kernel/linux.git/Documentation/ABI, branch v5.15.208

xhci: dbc: Allow users to modify DbC poll interval via sysfs

2025-12-06T21:09:15+00:00

[ Upstream commit de3edd47a18fe05a560847cc3165871474e08196 ] xhci DbC driver polls the host controller for DbC events at a reduced rate when DbC is enabled but there are no active data transfers. Allow users to modify this reduced poll interval via dbc_poll_interval_ms sysfs entry. Unit is milliseconds and accepted range is 0 to 5000. Max interval of 5000 ms is selected as it matches the common 5 second timeout used in usb stack. Default value is 64 milliseconds. A long interval is useful when users know there won't be any activity on systems connected via DbC for long periods, and want to avoid battery drainage due to unnecessary CPU usage. Example being Android Debugger (ADB) usage over DbC on ChromeOS systems running Android Runtime. [minor changes and rewording -Mathias] Co-developed-by: Samuel Jacob Signed-off-by: Samuel Jacob Signed-off-by: Uday M Bhat Signed-off-by: Mathias Nyman Link: https://lore.kernel.org/r/20240626124835.1023046-5-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman Stable-dep-of: f3d12ec847b9 ("xhci: dbc: fix bogus 1024 byte prefix if ttyDBC read races with stall event") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

xhci: dbc: Provide sysfs option to configure dbc descriptors

2025-12-06T21:09:15+00:00

[ Upstream commit edf1664f3249a091a2b91182fc087b3253b0b4c2 ] When DbC is enabled the first port on the xHC host acts as a usb device. xHC provides the descriptors automatically when the DbC device is enumerated. Most of the values are hardcoded, but some fields such as idProduct, idVendor, bcdDevice and bInterfaceProtocol can be modified. Add sysfs entries that allow userspace to change these. User can only change them before dbc is enabled, i.e. before writing "enable" to dbc sysfs file as we don't want these values to change while device is connected, or during enumeration. Add documentation for these entries in Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd Signed-off-by: Mathias Nyman Link: https://lore.kernel.org/r/20230317154715.535523-9-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman Stable-dep-of: f3d12ec847b9 ("xhci: dbc: fix bogus 1024 byte prefix if ttyDBC read races with stall event") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

x86/vmscape: Enable the mitigation

2025-09-11T15:17:17+00:00

commit 556c1ad666ad90c50ec8fccb930dd5046cfbecfb upstream. Enable the previously added mitigation for VMscape. Add the cmdline vmscape={off|ibpb|force} and sysfs reporting. Signed-off-by: Pawan Gupta Signed-off-by: Dave Hansen Reviewed-by: Borislav Petkov (AMD) Reviewed-by: Dave Hansen Signed-off-by: Amit Shah Signed-off-by: Greg Kroah-Hartman

x86/bugs: Add a Transient Scheduler Attacks mitigation

2025-07-10T13:57:50+00:00

commit d8010d4ba43e9f790925375a7de100604a5e2dba upstream. Add the required features detection glue to bugs.c et all in order to support the TSA mitigation. Co-developed-by: Kim Phillips Signed-off-by: Kim Phillips Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Pawan Gupta Signed-off-by: Greg Kroah-Hartman

scsi: ufs: core: Fix spelling of a sysfs attribute name

2025-07-10T13:57:44+00:00

[ Upstream commit 021f243627ead17eb6500170256d3d9be787dad8 ] Change "resourse" into "resource" in the name of a sysfs attribute. Fixes: d829fc8a1058 ("scsi: ufs: sysfs: unit descriptor") Signed-off-by: Bart Van Assche Link: https://lore.kernel.org/r/20250624181658.336035-1-bvanassche@acm.org Reviewed-by: Avri Altman Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin

x86/its: Enable Indirect Target Selection mitigation

2025-05-22T12:08:24+00:00

commit f4818881c47fd91fcb6d62373c57c7844e3de1c0 upstream. Indirect Target Selection (ITS) is a bug in some pre-ADL Intel CPUs with eIBRS. It affects prediction of indirect branch and RETs in the lower half of cacheline. Due to ITS such branches may get wrongly predicted to a target of (direct or indirect) branch that is located in the upper half of the cacheline. Scope of impact =============== Guest/host isolation -------------------- When eIBRS is used for guest/host isolation, the indirect branches in the VMM may still be predicted with targets corresponding to branches in the guest. Intra-mode ---------- cBPF or other native gadgets can be used for intra-mode training and disclosure using ITS. User/kernel isolation --------------------- When eIBRS is enabled user/kernel isolation is not impacted. Indirect Branch Prediction Barrier (IBPB) ----------------------------------------- After an IBPB, indirect branches may be predicted with targets corresponding to direct branches which were executed prior to IBPB. This is mitigated by a microcode update. Add cmdline parameter indirect_target_selection=off|on|force to control the mitigation to relocate the affected branches to an ITS-safe thunk i.e. located in the upper half of cacheline. Also add the sysfs reporting. When retpoline mitigation is deployed, ITS safe-thunks are not needed, because retpoline sequence is already ITS-safe. Similarly, when call depth tracking (CDT) mitigation is deployed (retbleed=stuff), ITS safe return thunk is not used, as CDT prevents RSB-underflow. To not overcomplicate things, ITS mitigation is not supported with spectre-v2 lfence;jmp mitigation. Moreover, it is less practical to deploy lfence;jmp mitigation on ITS affected parts anyways. Signed-off-by: Pawan Gupta Signed-off-by: Dave Hansen Reviewed-by: Josh Poimboeuf Reviewed-by: Alexandre Chartre Signed-off-by: Greg Kroah-Hartman

PCI: Add 'reset_subordinate' to reset hierarchy below bridge

2024-12-14T18:51:42+00:00

[ Upstream commit 2fa046449a82a7d0f6d9721dd83e348816038444 ] The "bus" and "cxl_bus" reset methods reset a device by asserting Secondary Bus Reset on the bridge leading to the device. These only work if the device is the only device below the bridge. Add a sysfs 'reset_subordinate' attribute on bridges that can assert Secondary Bus Reset regardless of how many devices are below the bridge. This resets all the devices below a bridge in a single command, including the locking and config space save/restore that reset methods normally do. This may be the only way to reset devices that don't support other reset methods (ACPI, FLR, PM reset, etc). Link: https://lore.kernel.org/r/20241025222755.3756162-1-kbusch@meta.com Signed-off-by: Keith Busch [bhelgaas: commit log, add capable(CAP_SYS_ADMIN) check] Signed-off-by: Bjorn Helgaas Reviewed-by: Alex Williamson Reviewed-by: Amey Narkhede Signed-off-by: Sasha Levin

f2fs: introduce F2FS_IPU_HONOR_OPU_WRITE ipu policy

2024-10-17T13:11:05+00:00

[ Upstream commit 1018a5463a063715365784704c4e8cdf2eec4b04 ] Once F2FS_IPU_FORCE policy is enabled in some cases: a) f2fs forces to use F2FS_IPU_FORCE in a small-sized volume b) user sets F2FS_IPU_FORCE policy via sysfs Then we may fail to defragment file due to IPU policy check, it doesn't make sense, let's introduce a new IPU policy to allow OPU during file defragmentation. In small-sized volume, let's enable F2FS_IPU_HONOR_OPU_WRITE policy by default. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Stable-dep-of: 884ee6dc85b9 ("f2fs: get rid of online repaire on corrupted directory") Signed-off-by: Sasha Levin

x86/rfds: Mitigate Register File Data Sampling (RFDS)

2024-04-10T14:18:48+00:00

commit 8076fcde016c9c0e0660543e67bff86cb48a7c9c upstream. RFDS is a CPU vulnerability that may allow userspace to infer kernel stale data previously used in floating point registers, vector registers and integer registers. RFDS only affects certain Intel Atom processors. Intel released a microcode update that uses VERW instruction to clear the affected CPU buffers. Unlike MDS, none of the affected cores support SMT. Add RFDS bug infrastructure and enable the VERW based mitigation by default, that clears the affected buffers just before exiting to userspace. Also add sysfs reporting and cmdline parameter "reg_file_data_sampling" to control the mitigation. For details see: Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst [ pawan: - Resolved conflicts in sysfs reporting. - s/ATOM_GRACEMONT/ALDERLAKE_N/ATOM_GRACEMONT is called ALDERLAKE_N in 6.6. ] Signed-off-by: Pawan Gupta Signed-off-by: Dave Hansen Reviewed-by: Thomas Gleixner Acked-by: Josh Poimboeuf Signed-off-by: Greg Kroah-Hartman

platform/x86: asus-wmi: Document the dgpu_disable sysfs attribute

2024-03-01T12:21:52+00:00

[ Upstream commit 7e64c486e807c8edfbd3a0c8e44ad7a1896dbec8 ] The dgpu_disable attribute was not documented, this adds the required documentation. Fixes: 98829e84dc67 ("asus-wmi: Add dgpu disable method") Signed-off-by: Luke D. Jones Link: https://lore.kernel.org/r/20220812222509.292692-2-luke@ljones.dev Reviewed-by: Hans de Goede Signed-off-by: Hans de Goede Signed-off-by: Sasha Levin