	}
 
+	if (fl_dump_key_val(skb, &key->meta.l2_miss,
+			    TCA_FLOWER_L2_MISS, &mask->meta.l2_miss,
+			    TCA_FLOWER_UNSPEC, sizeof(key->meta.l2_miss)))
+		goto nla_put_failure;
+
 	if (fl_dump_key_val(skb, key->eth.dst, TCA_FLOWER_KEY_ETH_DST,
 			    mask->eth.dst, TCA_FLOWER_KEY_ETH_DST_MASK,
 			    sizeof(key->eth.dst)) ||
-- 
2.40.1

Adjust drivers that support the 'FLOW_DISSECTOR_KEY_META' key to reject
filters that try to match on the newly added layer 2 miss option. Add an
extack message to clearly communicate the failure reason to user space.

Example:

 # tc filter add dev swp1 egress pref 1 proto all flower skip_sw l2_miss true
action drop
 Error: mlxsw_spectrum: Can't match on "l2_miss".
 We have an error talking to the kernel

Signed-off-by: Ido Schimmel <idosch at nvidia.com>
---
 .../net/ethernet/marvell/prestera/prestera_flower.c    |  6 ++++++
 drivers/net/ethernet/mellanox/mlx5/core/en_tc.c        |  6 ++++++
 drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c  |  6 ++++++
 drivers/net/ethernet/mscc/ocelot_flower.c              | 10 ++++++++++
 4 files changed, 28 insertions(+)

diff --git a/drivers/net/ethernet/marvell/prestera/prestera_flower.c
b/drivers/net/ethernet/marvell/prestera/prestera_flower.c
index 91a478b75cbf..3e20e71b0f81 100644
--- a/drivers/net/ethernet/marvell/prestera/prestera_flower.c
+++ b/drivers/net/ethernet/marvell/prestera/prestera_flower.c
@@ -148,6 +148,12 @@ static int prestera_flower_parse_meta(struct
prestera_acl_rule *rule,
 	__be16 key, mask;
 
 	flow_rule_match_meta(f_rule, &match);
+
+	if (match.mask->l2_miss) {
+		NL_SET_ERR_MSG_MOD(f->common.extack, "Can't match on
\"l2_miss\"");
+		return -EOPNOTSUPP;
+	}
+
 	if (match.mask->ingress_ifindex != 0xFFFFFFFF) {
 		NL_SET_ERR_MSG_MOD(f->common.extack,
 				   "Unsupported ingress ifindex mask");
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index 728b82ce4031..516653568330 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -2586,6 +2586,12 @@ static int mlx5e_flower_parse_meta(struct net_device
*filter_dev,
 		return 0;
 
 	flow_rule_match_meta(rule, &match);
+
+	if (match.mask->l2_miss) {
+		NL_SET_ERR_MSG_MOD(f->common.extack, "Can't match on
\"l2_miss\"");
+		return -EOPNOTSUPP;
+	}
+
 	if (!match.mask->ingress_ifindex)
 		return 0;
 
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c
b/drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c
index 594cdcb90b3d..6fec9223250b 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c
@@ -294,6 +294,12 @@ static int mlxsw_sp_flower_parse_meta(struct
mlxsw_sp_acl_rule_info *rulei,
 		return 0;
 
 	flow_rule_match_meta(rule, &match);
+
+	if (match.mask->l2_miss) {
+		NL_SET_ERR_MSG_MOD(f->common.extack, "Can't match on
\"l2_miss\"");
+		return -EOPNOTSUPP;
+	}
+
 	if (match.mask->ingress_ifindex != 0xFFFFFFFF) {
 		NL_SET_ERR_MSG_MOD(f->common.extack, "Unsupported ingress ifindex
mask");
 		return -EINVAL;
diff --git a/drivers/net/ethernet/mscc/ocelot_flower.c
b/drivers/net/ethernet/mscc/ocelot_flower.c
index ee052404eb55..e0916afcddfb 100644
--- a/drivers/net/ethernet/mscc/ocelot_flower.c
+++ b/drivers/net/ethernet/mscc/ocelot_flower.c
@@ -592,6 +592,16 @@ ocelot_flower_parse_key(struct ocelot *ocelot, int port,
bool ingress,
 		return -EOPNOTSUPP;
 	}
 
+	if (flow_rule_match_key(rule, FLOW_DISSECTOR_KEY_META)) {
+		struct flow_match_meta match;
+
+		flow_rule_match_meta(rule, &match);
+		if (match.mask->l2_miss) {
+			NL_SET_ERR_MSG_MOD(extack, "Can't match on
\"l2_miss\"");
+			return -EOPNOTSUPP;
+		}
+	}
+
 	/* For VCAP ES0 (egress rewriter) we can match on the ingress port */
 	if (!ingress) {
 		ret = ocelot_flower_parse_indev(ocelot, port, f, filter);
-- 
2.40.1

Add the 'dmac_type' key element to supported key blocks and make use of
it to match on layer 2 miss.

