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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/translations/zh_CN/PCI/msi-howto.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
+.. include:: <isonum.txt>
+.. include:: ../disclaimer-zh_CN.rst
+
+:Original: Documentation/PCI/msi-howto.rst
+
+:翻译:
+
+ 司延腾 Yanteng Si <siyanteng@loongson.cn>
+
+:校译:
+
+
+
+===========
+MSI驱动指南
+===========
+
+:作者: Tom L Nguyen; Martine Silbermann; Matthew Wilcox
+
+:版权: 2003, 2008 Intel Corporation
+
+关于本指南
+==========
+
+本指南介绍了消息标记中断(MSI)的基本知识,使用MSI相对于传统中断机制的优势,如何
+改变你的驱动程序以使用MSI或MSI-X,以及在设备不支持MSI时可以尝试的一些基本诊断方法。
+
+
+什么是MSI?
+==========
+
+信息信号中断是指从设备写到一个特殊的地址,导致CPU接收到一个中断。
+
+MSI能力首次在PCI 2.2中规定,后来在PCI 3.0中得到增强,允许对每个中断进行单独屏蔽。
+MSI-X功能也随着PCI 3.0被引入。它比MSI支持每个设备更多的中断,并允许独立配置中断。
+
+设备可以同时支持MSI和MSI-X,但一次只能启用一个。
+
+
+为什么用MSI?
+============
+
+有三个原因可以说明为什么使用MSI比传统的基于针脚的中断有优势。
+
+基于针脚的PCI中断通常在几个设备之间共享。为了支持这一点,内核必须调用每个与中断相
+关的中断处理程序,这导致了整个系统性能的降低。MSI从不共享,所以这个问题不会出现。
+
+当一个设备将数据写入内存,然后引发一个基于引脚的中断时,有可能在所有的数据到达内存
+之前,中断就已经到达了(这在PCI-PCI桥后面的设备中变得更有可能)。为了确保所有的数
+据已经到达内存中,中断处理程序必须在引发中断的设备上读取一个寄存器。PCI事务排序规
+则要求所有的数据在返回寄存器的值之前到达内存。使用MSI可以避免这个问题,因为中断产
+生的写入不能通过数据写入,所以当中断发生时,驱动程序知道所有的数据已经到达内存中。
+
+PCI设备每个功能只能支持一个基于引脚的中断。通常情况下,驱动程序必须查询设备以找出
+发生了什么事件,这就减慢了对常见情况的中断处理。有了MSI,设备可以支持更多的中断,
+允许每个中断被专门用于不同的目的。一种可能的设计是给不经常发生的情况(如错误)提供
+自己的中断,这使得驱动程序可以更有效地处理正常的中断处理路径。其他可能的设计包括给
+网卡的每个数据包队列或存储控制器的每个端口提供一个中断。
+
+
+如何使用MSI
+===========
+
+PCI设备被初始化为使用基于引脚的中断。设备驱动程序必须将设备设置为使用MSI或MSI-X。
+并非所有的机器都能正确地支持MSI,对于这些机器,下面描述的API将简单地失败,设备将
+继续使用基于引脚的中断。
+
+加入内核对MSI的支持
+-------------------
+
+为了支持MSI或MSI-X,内核在构建时必须启用CONFIG_PCI_MSI选项。这个选项只在某些架
+构上可用,而且它可能取决于其他一些选项的设置。例如,在x86上,你必须同时启用X86_UP_APIC
+或SMP,才能看到CONFIG_PCI_MSI选项。
+
+使用MSI
+-------
+
+大部分沉重的工作是在PCI层为驱动程序完成的。驱动程序只需要请求PCI层为这个设备设置
+MSI功能。
+
+要自动使用MSI或MSI-X中断向量,请使用以下函数::
+
+ int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
+ unsigned int max_vecs, unsigned int flags);
+
+它为一个PCI设备分配最多至max_vecs的中断向量。它返回分配的向量数量或一个负的错误。
