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, 279 insertions, 0 deletions

diff --git a/Documentation/core-api/entry.rst b/Documentation/core-api/entry.rst
new file mode 100644
index 000000000..e12f22ab3
--- /dev/null
+++ b/Documentation/core-api/entry.rst
@@ -0,0 +1,279 @@
+Entry/exit handling for exceptions, interrupts, syscalls and KVM
+================================================================
+
+All transitions between execution domains require state updates which are
+subject to strict ordering constraints. State updates are required for the
+following:
+
+  * Lockdep
+  * RCU / Context tracking
+  * Preemption counter
+  * Tracing
+  * Time accounting
+
+The update order depends on the transition type and is explained below in
+the transition type sections: `Syscalls`_, `KVM`_, `Interrupts and regular
+exceptions`_, `NMI and NMI-like exceptions`_.
+
+Non-instrumentable code - noinstr
+---------------------------------
+
+Most instrumentation facilities depend on RCU, so intrumentation is prohibited
+for entry code before RCU starts watching and exit code after RCU stops
+watching. In addition, many architectures must save and restore register state,
+which means that (for example) a breakpoint in the breakpoint entry code would
+overwrite the debug registers of the initial breakpoint.
+
+Such code must be marked with the 'noinstr' attribute, placing that code into a
+special section inaccessible to instrumentation and debug facilities. Some
+functions are partially instrumentable, which is handled by marking them
+noinstr and using instrumentation_begin() and instrumentation_end() to flag the
+instrumentable ranges of code:
+
+.. code-block:: c
+
+  noinstr void entry(void)
+  {
+  	handle_entry();     // <-- must be 'noinstr' or '__always_inline'
+	...
+
+	instrumentation_begin();
+	handle_context();   // <-- instrumentable code
+	instrumentation_end();
+
+	...
+	handle_exit();      // <-- must be 'noinstr' or '__always_inline'
+  }
+
+This allows verification of the 'noinstr' restrictions via objtool on
+supported architectures.
+
+Invoking non-instrumentable functions from instrumentable context has no
+restrictions and is useful to protect e.g. state switching which would
+cause malfunction if instrumented.
+
+All non-instrumentable entry/exit code sections before and after the RCU
+state transitions must run with interrupts disabled.
+
+Syscalls
+--------
+
+Syscall-entry code starts in assembly code and calls out into low-level C code
+after establishing low-level architecture-specific state and stack frames. This
+low-level C code must not be instrumented. A typical syscall handling function
+invoked from low-level assembly code looks like this:
+
+.. code-block:: c
+
+  noinstr void syscall(struct pt_regs *regs, int nr)
+  {
+	arch_syscall_enter(regs);
+	nr = syscall_enter_from_user_mode(regs, nr);
+
+	instrumentation_begin();
+	if (!invoke_syscall(regs, nr) && nr != -1)
+	 	result_reg(regs) = __sys_ni_syscall(regs);
+	instrumentation_end();
+
+	syscall_exit_to_user_mode(regs);
+  }
+
+syscall_enter_from_user_mode() first invokes enter_from_user_mode() which
+establishes state in the following order:
+
+  * Lockdep
+  * RCU / Context tracking
+  * Tracing
+
+and then invokes the various entry work functions like ptrace, seccomp, audit,
+syscall tracing, etc. After all that is done, the instrumentable invoke_syscall
+function can be invoked. The instrumentable code section then ends, after which
+syscall_exit_to_user_mode() is invoked.
+
+syscall_exit_to_user_mode() handles all work which needs to be done before
+returning to user space like tracing, audit, signals, task work etc. After
+that it invokes exit_to_user_mode() which again handles the state
+transition in the reverse order:
+
+  * Tracing
+  * RCU / Context tracking
+  * Lockdep
+
+syscall_enter_from_user_mode() and syscall_exit_to_user_mode() are also
+available as fine grained subfunctions in cases where the architecture code
+has to do extra work between the various steps. In such cases it has to
+ensure that enter_from_user_mode() is called first on entry and
+exit_to_user_mode() is called last on exit.
+
+Do not nest syscalls. Nested systcalls will cause RCU and/or context tracking
+to print a warning.
+
+KVM
+---
+
+Entering or exiting guest mode is very similar to syscalls. From the host
+kernel point of view the CPU goes off into user space when entering the
+guest and returns to the kernel on exit.
+
+kvm_guest_enter_irqoff() is a KVM-specific variant of exit_to_user_mode()
+and kvm_guest_exit_irqoff() is the KVM variant of enter_from_user_mode().
+The state operations have the same ordering.
+
+Task work handling is done separately for guest at the boundary of the
+vcpu_run() loop via xfer_to_guest_mode_handle_work() which is a subset of
+the work handled on return to user space.
+
+Do not nest KVM entry/exit transitions because doing so is nonsensical.
+
+Interrupts and regular exceptions
+---------------------------------
+
+Interrupts entry and exit handling is slightly more complex than syscalls
+and KVM transitions.
+
+If an interrupt is raised while the CPU executes in user space, the entry
+and exit handling is exactly the same as for syscalls.
