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Per PCIe r7.0 sec 6.2.4.3, certain Non-Fatal Errors may be signaled using ERR_COR instead of ERR_NONFATAL. These "Advisory Non-Fatal Errors" are listed in sec 6.2.7 and explained in detail in sec 6.2.3.2.4. Advisory Non-Fatal Errors set bits in the Uncorrectable Error Status Register as well as one bit in the Correctable Error Status Register (Advisory Non-Fatal Error Status, bit 13). The latter is masked by default, hence these errors are currently not signaled at all (except on non-compliant products which choose to unmask the bit). Unmask Advisory Non-Fatal Errors on device enumeration. Some Non-Fatal Errors are always Advisory, others may be Advisory at the discretion of the detecting agent. If multiple errors occur, the agent may qualify a portion as non-Advisory and signal ERR_NONFATAL in addition to ERR_COR. In this case, there's no way to determine which Non-Fatal Error was Advisory. Assume none is to ensure that the Uncorrectable Error code path is taken to recover from the errors. Introduce aer_compute_anfe_status() to compute Advisory Non-Fatal Error bits from AER registers, based on this policy. Use it for Firmware First error handling in pci_print_aer(), which receives an AER register dump from the platform (UEFI r2.11 sec N.2.7). Introduce aer_get_anfe_status() to read AER registers from a device and feed them to aer_compute_anfe_status(). Use it for native error handling in aer_get_device_error_info(), which gathers registers from the device and caches the computed Advisory Non-Fatal Error bits in a new anfe_status field in struct aer_err_info. Regardless whether error handling is native or Firmware First, the AER driver needs to increment error counters, signal a trace event and log each error. When Advisory Non-Fatal Errors occur, these steps must be performed for Correctable Errors and for Uncorrectable Errors. Achieve this through a recursive invocation of aer_print_error() (for native error handling) and pci_print_aer() (for Firmware First error handling). The recursive invocation reports the (Advisory) Uncorrectable Errors after reporting the Correctable Errors. Note that the First Error Pointer and TLP Prefix Log is only meaningful for Uncorrectable Errors, but when Advisory Non-Fatal Errors occur, aer_get_device_error_info() has to populate the first_error and tlp_header_valid fields in struct aer_err_info for a Correctable Error. Avoid incorrectly logging those fields for Correctable Errors by amending __aer_print_error() and aer_print_error() with conditionals. Sample log output for an Advisory Unsupported Request Error: pcieport 0001:00:00.4: AER: Multiple Correctable Error messages received, first one from 0001:0e:00.0 idxd 0001:0e:00.0: PCIe Bus Error: severity=Correctable idxd 0001:0e:00.0: device [8086:1216] error status/mask=00002000/00000000 idxd 0001:0e:00.0: [13] NonFatalErr | | idxd 0001:0e:00.0: PCIe Bus Error: severity=Uncorrectable (Non-Fatal) idxd 0001:0e:00.0: device [8086:1216] error status/mask=00100000/00000000 idxd 0001:0e:00.0: [20] UnsupReq | Receiver | Transaction Layer (First) idxd 0001:0e:00.0: AER: TLP Header (Flit): 0x01000104 0x00000000 0x0000080e 0x0f800001 This commit takes inspiration (but differs significantly) from an earlier submission by Zhenzhong Duan, which in turn was based on a submission by Qingshun Wang: https://lore.kernel.org/r/20240620025857.206647-1-zhenzhong.duan@intel.com/ Prior attempts at supporting Advisory Non-Fatal Errors were submitted by Yicong Yang and Dio Sun: https://lore.kernel.org/r/1614689994-10925-1-git-send-email-yangyicong@hisilicon.com/ https://lore.kernel.org/r/BJXPR01MB0614C01A9523786117B1F1CBCEC8A@BJXPR01MB0614.CHNPR01.prod.partner.outlook.cn/ Signed-off-by: Lukas Wunner <lukas@wunner.de> [bhelgaas: fold in https://lore.kernel.org/all/amdnMg_J6T3Sys45@wunner.de, https://lore.kernel.org/all/120da0565eac0157ffd913423c7cfa66e985ff59.1786800931.git.lukas@wunner.de] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Link: https://lore.kernel.org/r/20240620025857.206647-1-zhenzhong.duan@intel.com/ Link: https://lore.kernel.org/r/1614689994-10925-1-git-send-email-yangyicong@hisilicon.com/ Link: https://lore.kernel.org/r/BJXPR01MB0614C01A9523786117B1F1CBCEC8A@BJXPR01MB0614.CHNPR01.prod.partner.outlook.cn/ Link: https://patch.msgid.link/1b62915ffe06ee5b08e846531c42392e5f244337.1784905909.git.lukas@wunner.de
Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros * AI Coding Assistant - LLMs and AI-powered development tools For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst