From 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 21 Feb 2023 18:24:12 -0800 Subject: Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 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(). ... --- Documentation/driver-api/cxl/memory-devices.rst | 383 ++++++++++++++++++++++++ 1 file changed, 383 insertions(+) create mode 100644 Documentation/driver-api/cxl/memory-devices.rst (limited to 'Documentation/driver-api/cxl/memory-devices.rst') diff --git a/Documentation/driver-api/cxl/memory-devices.rst b/Documentation/driver-api/cxl/memory-devices.rst new file mode 100644 index 000000000..5149ecdc5 --- /dev/null +++ b/Documentation/driver-api/cxl/memory-devices.rst @@ -0,0 +1,383 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. include:: + +=================================== +Compute Express Link Memory Devices +=================================== + +A Compute Express Link Memory Device is a CXL component that implements the +CXL.mem protocol. It contains some amount of volatile memory, persistent memory, +or both. It is enumerated as a PCI device for configuration and passing +messages over an MMIO mailbox. Its contribution to the System Physical +Address space is handled via HDM (Host Managed Device Memory) decoders +that optionally define a device's contribution to an interleaved address +range across multiple devices underneath a host-bridge or interleaved +across host-bridges. + +CXL Bus: Theory of Operation +============================ +Similar to how a RAID driver takes disk objects and assembles them into a new +logical device, the CXL subsystem is tasked to take PCIe and ACPI objects and +assemble them into a CXL.mem decode topology. The need for runtime configuration +of the CXL.mem topology is also similar to RAID in that different environments +with the same hardware configuration may decide to assemble the topology in +contrasting ways. One may choose performance (RAID0) striping memory across +multiple Host Bridges and endpoints while another may opt for fault tolerance +and disable any striping in the CXL.mem topology. + +Platform firmware enumerates a menu of interleave options at the "CXL root port" +(Linux term for the top of the CXL decode topology). From there, PCIe topology +dictates which endpoints can participate in which Host Bridge decode regimes. +Each PCIe Switch in the path between the root and an endpoint introduces a point +at which the interleave can be split. For example platform firmware may say at a +given range only decodes to 1 one Host Bridge, but that Host Bridge may in turn +interleave cycles across multiple Root Ports. An intervening Switch between a +port and an endpoint may interleave cycles across multiple Downstream Switch +Ports, etc. + +Here is a sample listing of a CXL topology defined by 'cxl_test'. The 'cxl_test' +module generates an emulated CXL topology of 2 Host Bridges each with 2 Root +Ports. Each of those Root Ports are connected to 2-way switches with endpoints +connected to those downstream ports for a total of 8 endpoints:: + + # cxl list -BEMPu -b cxl_test + { + "bus":"root3", + "provider":"cxl_test", + "ports:root3":[ + { + "port":"port5", + "host":"cxl_host_bridge.1", + "ports:port5":[ + { + "port":"port8", + "host":"cxl_switch_uport.1", + "endpoints:port8":[ + { + "endpoint":"endpoint9", + "host":"mem2", + "memdev":{ + "memdev":"mem2", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0x1", + "numa_node":1, + "host":"cxl_mem.1" + } + }, + { + "endpoint":"endpoint15", + "host":"mem6", + "memdev":{ + "memdev":"mem6", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0x5", + "numa_node":1, + "host":"cxl_mem.5" + } + } + ] + }, + { + "port":"port12", + "host":"cxl_switch_uport.3", + "endpoints:port12":[ + { + "endpoint":"endpoint17", + "host":"mem8", + "memdev":{ + "memdev":"mem8", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0x7", + "numa_node":1, + "host":"cxl_mem.7" + } + }, + { + "endpoint":"endpoint13", + "host":"mem4", + "memdev":{ + "memdev":"mem4", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0x3", + "numa_node":1, + "host":"cxl_mem.3" + } + } + ] + } + ] + }, + { + "port":"port4", + "host":"cxl_host_bridge.0", + "ports:port4":[ + { + "port":"port6", + "host":"cxl_switch_uport.0", + "endpoints:port6":[ + { + "endpoint":"endpoint7", + "host":"mem1", + "memdev":{ + "memdev":"mem1", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0", + "numa_node":0, + "host":"cxl_mem.0" + } + }, + { + "endpoint":"endpoint14", + "host":"mem5", + "memdev":{ + "memdev":"mem5", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0x4", + "numa_node":0, + "host":"cxl_mem.4" + } + } + ] + }, + { + "port":"port10", + "host":"cxl_switch_uport.2", + "endpoints:port10":[ + { + "endpoint":"endpoint16", + "host":"mem7", + "memdev":{ + "memdev":"mem7", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0x6", + "numa_node":0, + "host":"cxl_mem.6" + } + }, + { + "endpoint":"endpoint11", + "host":"mem3", + "memdev":{ + "memdev":"mem3", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0x2", + "numa_node":0, + "host":"cxl_mem.2" + } + } + ] + } + ] + } + ] + } + +In that listing each "root", "port", and "endpoint" object correspond a kernel +'struct cxl_port' object. A 'cxl_port' is a device that can decode CXL.mem to +its descendants. So "root" claims non-PCIe enumerable platform decode ranges and +decodes them to "ports", "ports" decode to "endpoints", and "endpoints" +represent the decode from SPA (System Physical Address) to DPA (Device Physical +Address). + +Continuing the RAID analogy, disks have both topology metadata and on device +metadata that determine RAID set assembly. CXL Port topology and CXL Port link +status is metadata for CXL.mem set assembly. The CXL Port topology is enumerated +by the arrival of a CXL.mem device. I.e. unless and until the PCIe core attaches +the cxl_pci driver to a CXL Memory Expander there is no role for CXL Port +objects. Conversely for hot-unplug / removal scenarios, there is no need for +the Linux PCI core to tear down switch-level CXL resources because the endpoint +->remove() event cleans up the port data that was established to support that +Memory Expander. + +The port metadata and potential decode schemes that a give memory device may +participate can be determined via a command like:: + + # cxl list -BDMu -d root -m mem3 + { + "bus":"root3", + "provider":"cxl_test", + "decoders:root3":[ + { + "decoder":"decoder3.1", + "resource":"0x8030000000", + "size":"512.00 MiB (536.87 MB)", + "volatile_capable":true, + "nr_targets":2 + }, + { + "decoder":"decoder3.3", + "resource":"0x8060000000", + "size":"512.00 MiB (536.87 MB)", + "pmem_capable":true, + "nr_targets":2 + }, + { + "decoder":"decoder3.0", + "resource":"0x8020000000", + "size":"256.00 MiB (268.44 MB)", + "volatile_capable":true, + "nr_targets":1 + }, + { + "decoder":"decoder3.2", + "resource":"0x8050000000", + "size":"256.00 MiB (268.44 MB)", + "pmem_capable":true, + "nr_targets":1 + } + ], + "memdevs:root3":[ + { + "memdev":"mem3", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0x2", + "numa_node":0, + "host":"cxl_mem.2" + } + ] + } + +...which queries the CXL topology to ask "given CXL Memory Expander with a kernel +device name of 'mem3' which platform level decode ranges may this device +participate". A given expander can participate in multiple CXL.mem interleave +sets simultaneously depending on how many decoder resource it has. In this +example mem3 can participate in one or more of a PMEM interleave that spans to +Host Bridges, a PMEM interleave that targets a single Host Bridge, a Volatile +memory interleave that spans 2 Host Bridges, and a Volatile memory interleave +that only targets a single Host Bridge. + +Conversely the memory devices that can participate in a given platform level +decode scheme can be determined via a command like the following:: + + # cxl list -MDu -d 3.2 + [ + { + "memdevs":[ + { + "memdev":"mem1", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0", + "numa_node":0, + "host":"cxl_mem.0" + }, + { + "memdev":"mem5", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0x4", + "numa_node":0, + "host":"cxl_mem.4" + }, + { + "memdev":"mem7", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0x6", + "numa_node":0, + "host":"cxl_mem.6" + }, + { + "memdev":"mem3", + "pmem_size":"256.00 MiB (268.44 MB)", + "ram_size":"256.00 MiB (268.44 MB)", + "serial":"0x2", + "numa_node":0, + "host":"cxl_mem.2" + } + ] + }, + { + "root decoders":[ + { + "decoder":"decoder3.2", + "resource":"0x8050000000", + "size":"256.00 MiB (268.44 MB)", + "pmem_capable":true, + "nr_targets":1 + } + ] + } + ] + +...where the naming scheme for decoders is "decoder.". + +Driver Infrastructure +===================== + +This section covers the driver infrastructure for a CXL memory device. + +CXL Memory Device +----------------- + +.. kernel-doc:: drivers/cxl/pci.c + :doc: cxl pci + +.. kernel-doc:: drivers/cxl/pci.c + :internal: + +.. kernel-doc:: drivers/cxl/mem.c + :doc: cxl mem + +CXL Port +-------- +.. kernel-doc:: drivers/cxl/port.c + :doc: cxl port + +CXL Core +-------- +.. kernel-doc:: drivers/cxl/cxl.h + :doc: cxl objects + +.. kernel-doc:: drivers/cxl/cxl.h + :internal: + +.. kernel-doc:: drivers/cxl/core/port.c + :doc: cxl core + +.. kernel-doc:: drivers/cxl/core/port.c + :identifiers: + +.. kernel-doc:: drivers/cxl/core/pci.c + :doc: cxl core pci + +.. kernel-doc:: drivers/cxl/core/pci.c + :identifiers: + +.. kernel-doc:: drivers/cxl/core/pmem.c + :doc: cxl pmem + +.. kernel-doc:: drivers/cxl/core/regs.c + :doc: cxl registers + +.. kernel-doc:: drivers/cxl/core/mbox.c + :doc: cxl mbox + +CXL Regions +----------- +.. kernel-doc:: drivers/cxl/core/region.c + :doc: cxl core region + +.. kernel-doc:: drivers/cxl/core/region.c + :identifiers: + +External Interfaces +=================== + +CXL IOCTL Interface +------------------- + +.. kernel-doc:: include/uapi/linux/cxl_mem.h + :doc: UAPI + +.. kernel-doc:: include/uapi/linux/cxl_mem.h + :internal: -- cgit v1.2.3