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().
  ...

2 files changed, 585 insertions, 0 deletions

diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
new file mode 100644
index 000000000..15b670926
--- /dev/null
+++ b/Documentation/fpga/dfl.rst
@@ -0,0 +1,568 @@
+=================================================
+FPGA Device Feature List (DFL) Framework Overview
+=================================================
+
+Authors:
+
+- Enno Luebbers <enno.luebbers@intel.com>
+- Xiao Guangrong <guangrong.xiao@linux.intel.com>
+- Wu Hao <hao.wu@intel.com>
+- Xu Yilun <yilun.xu@intel.com>
+
+The Device Feature List (DFL) FPGA framework (and drivers according to
+this framework) hides the very details of low layer hardware and provides
+unified interfaces to userspace. Applications could use these interfaces to
+configure, enumerate, open and access FPGA accelerators on platforms which
+implement the DFL in the device memory. Besides this, the DFL framework
+enables system level management functions such as FPGA reconfiguration.
+
+
+Device Feature List (DFL) Overview
+==================================
+Device Feature List (DFL) defines a linked list of feature headers within the
+device MMIO space to provide an extensible way of adding features. Software can
+walk through these predefined data structures to enumerate FPGA features:
+FPGA Interface Unit (FIU), Accelerated Function Unit (AFU) and Private Features,
+as illustrated below::
+
+    Header            Header            Header            Header
+ +----------+  +-->+----------+  +-->+----------+  +-->+----------+
+ |   Type   |  |   |  Type    |  |   |  Type    |  |   |  Type    |
+ |   FIU    |  |   | Private  |  |   | Private  |  |   | Private  |
+ +----------+  |   | Feature  |  |   | Feature  |  |   | Feature  |
+ | Next_DFH |--+   +----------+  |   +----------+  |   +----------+
+ +----------+      | Next_DFH |--+   | Next_DFH |--+   | Next_DFH |--> NULL
+ |    ID    |      +----------+      +----------+      +----------+
+ +----------+      |    ID    |      |    ID    |      |    ID    |
+ | Next_AFU |--+   +----------+      +----------+      +----------+
+ +----------+  |   | Feature  |      | Feature  |      | Feature  |
+ |  Header  |  |   | Register |      | Register |      | Register |
+ | Register |  |   |   Set    |      |   Set    |      |   Set    |
+ |   Set    |  |   +----------+      +----------+      +----------+
+ +----------+  |      Header
+               +-->+----------+
+                   |   Type   |
+                   |   AFU    |
+                   +----------+
+                   | Next_DFH |--> NULL
+                   +----------+
+                   |   GUID   |
+                   +----------+
+                   |  Header  |
+                   | Register |
+                   |   Set    |
+                   +----------+
+
+FPGA Interface Unit (FIU) represents a standalone functional unit for the
+interface to FPGA, e.g. the FPGA Management Engine (FME) and Port (more
+descriptions on FME and Port in later sections).
+
+Accelerated Function Unit (AFU) represents an FPGA programmable region and
+always connects to a FIU (e.g. a Port) as its child as illustrated above.
+
+Private Features represent sub features of the FIU and AFU. They could be
+various function blocks with different IDs, but all private features which
+belong to the same FIU or AFU, must be linked to one list via the Next Device
+Feature Header (Next_DFH) pointer.
+
+Each FIU, AFU and Private Feature could implement its own functional registers.
+The functional register set for FIU and AFU, is named as Header Register Set,
+e.g. FME Header Register Set, and the one for Private Feature, is named as
+Feature Register Set, e.g. FME Partial Reconfiguration Feature Register Set.
+
+This Device Feature List provides a way of linking features together, it's
+convenient for software to locate each feature by walking through this list,
+and can be implemented in register regions of any FPGA device.
+
+
+FIU - FME (FPGA Management Engine)
+==================================
+The FPGA Management Engine performs reconfiguration and other infrastructure
+functions. Each FPGA device only has one FME.
+
+User-space applications can acquire exclusive access to the FME using open(),
+and release it using close().
