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, 256 insertions, 0 deletions

diff --git a/Documentation/networking/msg_zerocopy.rst b/Documentation/networking/msg_zerocopy.rst
new file mode 100644
index 000000000..15920db8d
--- /dev/null
+++ b/Documentation/networking/msg_zerocopy.rst
@@ -0,0 +1,256 @@
+
+============
+MSG_ZEROCOPY
+============
+
+Intro
+=====
+
+The MSG_ZEROCOPY flag enables copy avoidance for socket send calls.
+The feature is currently implemented for TCP and UDP sockets.
+
+
+Opportunity and Caveats
+-----------------------
+
+Copying large buffers between user process and kernel can be
+expensive. Linux supports various interfaces that eschew copying,
+such as sendpage and splice. The MSG_ZEROCOPY flag extends the
+underlying copy avoidance mechanism to common socket send calls.
+
+Copy avoidance is not a free lunch. As implemented, with page pinning,
+it replaces per byte copy cost with page accounting and completion
+notification overhead. As a result, MSG_ZEROCOPY is generally only
+effective at writes over around 10 KB.
+
+Page pinning also changes system call semantics. It temporarily shares
+the buffer between process and network stack. Unlike with copying, the
+process cannot immediately overwrite the buffer after system call
+return without possibly modifying the data in flight. Kernel integrity
+is not affected, but a buggy program can possibly corrupt its own data
+stream.
+
+The kernel returns a notification when it is safe to modify data.
+Converting an existing application to MSG_ZEROCOPY is not always as
+trivial as just passing the flag, then.
+
+
+More Info
+---------
+
+Much of this document was derived from a longer paper presented at
+netdev 2.1. For more in-depth information see that paper and talk,
+the excellent reporting over at LWN.net or read the original code.
+
+  paper, slides, video
+    https://netdevconf.org/2.1/session.html?debruijn
+
+  LWN article
+    https://lwn.net/Articles/726917/
+
+  patchset
+    [PATCH net-next v4 0/9] socket sendmsg MSG_ZEROCOPY
+    https://lore.kernel.org/netdev/20170803202945.70750-1-willemdebruijn.kernel@gmail.com
+
+
+Interface
+=========
+
+Passing the MSG_ZEROCOPY flag is the most obvious step to enable copy
+avoidance, but not the only one.
+
+Socket Setup
+------------
+
+The kernel is permissive when applications pass undefined flags to the
+send system call. By default it simply ignores these. To avoid enabling
+copy avoidance mode for legacy processes that accidentally already pass
+this flag, a process must first signal intent by setting a socket option:
+
+::
+
+	if (setsockopt(fd, SOL_SOCKET, SO_ZEROCOPY, &one, sizeof(one)))
+		error(1, errno, "setsockopt zerocopy");
+
+Transmission
+------------
+
+The change to send (or sendto, sendmsg, sendmmsg) itself is trivial.
+Pass the new flag.
+
+::
+
+	ret = send(fd, buf, sizeof(buf), MSG_ZEROCOPY);
+
+A zerocopy failure will return -1 with errno ENOBUFS. This happens if
+the socket option was not set, the socket exceeds its optmem limit or
+the user exceeds its ulimit on locked pages.
+
+
+Mixing copy avoidance and copying
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Many workloads have a mixture of large and small buffers. Because copy
+avoidance is more expensive than copying for small packets, the
+feature is implemented as a flag. It is safe to mix calls with the flag
+with those without.
+
+
+Notifications
+-------------
+
+The kernel has to notify the process when it is safe to reuse a
+previously passed buffer. It queues completion notifications on the
+socket error queue, akin to the transmit timestamping interface.
+
+The notification itself is a simple scalar value. Each socket
+maintains an internal unsigned 32-bit counter. Each send call with
+MSG_ZEROCOPY that successfully sends data increments the counter. The
+counter is not incremented on failure or if called with length zero.
+The counter counts system call invocations, not bytes. It wraps after
+UINT_MAX calls.
+
+
+Notification Reception
+~~~~~~~~~~~~~~~~~~~~~~
+
+The below snippet demonstrates the API. In the simplest case, each
+send syscall is followed by a poll and recvmsg on the error queue.
+
+Reading from the error queue is always a non-blocking operation. The
+poll call is there to block until an error is outstanding. It will set
+POLLERR in its output flags. That flag does not have to be set in the
+events field. Errors are signaled unconditionally.