+如果设备对最小数量的向量有要求,驱动程序可以传递一个min_vecs参数,设置为这个限制,
+如果PCI核不能满足最小数量的向量,将返回-ENOSPC。
+
+flags参数用来指定设备和驱动程序可以使用哪种类型的中断(PCI_IRQ_LEGACY, PCI_IRQ_MSI,
+PCI_IRQ_MSIX)。一个方便的短语(PCI_IRQ_ALL_TYPES)也可以用来要求任何可能的中断类型。
+如果PCI_IRQ_AFFINITY标志被设置,pci_alloc_irq_vectors()将把中断分散到可用的CPU上。
+
+要获得传递给require_irq()和free_irq()的Linux IRQ号码和向量,请使用以下函数::
+
+ int pci_irq_vector(struct pci_dev *dev, unsigned int nr);
+
+在删除设备之前,应使用以下功能释放任何已分配的资源::
+
+ void pci_free_irq_vectors(struct pci_dev *dev);
+
+如果一个设备同时支持MSI-X和MSI功能,这个API将优先使用MSI-X,而不是MSI。MSI-X支
+持1到2048之间的任何数量的中断。相比之下,MSI被限制为最多32个中断(而且必须是2的幂)。
+此外,MSI中断向量必须连续分配,所以系统可能无法为MSI分配像MSI-X那样多的向量。在一
+些平台上,MSI中断必须全部针对同一组CPU,而MSI-X中断可以全部针对不同的CPU。
+
+如果一个设备既不支持MSI-X,也不支持MSI,它就会退回到一个传统的IRQ向量。
+
+MSI或MSI-X中断的典型用法是分配尽可能多的向量,可能达到设备支持的极限。如果nvec大于
+设备支持的数量,它将自动被限制在支持的限度内,所以没有必要事先查询支持的向量的数量。::
+
+ nvec = pci_alloc_irq_vectors(pdev, 1, nvec, PCI_IRQ_ALL_TYPES)
+ if (nvec < 0)
+ goto out_err;
+
+如果一个驱动程序不能或不愿意处理可变数量的MSI中断,它可以要求一个特定数量的中断,将该
+数量作为“min_vecs“和“max_vecs“参数传递给pci_alloc_irq_vectors()函数。::
+
+ ret = pci_alloc_irq_vectors(pdev, nvec, nvec, PCI_IRQ_ALL_TYPES);
+ if (ret < 0)
+ goto out_err;
+
+上述请求类型的最臭名昭著的例子是为一个设备启用单一的MSI模式。它可以通过传递两个1作为
+'min_vecs'和'max_vecs'来实现::
+
+ ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
+ if (ret < 0)
+ goto out_err;
+
+一些设备可能不支持使用传统的线路中断,在这种情况下,驱动程序可以指定只接受MSI或MSI-X。::
+
+ nvec = pci_alloc_irq_vectors(pdev, 1, nvec, PCI_IRQ_MSI | PCI_IRQ_MSIX);
+ if (nvec < 0)
+ goto out_err;
+
+传统API
+-----------
+
+以下用于启用和禁用MSI或MSI-X中断的旧API不应该在新代码中使用::
+
+ pci_enable_msi() /* deprecated */
+ pci_disable_msi() /* deprecated */
+ pci_enable_msix_range() /* deprecated */
+ pci_enable_msix_exact() /* deprecated */
+ pci_disable_msix() /* deprecated */
+
+此外,还有一些API来提供支持的MSI或MSI-X向量的数量:pci_msi_vec_count()和
+pci_msix_vec_count()。一般来说,应该避免使用这些方法,而是让pci_alloc_irq_vectors()
+来限制向量的数量。如果你对向量的数量有合法的特殊用例,我们可能要重新审视这个决定,
+并增加一个pci_nr_irq_vectors()助手,透明地处理MSI和MSI-X。
+
+使用MSI时需要考虑的因素
