Merge branch 'devlink-Add-support-for-control-packet-traps'

Ido Schimmel says:

====================
devlink: Add support for control packet traps

So far device drivers were only able to register drop and exception
packet traps with devlink. These traps are used for packets that were
either dropped by the underlying device or encountered an exception
(e.g., missing neighbour entry) during forwarding.

However, in the steady state, the majority of the packets being trapped
to the CPU are packets that are required for the correct functioning of
the control plane. For example, ARP request and IGMP query packets.

This patch set allows device drivers to register such control traps with
devlink and expose their default control plane policy to user space.
User space can then tune the packet trap policer settings according to
its needs, as with existing packet traps.

In a similar fashion to exception traps, the action associated with such
traps cannot be changed as it can easily break the control plane. Unlike
drop and exception traps, packets trapped via control traps are not
reported to the kernel's drop monitor as they are not indicative of any
problem.

Patch set overview:

Patches #1-#3 break out layer 3 exceptions to a different group to
provide better granularity. A future patch set will make this completely
configurable.

Patch #4 adds a new trap action ('mirror') that is used for packets that
are forwarded by the device and sent to the CPU. Such packets are marked
by device drivers with 'skb->offload_fwd_mark = 1' in order to prevent
the kernel from forwarding them again.

Patch #5 adds the new trap type, 'control'.

Patches #6-#8 gradually add various control traps to devlink with proper
documentation.

Patch #9 adds a few control traps to netdevsim, which are automatically
exercised by existing devlink-trap selftest.

Patches #10 performs small refactoring in mlxsw.

Patches #11-#13 change mlxsw to register its existing control traps with
devlink.

Patch #14 adds a selftest over mlxsw that exercises all the registered
control traps.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/devlink/devlink-trap.rst

@@ -55,7 +55,7 @@ The following diagram provides a general overview of ``devlink-trap``::
                           |                |
                           +-------^--------+
                                   |
-                                  |
+                                  | Non-control traps
                                   |
                              +----+----+
                              |         |      Kernel's Rx path
@@ -97,6 +97,12 @@ The ``devlink-trap`` mechanism supports the following packet trap types:
     processed by ``devlink`` and injected to the kernel's Rx path. Changing the
     action of such traps is not allowed, as it can easily break the control
     plane.
+  * ``control``: Trapped packets were trapped by the device because these are
+    control packets required for the correct functioning of the control plane.
+    For example, ARP request and IGMP query packets. Packets are injected to
+    the kernel's Rx path, but not reported to the kernel's drop monitor.
+    Changing the action of such traps is not allowed, as it can easily break
+    the control plane.
 
 .. _Trap-Actions:
 
@@ -108,6 +114,8 @@ The ``devlink-trap`` mechanism supports the following packet trap actions:
   * ``trap``: The sole copy of the packet is sent to the CPU.
   * ``drop``: The packet is dropped by the underlying device and a copy is not
     sent to the CPU.
+  * ``mirror``: The packet is forwarded by the underlying device and a copy is
+    sent to the CPU.
 
