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author | 2023-02-21 18:24:12 -0800 | |
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committer | 2023-02-21 18:24:12 -0800 | |
commit | 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch) | |
tree | cc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/networking/devlink/devlink-dpipe.rst | |
download | linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip |
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().
...
Diffstat (limited to 'Documentation/networking/devlink/devlink-dpipe.rst')
-rw-r--r-- | Documentation/networking/devlink/devlink-dpipe.rst | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/Documentation/networking/devlink/devlink-dpipe.rst b/Documentation/networking/devlink/devlink-dpipe.rst new file mode 100644 index 000000000..af37f250d --- /dev/null +++ b/Documentation/networking/devlink/devlink-dpipe.rst @@ -0,0 +1,252 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============= +Devlink DPIPE +============= + +Background +========== + +While performing the hardware offloading process, much of the hardware +specifics cannot be presented. These details are useful for debugging, and +``devlink-dpipe`` provides a standardized way to provide visibility into the +offloading process. + +For example, the routing longest prefix match (LPM) algorithm used by the +Linux kernel may differ from the hardware implementation. The pipeline debug +API (DPIPE) is aimed at providing the user visibility into the ASIC's +pipeline in a generic way. + +The hardware offload process is expected to be done in a way that the user +should not be able to distinguish between the hardware vs. software +implementation. In this process, hardware specifics are neglected. In +reality those details can have lots of meaning and should be exposed in some +standard way. + +This problem is made even more complex when one wishes to offload the +control path of the whole networking stack to a switch ASIC. Due to +differences in the hardware and software models some processes cannot be +represented correctly. + +One example is the kernel's LPM algorithm which in many cases differs +greatly to the hardware implementation. The configuration API is the same, +but one cannot rely on the Forward Information Base (FIB) to look like the +Level Path Compression trie (LPC-trie) in hardware. + +In many situations trying to analyze systems failure solely based on the +kernel's dump may not be enough. By combining this data with complementary +information about the underlying hardware, this debugging can be made +easier; additionally, the information can be useful when debugging +performance issues. + +Overview +======== + +The ``devlink-dpipe`` interface closes this gap. The hardware's pipeline is +modeled as a graph of match/action tables. Each table represents a specific +hardware block. This model is not new, first being used by the P4 language. + +Traditionally it has been used as an alternative model for hardware +configuration, but the ``devlink-dpipe`` interface uses it for visibility +purposes as a standard complementary tool. The system's view from +``devlink-dpipe`` should change according to the changes done by the +standard configuration tools. + +For example, it’s quite common to implement Access Control Lists (ACL) +using Ternary Content Addressable Memory (TCAM). The TCAM memory can be +divided into TCAM regions. Complex TC filters can have multiple rules with +different priorities and different lookup keys. On the other hand hardware +TCAM regions have a predefined lookup key. Offloading the TC filter rules +using TCAM engine can result in multiple TCAM regions being interconnected +in a chain (which may affect the data path latency). In response to a new TC +filter new tables should be created describing those regions. + +Model +===== + +The ``DPIPE`` model introduces several objects: + + * headers + * tables + * entries + +A ``header`` describes packet formats and provides names for fields within +the packet. A ``table`` describes hardware blocks. An ``entry`` describes +the actual content of a specific table. + +The hardware pipeline is not port specific, but rather describes the whole +ASIC. Thus it is tied to the top of the ``devlink`` infrastructure. + +Drivers can register and unregister tables at run time, in order to support +dynamic behavior. This dynamic behavior is mandatory for describing hardware +blocks like TCAM regions which can be allocated and freed dynamically. + +``devlink-dpipe`` generally is not intended for configuration. The exception +is hardware counting for a specific table. + +The following commands are used to obtain the ``dpipe`` objects from +userspace: + + * ``table_get``: Receive a table's description. + * ``headers_get``: Receive a device's supported headers. + * ``entries_get``: Receive a table's current entries. + * ``counters_set``: Enable or disable counters on a table. + +Table +----- + +The driver should implement the following operations for each table: + + * ``matches_dump``: Dump the supported matches. + * ``actions_dump``: Dump the supported