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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/driver-api/vfio-mediated-device.rst
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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(). ...
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+.. SPDX-License-Identifier: GPL-2.0-only
+.. include:: <isonum.txt>
+
+=====================
+VFIO Mediated devices
+=====================
+
+:Copyright: |copy| 2016, NVIDIA CORPORATION. All rights reserved.
+:Author: Neo Jia <cjia@nvidia.com>
+:Author: Kirti Wankhede <kwankhede@nvidia.com>
+
+
+
+Virtual Function I/O (VFIO) Mediated devices[1]
+===============================================
+
+The number of use cases for virtualizing DMA devices that do not have built-in
+SR_IOV capability is increasing. Previously, to virtualize such devices,
+developers had to create their own management interfaces and APIs, and then
+integrate them with user space software. To simplify integration with user space
+software, we have identified common requirements and a unified management
+interface for such devices.
+
+The VFIO driver framework provides unified APIs for direct device access. It is
+an IOMMU/device-agnostic framework for exposing direct device access to user
+space in a secure, IOMMU-protected environment. This framework is used for
+multiple devices, such as GPUs, network adapters, and compute accelerators. With
+direct device access, virtual machines or user space applications have direct
+access to the physical device. This framework is reused for mediated devices.
+
+The mediated core driver provides a common interface for mediated device
+management that can be used by drivers of different devices. This module
+provides a generic interface to perform these operations:
+
+* Create and destroy a mediated device
+* Add a mediated device to and remove it from a mediated bus driver
+* Add a mediated device to and remove it from an IOMMU group
+
+The mediated core driver also provides an interface to register a bus driver.
+For example, the mediated VFIO mdev driver is designed for mediated devices and
+supports VFIO APIs. The mediated bus driver adds a mediated device to and
+removes it from a VFIO group.
+
+The following high-level block diagram shows the main components and interfaces
+in the VFIO mediated driver framework. The diagram shows NVIDIA, Intel, and IBM
+devices as examples, as these devices are the first devices to use this module::
+
+ +---------------+
+ | |
+ | +-----------+ | mdev_register_driver() +--------------+
+ | | | +<------------------------+ |
+ | | mdev | | | |
+ | | bus | +------------------------>+ vfio_mdev.ko |<-> VFIO user
+ | | driver | | probe()/remove() | | APIs
+ | | | | +--------------+
+ | +-----------+ |
+ | |
+ | MDEV CORE |
+ | MODULE |
+ | mdev.ko |
+ | +-----------+ | mdev_register_parent() +--------------+
+ | | | +<------------------------+ |
+ | | | | | nvidia.ko |<-> physical
+ | | | +------------------------>+ | device
+ | | | | callbacks +--------------+
+ | | Physical | |
+ | | device | | mdev_register_parent() +--------------+
+ | | interface | |<------------------------+ |
+ | | | | | i915.ko |<-> physical
+ | | | +------------------------>+ | device
+ | | | | callbacks +--------------+
+ | | | |
+ | | | | mdev_register_parent() +--------------+
+ | | | +<------------------------+ |
+ | | | | | ccw_device.ko|<-> physical
+ | | | +------------------------>+ | device
+ | | | | callbacks +--------------+
+ | +-----------+ |
+ +---------------+
+
+
+Registration Interfaces
+=======================
+
+The mediated core driver provides the following types of registration
+interfaces:
+
+* Registration interface for a mediated bus driver
+* Physical device driver interface
+
+Registration Interface for a Mediated Bus Driver
+------------------------------------------------
+
+The registration interface for a mediated device driver provides the following
+structure to represent a mediated device's driver::
+
+ /*
+ * struct mdev_driver [2] - Mediated device's driver
+ * @probe: called when new device created
+ * @remove: called when device removed
+ * @driver: device driver structure
+ */
+ struct mdev_driver {
+ int (*probe) (struct mdev_device *dev);
+ void (*remove) (struct mdev_device *dev);
+ unsigned int (*get_available)(struct mdev_type *mtype);
+ ssize_t (*show_description)(struct mdev_type *mtype, char *buf);
+ struct device_driver driver;
+ };
+
+A mediated bus driver for mdev should use this structure in the function calls
+to register and unregister itself with the core driver:
+
+* Register::
+
+ int mdev_register_driver(struct mdev_driver *drv);
+
+* Unregister::
+
+ void mdev_unregister_driver(struct mdev_driver *drv);
+
+The mediated bus driver's probe function should create a vfio_device on top of
+the mdev_device and connect it to an appropriate implementation of
+vfio_device_ops.