+
+The following functions are exposed through ioctls:
+
+- Get driver API version (DFL_FPGA_GET_API_VERSION)
+- Check for extensions (DFL_FPGA_CHECK_EXTENSION)
+- Program bitstream (DFL_FPGA_FME_PORT_PR)
+- Assign port to PF (DFL_FPGA_FME_PORT_ASSIGN)
+- Release port from PF (DFL_FPGA_FME_PORT_RELEASE)
+- Get number of irqs of FME global error (DFL_FPGA_FME_ERR_GET_IRQ_NUM)
+- Set interrupt trigger for FME error (DFL_FPGA_FME_ERR_SET_IRQ)
+
+More functions are exposed through sysfs
+(/sys/class/fpga_region/regionX/dfl-fme.n/):
+
+ Read bitstream ID (bitstream_id)
+     bitstream_id indicates version of the static FPGA region.
+
+ Read bitstream metadata (bitstream_metadata)
+     bitstream_metadata includes detailed information of static FPGA region,
+     e.g. synthesis date and seed.
+
+ Read number of ports (ports_num)
+     one FPGA device may have more than one port, this sysfs interface indicates
+     how many ports the FPGA device has.
+
+ Global error reporting management (errors/)
+     error reporting sysfs interfaces allow user to read errors detected by the
+     hardware, and clear the logged errors.
+
+ Power management (dfl_fme_power hwmon)
+     power management hwmon sysfs interfaces allow user to read power management
+     information (power consumption, thresholds, threshold status, limits, etc.)
+     and configure power thresholds for different throttling levels.
+
+ Thermal management (dfl_fme_thermal hwmon)
+     thermal management hwmon sysfs interfaces allow user to read thermal
+     management information (current temperature, thresholds, threshold status,
+     etc.).
+
+ Performance reporting
+     performance counters are exposed through perf PMU APIs. Standard perf tool
+     can be used to monitor all available perf events. Please see performance
+     counter section below for more detailed information.
+
+
+FIU - PORT
+==========
+A port represents the interface between the static FPGA fabric and a partially
+reconfigurable region containing an AFU. It controls the communication from SW
+to the accelerator and exposes features such as reset and debug. Each FPGA
+device may have more than one port, but always one AFU per port.
+
+
+AFU
+===
+An AFU is attached to a port FIU and exposes a fixed length MMIO region to be
+used for accelerator-specific control registers.
+
+User-space applications can acquire exclusive access to an AFU attached to a
+port by using open() on the port device node and release it using close().
+
+The following functions are exposed through ioctls:
+
+- Get driver API version (DFL_FPGA_GET_API_VERSION)
+- Check for extensions (DFL_FPGA_CHECK_EXTENSION)
+- Get port info (DFL_FPGA_PORT_GET_INFO)
+- Get MMIO region info (DFL_FPGA_PORT_GET_REGION_INFO)
+- Map DMA buffer (DFL_FPGA_PORT_DMA_MAP)
+- Unmap DMA buffer (DFL_FPGA_PORT_DMA_UNMAP)
+- Reset AFU (DFL_FPGA_PORT_RESET)
+- Get number of irqs of port error (DFL_FPGA_PORT_ERR_GET_IRQ_NUM)
+- Set interrupt trigger for port error (DFL_FPGA_PORT_ERR_SET_IRQ)
+- Get number of irqs of UINT (DFL_FPGA_PORT_UINT_GET_IRQ_NUM)
+- Set interrupt trigger for UINT (DFL_FPGA_PORT_UINT_SET_IRQ)
+
+DFL_FPGA_PORT_RESET:
+  reset the FPGA Port and its AFU. Userspace can do Port
+  reset at any time, e.g. during DMA or Partial Reconfiguration. But it should
+  never cause any system level issue, only functional failure (e.g. DMA or PR
+  operation failure) and be recoverable from the failure.
+
+User-space applications can also mmap() accelerator MMIO regions.
+
+More functions are exposed through sysfs:
+(/sys/class/fpga_region/<regionX>/<dfl-port.m>/):
+
+ Read Accelerator GUID (afu_id)
+     afu_id indicates which PR bitstream is programmed to this AFU.
+
+ Error reporting (errors/)
+     error reporting sysfs interfaces allow user to read port/afu errors
+     detected by the hardware, and clear the logged errors.