+
+If the interrupt is raised while the CPU executes in kernel space the entry and
+exit handling is slightly different. RCU state is only updated when the
+interrupt is raised in the context of the CPU's idle task. Otherwise, RCU will
+already be watching. Lockdep and tracing have to be updated unconditionally.
+
+irqentry_enter() and irqentry_exit() provide the implementation for this.
+
+The architecture-specific part looks similar to syscall handling:
+
+.. code-block:: c
+
+  noinstr void interrupt(struct pt_regs *regs, int nr)
+  {
+	arch_interrupt_enter(regs);
+	state = irqentry_enter(regs);
+
+	instrumentation_begin();
+
+	irq_enter_rcu();
+	invoke_irq_handler(regs, nr);
+	irq_exit_rcu();
+
+	instrumentation_end();
+
+	irqentry_exit(regs, state);
+  }
+
+Note that the invocation of the actual interrupt handler is within a
+irq_enter_rcu() and irq_exit_rcu() pair.
+
+irq_enter_rcu() updates the preemption count which makes in_hardirq()
+return true, handles NOHZ tick state and interrupt time accounting. This
+means that up to the point where irq_enter_rcu() is invoked in_hardirq()
+returns false.
+
+irq_exit_rcu() handles interrupt time accounting, undoes the preemption
+count update and eventually handles soft interrupts and NOHZ tick state.
+
+In theory, the preemption count could be updated in irqentry_enter(). In
+practice, deferring this update to irq_enter_rcu() allows the preemption-count
+code to be traced, while also maintaining symmetry with irq_exit_rcu() and
+irqentry_exit(), which are described in the next paragraph. The only downside
+is that the early entry code up to irq_enter_rcu() must be aware that the
+preemption count has not yet been updated with the HARDIRQ_OFFSET state.
+
+Note that irq_exit_rcu() must remove HARDIRQ_OFFSET from the preemption count
+before it handles soft interrupts, whose handlers must run in BH context rather
+than irq-disabled context. In addition, irqentry_exit() might schedule, which
+also requires that HARDIRQ_OFFSET has been removed from the preemption count.
+
+Even though interrupt handlers are expected to run with local interrupts
+disabled, interrupt nesting is common from an entry/exit perspective. For
+example, softirq handling happens within an irqentry_{enter,exit}() block with
+local interrupts enabled. Also, although uncommon, nothing prevents an
+interrupt handler from re-enabling interrupts.
+
+Interrupt entry/exit code doesn't strictly need to handle reentrancy, since it
+runs with local interrupts disabled. But NMIs can happen anytime, and a lot of
+the entry code is shared between the two.
+
+NMI and NMI-like exceptions
+---------------------------
+
+NMIs and NMI-like exceptions (machine checks, double faults, debug
+interrupts, etc.) can hit any context and must be extra careful with
+the state.
+
+State changes for debug exceptions and machine-check exceptions depend on
+whether these exceptions happened in user-space (breakpoints or watchpoints) or
+in kernel mode (code patching). From user-space, they are treated like
+interrupts, while from kernel mode they are treated like NMIs.
+
+NMIs and other NMI-like exceptions handle state transitions without
+distinguishing between user-mode and kernel-mode origin.
+
+The state update on entry is handled in irqentry_nmi_enter() which updates
+state in the following order:
+
+  * Preemption counter
+  * Lockdep
+  * RCU / Context tracking
+  * Tracing
+
+The exit counterpart irqentry_nmi_exit() does the reverse operation in the
+reverse order.
+
+Note that the update of the preemption counter has to be the first
+operation on enter and the last operation on exit. The reason is that both
+lockdep and RCU rely on in_nmi() returning true in this case. The
+preemption count modification in the NMI entry/exit case must not be
+traced.
+
+Architecture-specific code looks like this:
+
+.. code-block:: c
+
+  noinstr void nmi(struct pt_regs *regs)
+  {
+	arch_nmi_enter(regs);
+	state = irqentry_nmi_enter(regs);
+
+	instrumentation_begin();
+	nmi_handler(regs);
+	instrumentation_end();
+
+	irqentry_nmi_exit(regs);
+  }
+
+and for e.g. a debug exception it can look like this:
+
+.. code-block:: c
+
+  noinstr void debug(struct pt_regs *regs)
+  {
+	arch_nmi_enter(regs);
+
+	debug_regs = save_debug_regs();
+
+	if (user_mode(regs)) {
+		state = irqentry_enter(regs);
+
+		instrumentation_begin();
+		user_mode_debug_handler(regs, debug_regs);
+		instrumentation_end();
+
+		irqentry_exit(regs, state);
+  	} else {
+  		state = irqentry_nmi_enter(regs);
+
+		instrumentation_begin();
+		kernel_mode_debug_handler(regs, debug_regs);
+		instrumentation_end();
+
+		irqentry_nmi_exit(regs, state);
+	}
+  }
+
+There is no combined irqentry_nmi_if_kernel() function available as the
+above cannot be handled in an exception-agnostic way.
+
+NMIs can happen in any context. For example, an NMI-like exception triggered
+while handling an NMI. So NMI entry code has to be reentrant and state updates
+need to handle nesting.