+
+When a driver wants to add the GUID creation sysfs to an existing device it has
+probe'd to then it should call::
+
+ int mdev_register_parent(struct mdev_parent *parent, struct device *dev,
+ struct mdev_driver *mdev_driver);
+
+This will provide the 'mdev_supported_types/XX/create' files which can then be
+used to trigger the creation of a mdev_device. The created mdev_device will be
+attached to the specified driver.
+
+When the driver needs to remove itself it calls::
+
+ void mdev_unregister_parent(struct mdev_parent *parent);
+
+Which will unbind and destroy all the created mdevs and remove the sysfs files.
+
+Mediated Device Management Interface Through sysfs
+==================================================
+
+The management interface through sysfs enables user space software, such as
+libvirt, to query and configure mediated devices in a hardware-agnostic fashion.
+This management interface provides flexibility to the underlying physical
+device's driver to support features such as:
+
+* Mediated device hot plug
+* Multiple mediated devices in a single virtual machine
+* Multiple mediated devices from different physical devices
+
+Links in the mdev_bus Class Directory
+-------------------------------------
+The /sys/class/mdev_bus/ directory contains links to devices that are registered
+with the mdev core driver.
+
+Directories and files under the sysfs for Each Physical Device
+--------------------------------------------------------------
+
+::
+
+ |- [parent physical device]
+ |--- Vendor-specific-attributes [optional]
+ |--- [mdev_supported_types]
+ | |--- [<type-id>]
+ | | |--- create
+ | | |--- name
+ | | |--- available_instances
+ | | |--- device_api
+ | | |--- description
+ | | |--- [devices]
+ | |--- [<type-id>]
+ | | |--- create
+ | | |--- name
+ | | |--- available_instances
+ | | |--- device_api
+ | | |--- description
+ | | |--- [devices]
+ | |--- [<type-id>]
+ | |--- create
+ | |--- name
+ | |--- available_instances
+ | |--- device_api
+ | |--- description
+ | |--- [devices]
+
+* [mdev_supported_types]
+
+ The list of currently supported mediated device types and their details.
+
+ [<type-id>], device_api, and available_instances are mandatory attributes
+ that should be provided by vendor driver.
+
+* [<type-id>]
+
+ The [<type-id>] name is created by adding the device driver string as a prefix
+ to the string provided by the vendor driver. This format of this name is as
+ follows::
+
+ sprintf(buf, "%s-%s", dev_driver_string(parent->dev), group->name);
+
+* device_api
+
+ This attribute shows which device API is being created, for example,
+ "vfio-pci" for a PCI device.
+
+* available_instances
+
+ This attribute shows the number of devices of type <type-id> that can be
+ created.
+
+* [device]
+
+ This directory contains links to the devices of type <type-id> that have been
+ created.
+
+* name
+
+ This attribute shows a human readable name.
+
+* description
+
+ This attribute can show brief features/description of the type. This is an
+ optional attribute.
+
+Directories and Files Under the sysfs for Each mdev Device
+----------------------------------------------------------
+
+::
+
+ |- [parent phy device]
+ |--- [$MDEV_UUID]
+ |--- remove
+ |--- mdev_type {link to its type}
+ |--- vendor-specific-attributes [optional]
+
+* remove (write only)
+
+Writing '1' to the 'remove' file destroys the mdev device. The vendor driver can
+fail the remove() callback if that device is active and the vendor driver
+doesn't support hot unplug.
+
+Example::
+
+ # echo 1 > /sys/bus/mdev/devices/$mdev_UUID/remove
+
+Mediated device Hot plug
+------------------------
+
+Mediated devices can be created and assigned at runtime. The procedure to hot
+plug a mediated device is the same as the procedure to hot plug a PCI device.
+
+Translation APIs for Mediated Devices
+=====================================
+
+The following APIs are provided for translating user pfn to host pfn in a VFIO
+driver::
+
+ int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,
+ int npage, int prot, struct page **pages);
+
+ void vfio_unpin_pages(struct vfio_device *device, dma_addr_t iova,
+ int npage);
+
+These functions call back into the back-end IOMMU module by using the pin_pages
+and unpin_pages callbacks of the struct vfio_iommu_driver_ops[4]. Currently
+these callbacks are supported in the TYPE1 IOMMU module. To enable them for
+other IOMMU backend modules, such as PPC64 sPAPR module, they need to provide
+these two callback functions.