+
+::
+
+	pfd.fd = fd;
+	pfd.events = 0;
+	if (poll(&pfd, 1, -1) != 1 || pfd.revents & POLLERR == 0)
+		error(1, errno, "poll");
+
+	ret = recvmsg(fd, &msg, MSG_ERRQUEUE);
+	if (ret == -1)
+		error(1, errno, "recvmsg");
+
+	read_notification(msg);
+
+The example is for demonstration purpose only. In practice, it is more
+efficient to not wait for notifications, but read without blocking
+every couple of send calls.
+
+Notifications can be processed out of order with other operations on
+the socket. A socket that has an error queued would normally block
+other operations until the error is read. Zerocopy notifications have
+a zero error code, however, to not block send and recv calls.
+
+
+Notification Batching
+~~~~~~~~~~~~~~~~~~~~~
+
+Multiple outstanding packets can be read at once using the recvmmsg
+call. This is often not needed. In each message the kernel returns not
+a single value, but a range. It coalesces consecutive notifications
+while one is outstanding for reception on the error queue.
+
+When a new notification is about to be queued, it checks whether the
+new value extends the range of the notification at the tail of the
+queue. If so, it drops the new notification packet and instead increases
+the range upper value of the outstanding notification.
+
+For protocols that acknowledge data in-order, like TCP, each
+notification can be squashed into the previous one, so that no more
+than one notification is outstanding at any one point.
+
+Ordered delivery is the common case, but not guaranteed. Notifications
+may arrive out of order on retransmission and socket teardown.
+
+
+Notification Parsing
+~~~~~~~~~~~~~~~~~~~~
+
+The below snippet demonstrates how to parse the control message: the
+read_notification() call in the previous snippet. A notification
+is encoded in the standard error format, sock_extended_err.
+
+The level and type fields in the control data are protocol family
+specific, IP_RECVERR or IPV6_RECVERR.
+
+Error origin is the new type SO_EE_ORIGIN_ZEROCOPY. ee_errno is zero,
+as explained before, to avoid blocking read and write system calls on
+the socket.
+
+The 32-bit notification range is encoded as [ee_info, ee_data]. This
+range is inclusive. Other fields in the struct must be treated as
+undefined, bar for ee_code, as discussed below.
+
+::
+
+	struct sock_extended_err *serr;
+	struct cmsghdr *cm;
+
+	cm = CMSG_FIRSTHDR(msg);
+	if (cm->cmsg_level != SOL_IP &&
+	    cm->cmsg_type != IP_RECVERR)
+		error(1, 0, "cmsg");
+
+	serr = (void *) CMSG_DATA(cm);
+	if (serr->ee_errno != 0 ||
+	    serr->ee_origin != SO_EE_ORIGIN_ZEROCOPY)
+		error(1, 0, "serr");
+
+	printf("completed: %u..%u\n", serr->ee_info, serr->ee_data);
+
+
+Deferred copies
+~~~~~~~~~~~~~~~
+
+Passing flag MSG_ZEROCOPY is a hint to the kernel to apply copy
+avoidance, and a contract that the kernel will queue a completion
+notification. It is not a guarantee that the copy is elided.
+
+Copy avoidance is not always feasible. Devices that do not support
+scatter-gather I/O cannot send packets made up of kernel generated
+protocol headers plus zerocopy user data. A packet may need to be
+converted to a private copy of data deep in the stack, say to compute
+a checksum.
+
+In all these cases, the kernel returns a completion notification when
+it releases its hold on the shared pages. That notification may arrive
+before the (copied) data is fully transmitted. A zerocopy completion
+notification is not a transmit completion notification, therefore.
+
+Deferred copies can be more expensive than a copy immediately in the
+system call, if the data is no longer warm in the cache. The process
+also incurs notification processing cost for no benefit. For this
+reason, the kernel signals if data was completed with a copy, by
+setting flag SO_EE_CODE_ZEROCOPY_COPIED in field ee_code on return.
+A process may use this signal to stop passing flag MSG_ZEROCOPY on
+subsequent requests on the same socket.
+
+
+Implementation
+==============
+
+Loopback
+--------
+
+Data sent to local sockets can be queued indefinitely if the receive
+process does not read its socket. Unbound notification latency is not
+acceptable. For this reason all packets generated with MSG_ZEROCOPY
+that are looped to a local socket will incur a deferred copy. This
+includes looping onto packet sockets (e.g., tcpdump) and tun devices.
+
+
+Testing
+=======
+
+More realistic example code can be found in the kernel source under
+tools/testing/selftests/net/msg_zerocopy.c.
+
+Be cognizant of the loopback constraint. The test can be run between
+a pair of hosts. But if run between a local pair of processes, for
+instance when run with msg_zerocopy.sh between a veth pair across
+namespaces, the test will not show any improvement. For testing, the
+loopback restriction can be temporarily relaxed by making
+skb_orphan_frags_rx identical to skb_orphan_frags.