 Generic Packet Traps
 ====================
@@ -244,6 +252,159 @@ be added to the following table:
    * - ``egress_flow_action_drop``
      - ``drop``
      - Traps packets dropped during processing of egress flow action drop
+   * - ``stp``
+     - ``control``
+     - Traps STP packets
+   * - ``lacp``
+     - ``control``
+     - Traps LACP packets
+   * - ``lldp``
+     - ``control``
+     - Traps LLDP packets
+   * - ``igmp_query``
+     - ``control``
+     - Traps IGMP Membership Query packets
+   * - ``igmp_v1_report``
+     - ``control``
+     - Traps IGMP Version 1 Membership Report packets
+   * - ``igmp_v2_report``
+     - ``control``
+     - Traps IGMP Version 2 Membership Report packets
+   * - ``igmp_v3_report``
+     - ``control``
+     - Traps IGMP Version 3 Membership Report packets
+   * - ``igmp_v2_leave``
+     - ``control``
+     - Traps IGMP Version 2 Leave Group packets
+   * - ``mld_query``
+     - ``control``
+     - Traps MLD Multicast Listener Query packets
+   * - ``mld_v1_report``
+     - ``control``
+     - Traps MLD Version 1 Multicast Listener Report packets
+   * - ``mld_v2_report``
+     - ``control``
+     - Traps MLD Version 2 Multicast Listener Report packets
+   * - ``mld_v1_done``
+     - ``control``
+     - Traps MLD Version 1 Multicast Listener Done packets
+   * - ``ipv4_dhcp``
+     - ``control``
+     - Traps IPv4 DHCP packets
+   * - ``ipv6_dhcp``
+     - ``control``
+     - Traps IPv6 DHCP packets
+   * - ``arp_request``
+     - ``control``
+     - Traps ARP request packets
+   * - ``arp_response``
+     - ``control``
+     - Traps ARP response packets
+   * - ``arp_overlay``
+     - ``control``
+     - Traps NVE-decapsulated ARP packets that reached the overlay network.
+       This is required, for example, when the address that needs to be
+       resolved is a local address
+   * - ``ipv6_neigh_solicit``
+     - ``control``
+     - Traps IPv6 Neighbour Solicitation packets
+   * - ``ipv6_neigh_advert``
+     - ``control``
+     - Traps IPv6 Neighbour Advertisement packets
+   * - ``ipv4_bfd``
+     - ``control``
+     - Traps IPv4 BFD packets
+   * - ``ipv6_bfd``
+     - ``control``
+     - Traps IPv6 BFD packets
+   * - ``ipv4_ospf``
+     - ``control``
+     - Traps IPv4 OSPF packets
+   * - ``ipv6_ospf``
+     - ``control``
+     - Traps IPv6 OSPF packets
+   * - ``ipv4_bgp``
+     - ``control``
+     - Traps IPv4 BGP packets
+   * - ``ipv6_bgp``
+     - ``control``
+     - Traps IPv6 BGP packets
+   * - ``ipv4_vrrp``
+     - ``control``
+     - Traps IPv4 VRRP packets
+   * - ``ipv6_vrrp``
+     - ``control``
+     - Traps IPv6 VRRP packets
+   * - ``ipv4_pim``
+     - ``control``
+     - Traps IPv4 PIM packets
+   * - ``ipv6_pim``
+     - ``control``
+     - Traps IPv6 PIM packets
+   * - ``uc_loopback``
+     - ``control``
+     - Traps unicast packets that need to be routed through the same layer 3
+       interface from which they were received. Such packets are routed by the
+       kernel, but also cause it to potentially generate ICMP redirect packets
+   * - ``local_route``
+     - ``control``
+     - Traps unicast packets that hit a local route and need to be locally
+       delivered
+   * - ``external_route``
+     - ``control``
+     - Traps packets that should be routed through an external interface (e.g.,
+       management interface) that does not belong to the same device (e.g.,
+       switch ASIC) as the ingress interface
+   * - ``ipv6_uc_dip_link_local_scope``
+     - ``control``
+     - Traps unicast IPv6 packets that need to be routed and have a destination
+       IP address with a link-local scope (i.e., fe80::/10). The trap allows
+       device drivers to avoid programming link-local routes, but still receive
+       packets for local delivery
+   * - ``ipv6_dip_all_nodes``
+     - ``control``
+     - Traps IPv6 packets that their destination IP address is the "All Nodes
+       Address" (i.e., ff02::1)
+   * - ``ipv6_dip_all_routers``
+     - ``control``
+     - Traps IPv6 packets that their destination IP address is the "All Routers
+       Address" (i.e., ff02::2)
+   * - ``ipv6_router_solicit``
+     - ``control``
+     - Traps IPv6 Router Solicitation packets
+   * - ``ipv6_router_advert``
+     - ``control``
+     - Traps IPv6 Router Advertisement packets
+   * - ``ipv6_redirect``
+     - ``control``
+     - Traps IPv6 Redirect Message packets
+   * - ``ipv4_router_alert``
+     - ``control``
+     - Traps IPv4 packets that need to be routed and include the Router Alert
+       option. Such packets need to be locally delivered to raw sockets that
+       have the IP_ROUTER_ALERT socket option set
+   * - ``ipv6_router_alert``
+     - ``control``
+     - Traps IPv6 packets that need to be routed and include the Router Alert
+       option in their Hop-by-Hop extension header. Such packets need to be
+       locally delivered to raw sockets that have the IPV6_ROUTER_ALERT socket
+       option set
+   * - ``ptp_event``
+     - ``control``
+     - Traps PTP time-critical event messages (Sync, Delay_req, Pdelay_Req and
+       Pdelay_Resp)
+   * - ``ptp_general``
+     - ``control``
+     - Traps PTP general messages (Announce, Follow_Up, Delay_Resp,
+       Pdelay_Resp_Follow_Up, management and signaling)
+   * - ``flow_action_sample``
+     - ``control``
+     - Traps packets sampled during processing of flow action sample (e.g., via
+       tc's sample action)
+   * - ``flow_action_trap``
+     - ``control``
+     - Traps packets logged during processing of flow action trap (e.g., via
+       tc's trap action)
 