This is a two bits key in hardware with the following values:
00b - Known multicast.
01b - Broadcast.
10b - Known unicast.
11b - Unknown unicast or unregistered multicast.

When 'l2_miss' is set we need to match on 01b or 11b. Therefore, only
match on the LSB in order to differentiate between both cases of
'l2_miss'.

Tested on Spectrum-{1,2,3,4}.

Signed-off-by: Ido Schimmel <idosch at nvidia.com>
---
 .../mellanox/mlxsw/core_acl_flex_keys.c       |  1 +
 .../mellanox/mlxsw/core_acl_flex_keys.h       |  3 ++-
 .../mellanox/mlxsw/spectrum_acl_flex_keys.c   |  5 +++++
 .../ethernet/mellanox/mlxsw/spectrum_flower.c | 20 ++++++++++++++-----
 4 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_keys.c
b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_keys.c
index bd1a51a0a540..81af0b9a4329 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_keys.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_keys.c
@@ -42,6 +42,7 @@ static const struct mlxsw_afk_element_info
mlxsw_afk_element_infos[] = {
 	MLXSW_AFK_ELEMENT_INFO_BUF(DST_IP_64_95, 0x34, 4),
 	MLXSW_AFK_ELEMENT_INFO_BUF(DST_IP_32_63, 0x38, 4),
 	MLXSW_AFK_ELEMENT_INFO_BUF(DST_IP_0_31, 0x3C, 4),
+	MLXSW_AFK_ELEMENT_INFO_U32(DMAC_TYPE, 0x40, 0, 2),
 };
 
 struct mlxsw_afk {
diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_keys.h
b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_keys.h
index 3a037fe47211..6f1649cfa4cb 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_keys.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_keys.h
@@ -35,6 +35,7 @@ enum mlxsw_afk_element {
 	MLXSW_AFK_ELEMENT_IP_DSCP,
 	MLXSW_AFK_ELEMENT_VIRT_ROUTER_MSB,
 	MLXSW_AFK_ELEMENT_VIRT_ROUTER_LSB,
+	MLXSW_AFK_ELEMENT_DMAC_TYPE,
 	MLXSW_AFK_ELEMENT_MAX,
 };
 
@@ -69,7 +70,7 @@ struct mlxsw_afk_element_info {
 	MLXSW_AFK_ELEMENT_INFO(MLXSW_AFK_ELEMENT_TYPE_BUF,			\
 			       _element, _offset, 0, _size)
 
-#define MLXSW_AFK_ELEMENT_STORAGE_SIZE 0x40
+#define MLXSW_AFK_ELEMENT_STORAGE_SIZE 0x44
 
 struct mlxsw_afk_element_inst { /* element instance in actual block */
 	enum mlxsw_afk_element element;
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_flex_keys.c
b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_flex_keys.c
index 00c32320f891..18a968cded36 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_flex_keys.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_flex_keys.c
@@ -26,6 +26,7 @@ static struct mlxsw_afk_element_inst
mlxsw_sp_afk_element_info_l2_smac[] = {
 static struct mlxsw_afk_element_inst mlxsw_sp_afk_element_info_l2_smac_ex[] = {
 	MLXSW_AFK_ELEMENT_INST_BUF(SMAC_32_47, 0x02, 2),
 	MLXSW_AFK_ELEMENT_INST_BUF(SMAC_0_31, 0x04, 4),
+	MLXSW_AFK_ELEMENT_INST_U32(DMAC_TYPE, 0x08, 0, 2),
 	MLXSW_AFK_ELEMENT_INST_U32(ETHERTYPE, 0x0C, 0, 16),
 };
 