+-----------------------
+
+自旋锁
+~~~~~~
+
+大多数设备驱动程序都有一个每的自旋锁,在中断处理程序中被占用。对于基于引脚的中断
+或单一的MSI,没有必要禁用中断(Linux保证同一中断不会被重新输入)。如果一个设备
+使用多个中断,驱动程序必须在锁被持有的时候禁用中断。如果设备发出一个不同的中断,
+驱动程序将死锁,试图递归地获取自旋锁。这种死锁可以通过使用spin_lock_irqsave()
+或spin_lock_irq()来避免,它们可以禁用本地中断并获取锁(见《不可靠的锁定指南》)。
+
+如何判断一个设备上是否启用了MSI/MSI-X
+-------------------------------------
+
+使用“lspci -v“(以root身份)可能会显示一些具有“MSI“、“Message Signalled Interrupts“
+或“MSI-X“功能的设备。这些功能中的每一个都有一个“启用“标志,后面是“+“(启用)
+或“-“(禁用)。
+
+
+MSI特性
+=======
+
+众所周知,一些PCI芯片组或设备不支持MSI。PCI协议栈提供了三种禁用MSI的方法:
+
+1. 全局的
+2. 在一个特定的桥后面的所有设备上
+3. 在单一设备上
+
+全局禁用MSI
+-----------
+
+一些主控芯片组根本无法正确支持MSI。如果我们幸运的话,制造商知道这一点,并在
+ACPI FADT表中指明了它。在这种情况下,Linux会自动禁用MSI。有些板卡在表中没
+有包括这一信息,因此我们必须自己检测它们。完整的列表可以在drivers/pci/quirks.c
+中的quirk_disable_all_msi()函数附近找到。
+
+如果你有一块有MSI问题的板子,你可以在内核命令行中传递pci=nomsi来禁用所有设
+备上的MSI。你最好把问题报告给linux-pci@vger.kernel.org,包括完整的
+“lspci -v“,这样我们就可以把这些怪癖添加到内核中。
+
+禁用桥下的MSI
+-------------
+
+一些PCI桥接器不能在总线之间正确地路由MSI。在这种情况下,必须在桥接器后面的所
+有设备上禁用MSI。
+
+一些桥接器允许你通过改变PCI配置空间的一些位来启用MSI(特别是Hypertransport
+芯片组,如nVidia nForce和Serverworks HT2000)。与主机芯片组一样,Linux大
+多知道它们,如果可以的话,会自动启用MSI。如果你有一个Linux不知道的网桥,你可以
+用你知道的任何方法在配置空间中启用MSI,然后通过以下方式在该网桥上启用MSI::
+
+ echo 1 > /sys/bus/pci/devices/$bridge/msi_bus
+
+其中$bridge是你所启用的桥的PCI地址(例如0000:00:0e.0)。
+
+要禁用MSI,请回显0而不是1。改变这个值应该谨慎进行,因为它可能会破坏这个桥下面所
+有设备的中断处理。
+
+同样,请通知 linux-pci@vger.kernel.org 任何需要特殊处理的桥。
+
+在单一设备上关闭MSIs
+--------------------
+
+众所周知,有些设备的MSI实现是有问题的。通常情况下,这是在单个设备驱动程序中处理的,
+但偶尔也有必要用一个古怪的方法来处理。一些驱动程序有一个选项可以禁用MSI的使用。虽然
+这对驱动程序的作者来说是一个方便的变通办法,但这不是一个好的做法,不应该被模仿。
+
+寻找设备上MSI被禁用的原因
+-------------------------
+
+从以上三个部分,你可以看到有许多原因导致MSI没有在某个设备上被启用。你的第一步应该是
+仔细检查你的dmesg以确定你的机器是否启用了MSI。你还应该检查你的.config以确定你已经
+启用了CONFIG_PCI_MSI。
+
+然后,“lspci -t“给出一个设备上面的网列表。读取 ``/sys/bus/pci/devices/*/msi_bus``
+将告诉你MSI是否被启用(1)或禁用(0)。如果在任何属于PCI根和设备之间的桥的msi_bus
+文件中发现0,说明MSI被禁用。
+
+也需要检查设备驱动程序,看它是否支持MSI。例如,它可能包含对带有PCI_IRQ_MSI或
+PCI_IRQ_MSIX标志的pci_alloc_irq_vectors()的调用。