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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>
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davem330 committed Jun 1, 2020
2 parents af0a248 + 9959b38 commit ff0f638
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219 changes: 216 additions & 3 deletions Documentation/networking/devlink/devlink-trap.rst
View file
Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,7 @@ The following diagram provides a general overview of ``devlink-trap``::
| |
+-------^--------+
|
|
| Non-control traps
|
+----+----+
| | Kernel's Rx path
Expand Down Expand Up @@ -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:

Expand All @@ -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
====================
Expand Down Expand Up @@ -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
============================
Expand Down Expand Up @@ -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
Expand All @@ -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
====================
Expand Down
2 changes: 1 addition & 1 deletion drivers/net/ethernet/mellanox/mlxsw/reg.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand All @@ -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,

Expand Down
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