@@ -50,6 +51,7 @@ static struct mlxsw_afk_element_inst
mlxsw_sp_afk_element_info_ipv4[] = {
 };
 
 static struct mlxsw_afk_element_inst mlxsw_sp_afk_element_info_ipv4_ex[] = {
+	MLXSW_AFK_ELEMENT_INST_U32(DMAC_TYPE, 0x00, 24, 2),
 	MLXSW_AFK_ELEMENT_INST_U32(VID, 0x00, 0, 12),
 	MLXSW_AFK_ELEMENT_INST_U32(PCP, 0x08, 29, 3),
 	MLXSW_AFK_ELEMENT_INST_U32(SRC_L4_PORT, 0x08, 0, 16),
@@ -78,6 +80,7 @@ static struct mlxsw_afk_element_inst
mlxsw_sp_afk_element_info_ipv6_sip_ex[] = {
 };
 
 static struct mlxsw_afk_element_inst mlxsw_sp_afk_element_info_packet_type[] =
{
+	MLXSW_AFK_ELEMENT_INST_U32(DMAC_TYPE, 0x00, 30, 2),
 	MLXSW_AFK_ELEMENT_INST_U32(ETHERTYPE, 0x00, 0, 16),
 };
 
@@ -123,6 +126,7 @@ const struct mlxsw_afk_ops mlxsw_sp1_afk_ops = {
 };
 
 static struct mlxsw_afk_element_inst mlxsw_sp_afk_element_info_mac_0[] = {
+	MLXSW_AFK_ELEMENT_INST_U32(DMAC_TYPE, 0x00, 0, 2),
 	MLXSW_AFK_ELEMENT_INST_BUF(DMAC_0_31, 0x04, 4),
 };
 
@@ -313,6 +317,7 @@ const struct mlxsw_afk_ops mlxsw_sp2_afk_ops = {
 };
 
 static struct mlxsw_afk_element_inst mlxsw_sp_afk_element_info_mac_5b[] = {
+	MLXSW_AFK_ELEMENT_INST_U32(DMAC_TYPE, 0x00, 2, 2),
 	MLXSW_AFK_ELEMENT_INST_U32(VID, 0x04, 18, 12),
 	MLXSW_AFK_ELEMENT_INST_EXT_U32(SRC_SYS_PORT, 0x04, 0, 9, -1, true), /*
RX_ACL_SYSTEM_PORT */
 };
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c
b/drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c
index 6fec9223250b..170a07f35897 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c
@@ -295,11 +295,6 @@ static int mlxsw_sp_flower_parse_meta(struct
mlxsw_sp_acl_rule_info *rulei,
 
 	flow_rule_match_meta(rule, &match);
 
-	if (match.mask->l2_miss) {
-		NL_SET_ERR_MSG_MOD(f->common.extack, "Can't match on
\"l2_miss\"");
-		return -EOPNOTSUPP;
-	}
-
 	if (match.mask->ingress_ifindex != 0xFFFFFFFF) {
 		NL_SET_ERR_MSG_MOD(f->common.extack, "Unsupported ingress ifindex
mask");
 		return -EINVAL;
@@ -327,6 +322,21 @@ static int mlxsw_sp_flower_parse_meta(struct
mlxsw_sp_acl_rule_info *rulei,
 				       MLXSW_AFK_ELEMENT_SRC_SYS_PORT,
 				       mlxsw_sp_port->local_port,
 				       0xFFFFFFFF);
+
+	/* This is a two bits key in hardware with the following values:
+	 * 00b - Known multicast.
+	 * 01b - Broadcast.
+	 * 10b - Known unicast.
+	 * 11b - Unknown unicast or unregistered multicast.
+	 *
+	 * When 'l2_miss' is set we need to match on 01b or 11b. Therefore,
+	 * only match on the LSB in order to differentiate between both cases
+	 * of 'l2_miss'.
+	 */
+	mlxsw_sp_acl_rulei_keymask_u32(rulei, MLXSW_AFK_ELEMENT_DMAC_TYPE,
+				       match.key->l2_miss,
+				       match.mask->l2_miss & BIT(0));
+
 	return 0;
 }
 
-- 
2.40.1

Add test cases to verify that the bridge driver correctly marks layer 2
misses only when it should and that the flower classifier can match on
this metadata.

