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/core-api/dma-attributes.rst | 132 ++++++++++++++++++++++++++++++ 1 file changed, 132 insertions(+) create mode 100644 Documentation/core-api/dma-attributes.rst (limited to 'Documentation/core-api/dma-attributes.rst') diff --git a/Documentation/core-api/dma-attributes.rst b/Documentation/core-api/dma-attributes.rst new file mode 100644 index 000000000..1887d92e8 --- /dev/null +++ b/Documentation/core-api/dma-attributes.rst @@ -0,0 +1,132 @@ +============== +DMA attributes +============== + +This document describes the semantics of the DMA attributes that are +defined in linux/dma-mapping.h. + +DMA_ATTR_WEAK_ORDERING +---------------------- + +DMA_ATTR_WEAK_ORDERING specifies that reads and writes to the mapping +may be weakly ordered, that is that reads and writes may pass each other. + +Since it is optional for platforms to implement DMA_ATTR_WEAK_ORDERING, +those that do not will simply ignore the attribute and exhibit default +behavior. + +DMA_ATTR_WRITE_COMBINE +---------------------- + +DMA_ATTR_WRITE_COMBINE specifies that writes to the mapping may be +buffered to improve performance. + +Since it is optional for platforms to implement DMA_ATTR_WRITE_COMBINE, +those that do not will simply ignore the attribute and exhibit default +behavior. + +DMA_ATTR_NO_KERNEL_MAPPING +-------------------------- + +DMA_ATTR_NO_KERNEL_MAPPING lets the platform to avoid creating a kernel +virtual mapping for the allocated buffer. On some architectures creating +such mapping is non-trivial task and consumes very limited resources +(like kernel virtual address space or dma consistent address space). +Buffers allocated with this attribute can be only passed to user space +by calling dma_mmap_attrs(). By using this API, you are guaranteeing +that you won't dereference the pointer returned by dma_alloc_attr(). You +can treat it as a cookie that must be passed to dma_mmap_attrs() and +dma_free_attrs(). Make sure that both of these also get this attribute +set on each call. + +Since it is optional for platforms to implement +DMA_ATTR_NO_KERNEL_MAPPING, those that do not will simply ignore the +attribute and exhibit default behavior. + +DMA_ATTR_SKIP_CPU_SYNC +---------------------- + +By default dma_map_{single,page,sg} functions family transfer a given +buffer from CPU domain to device domain. Some advanced use cases might +require sharing a buffer between more than one device. This requires +having a mapping created separately for each device and is usually +performed by calling dma_map_{single,page,sg} function more than once +for the given buffer with device pointer to each device taking part in +the buffer sharing. The first call transfers a buffer from 'CPU' domain +to 'device' domain, what synchronizes CPU caches for the given region +(usually it means that the cache has been flushed or invalidated +depending on the dma direction). However, next calls to +dma_map_{single,page,sg}() for other devices will perform exactly the +same synchronization operation on the CPU cache. CPU cache synchronization +might be a time consuming operation, especially if the buffers are +large, so it is highly recommended to avoid it if possible. +DMA_ATTR_SKIP_CPU_SYNC allows platform code to skip synchronization of +the CPU cache for the given buffer assuming that it has been already +transferred to 'device' domain. This attribute can be also used for +dma_unmap_{single,page,sg} functions family to force buffer to stay in +device domain after releasing a mapping for it. Use this attribute with +care! + +DMA_ATTR_FORCE_CONTIGUOUS +------------------------- + +By default DMA-mapping subsystem is allowed to assemble the buffer +allocated by dma_alloc_attrs() function from individual pages if it can +be mapped as contiguous chunk into device dma address space. By +specifying this attribute the allocated buffer is forced to be contiguous +also in physical memory. + +DMA_ATTR_ALLOC_SINGLE_PAGES +--------------------------- + +This is a hint to the DMA-mapping subsystem that it's probably not worth +the time to try to allocate memory to in a way that gives better TLB +efficiency (AKA it's not worth trying to build the mapping out of larger +pages). You might want to specify this if: + +- You know that the accesses to this memory won't thrash the TLB. + You might know that the accesses are likely to be sequential or + that they aren't sequential but it's unlikely you'll ping-pong + between many addresses that are likely to be in different physical + pages. +- You know that the penalty of TLB misses while accessing the + memory will be small enough to be inconsequential. If you are + doing a heavy operation like decryption or decompression this + might be the case. +- You know that the DMA mapping is fairly transitory. If you expect + the mapping to have a short lifetime then it may be worth it to + optimize allocation (avoid coming up with large pages) instead of + getting the slight performance win of larger pages. + +Setting this hint doesn't guarantee that you won't get huge pages, but it +means that we won't try quite as hard to get them. + +.. note:: At the moment DMA_ATTR_ALLOC_SINGLE_PAGES is only implemented on ARM, + though ARM64 patches will likely be posted soon. + +DMA_ATTR_NO_WARN +---------------- + +This tells the DMA-mapping subsystem to suppress allocation failure reports +(similarly to __GFP_NOWARN). + +On some architectures allocation failures are reported with error messages +to the system logs. Although this can help to identify and debug problems, +drivers which handle failures (eg, retry later) have no problems with them, +and can actually flood the system logs with error messages that aren't any +problem at all, depending on the implementation of the retry mechanism. + +So, this provides a way for drivers to avoid those error messages on calls +where allocation failures are not a problem, and shouldn't bother the logs. + +.. note:: At the moment DMA_ATTR_NO_WARN is only implemented on PowerPC. + +DMA_ATTR_PRIVILEGED +------------------- + +Some advanced peripherals such as remote processors and GPUs perform +accesses to DMA buffers in both privileged "supervisor" and unprivileged +"user" modes. This attribute is used to indicate to the DMA-mapping +subsystem that the buffer is fully accessible at the elevated privilege +level (and ideally inaccessible or at least read-only at the +lesser-privileged levels). -- cgit v1.2.3