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2025-02-28x86/bugs: Add X86_BUG_SPECTRE_V2_USERDavid Kaplan
All CPU vulnerabilities with command line options map to a single X86_BUG bit except for Spectre V2 where both the spectre_v2 and spectre_v2_user command line options are related to the same bug. The spectre_v2 command line options mostly relate to user->kernel and guest->host mitigations, while the spectre_v2_user command line options relate to user->user or guest->guest protections. Define a new X86_BUG bit for spectre_v2_user so each *_select_mitigation() function in bugs.c is related to a unique X86_BUG bit. No functional changes. Signed-off-by: David Kaplan <david.kaplan@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20250108202515.385902-2-david.kaplan@amd.com
2025-02-28x86/cpu: Enable modifying CPU bug flags with '{clear,set}puid='Brendan Jackman
Sometimes it can be very useful to run CPU vulnerability mitigations on systems where they aren't known to mitigate any real-world vulnerabilities. This can be handy for mundane reasons like debugging HW-agnostic logic on whatever machine is to hand, but also for research reasons: while some mitigations are focused on individual vulns and uarches, others are fairly general, and it's strategically useful to have an idea how they'd perform on systems where they aren't currently needed. As evidence for this being useful, a flag specifically for Retbleed was added in: 5c9a92dec323 ("x86/bugs: Add retbleed=force"). Since CPU bugs are tracked using the same basic mechanism as features, and there are already parameters for manipulating them by hand, extend that mechanism to support bug as well as capabilities. With this patch and setcpuid=srso, a QEMU guest running on an Intel host will boot with Safe-RET enabled. Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20241220-force-cpu-bug-v2-3-7dc71bce742a@google.com
2025-02-28x86/cpu: Add the 'setcpuid=' boot parameterBrendan Jackman
In preparation for adding support to inject fake CPU bugs at boot-time, add a general facility to force enablement of CPU flags. The flag taints the kernel and the documentation attempts to be clear that this is highly unsuitable for uses outside of kernel development and platform experimentation. The new arg is parsed just like clearcpuid, but instead of leading to setup_clear_cpu_cap() it leads to setup_force_cpu_cap(). I've tested this by booting a nested QEMU guest on an Intel host, which with setcpuid=svm will claim that it supports AMD virtualization. Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20241220-force-cpu-bug-v2-2-7dc71bce742a@google.com
2025-02-28x86/cpu: Create helper function to parse the 'clearcpuid=' boot parameterBrendan Jackman
This is in preparation for a later commit that will reuse this code, to make review convenient. Factor out a helper function which does the full handling for this arg including printing info to the console. No functional change intended. Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20241220-force-cpu-bug-v2-1-7dc71bce742a@google.com
2025-02-28x86/cpu: Don't clear X86_FEATURE_LAHF_LM flag in init_amd_k8() on AMD when ↵Max Grobecker
running in a virtual machine When running in a virtual machine, we might see the original hardware CPU vendor string (i.e. "AuthenticAMD"), but a model and family ID set by the hypervisor. In case we run on AMD hardware and the hypervisor sets a model ID < 0x14, the LAHF cpu feature is eliminated from the the list of CPU capabilities present to circumvent a bug with some BIOSes in conjunction with AMD K8 processors. Parsing the flags list from /proc/cpuinfo seems to be happening mostly in bash scripts and prebuilt Docker containers, as it does not need to have additionals tools present – even though more reliable ways like using "kcpuid", which calls the CPUID instruction instead of parsing a list, should be preferred. Scripts, that use /proc/cpuinfo to determine if the current CPU is "compliant" with defined microarchitecture levels like x86-64-v2 will falsely claim the CPU is incapable of modern CPU instructions when "lahf_lm" is missing in that flags list. This can prevent some docker containers