Example output:

 # ./tc_flower_l2_miss.sh
 TEST: L2 miss - Unicast                                             [ OK ]
 TEST: L2 miss - Multicast (IPv4)                                    [ OK ]
 TEST: L2 miss - Multicast (IPv6)                                    [ OK ]
 TEST: L2 miss - Link-local multicast (IPv4)                         [ OK ]
 TEST: L2 miss - Link-local multicast (IPv6)                         [ OK ]
 TEST: L2 miss - Broadcast                                           [ OK ]

Signed-off-by: Ido Schimmel <idosch at nvidia.com>
---
 .../testing/selftests/net/forwarding/Makefile |   1 +
 .../net/forwarding/tc_flower_l2_miss.sh       | 343 ++++++++++++++++++
 2 files changed, 344 insertions(+)
 create mode 100755 tools/testing/selftests/net/forwarding/tc_flower_l2_miss.sh

diff --git a/tools/testing/selftests/net/forwarding/Makefile
b/tools/testing/selftests/net/forwarding/Makefile
index a474c60fe348..9d0062b542e5 100644
--- a/tools/testing/selftests/net/forwarding/Makefile
+++ b/tools/testing/selftests/net/forwarding/Makefile
@@ -83,6 +83,7 @@ TEST_PROGS = bridge_igmp.sh \
 	tc_chains.sh \
 	tc_flower_router.sh \
 	tc_flower.sh \
+	tc_flower_l2_miss.sh \
 	tc_mpls_l2vpn.sh \
 	tc_police.sh \
 	tc_shblocks.sh \
diff --git a/tools/testing/selftests/net/forwarding/tc_flower_l2_miss.sh
b/tools/testing/selftests/net/forwarding/tc_flower_l2_miss.sh
new file mode 100755
index 000000000000..fbf0a960b2c8
--- /dev/null
+++ b/tools/testing/selftests/net/forwarding/tc_flower_l2_miss.sh
@@ -0,0 +1,343 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# +-----------------------+                            
+----------------------+
+# | H1 (vrf)              |                             | H2 (vrf)            
|
+# |    + $h1              |                             |              $h2 +  
|
+# |    | 192.0.2.1/28     |                             |     192.0.2.2/28 |  
|
+# |    | 2001:db8:1::1/64 |                             | 2001:db8:1::2/64 |  
|
+# +----|------------------+                            
+------------------|---+
+#      |                                                                   |
+#
+----|-------------------------------------------------------------------|---+
+# | SW |                                                                   |  
|
+# |  +-|-------------------------------------------------------------------|-+
|
+# |  | + $swp1                       BR                              $swp2 + |
|
+# |  +-----------------------------------------------------------------------+
|
+#
+----------------------------------------------------------------------------+
+
+ALL_TESTS="
+	test_l2_miss_unicast
+	test_l2_miss_multicast
+	test_l2_miss_ll_multicast
+	test_l2_miss_broadcast
+"
+
+NUM_NETIFS=4
+source lib.sh
+source tc_common.sh
+
+h1_create()
+{
+	simple_if_init $h1 192.0.2.1/28 2001:db8:1::1/64
+}
+
+h1_destroy()
+{
+	simple_if_fini $h1 192.0.2.1/28 2001:db8:1::1/64
+}
+
+h2_create()
+{
+	simple_if_init $h2 192.0.2.2/28 2001:db8:1::2/64
+}
+
+h2_destroy()
+{
+	simple_if_fini $h2 192.0.2.2/28 2001:db8:1::2/64
+}
+
+switch_create()
+{
+	ip link add name br1 up type bridge
+	ip link set dev $swp1 master br1
+	ip link set dev $swp1 up
+	ip link set dev $swp2 master br1
+	ip link set dev $swp2 up
+
+	tc qdisc add dev $swp2 clsact
+}
+
+switch_destroy()
+{
+	tc qdisc del dev $swp2 clsact
+
+	ip link set dev $swp2 down
+	ip link set dev $swp2 nomaster
+	ip link set dev $swp1 down
+	ip link set dev $swp1 nomaster
+	ip link del dev br1
+}
+
