Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 640 insertions, 0 deletions

diff --git a/Documentation/networking/devlink/devlink-trap.rst b/Documentation/networking/devlink/devlink-trap.rst
new file mode 100644
index 000000000..2c14dfe69
--- /dev/null
+++ b/Documentation/networking/devlink/devlink-trap.rst
@@ -0,0 +1,640 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============
+Devlink Trap
+============
+
+Background
+==========
+
+Devices capable of offloading the kernel's datapath and perform functions such
+as bridging and routing must also be able to send specific packets to the
+kernel (i.e., the CPU) for processing.
+
+For example, a device acting as a multicast-aware bridge must be able to send
+IGMP membership reports to the kernel for processing by the bridge module.
+Without processing such packets, the bridge module could never populate its
+MDB.
+
+As another example, consider a device acting as router which has received an IP
+packet with a TTL of 1. Upon routing the packet the device must send it to the
+kernel so that it will route it as well and generate an ICMP Time Exceeded
+error datagram. Without letting the kernel route such packets itself, utilities
+such as ``traceroute`` could never work.
+
+The fundamental ability of sending certain packets to the kernel for processing
+is called "packet trapping".
+
+Overview
+========
+
+The ``devlink-trap`` mechanism allows capable device drivers to register their
+supported packet traps with ``devlink`` and report trapped packets to
+``devlink`` for further analysis.
+
+Upon receiving trapped packets, ``devlink`` will perform a per-trap packets and
+bytes accounting and potentially report the packet to user space via a netlink
+event along with all the provided metadata (e.g., trap reason, timestamp, input
+port). This is especially useful for drop traps (see :ref:`Trap-Types`)
+as it allows users to obtain further visibility into packet drops that would
+otherwise be invisible.
+
+The following diagram provides a general overview of ``devlink-trap``::
+
+                                    Netlink event: Packet w/ metadata
+                                                   Or a summary of recent drops
+                                  ^
+                                  |
+         Userspace                |
+        +---------------------------------------------------+
+         Kernel                   |
+                                  |
+                          +-------+--------+
+                          |                |
+                          |  drop_monitor  |
+                          |                |
+                          +-------^--------+
+                                  |
+                                  | Non-control traps
+                                  |
+                             +----+----+
+                             |         |      Kernel's Rx path
+                             | devlink |      (non-drop traps)
+                             |         |
+                             +----^----+      ^
+                                  |           |
+                                  +-----------+
+                                  |
+                          +-------+-------+
+                          |               |
+                          | Device driver |
+                          |               |
+                          +-------^-------+
+         Kernel                   |
+        +---------------------------------------------------+
+         Hardware                 |
+                                  | Trapped packet
+                                  |
+                               +--+---+
+                               |      |
+                               | ASIC |
+                               |      |
+                               +------+
+
+.. _Trap-Types:
+
+Trap Types
+==========
+
+The ``devlink-trap`` mechanism supports the following packet trap types:
+
+  * ``drop``: Trapped packets were dropped by the underlying device. Packets
+    are only processed by ``devlink`` and not injected to the kernel's Rx path.
+    The trap action (see :ref:`Trap-Actions`) can be changed.
+  * ``exception``: Trapped packets were not forwarded as intended by the
+    underlying device due to an exception (e.g., TTL error, missing neighbour
+    entry) and trapped to the control plane for resolution. Packets are
+    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:
+
+Trap Actions
+============
+
+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
+====================
+
+Generic packet traps are used to describe traps that trap well-defined packets
+or packets that are trapped due to well-defined conditions (e.g., TTL error).