from starting or build scripts to create unoptimized binaries. Admittably, this is more a small inconvenience than a severe bug in the kernel and the shoddy scripts that rely on parsing /proc/cpuinfo should be fixed instead. This patch adds an additional check to see if we're running inside a virtual machine (X86_FEATURE_HYPERVISOR is present), which, to my understanding, can't be present on a real K8 processor as it was introduced only with the later/other Athlon64 models. Example output with the "lahf_lm" flag missing in the flags list (should be shown between "hypervisor" and "abm"): $ cat /proc/cpuinfo processor : 0 vendor_id : AuthenticAMD cpu family : 15 model : 6 model name : Common KVM processor stepping : 1 microcode : 0x1000065 cpu MHz : 2599.998 cache size : 512 KB physical id : 0 siblings : 1 core id : 0 cpu cores : 1 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx rdtscp lm rep_good nopl cpuid extd_apicid tsc_known_freq pni pclmulqdq ssse3 fma cx16 sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c hypervisor abm 3dnowprefetch vmmcall bmi1 avx2 bmi2 xsaveopt ... while kcpuid shows the feature to be present in the CPU: # kcpuid -d | grep lahf lahf_lm - LAHF/SAHF available in 64-bit mode [ mingo: Updated the comment a bit, incorporated Boris's review feedback. ] Signed-off-by: Max Grobecker <max@grobecker.info> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: linux-kernel@vger.kernel.org Cc: Borislav Petkov <bp@alien8.de>
2025-02-27x86/cpu: Remove get_this_hybrid_cpu_*()Pawan Gupta
Because calls to get_this_hybrid_cpu_type() and get_this_hybrid_cpu_native_id() are not required now. cpu-type and native-model-id are cached at boot in per-cpu struct cpuinfo_topology. Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/r/20241211-add-cpu-type-v5-4-2ae010f50370@linux.intel.com
2025-02-27x86/cpu: Prefix hexadecimal values with 0x in cpu_debug_show()Pawan Gupta
The hex values in CPU debug interface are not prefixed with 0x. This may cause misinterpretation of values. Fix it. [ mingo: Restore previous vertical alignment of the output. ] Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/r/20241211-add-cpu-type-v5-1-2ae010f50370@linux.intel.com
2025-02-27Merge branch 'x86/mm' into x86/cpu, to avoid conflictsIngo Molnar
We are going to apply a new series that conflicts with pending work in x86/mm, so merge in x86/mm to avoid it, and also to refresh the x86/cpu branch with fixes. Signed-off-by: Ingo Molnar <mingo@kernel.org>
2025-02-27x86/bugs: Remove X86_FEATURE_USE_IBPBYosry Ahmed
X86_FEATURE_USE_IBPB was introduced in: 2961298efe1e ("x86/cpufeatures: Clean up Spectre v2 related CPUID flags") to have separate flags for when the CPU supports IBPB (i.e. X86_FEATURE_IBPB) and when an IBPB is actually used to mitigate Spectre v2. Ever since then, the uses of IBPB expanded. The name became confusing because it does not control all IBPB executions in the kernel. Furthermore, because its name is generic and it's buried within indirect_branch_prediction_barrier(), it's easy to use it not knowing that it is specific to Spectre v2. X86_FEATURE_USE_IBPB is no longer needed because all the IBPB executions it used to control are now controlled through other means (e.g. switch_mm_*_ibpb static branches). Remove the unused feature bit. Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20250227012712.3193063-7-yosry.ahmed@linux.dev
2025-02-27x86/bugs: Use a static branch to guard IBPB on vCPU switchYosry Ahmed
Instead of using X86_FEATURE_USE_IBPB to guard the IBPB execution in KVM when a new vCPU is loaded, introduce a static branch, similar to switch_mm_*_ibpb. This makes it obvious in spectre_v2_user_select_mitigation() what exactly is being toggled, instead of the unclear X86_FEATURE_USE_IBPB (which will be shortly removed). It also provides more fine-grained control, making it simpler to change/add paths that control the IBPB in the vCPU switch path without affecting other IBPBs. Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Acked-by: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/r/20250227012712.3193063-5-yosry.ahmed@linux.dev
2025-02-27x86/bugs: Remove the X86_FEATURE_USE_IBPB check in ib_prctl_set()Yosry Ahmed