+
+
+DFL Framework Overview
+======================
+
+::
+
+         +----------+    +--------+ +--------+ +--------+
+         |   FME    |    |  AFU   | |  AFU   | |  AFU   |
+         |  Module  |    | Module | | Module | | Module |
+         +----------+    +--------+ +--------+ +--------+
+                 +-----------------------+
+                 | FPGA Container Device |    Device Feature List
+                 |  (FPGA Base Region)   |         Framework
+                 +-----------------------+
+  ------------------------------------------------------------------
+               +----------------------------+
+               |   FPGA DFL Device Module   |
+               | (e.g. PCIE/Platform Device)|
+               +----------------------------+
+                 +------------------------+
+                 |  FPGA Hardware Device  |
+                 +------------------------+
+
+DFL framework in kernel provides common interfaces to create container device
+(FPGA base region), discover feature devices and their private features from the
+given Device Feature Lists and create platform devices for feature devices
+(e.g. FME, Port and AFU) with related resources under the container device. It
+also abstracts operations for the private features and exposes common ops to
+feature device drivers.
+
+The FPGA DFL Device could be different hardware, e.g. PCIe device, platform
+device and etc. Its driver module is always loaded first once the device is
+created by the system. This driver plays an infrastructural role in the
+driver architecture. It locates the DFLs in the device memory, handles them
+and related resources to common interfaces from DFL framework for enumeration.
+(Please refer to drivers/fpga/dfl.c for detailed enumeration APIs).
+
+The FPGA Management Engine (FME) driver is a platform driver which is loaded
+automatically after FME platform device creation from the DFL device module. It
+provides the key features for FPGA management, including:
+
+	a) Expose static FPGA region information, e.g. version and metadata.
+	   Users can read related information via sysfs interfaces exposed
+	   by FME driver.
+
+	b) Partial Reconfiguration. The FME driver creates FPGA manager, FPGA
+	   bridges and FPGA regions during PR sub feature initialization. Once
+	   it receives a DFL_FPGA_FME_PORT_PR ioctl from user, it invokes the
+	   common interface function from FPGA Region to complete the partial
+	   reconfiguration of the PR bitstream to the given port.
+
+Similar to the FME driver, the FPGA Accelerated Function Unit (AFU) driver is
+probed once the AFU platform device is created. The main function of this module
+is to provide an interface for userspace applications to access the individual
+accelerators, including basic reset control on port, AFU MMIO region export, dma
+buffer mapping service functions.
+
+After feature platform devices creation, matched platform drivers will be loaded
+automatically to handle different functionalities. Please refer to next sections
+for detailed information on functional units which have been already implemented
+under this DFL framework.
+
+
+Partial Reconfiguration
+=======================
+As mentioned above, accelerators can be reconfigured through partial
+reconfiguration of a PR bitstream file. The PR bitstream file must have been
+generated for the exact static FPGA region and targeted reconfigurable region
+(port) of the FPGA, otherwise, the reconfiguration operation will fail and
+possibly cause system instability. This compatibility can be checked by
+comparing the compatibility ID noted in the header of PR bitstream file against
+the compat_id exposed by the target FPGA region. This check is usually done by
+userspace before calling the reconfiguration IOCTL.
+
+
+FPGA virtualization - PCIe SRIOV
+================================
+This section describes the virtualization support on DFL based FPGA device to
+enable accessing an accelerator from applications running in a virtual machine
+(VM). This section only describes the PCIe based FPGA device with SRIOV support.
+
+Features supported by the particular FPGA device are exposed through Device
+Feature Lists, as illustrated below:
+
+::
+
+    +-------------------------------+  +-------------+
+    |              PF               |  |     VF      |
+    +-------------------------------+  +-------------+
+        ^            ^         ^              ^
+        |            |         |              |
+  +-----|------------|---------|--------------|-------+
+  |     |            |         |              |       |
+  |  +-----+     +-------+ +-------+      +-------+   |
+  |  | FME |     | Port0 | | Port1 |      | Port2 |   |
+  |  +-----+     +-------+ +-------+      +-------+   |
+  |                  ^         ^              ^       |
+  |                  |         |              |       |
+  |              +-------+ +------+       +-------+   |
+  |              |  AFU  | |  AFU |       |  AFU  |   |
+  |              +-------+ +------+       +-------+   |
+  |                                                   |
+  |            DFL based FPGA PCIe Device             |
+  +---------------------------------------------------+
+
+FME is always accessed through the physical function (PF).