+test_l2_miss_unicast()
+{
+	local dmac=00:01:02:03:04:05
+	local dip=192.0.2.2
+	local sip=192.0.2.1
+
+	RET=0
+
+	# Unknown unicast.
+	tc filter add dev $swp2 egress protocol ipv4 handle 101 pref 1 \
+	   flower indev $swp1 l2_miss true dst_mac $dmac src_ip $sip \
+	   dst_ip $dip action pass
+	# Known unicast.
+	tc filter add dev $swp2 egress protocol ipv4 handle 102 pref 1 \
+	   flower indev $swp1 l2_miss false dst_mac $dmac src_ip $sip \
+	   dst_ip $dip action pass
+
+	# Before adding FDB entry.
+	$MZ $h1 -a own -b $dmac -t ip -A $sip -B $dip -c 1 -p 100 -q
+
+	tc_check_packets "dev $swp2 egress" 101 1
+	check_err $? "Unknown unicast filter was not hit before adding FDB
entry"
+
+	tc_check_packets "dev $swp2 egress" 102 0
+	check_err $? "Known unicast filter was hit before adding FDB entry"
+
+	# Adding FDB entry.
+	bridge fdb replace $dmac dev $swp2 master static
+
+	$MZ $h1 -a own -b $dmac -t ip -A $sip -B $dip -c 1 -p 100 -q
+
+	tc_check_packets "dev $swp2 egress" 101 1
+	check_err $? "Unknown unicast filter was hit after adding FDB entry"
+
+	tc_check_packets "dev $swp2 egress" 102 1
+	check_err $? "Known unicast filter was not hit after adding FDB
entry"
+
+	# Deleting FDB entry.
+	bridge fdb del $dmac dev $swp2 master static
+
+	$MZ $h1 -a own -b $dmac -t ip -A $sip -B $dip -c 1 -p 100 -q
+
+	tc_check_packets "dev $swp2 egress" 101 2
+	check_err $? "Unknown unicast filter was not hit after deleting FDB
entry"
+
+	tc_check_packets "dev $swp2 egress" 102 1
+	check_err $? "Known unicast filter was hit after deleting FDB entry"
+
+	tc filter del dev $swp2 egress protocol ipv4 pref 1 handle 102 flower
+	tc filter del dev $swp2 egress protocol ipv4 pref 1 handle 101 flower
+
+	log_test "L2 miss - Unicast"
+}
+
+test_l2_miss_multicast_common()
+{
+	local proto=$1; shift
+	local sip=$1; shift
+	local dip=$1; shift
+	local mode=$1; shift
+	local name=$1; shift
+
+	RET=0
+
+	# Unregistered multicast.
+	tc filter add dev $swp2 egress protocol $proto handle 101 pref 1 \
+	   flower indev $swp1 l2_miss true src_ip $sip dst_ip $dip \
+	   action pass
+	# Registered multicast.
+	tc filter add dev $swp2 egress protocol $proto handle 102 pref 1 \
+	   flower indev $swp1 l2_miss false src_ip $sip dst_ip $dip \
+	   action pass
+
+	# Before adding MDB entry.
+	$MZ $mode $h1 -t ip -A $sip -B $dip -c 1 -p 100 -q
+
+	tc_check_packets "dev $swp2 egress" 101 1
+	check_err $? "Unregistered multicast filter was not hit before adding MDB
entry"
+
+	tc_check_packets "dev $swp2 egress" 102 0
+	check_err $? "Registered multicast filter was hit before adding MDB
entry"
+
+	# Adding MDB entry.
+	bridge mdb replace dev br1 port $swp2 grp $dip permanent
+
+	$MZ $mode $h1 -t ip -A $sip -B $dip -c 1 -p 100 -q
+
+	tc_check_packets "dev $swp2 egress" 101 1
+	check_err $? "Unregistered multicast filter was hit after adding MDB
entry"
+
+	tc_check_packets "dev $swp2 egress" 102 1
+	check_err $? "Registered multicast filter was not hit after adding MDB
entry"
+
+	# Deleting MDB entry.
+	bridge mdb del dev br1 port $swp2 grp $dip
+
+	$MZ $mode $h1 -t ip -A $sip -B $dip -c 1 -p 100 -q
+
+	tc_check_packets "dev $swp2 egress" 101 2
+	check_err $? "Unregistered multicast filter was not hit after deleting
MDB entry"
+
+	tc_check_packets "dev $swp2 egress" 102 1
+	check_err $? "Registered multicast filter was hit after deleting MDB
entry"
+
+	tc filter del dev $swp2 egress protocol $proto pref 1 handle 102 flower
+	tc filter del dev $swp2 egress protocol $proto pref 1 handle 101 flower
+
+	log_test "L2 miss - Multicast ($name)"