If X86_FEATURE_USE_IBPB is not set, then both spectre_v2_user_ibpb and spectre_v2_user_stibp are set to SPECTRE_V2_USER_NONE in spectre_v2_user_select_mitigation(). Since ib_prctl_set() already checks for this before performing the IBPB, the X86_FEATURE_USE_IBPB check is redundant. Remove it. Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20250227012712.3193063-4-yosry.ahmed@linux.dev
2025-02-27x86/bugs: Move the X86_FEATURE_USE_IBPB check into callersYosry Ahmed
indirect_branch_prediction_barrier() only performs the MSR write if X86_FEATURE_USE_IBPB is set, using alternative_msr_write(). In preparation for removing X86_FEATURE_USE_IBPB, move the feature check into the callers so that they can be addressed one-by-one, and use X86_FEATURE_IBPB instead to guard the MSR write. Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Acked-by: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/r/20250227012712.3193063-2-yosry.ahmed@linux.dev
2025-02-26x86/bugs: KVM: Add support for SRSO_MSR_FIXBorislav Petkov
Add support for CPUID Fn8000_0021_EAX[31] (SRSO_MSR_FIX). If this bit is 1, it indicates that software may use MSR BP_CFG[BpSpecReduce] to mitigate SRSO. Enable BpSpecReduce to mitigate SRSO across guest/host boundaries. Switch back to enabling the bit when virtualization is enabled and to clear the bit when virtualization is disabled because using a MSR slot would clear the bit when the guest is exited and any training the guest has done, would potentially influence the host kernel when execution enters the kernel and hasn't VMRUN the guest yet. More detail on the public thread in Link below. Co-developed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20241202120416.6054-1-bp@kernel.org
2025-02-26x86/mce/inject: Remove call to mce_notify_irq()Nikolay Borisov
The call to mce_notify_irq() has been there since the initial version of the soft inject mce machinery, introduced in ea149b36c7f5 ("x86, mce: add basic error injection infrastructure"). At that time it was functional since injecting an MCE resulted in the following call chain: raise_mce() ->machine_check_poll() ->mce_log() - sets notfiy_user_bit ->mce_notify_user() (current mce_notify_irq) consumed the bit and called the usermode helper. However, with the introduction of 011d82611172 ("RAS: Add a Corrected Errors Collector") the code got moved around and the usermode helper began to be called via the early notifier mce_first_notifier() rendering the call in raise_local() defunct as the mce_need_notify bit (ex notify_user) is only being set from the early notifier. Remove the noop call and make mce_notify_irq() static. No functional changes. Signed-off-by: Nikolay Borisov <nik.borisov@suse.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20250225143348.268469-1-nik.borisov@suse.com
2025-02-25x86/CPU: Fix warm boot hang regression on AMD SC1100 SoC systemsRussell Senior
I still have some Soekris net4826 in a Community Wireless Network I volunteer with. These devices use an AMD SC1100 SoC. I am running OpenWrt on them, which uses a patched kernel, that naturally has evolved over time. I haven't updated the ones in the field in a number of years (circa 2017), but have one in a test bed, where I have intermittently tried out test builds. A few years ago, I noticed some trouble, particularly when "warm booting", that is, doing a reboot without removing power, and noticed the device was hanging after the kernel message: [ 0.081615] Working around Cyrix MediaGX virtual DMA bugs. If I removed power and then restarted, it would boot fine, continuing through the message above, thusly: [ 0.081615] Working around Cyrix MediaGX virtual DMA bugs. [ 0.090076] Enable Memory-Write-back mode on Cyrix/NSC processor. [ 0.100000] Enable Memory access reorder on Cyrix/NSC processor. [ 0.100070] Last level iTLB entries: 4KB 0, 2MB 0, 4MB 0 [ 0.110058] Last level dTLB entries: 4KB 0, 2MB 0, 4MB 0, 1GB 0 [ 0.120037] CPU: NSC Geode(TM) Integrated Processor by National Semi (family: 0x5, model: 0x9, stepping: 0x1) [...] In order to continue using modern tools, like ssh, to interact with the software on these old devices, I need modern builds of the OpenWrt firmware on the