actions. + * ``entries_dump``: Dump the actual content of the table. + * ``counters_set_update``: Synchronize hardware with counters enabled or + disabled. + +Header/Field +------------ + +In a similar way to P4 headers and fields are used to describe a table's +behavior. There is a slight difference between the standard protocol headers +and specific ASIC metadata. The protocol headers should be declared in the +``devlink`` core API. On the other hand ASIC meta data is driver specific +and should be defined in the driver. Additionally, each driver-specific +devlink documentation file should document the driver-specific ``dpipe`` +headers it implements. The headers and fields are identified by enumeration. + +In order to provide further visibility some ASIC metadata fields could be +mapped to kernel objects. For example, internal router interface indexes can +be directly mapped to the net device ifindex. FIB table indexes used by +different Virtual Routing and Forwarding (VRF) tables can be mapped to +internal routing table indexes. + +Match +----- + +Matches are kept primitive and close to hardware operation. Match types like +LPM are not supported due to the fact that this is exactly a process we wish +to describe in full detail. Example of matches: + + * ``field_exact``: Exact match on a specific field. + * ``field_exact_mask``: Exact match on a specific field after masking. + * ``field_range``: Match on a specific range. + +The id's of the header and the field should be specified in order to +identify the specific field. Furthermore, the header index should be +specified in order to distinguish multiple headers of the same type in a +packet (tunneling). + +Action +------ + +Similar to match, the actions are kept primitive and close to hardware +operation. For example: + + * ``field_modify``: Modify the field value. + * ``field_inc``: Increment the field value. + * ``push_header``: Add a header. + * ``pop_header``: Remove a header. + +Entry +----- + +Entries of a specific table can be dumped on demand. Each eentry is +identified with an index and its properties are described by a list of +match/action values and specific counter. By dumping the tables content the +interactions between tables can be resolved. + +Abstraction Example +=================== + +The following is an example of the abstraction model of the L3 part of +Mellanox Spectrum ASIC. The blocks are described in the order they appear in +the pipeline. The table sizes in the following examples are not real +hardware sizes and are provided for demonstration purposes. + +LPM +--- + +The LPM algorithm can be implemented as a list of hash tables. Each hash +table contains routes with the same prefix length. The root of the list is +/32, and in case of a miss the hardware will continue to the next hash +table. The depth of the search will affect the data path latency. + +In case of a hit the entry contains information about the next stage of the +pipeline which resolves the MAC address. The next stage can be either local +host table for directly connected routes, or adjacency table for next-hops. +The ``meta.lpm_prefix`` field is used to connect two LPM tables. + +.. code:: + + table lpm_prefix_16 { + size: 4096, + counters_enabled: true, + match: { meta.vr_id: exact, + ipv4.dst_addr: exact_mask, + ipv6.dst_addr: exact_mask, + meta.lpm_prefix: exact }, + action: { meta.adj_index: set, + meta.adj_group_size: set, + meta.rif_port: set, + meta.lpm_prefix: set }, + } + +Local Host +---------- + +In the case of local routes the LPM lookup already resolves the egress +router interface (RIF), yet the exact MAC address is not known. The local +host table is a hash table combining the output interface id with +destination IP address as a key. The result is the MAC address. + +.. code:: + + table local_host { + size: 4096, + counters_enabled: true, + match: { meta.rif_port: exact, + ipv4.dst_addr: exact}, + action: { ethernet.daddr: set } + } + +Adjacency +--------- + +In case of remote routes this table does the ECMP. The LPM lookup results in +ECMP group size and index that serves as a global offset into this table. +Concurrently a hash of the packet is generated. Based on the ECMP group size +and the packet's hash a local offset is generated. Multiple LPM entries can +point to the same adjacency group. + +.. code:: + + table adjacency { + size: 4096, + counters_enabled: true, + match: { meta.adj_index: exact, + meta.adj_group_size: exact, + meta.packet_hash_index: exact }, + action: { ethernet.daddr: set, + meta.erif: set } + } + +ERIF +---- + +In case the egress RIF and destination MAC have been resolved by previous +tables this table does multiple operations like TTL decrease and MTU check. +Then the decision of forward/drop is taken and the port L3 statistics are +updated based on the packet's type (broadcast, unicast, multicast). + +.. code:: + + table erif { + size: 800, + counters_enabled: true, + match: { meta.rif_port: exact, + meta.is_l3_unicast: exact, + meta.is_l3_broadcast: exact, + meta.is_l3_multicast, exact }, + action: { meta.l3_drop: set, + meta.l3_forward: set } + } |