+
+Ports (and related AFUs) are accessed via PF by default, but could be exposed
+through virtual function (VF) devices via PCIe SRIOV. Each VF only contains
+1 Port and 1 AFU for isolation. Users could assign individual VFs (accelerators)
+created via PCIe SRIOV interface, to virtual machines.
+
+The driver organization in virtualization case is illustrated below:
+::
+
+    +-------++------++------+             |
+    | FME   || FME  || FME  |             |
+    | FPGA  || FPGA || FPGA |             |
+    |Manager||Bridge||Region|             |
+    +-------++------++------+             |
+    +-----------------------+  +--------+ |             +--------+
+    |          FME          |  |  AFU   | |             |  AFU   |
+    |         Module        |  | Module | |             | Module |
+    +-----------------------+  +--------+ |             +--------+
+          +-----------------------+       |       +-----------------------+
+          | FPGA Container Device |       |       | FPGA Container Device |
+          |  (FPGA Base Region)   |       |       |  (FPGA Base Region)   |
+          +-----------------------+       |       +-----------------------+
+            +------------------+          |         +------------------+
+            | FPGA PCIE Module |          | Virtual | FPGA PCIE Module |
+            +------------------+   Host   | Machine +------------------+
+   -------------------------------------- | ------------------------------
+             +---------------+            |          +---------------+
+             | PCI PF Device |            |          | PCI VF Device |
+             +---------------+            |          +---------------+
+
+FPGA PCIe device driver is always loaded first once an FPGA PCIe PF or VF device
+is detected. It:
+
+* Finishes enumeration on both FPGA PCIe PF and VF device using common
+  interfaces from DFL framework.
+* Supports SRIOV.
+
+The FME device driver plays a management role in this driver architecture, it
+provides ioctls to release Port from PF and assign Port to PF. After release
+a port from PF, then it's safe to expose this port through a VF via PCIe SRIOV
+sysfs interface.
+
+To enable accessing an accelerator from applications running in a VM, the
+respective AFU's port needs to be assigned to a VF using the following steps:
+
+#. The PF owns all AFU ports by default. Any port that needs to be
+   reassigned to a VF must first be released through the
+   DFL_FPGA_FME_PORT_RELEASE ioctl on the FME device.
+
+#. Once N ports are released from PF, then user can use command below
+   to enable SRIOV and VFs. Each VF owns only one Port with AFU.
+
+   ::
+
+      echo N > $PCI_DEVICE_PATH/sriov_numvfs
+
+#. Pass through the VFs to VMs
+
+#. The AFU under VF is accessible from applications in VM (using the
+   same driver inside the VF).
+
+Note that an FME can't be assigned to a VF, thus PR and other management
+functions are only available via the PF.
+
+Device enumeration
+==================
+This section introduces how applications enumerate the fpga device from
+the sysfs hierarchy under /sys/class/fpga_region.
+
+In the example below, two DFL based FPGA devices are installed in the host. Each
+fpga device has one FME and two ports (AFUs).
+
+FPGA regions are created under /sys/class/fpga_region/::
+
+	/sys/class/fpga_region/region0
+	/sys/class/fpga_region/region1
+	/sys/class/fpga_region/region2
+	...
+
+Application needs to search each regionX folder, if feature device is found,
+(e.g. "dfl-port.n" or "dfl-fme.m" is found), then it's the base
+fpga region which represents the FPGA device.
+
+Each base region has one FME and two ports (AFUs) as child devices::
+
+	/sys/class/fpga_region/region0/dfl-fme.0
+	/sys/class/fpga_region/region0/dfl-port.0
+	/sys/class/fpga_region/region0/dfl-port.1
+	...
+
+	/sys/class/fpga_region/region3/dfl-fme.1
+	/sys/class/fpga_region/region3/dfl-port.2
+	/sys/class/fpga_region/region3/dfl-port.3
+	...
+
+In general, the FME/AFU sysfs interfaces are named as follows::
+
+	/sys/class/fpga_region/<regionX>/<dfl-fme.n>/
+	/sys/class/fpga_region/<regionX>/<dfl-port.m>/
+
+with 'n' consecutively numbering all FMEs and 'm' consecutively numbering all
+ports.
+
+The device nodes used for ioctl() or mmap() can be referenced through::
+
+	/sys/class/fpga_region/<regionX>/<dfl-fme.n>/dev
+	/sys/class/fpga_region/<regionX>/<dfl-port.n>/dev
+
+
+Performance Counters
+====================
+Performance reporting is one private feature implemented in FME. It could
+supports several independent, system-wide, device counter sets in hardware to
+monitor and count for performance events, including "basic", "cache", "fabric",
+"vtd" and "vtd_sip" counters. Users could use standard perf tool to monitor
+FPGA cache hit/miss rate, transaction number, interface clock counter of AFU
+and other FPGA performance events.
+
+Different FPGA devices may have different counter sets, depending on hardware
+implementation. E.g., some discrete FPGA cards don't have any cache. User could
+use "perf list" to check which perf events are supported by target hardware.
+
+In order to allow user to use standard perf API to access these performance
+counters, driver creates a perf PMU, and related sysfs interfaces in
+/sys/bus/event_source/devices/dfl_fme* to describe available perf events and
+configuration options.
+
+The "format" directory describes the format of the config field of struct
+perf_event_attr. There are 3 bitfields for config: "evtype" defines which type
+the perf event belongs to; "event" is the identity of the event within its
+category; "portid" is introduced to decide counters set to monitor on FPGA
+overall data or a specific port.
+
+The "events" directory describes the configuration templates for all available
+events which can be used with perf tool directly. For example, fab_mmio_read
+has the configuration "event=0x06,evtype=0x02,portid=0xff", which shows this
+event belongs to fabric type (0x02), the local event id is 0x06 and it is for
+overall monitoring (portid=0xff).
+
+Example usage of perf::
+
+  $# perf list |grep dfl_fme
+
+  dfl_fme0/fab_mmio_read/                              [Kernel PMU event]
+  <...>
+  dfl_fme0/fab_port_mmio_read,portid=?/                [Kernel PMU event]
+  <...>
+
+  $# perf stat -a -e dfl_fme0/fab_mmio_read/ <command>
+  or
+  $# perf stat -a -e dfl_fme0/event=0x06,evtype=0x02,portid=0xff/ <command>
+  or
+  $# perf stat -a -e dfl_fme0/config=0xff2006/ <command>
+
+Another example, fab_port_mmio_read monitors mmio read of a specific port. So
+its configuration template is "event=0x06,evtype=0x01,portid=?". The portid
+should be explicitly set.
+
+Its usage of perf::
+
+  $# perf stat -a -e dfl_fme0/fab_port_mmio_read,portid=0x0/ <command>
+  or
+  $# perf stat -a -e dfl_fme0/event=0x06,evtype=0x02,portid=0x0/ <command>
+  or
+  $# perf stat -a -e dfl_fme0/config=0x2006/ <command>
+
+Please note for fabric counters, overall perf events (fab_*) and port perf
+events (fab_port_*) actually share one set of counters in hardware, so it can't
+monitor both at the same time. If this set of counters is configured to monitor
+overall data, then per port perf data is not supported. See below example::
+
+  $# perf stat -e dfl_fme0/fab_mmio_read/,dfl_fme0/fab_port_mmio_write,\
+                                                    portid=0/ sleep 1
+
+  Performance counter stats for 'system wide':
+
+                 3      dfl_fme0/fab_mmio_read/
+   <not supported>      dfl_fme0/fab_port_mmio_write,portid=0x0/
+
+       1.001750904 seconds time elapsed
+
+The driver also provides a "cpumask" sysfs attribute, which contains only one
+CPU id used to access these perf events. Counting on multiple CPU is not allowed
+since they are system-wide counters on FPGA device.
+
+The current driver does not support sampling. So "perf record" is unsupported.
+
+
+Interrupt support
+=================
+Some FME and AFU private features are able to generate interrupts. As mentioned
+above, users could call ioctl (DFL_FPGA_*_GET_IRQ_NUM) to know whether or how
+many interrupts are supported for this private feature. Drivers also implement
+an eventfd based interrupt handling mechanism for users to get notified when
+interrupt happens. Users could set eventfds to driver via
+ioctl (DFL_FPGA_*_SET_IRQ), and then poll/select on these eventfds waiting for
+notification.