devices. I confirmed that the warm boot hang was still an issue in modern OpenWrt builds (currently using a patched linux v6.6.65). Last night, I decided it was time to get to the bottom of the warm boot hang, and began bisecting. From preserved builds, I narrowed down the bisection window from late February to late May 2019. During this period, the OpenWrt builds were using 4.14.x. I was able to build using period-correct Ubuntu 18.04.6. After a number of bisection iterations, I identified a kernel bump from 4.14.112 to 4.14.113 as the commit that introduced the warm boot hang. https://github.com/openwrt/openwrt/commit/07aaa7e3d62ad32767d7067107db64b6ade81537 Looking at the upstream changes in the stable kernel between 4.14.112 and 4.14.113 (tig v4.14.112..v4.14.113), I spotted a likely suspect: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=20afb90f730982882e65b01fb8bdfe83914339c5 So, I tried reverting just that kernel change on top of the breaking OpenWrt commit, and my warm boot hang went away. Presumably, the warm boot hang is due to some register not getting cleared in the same way that a loss of power does. That is approximately as much as I understand about the problem. More poking/prodding and coaching from Jonas Gorski, it looks like this test patch fixes the problem on my board: Tested against v6.6.67 and v4.14.113. Fixes: 18fb053f9b82 ("x86/cpu/cyrix: Use correct macros for Cyrix calls on Geode processors") Debugged-by: Jonas Gorski <jonas.gorski@gmail.com> Signed-off-by: Russell Senior <russell@personaltelco.net> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/CAHP3WfOgs3Ms4Z+L9i0-iBOE21sdMk5erAiJurPjnrL9LSsgRA@mail.gmail.com Cc: Matthew Whitehead <tedheadster@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de>
2025-02-25x86/mtrr: Remove unnecessary strlen() in mtrr_write()Thorsten Blum
The local variable length already holds the string length after calling strncpy_from_user(). Using another local variable linlen and calling strlen() is therefore unnecessary and can be removed. Remove linlen and strlen() and use length instead. No change in functionality intended. Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20250225131621.329699-2-thorsten.blum@linux.dev
2025-02-22Merge tag 'x86-urgent-2025-02-22' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fixes from Ingo Molnar: - Fix AVX-VNNI CPU feature dependency bug triggered via the 'noxsave' boot option - Fix typos in the SVA documentation - Add Tony Luck as RDT co-maintainer and remove Fenghua Yu * tag 'x86-urgent-2025-02-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: docs: arch/x86/sva: Fix two grammar errors under Background and FAQ x86/cpufeatures: Make AVX-VNNI depend on AVX MAINTAINERS: Change maintainer for RDT
2025-02-22x86/microcode/AMD: Load only SHA256-checksummed patchesBorislav Petkov (AMD)
Load patches for which the driver carries a SHA256 checksum of the patch blob. This can be disabled by adding "microcode.amd_sha_check=off" on the kernel cmdline. But it is highly NOT recommended. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
2025-02-22hyperv: Change hv_root_partition into a functionNuno Das Neves
Introduce hv_curr_partition_type to store the partition type as an enum. Right now this is limited to guest or root partition, but there will be other kinds in future and the enum is easily extensible. Set up hv_curr_partition_type early in Hyper-V initialization with hv_identify_partition_type(). hv_root_partition() just queries this value, and shouldn't be called before that. Making this check into a function sets the stage for adding a config option to gate the compilation of root partition code. In particular, hv_root_partition() can be stubbed out always be false if root partition support isn't desired. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Link: https://lore.kernel.org/r/1740167795-13296-3-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1740167795-13296-3-git-send-email-nunodasneves@linux.microsoft.com>
2025-02-21x86/cpufeatures: Make AVX-VNNI depend on AVXEric Biggers
The 'noxsave' boot option disables support for AVX, but support for the AVX-VNNI feature was still declared on CPUs that support it. Fix this. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/r/20250220060124.89622-1-ebiggers@kernel.org
