linux-rng/include/linux/cpu.h, branch linus/master

Merge commit 'its-for-linus-20250509-merge' into x86/core, to resolve conflicts

2025-05-13T08:47:10Z

Conflicts: Documentation/admin-guide/hw-vuln/index.rst arch/x86/include/asm/cpufeatures.h arch/x86/kernel/alternative.c arch/x86/kernel/cpu/bugs.c arch/x86/kernel/cpu/common.c drivers/base/cpu.c include/linux/cpu.h Signed-off-by: Ingo Molnar

x86/its: Enable Indirect Target Selection mitigation

2025-05-09T20:22:05Z

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

x86/cpu: Help users notice when running old Intel microcode

2025-04-22T06:33:52Z

Old microcode is bad for users and for kernel developers. For users, it exposes them to known fixed security and/or functional issues. These obviously rarely result in instant dumpster fires in every environment. But it is as important to keep your microcode up to date as it is to keep your kernel up to date. Old microcode also makes kernels harder to debug. A developer looking at an oops need to consider kernel bugs, known CPU issues and unknown CPU issues as possible causes. If they know the microcode is up to date, they can mostly eliminate known CPU issues as the cause. Make it easier to tell if CPU microcode is out of date. Add a list of released microcode. If the loaded microcode is older than the release, tell users in a place that folks can find it: /sys/devices/system/cpu/vulnerabilities/old_microcode Tell kernel kernel developers about it with the existing taint flag: TAINT_CPU_OUT_OF_SPEC == Discussion == When a user reports a potential kernel issue, it is very common to ask them to reproduce the issue on mainline. Running mainline, they will (independently from the distro) acquire a more up-to-date microcode version list. If their microcode is old, they will get a warning about the taint and kernel developers can take that into consideration when debugging. Just like any other entry in "vulnerabilities/", users are free to make their own assessment of their exposure. == Microcode Revision Discussion == The microcode versions in the table were generated from the Intel microcode git repo: 8ac9378a8487 ("microcode-20241112 Release") which as of this writing lags behind the latest microcode-20250211. It can be argued that the versions that the kernel picks to call "old" should be a revision or two old. Which specific version is picked is less important to me than picking *a* version and enforcing it. This repository contains only microcode versions that Intel has deemed to be OS-loadable. It is quite possible that the BIOS has loaded a newer microcode than the latest in this repo. If this happens, the system is considered to have new microcode, not old. Specifically, the sysfs file and taint flag answer the question: Is the CPU running on the latest OS-loadable microcode, or something even later that the BIOS loaded? In other words, Intel never publishes an authoritative list of CPUs and latest microcode revisions. Until it does, this is the best that Linux can do. Also note that the "intel-ucode-defs.h" file is simple, ugly and has lots of magic numbers. That's on purpose and should allow a single file to be shared across lots of stable kernel regardless of if they have the new "VFM" infrastructure or not. It was generated with a dumb script. == FAQ == Q: Does this tell me if my system is secure or insecure? A: No. It only tells you if your microcode was old when the system booted. Q: Should the kernel warn if the microcode list itself is too old? A: No. New kernels will get new microcode lists, both mainline and stable. The only way to have an old list is to be running an old kernel in which case you have bigger problems. Q: Is this for security or functional issues? A: Both. Q: If a given microcode update only has functional problems but no security issues, will it be considered old? A: Yes. All microcode image versions within a microcode release are treated identically. Intel appears to make security updates without disclosing them in the release notes. Thus, all updates are considered to be security-relevant. Q: Who runs old microcode? A: Anybody with an old distro. This happens all the time inside of Intel where there are lots of weird systems in labs that might not be getting regular distro updates and might also be running rather exotic microcode images. Q: If I update my microcode after booting will it stop saying "Vulnerable"? A: No. Just like all the other vulnerabilies, you need to reboot before the kernel will reassess your vulnerability. Signed-off-by: Dave Hansen Signed-off-by: Ingo Molnar Cc: "Ahmed S. Darwish" Cc: Andrew Cooper Cc: Andy Lutomirski Cc: Brian Gerst Cc: John Ogness Cc: Josh Poimboeuf Cc: Juergen Gross Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Link: https://lore.kernel.org/all/20250421195659.CF426C07%40davehans-spike.ostc.intel.com (cherry picked from commit 9127865b15eb0a1bd05ad7efe29489c44394bdc1)

cpu: remove needless return in void API suspend_enable_secondary_cpus()

2025-03-17T06:24:15Z

Remove needless 'return' in void API suspend_enable_secondary_cpus() since both the API and thaw_secondary_cpus() are void functions. Link: https://lkml.kernel.org/r/20250221-rmv_return-v1-2-cc8dff275827@quicinc.com Signed-off-by: Zijun Hu Signed-off-by: Andrew Morton

riscv: Add ghostwrite vulnerability

2025-01-18T20:33:39Z

Follow the patterns of the other architectures that use GENERIC_CPU_VULNERABILITIES for riscv to introduce the ghostwrite vulnerability and mitigation. The mitigation is to disable all vector which is accomplished by clearing the bit from the cpufeature field. Ghostwrite only affects thead c9xx CPUs that impelment xtheadvector, so the vulerability will only be mitigated on these CPUs. Signed-off-by: Charlie Jenkins Tested-by: Yangyu Chen Link: https://lore.kernel.org/r/20241113-xtheadvector-v11-14-236c22791ef9@rivosinc.com Signed-off-by: Palmer Dabbelt