+}
+
+test_l2_miss_multicast_ipv4()
+{
+	local proto="ipv4"
+	local sip=192.0.2.1
+	local dip=239.1.1.1
+	local mode="-4"
+	local name="IPv4"
+
+	test_l2_miss_multicast_common $proto $sip $dip $mode $name
+}
+
+test_l2_miss_multicast_ipv6()
+{
+	local proto="ipv6"
+	local sip=2001:db8:1::1
+	local dip=ff0e::1
+	local mode="-6"
+	local name="IPv6"
+
+	test_l2_miss_multicast_common $proto $sip $dip $mode $name
+}
+
+test_l2_miss_multicast()
+{
+	# Configure $swp2 as a multicast router port so that it will forward
+	# both registered and unregistered multicast traffic.
+	bridge link set dev $swp2 mcast_router 2
+
+	# Forwarding according to MDB entries only takes place when the bridge
+	# detects that there is a valid querier in the network. Set the bridge
+	# as the querier and assign it a valid IPv6 link-local address to be
+	# used as the source address for MLD queries.
+	ip link set dev br1 type bridge mcast_querier 1
+	ip -6 address add fe80::1/64 nodad dev br1
+	# Wait the default Query Response Interval (10 seconds) for the bridge
+	# to determine that there are no other queriers in the network.
+	sleep 10
+
+	test_l2_miss_multicast_ipv4
+	test_l2_miss_multicast_ipv6
+
+	ip -6 address del fe80::1/64 dev br1
+	ip link set dev br1 type bridge mcast_querier 0
+	bridge link set dev $swp2 mcast_router 1
+}
+
+test_l2_miss_multicast_common2()
+{
+	local name=$1; shift
+	local dmac=$1; shift
+	local dip=224.0.0.1
+	local sip=192.0.2.1
+
+}
+
+test_l2_miss_ll_multicast_common()
+{
+	local proto=$1; shift
+	local dmac=$1; shift
+	local sip=$1; shift
+	local dip=$1; shift
+	local mode=$1; shift
+	local name=$1; shift
+
+	RET=0
+
+	tc filter add dev $swp2 egress protocol $proto handle 101 pref 1 \
+	   flower indev $swp1 l2_miss true dst_mac $dmac src_ip $sip \
+	   dst_ip $dip action pass
+
+	$MZ $mode $h1 -a own -b $dmac -t ip -A $sip -B $dip -c 1 -p 100 -q
+
+	tc_check_packets "dev $swp2 egress" 101 1
+	check_err $? "Filter was not hit"
+
+	tc filter del dev $swp2 egress protocol $proto pref 1 handle 101 flower
+
+	log_test "L2 miss - Link-local multicast ($name)"
+}
+
+test_l2_miss_ll_multicast_ipv4()
+{
+	local proto=ipv4
+	local dmac=01:00:5e:00:00:01
+	local sip=192.0.2.1
+	local dip=224.0.0.1
+	local mode="-4"
+	local name="IPv4"
+
+	test_l2_miss_ll_multicast_common $proto $dmac $sip $dip $mode $name
+}
+
+test_l2_miss_ll_multicast_ipv6()
+{
+	local proto=ipv6
+	local dmac=33:33:00:00:00:01
+	local sip=2001:db8:1::1
+	local dip=ff02::1
+	local mode="-6"
+	local name="IPv6"
+
+	test_l2_miss_ll_multicast_common $proto $dmac $sip $dip $mode $name
+}
+
+test_l2_miss_ll_multicast()
+{
+	test_l2_miss_ll_multicast_ipv4
+	test_l2_miss_ll_multicast_ipv6
+}
+
+test_l2_miss_broadcast()
+{
+	local dmac=ff:ff:ff:ff:ff:ff
+	local smac=00:01:02:03:04:05
+
+	RET=0
+
+	tc filter add dev $swp2 egress protocol all handle 101 pref 1 \
+	   flower indev $swp1 l2_miss true dst_mac $dmac src_mac $smac \
+	   action pass
+
+	$MZ $h1 -a $smac -b $dmac -c 1 -p 100 -q
+
+	tc_check_packets "dev $swp2 egress" 101 1
+	check_err $? "Filter was not hit"
+
+	tc filter del dev $swp2 egress protocol all pref 1 handle 101 flower
+
+	log_test "L2 miss - Broadcast"
+}
+
+setup_prepare()
+{
+	h1=${NETIFS[p1]}
+	swp1=${NETIFS[p2]}
+
+	swp2=${NETIFS[p3]}
+	h2=${NETIFS[p4]}
+
+	vrf_prepare
+	h1_create
+	h2_create
+	switch_create
+}
+
+cleanup()
+{
+	pre_cleanup
+
+	switch_destroy
+	h2_destroy
+	h1_destroy
+	vrf_cleanup
+}
+
+trap cleanup EXIT
+
+setup_prepare
+setup_wait
+
+tests_run
+
+exit $EXIT_STATUS
-- 
2.40.1