2025-02-18x86/percpu/64: Remove fixed_percpu_dataBrian Gerst
Now that the stack protector canary value is a normal percpu variable, fixed_percpu_data is unused and can be removed. Signed-off-by: Brian Gerst <brgerst@gmail.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Uros Bizjak <ubizjak@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20250123190747.745588-10-brgerst@gmail.com
2025-02-18x86/stackprotector/64: Convert to normal per-CPU variableBrian Gerst
Older versions of GCC fixed the location of the stack protector canary at %gs:40. This constraint forced the percpu section to be linked at absolute address 0 so that the canary could be the first data object in the percpu section. Supporting the zero-based percpu section requires additional code to handle relocations for RIP-relative references to percpu data, extra complexity to kallsyms, and workarounds for linker bugs due to the use of absolute symbols. GCC 8.1 supports redefining where the canary is located, allowing it to become a normal percpu variable instead of at a fixed location. This removes the constraint that the percpu section must be zero-based. Signed-off-by: Brian Gerst <brgerst@gmail.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Uros Bizjak <ubizjak@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20250123190747.745588-8-brgerst@gmail.com
2025-02-17cpufreq: Allow arch_freq_get_on_cpu to return an errorBeata Michalska
Allow arch_freq_get_on_cpu to return an error for cases when retrieving current CPU frequency is not possible, whether that being due to lack of required arch support or due to other circumstances when the current frequency cannot be determined at given point of time. Signed-off-by: Beata Michalska <beata.michalska@arm.com> Reviewed-by: Prasanna Kumar T S M <ptsm@linux.microsoft.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Rafael J. Wysocki <rafael@kernel.org> Link: https://lore.kernel.org/r/20250131162439.3843071-2-beata.michalska@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2025-02-17x86/microcode/AMD: Add get_patch_level()Borislav Petkov (AMD)
Put the MSR_AMD64_PATCH_LEVEL reading of the current microcode revision the hw has, into a separate function. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20250211163648.30531-6-bp@kernel.org
2025-02-17x86/microcode/AMD: Get rid of the _load_microcode_amd() forward declarationBorislav Petkov (AMD)
Simply move save_microcode_in_initrd() down. No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20250211163648.30531-5-bp@kernel.org
2025-02-17x86/microcode/AMD: Merge early_apply_microcode() into its single callsiteBorislav Petkov (AMD)
No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20250211163648.30531-4-bp@kernel.org
2025-02-17x86/microcode/AMD: Remove unused save_microcode_in_initrd_amd() declarationsBorislav Petkov (AMD)
Commit a7939f016720 ("x86/microcode/amd: Cache builtin/initrd microcode early") renamed it to save_microcode_in_initrd() and made it static. Zap the forgotten declarations. No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20250211163648.30531-3-bp@kernel.org
2025-02-17x86/microcode/AMD: Remove ugly linebreak in __verify_patch_section() signatureBorislav Petkov (AMD)
No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20250211163648.30531-2-bp@kernel.org
2025-02-17Merge 6.14-rc3 into driver-core-nextGreg Kroah-Hartman
We need the faux_device changes in here for future work. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-02-15kernfs: Use RCU to access kernfs_node::name.Sebastian Andrzej Siewior
