user/sven/linux.git/Documentation/admin-guide, branch v6.12.46

x86/bugs: Add a Transient Scheduler Attacks mitigation

2025-07-10T14:05:14Z

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

x86/bugs: Rename MDS machinery to something more generic

2025-07-10T14:05:14Z

Commit f9af88a3d384c8b55beb5dc5483e5da0135fadbd upstream. It will be used by other x86 mitigations. No functional changes. Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Pawan Gupta Signed-off-by: Greg Kroah-Hartman

x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2

2025-05-29T09:02:33Z

[ Upstream commit 98fdaeb296f51ef08e727a7cc72e5b5c864c4f4d ] Change the default value of spectre v2 in user mode to respect the CONFIG_MITIGATION_SPECTRE_V2 config option. Currently, user mode spectre v2 is set to auto (SPECTRE_V2_USER_CMD_AUTO) by default, even if CONFIG_MITIGATION_SPECTRE_V2 is disabled. Set the spectre_v2 value to auto (SPECTRE_V2_USER_CMD_AUTO) if the Spectre v2 config (CONFIG_MITIGATION_SPECTRE_V2) is enabled, otherwise set the value to none (SPECTRE_V2_USER_CMD_NONE). Important to say the command line argument "spectre_v2_user" overwrites the default value in both cases. When CONFIG_MITIGATION_SPECTRE_V2 is not set, users have the flexibility to opt-in for specific mitigations independently. In this scenario, setting spectre_v2= will not enable spectre_v2_user=, and command line options spectre_v2_user and spectre_v2 are independent when CONFIG_MITIGATION_SPECTRE_V2=n. Signed-off-by: Breno Leitao Signed-off-by: Ingo Molnar Reviewed-by: Pawan Gupta Acked-by: Josh Poimboeuf Cc: Peter Zijlstra Cc: David Kaplan Link: https://lore.kernel.org/r/20241031-x86_bugs_last_v2-v2-2-b7ff1dab840e@debian.org Signed-off-by: Sasha Levin

x86/its: Add support for RSB stuffing mitigation

2025-05-18T06:24:59Z

commit facd226f7e0c8ca936ac114aba43cb3e8b94e41e upstream. When retpoline mitigation is enabled for spectre-v2, enabling call-depth-tracking and RSB stuffing also mitigates ITS. Add cmdline option indirect_target_selection=stuff to allow enabling RSB stuffing mitigation. When retpoline mitigation is not enabled, =stuff option is ignored, and default mitigation for ITS is deployed. Signed-off-by: Pawan Gupta Signed-off-by: Dave Hansen Reviewed-by: Josh Poimboeuf Reviewed-by: Alexandre Chartre Signed-off-by: Greg Kroah-Hartman

x86/its: Add "vmexit" option to skip mitigation on some CPUs

2025-05-18T06:24:59Z

commit 2665281a07e19550944e8354a2024635a7b2714a upstream. Ice Lake generation CPUs are not affected by guest/host isolation part of ITS. If a user is only concerned about KVM guests, they can now choose a new cmdline option "vmexit" that will not deploy the ITS mitigation when CPU is not affected by guest/host isolation. This saves the performance overhead of ITS mitigation on Ice Lake gen CPUs. When "vmexit" option selected, if the CPU is affected by ITS guest/host isolation, the default ITS mitigation is deployed. Signed-off-by: Pawan Gupta Signed-off-by: Dave Hansen Reviewed-by: Josh Poimboeuf Reviewed-by: Alexandre Chartre Signed-off-by: Greg Kroah-Hartman

x86/its: Enable Indirect Target Selection mitigation

2025-05-18T06:24:59Z

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

Documentation: x86/bugs/its: Add ITS documentation

2025-05-18T06:24:59Z

commit 1ac116ce6468670eeda39345a5585df308243dca upstream. Add the admin-guide for Indirect Target Selection (ITS). Signed-off-by: Pawan Gupta Signed-off-by: Dave Hansen Reviewed-by: Josh Poimboeuf Reviewed-by: Alexandre Chartre Signed-off-by: Greg Kroah-Hartman

ata: libata-core: Add 'external' to the libata.force kernel parameter

2025-04-20T08:15:16Z

[ Upstream commit deca423213cb33feda15e261e7b5b992077a6a08 ] Commit ae1f3db006b7 ("ata: ahci: do not enable LPM on external ports") changed so that LPM is not enabled on external ports (hotplug-capable or eSATA ports). This is because hotplug and LPM are mutually exclusive, see 7.3.1 Hot Plug Removal Detection and Power Management Interaction in AHCI 1.3.1. This does require that firmware has set the appropate bits (HPCP or ESP) in PxCMD (which is a per port register in the AHCI controller). If the firmware has failed to mark a port as hotplug-capable or eSATA in PxCMD, then there is currently not much a user can do. If LPM is enabled on the port, hotplug insertions and removals will not be detected on that port. In order to allow a user to fix up broken firmware, add 'external' to the libata.force kernel parameter. libata.force can be specified either on the kernel command line, or as a kernel module parameter. For more information, see Documentation/admin-guide/kernel-parameters.txt. Reviewed-by: Damien Le Moal Link: https://lore.kernel.org/r/20250130133544.219297-4-cassel@kernel.org Signed-off-by: Niklas Cassel Signed-off-by: Sasha Levin

coredump: Only sort VMAs when core_sort_vma sysctl is set

2025-03-13T12:02:01Z

[ Upstream commit 39ec9eaaa165d297d008d1fa385748430bd18e4d ] The sorting of VMAs by size in commit 7d442a33bfe8 ("binfmt_elf: Dump smaller VMAs first in ELF cores") breaks elfutils[1]. Instead, sort based on the setting of the new sysctl, core_sort_vma, which defaults to 0, no sorting. Reported-by: Michael Stapelberg Closes: https://lore.kernel.org/all/20250218085407.61126-1-michael@stapelberg.de/ [1] Fixes: 7d442a33bfe8 ("binfmt_elf: Dump smaller VMAs first in ELF cores") Signed-off-by: Kees Cook Signed-off-by: Sasha Levin

fs/writeback: convert wbc_account_cgroup_owner to take a folio

2025-01-17T12:40:33Z

[ Upstream commit 30dac24e14b52e1787572d1d4e06eeabe8a63630 ] Most of the callers of wbc_account_cgroup_owner() are converting a folio to page before calling the function. wbc_account_cgroup_owner() is converting the page back to a folio to call mem_cgroup_css_from_folio(). Convert wbc_account_cgroup_owner() to take a folio instead of a page, and convert all callers to pass a folio directly except f2fs. Convert the page to folio for all the callers from f2fs as they were the only callers calling wbc_account_cgroup_owner() with a page. As f2fs is already in the process of converting to folios, these call sites might also soon be calling wbc_account_cgroup_owner() with a folio directly in the future. No functional changes. Only compile tested. Signed-off-by: Pankaj Raghav Link: https://lore.kernel.org/r/20240926140121.203821-1-kernel@pankajraghav.com Acked-by: David Sterba Acked-by: Tejun Heo Signed-off-by: Christian Brauner Stable-dep-of: 51d20d1dacbe ("iomap: fix zero padding data issue in concurrent append writes") Signed-off-by: Sasha Levin