kernel/linux.git/include/linux/cpu.h, branch v6.6.132

x86/vmscape: Enable the mitigation

2025-09-11T15:20:27+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: Borislav Petkov (AMD) Signed-off-by: Greg Kroah-Hartman

x86/bugs: Add a Transient Scheduler Attacks mitigation

2025-07-10T14:03:21+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

x86/its: Enable Indirect Target Selection mitigation

2025-05-18T06:24:11+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

cpu: Ignore "mitigations" kernel parameter if CPU_MITIGATIONS=n

2024-06-12T09:11:24+00:00

[ Upstream commit ce0abef6a1d540acef85068e0e82bdf1fbeeb0e9 ] Explicitly disallow enabling mitigations at runtime for kernels that were built with CONFIG_CPU_MITIGATIONS=n, as some architectures may omit code entirely if mitigations are disabled at compile time. E.g. on x86, a large pile of Kconfigs are buried behind CPU_MITIGATIONS, and trying to provide sane behavior for retroactively enabling mitigations is extremely difficult, bordering on impossible. E.g. page table isolation and call depth tracking require build-time support, BHI mitigations will still be off without additional kernel parameters, etc. [ bp: Touchups. ] Signed-off-by: Sean Christopherson Signed-off-by: Borislav Petkov (AMD) Acked-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240420000556.2645001-3-seanjc@google.com Signed-off-by: Sasha Levin

sched: Simplify tg_set_cfs_bandwidth()

2024-04-03T13:28:18+00:00

[ Upstream commit 6fb45460615358157a6d3c990e74f9c1395247e2 ] Use guards to reduce gotos and simplify control flow. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Stable-dep-of: 1aa09b9379a7 ("powercap: intel_rapl: Fix locking in TPMI RAPL") Signed-off-by: Sasha Levin

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

2024-03-15T14:48:22+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 Signed-off-by: Pawan Gupta Signed-off-by: Dave Hansen Reviewed-by: Thomas Gleixner Acked-by: Josh Poimboeuf Signed-off-by: Greg Kroah-Hartman

cpu-hotplug: Provide prototypes for arch CPU registration

2023-10-11T12:27:37+00:00

Provide common prototypes for arch_register_cpu() and arch_unregister_cpu(). These are called by acpi_processor.c, with weak versions, so the prototype for this is already set. It is generally not necessary for function prototypes to be conditional on preprocessor macros. Some architectures (e.g. Loongarch) are missing the prototype for this, and rather than add it to Loongarch's asm/cpu.h, do the job once for everyone. Since this covers everyone, remove the now unnecessary prototypes in asm/cpu.h, and therefore remove the 'static' from one of ia64's arch_register_cpu() definitions. [ tglx: Bring back the ia64 part and remove the ACPI prototypes ] Signed-off-by: Russell King (Oracle) Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/E1qkoRr-0088Q8-Da@rmk-PC.armlinux.org.uk

Merge tag 'smp-core-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-08-28T22:04:43+00:00

Pull CPU hotplug updates from Thomas Gleixner: "Updates for the CPU hotplug core: - Support partial SMT enablement. So far the sysfs SMT control only allows to toggle between SMT on and off. That's sufficient for x86 which usually has at max two threads except for the Xeon PHI platform which has four threads per core Though PowerPC has up to 16 threads per core and so far it's only possible to control the number of enabled threads per core via a command line option. There is some way to control this at runtime, but that lacks enforcement and the usability is awkward This update expands the sysfs interface and the core infrastructure to accept numerical values so PowerPC can build SMT runtime control for partial SMT enablement on top The core support has also been provided to the PowerPC maintainers who added the PowerPC related changes on top - Minor cleanups and documentation updates" * tag 'smp-core-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: Documentation: core-api/cpuhotplug: Fix state names cpu/hotplug: Remove unused function declaration cpu_set_state_online() cpu/SMT: Fix cpu_smt_possible() comment cpu/SMT: Allow enabling partial SMT states via sysfs cpu/SMT: Create topology_smt_thread_allowed() cpu/SMT: Remove topology_smt_supported() cpu/SMT: Store the current/max number of threads cpu/SMT: Move smt/control simple exit cases earlier cpu/SMT: Move SMT prototypes into cpu_smt.h cpu/hotplug: Remove dependancy against cpu_primary_thread_mask

x86/speculation: Add cpu_show_gds() prototype

2023-08-10T16:12:18+00:00

The newly added function has two definitions but no prototypes: drivers/base/cpu.c:605:16: error: no previous prototype for 'cpu_show_gds' [-Werror=missing-prototypes] Add a declaration next to the other ones for this file to avoid the warning. Fixes: 8974eb588283b ("x86/speculation: Add Gather Data Sampling mitigation") Signed-off-by: Arnd Bergmann Signed-off-by: Dave Hansen Tested-by: Daniel Sneddon Cc: stable@kernel.org Link: https://lore.kernel.org/all/20230809130530.1913368-1-arnd%40kernel.org

cpu/hotplug: Remove unused function declaration cpu_set_state_online()

2023-08-07T16:22:42+00:00

Commit 5356297d12d9 ("cpu/hotplug: Remove cpu_report_state() and related unused cruft") removed function but leave the declaration. Signed-off-by: Yue Haibing Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230805110406.45900-1-yuehaibing@huawei.com