 Driver-specific Packet Traps
 ============================
@@ -277,8 +438,11 @@ narrow. The description of these groups must be added to the following table:
      - Contains packet traps for packets that were dropped by the device during
        layer 2 forwarding (i.e., bridge)
    * - ``l3_drops``
-     - Contains packet traps for packets that were dropped by the device or hit
-       an exception (e.g., TTL error) during layer 3 forwarding
+     - Contains packet traps for packets that were dropped by the device during
+       layer 3 forwarding
+   * - ``l3_exceptions``
+     - Contains packet traps for packets that hit an exception (e.g., TTL
+       error) during layer 3 forwarding
    * - ``buffer_drops``
      - Contains packet traps for packets that were dropped by the device due to
        an enqueue decision
@@ -288,6 +452,55 @@ narrow. The description of these groups must be added to the following table:
    * - ``acl_drops``
      - Contains packet traps for packets that were dropped by the device during
        ACL processing
+   * - ``stp``
+     - Contains packet traps for STP packets
+   * - ``lacp``
+     - Contains packet traps for LACP packets
+   * - ``lldp``
+     - Contains packet traps for LLDP packets
+   * - ``mc_snooping``
+     - Contains packet traps for IGMP and MLD packets required for multicast
+       snooping
+   * - ``dhcp``
+     - Contains packet traps for DHCP packets
+   * - ``neigh_discovery``
+     - Contains packet traps for neighbour discovery packets (e.g., ARP, IPv6
+       ND)
+   * - ``bfd``
+     - Contains packet traps for BFD packets
+   * - ``ospf``
+     - Contains packet traps for OSPF packets
+   * - ``bgp``
+     - Contains packet traps for BGP packets
+   * - ``vrrp``
+     - Contains packet traps for VRRP packets
+   * - ``pim``
+     - Contains packet traps for PIM packets
+   * - ``uc_loopback``
+     - Contains a packet trap for unicast loopback packets (i.e.,
+       ``uc_loopback``). This trap is singled-out because in cases such as
+       one-armed router it will be constantly triggered. To limit the impact on
+       the CPU usage, a packet trap policer with a low rate can be bound to the
+       group without affecting other traps
+   * - ``local_delivery``
+     - Contains packet traps for packets that should be locally delivered after
+       routing, but do not match more specific packet traps (e.g.,
+       ``ipv4_bgp``)
+   * - ``ipv6``
+     - Contains packet traps for various IPv6 control packets (e.g., Router
+       Advertisements)
+   * - ``ptp_event``
+     - Contains packet traps for PTP time-critical event messages (Sync,
+       Delay_req, Pdelay_Req and Pdelay_Resp)
+   * - ``ptp_general``
+     - Contains packet traps for PTP general messages (Announce, Follow_Up,
+       Delay_Resp, Pdelay_Resp_Follow_Up, management and signaling)
+   * - ``acl_sample``
+     - Contains packet traps for packets that were sampled by the device during
+       ACL processing
+   * - ``acl_trap``
+     - Contains packet traps for packets that were trapped (logged) by the
+       device during ACL processing
 
 Packet Trap Policers
 ====================

drivers/net/ethernet/mellanox/mlxsw/reg.h

@@ -5536,7 +5536,6 @@ enum mlxsw_reg_htgt_trap_group {
 	MLXSW_REG_HTGT_TRAP_GROUP_SP_MULTICAST,
 	MLXSW_REG_HTGT_TRAP_GROUP_SP_NEIGH_DISCOVERY,
 	MLXSW_REG_HTGT_TRAP_GROUP_SP_ROUTER_EXP,
-	MLXSW_REG_HTGT_TRAP_GROUP_SP_REMOTE_ROUTE,
 	MLXSW_REG_HTGT_TRAP_GROUP_SP_IP2ME,
 	MLXSW_REG_HTGT_TRAP_GROUP_SP_DHCP,
 	MLXSW_REG_HTGT_TRAP_GROUP_SP_EVENT,
@@ -5552,6 +5551,7 @@ enum mlxsw_reg_htgt_trap_group {
 	MLXSW_REG_HTGT_TRAP_GROUP_SP_DUMMY,
 	MLXSW_REG_HTGT_TRAP_GROUP_SP_L2_DISCARDS,
 	MLXSW_REG_HTGT_TRAP_GROUP_SP_L3_DISCARDS,
+	MLXSW_REG_HTGT_TRAP_GROUP_SP_L3_EXCEPTIONS,
 	MLXSW_REG_HTGT_TRAP_GROUP_SP_TUNNEL_DISCARDS,
 	MLXSW_REG_HTGT_TRAP_GROUP_SP_ACL_DISCARDS,