kernel/linux.git/Documentation/userspace-api/ioctl, branch v6.19.11

liveupdate: luo_core: Live Update Orchestrator

2025-11-27T22:24:37+00:00

Patch series "Live Update Orchestrator", v8. This series introduces the Live Update Orchestrator, a kernel subsystem designed to facilitate live kernel updates using a kexec-based reboot. This capability is critical for cloud environments, allowing hypervisors to be updated with minimal downtime for running virtual machines. LUO achieves this by preserving the state of selected resources, such as memory, devices and their dependencies, across the kernel transition. As a key feature, this series includes support for preserving memfd file descriptors, which allows critical in-memory data, such as guest RAM or any other large memory region, to be maintained in RAM across the kexec reboot. The other series that use LUO, are VFIO [1], IOMMU [2], and PCI [3] preservations. Github repo of this series [4]. The core of LUO is a framework for managing the lifecycle of preserved resources through a userspace-driven interface. Key features include: - Session Management Userspace agent (i.e. luod [5]) creates named sessions, each represented by a file descriptor (via centralized agent that controls /dev/liveupdate). The lifecycle of all preserved resources within a session is tied to this FD, ensuring automatic kernel cleanup if the controlling userspace agent crashes or exits unexpectedly. - File Preservation A handler-based framework allows specific file types (demonstrated here with memfd) to be preserved. Handlers manage the serialization, restoration, and lifecycle of their specific file types. - File-Lifecycle-Bound State A new mechanism for managing shared global state whose lifecycle is tied to the preservation of one or more files. This is crucial for subsystems like IOMMU or HugeTLB, where multiple file descriptors may depend on a single, shared underlying resource that must be preserved only once. - KHO Integration LUO drives the Kexec Handover framework programmatically to pass its serialized metadata to the next kernel. The LUO state is finalized and added to the kexec image just before the reboot is triggered. In the future this step will also be removed once stateless KHO is merged [6]. - Userspace Interface Control is provided via ioctl commands on /dev/liveupdate for creating and retrieving sessions, as well as on session file descriptors for managing individual files. - Testing The series includes a set of selftests, including userspace API validation, kexec-based lifecycle tests for various session and file scenarios, and a new in-kernel test module to validate the FLB logic. Introduce LUO, a mechanism intended to facilitate kernel updates while keeping designated devices operational across the transition (e.g., via kexec). The primary use case is updating hypervisors with minimal disruption to running virtual machines. For userspace side of hypervisor update we have copyless migration. LUO is for updating the kernel. This initial patch lays the groundwork for the LUO subsystem. Further functionality, including the implementation of state transition logic, integration with KHO, and hooks for subsystems and file descriptors, will be added in subsequent patches. Create a character device at /dev/liveupdate. A new uAPI header, , will define the necessary structures. The magic number for IOCTL is registered in Documentation/userspace-api/ioctl/ioctl-number.rst. Link: https://lkml.kernel.org/r/20251125165850.3389713-1-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20251125165850.3389713-2-pasha.tatashin@soleen.com Link: https://lore.kernel.org/all/20251018000713.677779-1-vipinsh@google.com/ [1] Link: https://lore.kernel.org/linux-iommu/20250928190624.3735830-1-skhawaja@google.com [2] Link: https://lore.kernel.org/linux-pci/20250916-luo-pci-v2-0-c494053c3c08@kernel.org [3] Link: https://github.com/googleprodkernel/linux-liveupdate/tree/luo/v8 [4] Link: https://tinyurl.com/luoddesign [5] Link: https://lore.kernel.org/all/20251020100306.2709352-1-jasonmiu@google.com [6] Link: https://lore.kernel.org/all/20251115233409.768044-1-pasha.tatashin@soleen.com [7] Link: https://github.com/soleen/linux/blob/luo/v8b03/diff.v7.v8 [8] Signed-off-by: Pasha Tatashin Reviewed-by: Pratyush Yadav Reviewed-by: Mike Rapoport (Microsoft) Tested-by: David Matlack Cc: Aleksander Lobakin Cc: Alexander Graf Cc: Alice Ryhl Cc: Andriy Shevchenko Cc: anish kumar Cc: Anna Schumaker Cc: Bartosz Golaszewski Cc: Bjorn Helgaas Cc: Borislav Betkov Cc: Chanwoo Choi Cc: Chen Ridong Cc: Chris Li Cc: Christian Brauner Cc: Daniel Wagner Cc: Danilo Krummrich Cc: Dan Williams Cc: David Hildenbrand Cc: David Jeffery Cc: David Rientjes Cc: Greg Kroah-Hartman Cc: Guixin Liu Cc: "H. Peter Anvin" Cc: Hugh Dickins Cc: Ilpo Järvinen Cc: Ingo Molnar Cc: Ira Weiny Cc: Jann Horn Cc: Jason Gunthorpe Cc: Jens Axboe Cc: Joanthan Cameron Cc: Joel Granados Cc: Johannes Weiner Cc: Jonathan Corbet Cc: Lennart Poettering Cc: Leon Romanovsky Cc: Leon Romanovsky Cc: Lukas Wunner Cc: Marc Rutland Cc: Masahiro Yamada Cc: Matthew Maurer Cc: Miguel Ojeda Cc: Myugnjoo Ham Cc: Parav Pandit Cc: Randy Dunlap Cc: Roman Gushchin Cc: Saeed Mahameed Cc: Samiullah Khawaja Cc: Song Liu Cc: Steven Rostedt Cc: Stuart Hayes Cc: Tejun Heo Cc: Thomas Gleinxer Cc: Thomas Weißschuh Cc: Vincent Guittot Cc: William Tu Cc: Yoann Congal Cc: Zijun Hu Cc: Pratyush Yadav Cc: Zhu Yanjun Signed-off-by: Andrew Morton