+
+Using the Sample Code
+=====================
+
+mtty.c in samples/vfio-mdev/ directory is a sample driver program to
+demonstrate how to use the mediated device framework.
+
+The sample driver creates an mdev device that simulates a serial port over a PCI
+card.
+
+1. Build and load the mtty.ko module.
+
+ This step creates a dummy device, /sys/devices/virtual/mtty/mtty/
+
+ Files in this device directory in sysfs are similar to the following::
+
+ # tree /sys/devices/virtual/mtty/mtty/
+ /sys/devices/virtual/mtty/mtty/
+ |-- mdev_supported_types
+ | |-- mtty-1
+ | | |-- available_instances
+ | | |-- create
+ | | |-- device_api
+ | | |-- devices
+ | | `-- name
+ | `-- mtty-2
+ | |-- available_instances
+ | |-- create
+ | |-- device_api
+ | |-- devices
+ | `-- name
+ |-- mtty_dev
+ | `-- sample_mtty_dev
+ |-- power
+ | |-- autosuspend_delay_ms
+ | |-- control
+ | |-- runtime_active_time
+ | |-- runtime_status
+ | `-- runtime_suspended_time
+ |-- subsystem -> ../../../../class/mtty
+ `-- uevent
+
+2. Create a mediated device by using the dummy device that you created in the
+ previous step::
+
+ # echo "83b8f4f2-509f-382f-3c1e-e6bfe0fa1001" > \
+ /sys/devices/virtual/mtty/mtty/mdev_supported_types/mtty-2/create
+
+3. Add parameters to qemu-kvm::
+
+ -device vfio-pci,\
+ sysfsdev=/sys/bus/mdev/devices/83b8f4f2-509f-382f-3c1e-e6bfe0fa1001
+
+4. Boot the VM.
+
+ In the Linux guest VM, with no hardware on the host, the device appears
+ as follows::
+
+ # lspci -s 00:05.0 -xxvv
+ 00:05.0 Serial controller: Device 4348:3253 (rev 10) (prog-if 02 [16550])
+ Subsystem: Device 4348:3253
+ Physical Slot: 5
+ Control: I/O+ Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr-
+ Stepping- SERR- FastB2B- DisINTx-
+ Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort-
+ <TAbort- <MAbort- >SERR- <PERR- INTx-
+ Interrupt: pin A routed to IRQ 10
+ Region 0: I/O ports at c150 [size=8]
+ Region 1: I/O ports at c158 [size=8]
+ Kernel driver in use: serial
+ 00: 48 43 53 32 01 00 00 02 10 02 00 07 00 00 00 00
+ 10: 51 c1 00 00 59 c1 00 00 00 00 00 00 00 00 00 00
+ 20: 00 00 00 00 00 00 00 00 00 00 00 00 48 43 53 32
+ 30: 00 00 00 00 00 00 00 00 00 00 00 00 0a 01 00 00
+
+ In the Linux guest VM, dmesg output for the device is as follows:
+
+ serial 0000:00:05.0: PCI INT A -> Link[LNKA] -> GSI 10 (level, high) -> IRQ 10
+ 0000:00:05.0: ttyS1 at I/O 0xc150 (irq = 10) is a 16550A
+ 0000:00:05.0: ttyS2 at I/O 0xc158 (irq = 10) is a 16550A
+
+
+5. In the Linux guest VM, check the serial ports::
+
+ # setserial -g /dev/ttyS*
+ /dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4
+ /dev/ttyS1, UART: 16550A, Port: 0xc150, IRQ: 10
+ /dev/ttyS2, UART: 16550A, Port: 0xc158, IRQ: 10
+
+6. Using minicom or any terminal emulation program, open port /dev/ttyS1 or
+ /dev/ttyS2 with hardware flow control disabled.
+
+7. Type data on the minicom terminal or send data to the terminal emulation
+ program and read the data.
+
+ Data is loop backed from hosts mtty driver.
+
+8. Destroy the mediated device that you created::
+
+ # echo 1 > /sys/bus/mdev/devices/83b8f4f2-509f-382f-3c1e-e6bfe0fa1001/remove
+
+References
+==========
+
+1. See Documentation/driver-api/vfio.rst for more information on VFIO.
+2. struct mdev_driver in include/linux/mdev.h
+3. struct mdev_parent_ops in include/linux/mdev.h
+4. struct vfio_iommu_driver_ops in include/linux/vfio.h