Merge tag 'mm-nonmm-stable-2024-07-21-15-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-07-22T00:56:22Z

Pull non-MM updates from Andrew Morton: - In the series "treewide: Refactor heap related implementation", Kuan-Wei Chiu has significantly reworked the min_heap library code and has taught bcachefs to use the new more generic implementation. - Yury Norov's series "Cleanup cpumask.h inclusion in core headers" reworks the cpumask and nodemask headers to make things generally more rational. - Kuan-Wei Chiu has sent along some maintenance work against our sorting library code in the series "lib/sort: Optimizations and cleanups". - More library maintainance work from Christophe Jaillet in the series "Remove usage of the deprecated ida_simple_xx() API". - Ryusuke Konishi continues with the nilfs2 fixes and clanups in the series "nilfs2: eliminate the call to inode_attach_wb()". - Kuan-Ying Lee has some fixes to the gdb scripts in the series "Fix GDB command error". - Plus the usual shower of singleton patches all over the place. Please see the relevant changelogs for details. * tag 'mm-nonmm-stable-2024-07-21-15-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (98 commits) ia64: scrub ia64 from poison.h watchdog/perf: properly initialize the turbo mode timestamp and rearm counter tsacct: replace strncpy() with strscpy() lib/bch.c: use swap() to improve code test_bpf: convert comma to semicolon init/modpost: conditionally check section mismatch to __meminit* init: remove unused __MEMINIT* macros nilfs2: Constify struct kobj_type nilfs2: avoid undefined behavior in nilfs_cnt32_ge macro math: rational: add missing MODULE_DESCRIPTION() macro lib/zlib: add missing MODULE_DESCRIPTION() macro fs: ufs: add MODULE_DESCRIPTION() lib/rbtree.c: fix the example typo ocfs2: add bounds checking to ocfs2_check_dir_entry() fs: add kernel-doc comments to ocfs2_prepare_orphan_dir() coredump: simplify zap_process() selftests/fpu: add missing MODULE_DESCRIPTION() macro compiler.h: simplify data_race() macro build-id: require program headers to be right after ELF header resource: add missing MODULE_DESCRIPTION() ...

cpumask: cleanup core headers inclusion

2024-06-25T05:25:02Z

Many core headers include cpumask.h for nothing. Drop it. Link: https://lkml.kernel.org/r/20240528005648.182376-6-yury.norov@gmail.com Signed-off-by: Yury Norov Cc: Amit Daniel Kachhap Cc: Anna-Maria Behnsen Cc: Christoph Lameter Cc: Daniel Lezcano Cc: Dennis Zhou Cc: Frederic Weisbecker Cc: Johannes Weiner Cc: Juri Lelli Cc: Kees Cook Cc: Mathieu Desnoyers Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Rafael J. Wysocki Cc: Rasmus Villemoes Cc: Tejun Heo Cc: Thomas Gleixner Cc: Ulf Hansson Cc: Vincent Guittot Cc: Viresh Kumar Cc: Yury Norov Signed-off-by: Andrew Morton

cpu: Move CPU hotplug function declarations into their own header

2024-06-10T06:50:01Z

Avoid upcoming #include hell when wants to use lockdep_assert_cpus_held() and creates a #include loop that would break the build for arch/riscv. [ bp: s/cpu/CPU/g ] Signed-off-by: Tony Luck Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240610003927.341707-2-tony.luck@intel.com

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

2024-04-25T13:47:39Z

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

Merge tag 'driver-core-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2024-03-21T20:34:15Z

Pull driver core updates from Greg KH: "Here is the "big" set of driver core and kernfs changes for 6.9-rc1. Nothing all that crazy here, just some good updates that include: - automatic attribute group hiding from Dan Williams (he fixed up my horrible attempt at doing this.) - kobject lock contention fixes from Eric Dumazet - driver core cleanups from Andy - kernfs rcu work from Tejun - fw_devlink changes to resolve some reported issues - other minor changes, all details in the shortlog All of these have been in linux-next for a long time with no reported issues" * tag 'driver-core-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (28 commits) device: core: Log warning for devices pending deferred probe on timeout driver: core: Use dev_* instead of pr_* so device metadata is added driver: core: Log probe failure as error and with device metadata of: property: fw_devlink: Add support for "post-init-providers" property driver core: Add FWLINK_FLAG_IGNORE to completely ignore a fwnode link driver core: Adds flags param to fwnode_link_add() debugfs: fix wait/cancellation handling during remove device property: Don't use "proxy" headers device property: Move enum dev_dma_attr to fwnode.h driver core: Move fw_devlink stuff to where it belongs driver core: Drop unneeded 'extern' keyword in fwnode.h firmware_loader: Suppress warning on FW_OPT_NO_WARN flag sysfs:Addresses documentation in sysfs_merge_group and sysfs_unmerge_group. firmware_loader: introduce __free() cleanup hanler platform-msi: Remove usage of the deprecated ida_simple_xx() API sysfs: Introduce DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE() sysfs: Document new "group visible" helpers sysfs: Fix crash on empty group attributes array sysfs: Introduce a mechanism to hide static attribute_groups sysfs: Introduce a mechanism to hide static attribute_groups ...