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Lukas Wunner eddba19b8b PCI/AER: Support Advisory Non-Fatal Errors
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
2026-08-18 17:31:54 -05:00
arch LoongArch changes for v7.2 2026-06-26 08:42:49 -07:00
block block: handle REQ_OP_ZONE_APPEND in __bio_integrity_action 2026-06-24 06:53:25 -06:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
Documentation RTC for 7.2 2026-06-27 11:00:18 -07:00
drivers PCI/AER: Support Advisory Non-Fatal Errors 2026-08-18 17:31:54 -05:00
fs fscrypt fixes for 7.2 2026-06-27 09:20:16 -07:00
include NTB updates include an EPF bug fix to prevent an invalid unmap during 2026-06-28 07:46:12 -07:00
init mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
io_uring io_uring-7.2-20260625 2026-06-25 09:53:31 -07:00
ipc kernel-7.2-rc1.misc 2026-06-15 03:05:50 +05:30
kernel Power management fixes for 7.2-rc1 2026-06-26 13:14:18 -07:00
lib Misc fixes: 2026-06-23 16:05:54 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm block-7.2-20260625 2026-06-25 09:56:47 -07:00
net bpf-fixes 2026-06-25 14:09:26 -07:00
rust Rust changes for v7.2 (addendum) 2026-06-24 15:11:08 -07:00
samples Char/Misc/IIO/FPGA/GPIB/etc driver updates for 7.2-rc1 2026-06-22 12:20:21 -07:00
scripts Second round of Kbuild changes for 7.2 2026-06-25 09:06:12 -07:00
security * add Georgia Garcia as co-maintainer of apparmor 2026-06-24 12:33:40 -07:00
sound sound fixes for 7.2-rc1 2026-06-27 12:15:23 -07:00
tools LoongArch changes for v7.2 2026-06-26 08:42:49 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt s390: 2026-06-25 10:21:13 -07:00
.clang-format clang-format: fix formatting of guard() and scoped_guard() statements 2026-05-28 21:24:41 -07:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add myself 2026-04-02 16:48:25 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore SPDX patches for 7.2-rc1 2026-06-22 12:06:22 -07:00
.mailmap Including fixes from netfilter and IPsec. 2026-06-25 12:25:36 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Including fixes from netfilter and IPsec. 2026-06-25 12:25:36 -07:00
Makefile Linux 7.2-rc1 2026-06-28 12:01:31 -07:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -07:00

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