+Such traps can be shared by multiple device drivers and their description must
+be added to the following table:
+
+.. list-table:: List of Generic Packet Traps
+   :widths: 5 5 90
+
+   * - Name
+     - Type
+     - Description
+   * - ``source_mac_is_multicast``
+     - ``drop``
+     - Traps incoming packets that the device decided to drop because of a
+       multicast source MAC
+   * - ``vlan_tag_mismatch``
+     - ``drop``
+     - Traps incoming packets that the device decided to drop in case of VLAN
+       tag mismatch: The ingress bridge port is not configured with a PVID and
+       the packet is untagged or prio-tagged
+   * - ``ingress_vlan_filter``
+     - ``drop``
+     - Traps incoming packets that the device decided to drop in case they are
+       tagged with a VLAN that is not configured on the ingress bridge port
+   * - ``ingress_spanning_tree_filter``
+     - ``drop``
+     - Traps incoming packets that the device decided to drop in case the STP
+       state of the ingress bridge port is not "forwarding"
+   * - ``port_list_is_empty``
+     - ``drop``
+     - Traps packets that the device decided to drop in case they need to be
+       flooded (e.g., unknown unicast, unregistered multicast) and there are
+       no ports the packets should be flooded to
+   * - ``port_loopback_filter``
+     - ``drop``
+     - Traps packets that the device decided to drop in case after layer 2
+       forwarding the only port from which they should be transmitted through
+       is the port from which they were received
+   * - ``blackhole_route``
+     - ``drop``
+     - Traps packets that the device decided to drop in case they hit a
+       blackhole route
+   * - ``ttl_value_is_too_small``
+     - ``exception``
+     - Traps unicast packets that should be forwarded by the device whose TTL
+       was decremented to 0 or less
+   * - ``tail_drop``
+     - ``drop``
+     - Traps packets that the device decided to drop because they could not be
+       enqueued to a transmission queue which is full
+   * - ``non_ip``
+     - ``drop``
+     - Traps packets that the device decided to drop because they need to
+       undergo a layer 3 lookup, but are not IP or MPLS packets
+   * - ``uc_dip_over_mc_dmac``
+     - ``drop``
+     - Traps packets that the device decided to drop because they need to be
+       routed and they have a unicast destination IP and a multicast destination
+       MAC
+   * - ``dip_is_loopback_address``
+     - ``drop``
+     - Traps packets that the device decided to drop because they need to be
+       routed and their destination IP is the loopback address (i.e., 127.0.0.0/8
+       and ::1/128)
+   * - ``sip_is_mc``
+     - ``drop``
+     - Traps packets that the device decided to drop because they need to be
+       routed and their source IP is multicast (i.e., 224.0.0.0/8 and ff::/8)
+   * - ``sip_is_loopback_address``
+     - ``drop``
+     - Traps packets that the device decided to drop because they need to be
+       routed and their source IP is the loopback address (i.e., 127.0.0.0/8 and ::1/128)
+   * - ``ip_header_corrupted``
+     - ``drop``
+     - Traps packets that the device decided to drop because they need to be
+       routed and their IP header is corrupted: wrong checksum, wrong IP version
+       or too short Internet Header Length (IHL)
+   * - ``ipv4_sip_is_limited_bc``
+     - ``drop``
+     - Traps packets that the device decided to drop because they need to be
+       routed and their source IP is limited broadcast (i.e., 255.255.255.255/32)
+   * - ``ipv6_mc_dip_reserved_scope``
+     - ``drop``
+     - Traps IPv6 packets that the device decided to drop because they need to
+       be routed and their IPv6 multicast destination IP has a reserved scope
+       (i.e., ffx0::/16)
+   * - ``ipv6_mc_dip_interface_local_scope``
+     - ``drop``
+     - Traps IPv6 packets that the device decided to drop because they need to
+       be routed and their IPv6 multicast destination IP has an interface-local scope
+       (i.e., ffx1::/16)
+   * - ``mtu_value_is_too_small``
+     - ``exception``
+     - Traps packets that should have been routed by the device, but were bigger
+       than the MTU of the egress interface
+   * - ``unresolved_neigh``
+     - ``exception``
+     - Traps packets that did not have a matching IP neighbour after routing
+   * - ``mc_reverse_path_forwarding``
+     - ``exception``
+     - Traps multicast IP packets that failed reverse-path forwarding (RPF)
+       check during multicast routing
+   * - ``reject_route``
+     - ``exception``
+     - Traps packets that hit reject routes (i.e., "unreachable", "prohibit")
+   * - ``ipv4_lpm_miss``
+     - ``exception``
+     - Traps unicast IPv4 packets that did not match any route
+   * - ``ipv6_lpm_miss``
+     - ``exception``
+     - Traps unicast IPv6 packets that did not match any route
+   * - ``non_routable_packet``
+     - ``drop``
+     - Traps packets that the device decided to drop because they are not
+       supposed to be routed. For example, IGMP queries can be flooded by the
+       device in layer 2 and reach the router. Such packets should not be
+       routed and instead dropped
+   * - ``decap_error``
+     - ``exception``
+     - Traps NVE and IPinIP packets that the device decided to drop because of
+       failure during decapsulation (e.g., packet being too short, reserved
+       bits set in VXLAN header)
+   * - ``overlay_smac_is_mc``
+     - ``drop``
+     - Traps NVE packets that the device decided to drop because their overlay
+       source MAC is multicast
+   * - ``ingress_flow_action_drop``
+     - ``drop``
+     - Traps packets dropped during processing of ingress flow action drop
+   * - ``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)
+   * - ``early_drop``
+     - ``drop``
+     - Traps packets dropped due to the RED (Random Early Detection) algorithm
+       (i.e., early drops)
+   * - ``vxlan_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the VXLAN header parsing which
+       might be because of packet truncation or the I flag is not set.
+   * - ``llc_snap_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the LLC+SNAP header parsing
+   * - ``vlan_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the VLAN header parsing. Could
+       include unexpected packet truncation.
+   * - ``pppoe_ppp_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the PPPoE+PPP header parsing.
+       This could include finding a session ID of 0xFFFF (which is reserved and
+       not for use), a PPPoE length which is larger than the frame received or
+       any common error on this type of header
+   * - ``mpls_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the MPLS header parsing which
+       could include unexpected header truncation
+   * - ``arp_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the ARP header parsing
+   * - ``ip_1_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the first IP header parsing.
+       This packet trap could include packets which do not pass an IP checksum
+       check, a header length check (a minimum of 20 bytes), which might suffer
+       from packet truncation thus the total length field exceeds the received
+       packet length etc
+   * - ``ip_n_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the parsing of the last IP
+       header (the inner one in case of an IP over IP tunnel). The same common
+       error checking is performed here as for the ip_1_parsing trap
+   * - ``gre_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the GRE header parsing
+   * - ``udp_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the UDP header parsing.
+       This packet trap could include checksum errorrs, an improper UDP
+       length detected (smaller than 8 bytes) or detection of header
+       truncation.
+   * - ``tcp_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the TCP header parsing.
+       This could include TCP checksum errors, improper combination of SYN, FIN
+       and/or RESET etc.
+   * - ``ipsec_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the IPSEC header parsing
+   * - ``sctp_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the SCTP header parsing.
+       This would mean that port number 0 was used or that the header is
+       truncated.
+   * - ``dccp_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the DCCP header parsing
+   * - ``gtp_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the GTP header parsing
+   * - ``esp_parsing``
+     - ``drop``
+     - Traps packets dropped due to an error in the ESP header parsing
+   * - ``blackhole_nexthop``
+     - ``drop``
+     - Traps packets that the device decided to drop in case they hit a
+       blackhole nexthop
+   * - ``dmac_filter``
+     - ``drop``
+     - Traps incoming packets that the device decided to drop because
+       the destination MAC is not configured in the MAC table and
+       the interface is not in promiscuous mode
+   * - ``eapol``
+     - ``control``
+     - Traps "Extensible Authentication Protocol over LAN" (EAPOL) packets
+       specified in IEEE 802.1X
+   * - ``locked_port``
+     - ``drop``
+     - Traps packets that the device decided to drop because they failed the
+       locked bridge port check. That is, packets that were received via a
+       locked port and whose {SMAC, VID} does not correspond to an FDB entry
+       pointing to the port
+
+Driver-specific Packet Traps
+============================
+
+Device drivers can register driver-specific packet traps, but these must be
+clearly documented. Such traps can correspond to device-specific exceptions and
+help debug packet drops caused by these exceptions. The following list includes
+links to the description of driver-specific traps registered by various device
+drivers:
+
+  * Documentation/networking/devlink/netdevsim.rst
+  * Documentation/networking/devlink/mlxsw.rst
+  * Documentation/networking/devlink/prestera.rst
+
+.. _Generic-Packet-Trap-Groups:
+
+Generic Packet Trap Groups
+==========================
+
+Generic packet trap groups are used to aggregate logically related packet
+traps. These groups allow the user to batch operations such as setting the trap
+action of all member traps. In addition, ``devlink-trap`` can report aggregated
+per-group packets and bytes statistics, in case per-trap statistics are too
+narrow. The description of these groups must be added to the following table:
+
+.. list-table:: List of Generic Packet Trap Groups
+   :widths: 10 90
+
+   * - Name
+     - Description
+   * - ``l2_drops``
+     - 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 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
+   * - ``tunnel_drops``
+     - Contains packet traps for packets that were dropped by the device during
+       tunnel encapsulation / decapsulation
+   * - ``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``)
+   * - ``external_delivery``
+     - Contains packet traps for 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``
+     - 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
+   * - ``parser_error_drops``
+     - Contains packet traps for packets that were marked by the device during
+       parsing as erroneous
+   * - ``eapol``
+     - Contains packet traps for "Extensible Authentication Protocol over LAN"
+       (EAPOL) packets specified in IEEE 802.1X
+
+Packet Trap Policers
+====================
+
+As previously explained, the underlying device can trap certain packets to the
+CPU for processing. In most cases, the underlying device is capable of handling
+packet rates that are several orders of magnitude higher compared to those that
+can be handled by the CPU.
+
+Therefore, in order to prevent the underlying device from overwhelming the CPU,
+devices usually include packet trap policers that are able to police the
+trapped packets to rates that can be handled by the CPU.
+
+The ``devlink-trap`` mechanism allows capable device drivers to register their
+supported packet trap policers with ``devlink``. The device driver can choose
+to associate these policers with supported packet trap groups (see
+:ref:`Generic-Packet-Trap-Groups`) during its initialization, thereby exposing
+its default control plane policy to user space.
+
+Device drivers should allow user space to change the parameters of the policers
+(e.g., rate, burst size) as well as the association between the policers and
+trap groups by implementing the relevant callbacks.
+
+If possible, device drivers should implement a callback that allows user space
+to retrieve the number of packets that were dropped by the policer because its
+configured policy was violated.
+
+Testing
+=======
+
+See ``tools/testing/selftests/drivers/net/netdevsim/devlink_trap.sh`` for a
+test covering the core infrastructure. Test cases should be added for any new
+functionality.
+
+Device drivers should focus their tests on device-specific functionality, such
+as the triggering of supported packet traps.