+In Current DFL, 3 sub features (Port error, FME global error and AFU interrupt)
+support interrupts.
+
+
+Add new FIUs support
+====================
+It's possible that developers made some new function blocks (FIUs) under this
+DFL framework, then new platform device driver needs to be developed for the
+new feature dev (FIU) following the same way as existing feature dev drivers
+(e.g. FME and Port/AFU platform device driver). Besides that, it requires
+modification on DFL framework enumeration code too, for new FIU type detection
+and related platform devices creation.
+
+
+Add new private features support
+================================
+In some cases, we may need to add some new private features to existing FIUs
+(e.g. FME or Port). Developers don't need to touch enumeration code in DFL
+framework, as each private feature will be parsed automatically and related
+mmio resources can be found under FIU platform device created by DFL framework.
+Developer only needs to provide a sub feature driver with matched feature id.
+FME Partial Reconfiguration Sub Feature driver (see drivers/fpga/dfl-fme-pr.c)
+could be a reference.
+
+Please refer to below link to existing feature id table and guide for new feature
+ids application.
+https://github.com/OPAE/dfl-feature-id
+
+
+Location of DFLs on a PCI Device
+================================
+The original method for finding a DFL on a PCI device assumed the start of the
+first DFL to offset 0 of bar 0.  If the first node of the DFL is an FME,
+then further DFLs in the port(s) are specified in FME header registers.
+Alternatively, a PCIe vendor specific capability structure can be used to
+specify the location of all the DFLs on the device, providing flexibility
+for the type of starting node in the DFL.  Intel has reserved the
+VSEC ID of 0x43 for this purpose.  The vendor specific
+data begins with a 4 byte vendor specific register for the number of DFLs followed 4 byte
+Offset/BIR vendor specific registers for each DFL. Bits 2:0 of Offset/BIR register
+indicates the BAR, and bits 31:3 form the 8 byte aligned offset where bits 2:0 are
+zero.
+::
+
+        +----------------------------+
+        |31     Number of DFLS      0|
+        +----------------------------+
+        |31     Offset     3|2 BIR  0|
+        +----------------------------+
+                      . . .
+        +----------------------------+
+        |31     Offset     3|2 BIR  0|
+        +----------------------------+
+
+Being able to specify more than one DFL per BAR has been considered, but it
+was determined the use case did not provide value.  Specifying a single DFL
+per BAR simplifies the implementation and allows for extra error checking.
+
+
+Userspace driver support for DFL devices
+========================================
+The purpose of an FPGA is to be reprogrammed with newly developed hardware
+components. New hardware can instantiate a new private feature in the DFL, and
+then present a DFL device in the system. In some cases users may need a
+userspace driver for the DFL device:
+
+* Users may need to run some diagnostic test for their hardware.
+* Users may prototype the kernel driver in user space.
+* Some hardware is designed for specific purposes and does not fit into one of
+  the standard kernel subsystems.
+
+This requires direct access to MMIO space and interrupt handling from
+userspace. The uio_dfl module exposes the UIO device interfaces for this
+purpose.
+
+Currently the uio_dfl driver only supports the Ether Group sub feature, which
+has no irq in hardware. So the interrupt handling is not added in this driver.
+
+UIO_DFL should be selected to enable the uio_dfl module driver. To support a
+new DFL feature via UIO direct access, its feature id should be added to the
+driver's id_table.
+
+
+Open discussion
+===============
+FME driver exports one ioctl (DFL_FPGA_FME_PORT_PR) for partial reconfiguration
+to user now. In the future, if unified user interfaces for reconfiguration are
+added, FME driver should switch to them from ioctl interface.
diff --git a/Documentation/fpga/index.rst b/Documentation/fpga/index.rst
new file mode 100644
index 000000000..f80f95667
--- /dev/null
+++ b/Documentation/fpga/index.rst
@@ -0,0 +1,17 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====
+fpga
+====
+
+.. toctree::
+    :maxdepth: 1
+
+    dfl
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`