powerpc/pseries: Define papr-hvpipe ioctl

2025-09-15T08:08:39+00:00

PowerPC FW introduced HVPIPE RTAS calls such as ibm,send-hvpipe-msg and ibm,receive-hvpipe-msg for the user space to exchange information with different sources such as Hardware Management Consoles (HMC). HVPIPE_IOC_CREATE_HANDLE is defined to use /dev/papr-hvpipe interface for ibm,send-hvpipe-msg and ibm,receive-hvpipe-msg RTAS calls. Also defined papr_hvpipe_hdr which will added in the payload that is passed between the kernel and the user space. Signed-off-by: Haren Myneni Tested-by: Shashank MS Reviewed-by: Mahesh Salgaonkar Reviewed-by: Tyrel Datwyler Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20250909084402.1488456-2-haren@linux.ibm.com

Merge tag 'docs-6.17' of git://git.lwn.net/linux

2025-07-31T15:36:51+00:00

Pull documentation updates from Jonathan Corbet: "It has been a relatively busy cycle for docs, especially the build system: - The Perl kernel-doc script was added to 2.3.52pre1 just after the turn of the millennium. Over the following 25 years, it accumulated a vast amount of cruft, all in a language few people want to deal with anymore. Mauro's Python replacement in 6.16 faithfully reproduced all of the cruft in the hope of avoiding regressions. Now that we have a more reasonable code base, though, we can work on cleaning it up; many of the changes this time around are toward that end. - A reorganization of the ext4 docs into the usual TOC format. - Various Chinese translations and updates. - A new script from Mauro to help with docs-build testing. - A new document for linked lists - A sweep through MAINTAINERS fixing broken GitHub git:// repository links. ...and lots of fixes and updates" * tag 'docs-6.17' of git://git.lwn.net/linux: (147 commits) scripts: add origin commit identification based on specific patterns sphinx: kernel_abi: fix performance regression with O= Documentation: core-api: entry: Replace deprecated KVM entry/exit functions docs: fault-injection: drop reference to md-faulty docs: document linked lists scripts: kdoc: make it backward-compatible with Python 3.7 docs: kernel-doc: emit warnings for ancient versions of Python Documentation/rtla: Describe exit status Documentation/rtla: Add include common_appendix.rst docs: kernel: Clarify printk_ratelimit_burst reset behavior Documentation: ioctl-number: Don't repeat macro names Documentation: ioctl-number: Shorten macros table Documentation: ioctl-number: Correct full path to papr-physical-attestation.h Documentation: ioctl-number: Extend "Include File" column width Documentation: ioctl-number: Fix linuxppc-dev mailto link overlayfs.rst: fix typos docs: kdoc: emit a warning for ancient versions of Python docs: kdoc: clean up check_sections() docs: kdoc: directly access the always-there KdocItem fields docs: kdoc: straighten up dump_declaration() ...

Documentation: ioctl-number: Don't repeat macro names

2025-07-15T20:04:30+00:00

Don't repeat mentioning macro names (_IO, _IOW, _IOR, and _IOWR) to keep the wording effective. Signed-off-by: Bagas Sanjaya Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250715024258.16882-3-bagasdotme@gmail.com

Documentation: ioctl-number: Shorten macros table

2025-07-15T20:04:30+00:00

The macros table has three columns: the second one is "an" and the third one writes "an ioctl with ... parameters". Simplify the table by adding heading row that indicates macro name and accepted parameters. Signed-off-by: Bagas Sanjaya Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250715024258.16882-2-bagasdotme@gmail.com

Documentation: ioctl-number: Correct full path to papr-physical-attestation.h

2025-07-15T20:02:23+00:00

Commit 03c9d1a5a30d93 ("Documentation: Fix description format for powerpc RTAS ioctls") fixes Sphinx warning by chopping arch/ path component of papr-physical-attestation.h to fit existing "Include File" column. Now that the column has been widened just enough for that header file, add back its arch/ path component. Reviewed-by: Haren Myneni Signed-off-by: Bagas Sanjaya Acked-by: Madhavan Srinivasan Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250714015711.14525-4-bagasdotme@gmail.com

Documentation: ioctl-number: Extend "Include File" column width

2025-07-15T20:02:23+00:00

Extend width of "Include File" column to fit full path to papr-physical-attestation.h in later commit. Reviewed-by: Haren Myneni Signed-off-by: Bagas Sanjaya Acked-by: Madhavan Srinivasan Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250714015711.14525-3-bagasdotme@gmail.com

Documentation: ioctl-number: Fix linuxppc-dev mailto link

2025-07-15T20:02:05+00:00

Spell out full Linux PPC mailing list address like other subsystem mailing lists listed in the table. Reviewed-by: Haren Myneni Signed-off-by: Bagas Sanjaya Acked-by: Madhavan Srinivasan Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250714015711.14525-2-bagasdotme@gmail.com

block: remove pktcdvd driver

2025-07-07T13:02:42+00:00

This driver has long outlived it's utility, and it's broken and unloved. The main use case for this was direct mount with UDF of cd-rw drives that required 32kb packets. It would collect writes into that size and write them out in multiples of that. That's not a common use case anymore, the world has moved on from those kinds of media. To make matters worse, it's actively breaking setups where it's not even required or useful. Link: https://lore.kernel.org/linux-block/fxg6dksau4jsk3u5xldlyo2m7qgiux6vtdrz5rywseotsouqdv@urcrwz6qtd3r/ Link: https://lore.kernel.org/linux-block/dcc4836e-6da9-4208-ad27-bbd44b3a2063@kernel.dk/ Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe

Merge tag 'char-misc-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

2025-06-06T18:50:47+00:00

Pull char / misc / iio driver updates from Greg KH: "Here is the big char/misc/iio and other small driver subsystem pull request for 6.16-rc1. Overall, a lot of individual changes, but nothing major, just the normal constant forward progress of new device support and cleanups to existing subsystems. Highlights in here are: - Large IIO driver updates and additions and device tree changes - Android binder bugfixes and logfile fixes - mhi driver updates - comedi driver updates - counter driver updates and additions - coresight driver updates and additions - echo driver removal as there are no in-kernel users of it - nvmem driver updates - spmi driver updates - new amd-sbi driver "subsystem" and drivers added - rust miscdriver binding documentation fix - other small driver fixes and updates (uio, w1, acrn, hpet, xillybus, cardreader drivers, fastrpc and others) All of these have been in linux-next for quite a while with no reported problems" * tag 'char-misc-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (390 commits) binder: fix yet another UAF in binder_devices counter: microchip-tcb-capture: Add watch validation support dt-bindings: iio: adc: Add ROHM BD79100G iio: adc: add support for Nuvoton NCT7201 dt-bindings: iio: adc: add NCT7201 ADCs iio: chemical: Add driver for SEN0322 dt-bindings: trivial-devices: Document SEN0322 iio: adc: ad7768-1: reorganize driver headers iio: bmp280: zero-init buffer iio: ssp_sensors: optimalize -> optimize HID: sensor-hub: Fix typo and improve documentation iio: admv1013: replace redundant ternary operator with just len iio: chemical: mhz19b: Fix error code in probe() iio: adc: at91-sama5d2: use IIO_DECLARE_BUFFER_WITH_TS iio: accel: sca3300: use IIO_DECLARE_BUFFER_WITH_TS iio: adc: ad7380: use IIO_DECLARE_DMA_BUFFER_WITH_TS iio: adc: ad4695: rename AD4695_MAX_VIN_CHANNELS iio: adc: ad4695: use IIO_DECLARE_DMA_BUFFER_WITH_TS iio: introduce IIO_DECLARE_BUFFER_WITH_TS macros iio: make IIO_DMA_MINALIGN minimum of 8 bytes ...