Using RCU lifetime rules to access kernfs_node::name can avoid the trouble with kernfs_rename_lock in kernfs_name() and kernfs_path_from_node() if the fs was created with KERNFS_ROOT_INVARIANT_PARENT. This is usefull as it allows to implement kernfs_path_from_node() only with RCU protection and avoiding kernfs_rename_lock. The lock is only required if the __parent node can be changed and the function requires an unchanged hierarchy while it iterates from the node to its parent. The change is needed to allow the lookup of the node's path (kernfs_path_from_node()) from context which runs always with disabled preemption and or interrutps even on PREEMPT_RT. The problem is that kernfs_rename_lock becomes a sleeping lock on PREEMPT_RT. I went through all ::name users and added the required access for the lookup with a few extensions: - rdtgroup_pseudo_lock_create() drops all locks and then uses the name later on. resctrl supports rename with different parents. Here I made a temporal copy of the name while it is used outside of the lock. - kernfs_rename_ns() accepts NULL as new_parent. This simplifies sysfs_move_dir_ns() where it can set NULL in order to reuse the current name. - kernfs_rename_ns() is only using kernfs_rename_lock if the parents are different. All users use either kernfs_rwsem (for stable path view) or just RCU for the lookup. The ::name uses always RCU free. Use RCU lifetime guarantees to access kernfs_node::name. Suggested-by: Tejun Heo <tj@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Reported-by: syzbot+6ea37e2e6ffccf41a7e6@syzkaller.appspotmail.com Closes: https://lore.kernel.org/lkml/67251dc6.050a0220.529b6.015e.GAE@google.com/ Reported-by: Hillf Danton <hdanton@sina.com> Closes: https://lore.kernel.org/20241102001224.2789-1-hdanton@sina.com Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://lore.kernel.org/r/20250213145023.2820193-7-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-02-15kernfs: Use RCU to access kernfs_node::parent.Sebastian Andrzej Siewior
kernfs_rename_lock is used to obtain stable kernfs_node::{name|parent} pointer. This is a preparation to access kernfs_node::parent under RCU and ensure that the pointer remains stable under the RCU lifetime guarantees. For a complete path, as it is done in kernfs_path_from_node(), the kernfs_rename_lock is still required in order to obtain a stable parent relationship while computing the relevant node depth. This must not change while the nodes are inspected in order to build the path. If the kernfs user never moves the nodes (changes the parent) then the kernfs_rename_lock is not required and the RCU guarantees are sufficient. This "restriction" can be set with KERNFS_ROOT_INVARIANT_PARENT. Otherwise the lock is required. Rename kernfs_node::parent to kernfs_node::__parent to denote the RCU access and use RCU accessor while accessing the node. Make cgroup use KERNFS_ROOT_INVARIANT_PARENT since the parent here can not change. Acked-by: Tejun Heo <tj@kernel.org> Cc: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://lore.kernel.org/r/20250213145023.2820193-6-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-02-11x86/cpu/kvm: SRSO: Fix possible missing IBPB on VM-ExitPatrick Bellasi
In [1] the meaning of the synthetic IBPB flags has been redefined for a better separation of concerns: - ENTRY_IBPB -- issue IBPB on entry only - IBPB_ON_VMEXIT -- issue IBPB on VM-Exit only and the Retbleed mitigations have been updated to match this new semantics. Commit [2] was merged shortly before [1], and their interaction was not handled properly. This resulted in IBPB not being triggered on VM-Exit in all SRSO mitigation configs requesting an IBPB there. Specifically, an IBPB on VM-Exit is triggered only when X86_FEATURE_IBPB_ON_VMEXIT is set. However: - X86_FEATURE_IBPB_ON_VMEXIT is not set for "spec_rstack_overflow=ibpb", because before [1] having X86_FEATURE_ENTRY_IBPB was enough. Hence, an IBPB is triggered on entry but the expected IBPB on VM-exit is not. - X86_FEATURE_IBPB_ON_VMEXIT is not set also when "spec_rstack_overflow=ibpb-vmexit" if X86_FEATURE_ENTRY_IBPB is already set. That's because before [1] this was effectively redundant. Hence, e.g. a "retbleed=ibpb spec_rstack_overflow=bpb-vmexit" config mistakenly reports the machine still vulnerable to SRSO, despite an IBPB being triggered both on entry and VM-Exit, because of the Retbleed selected mitigation config. - UNTRAIN_RET_VM won't still actually do anything unless CONFIG_MITIGATION_IBPB_ENTRY is set. For "spec_rstack_overflow=ibpb", enable IBPB on both entry and VM-Exit and clear X86_FEATURE_RSB_VMEXIT which is made superfluous by X86_FEATURE_IBPB_ON_VMEXIT. This effectively makes this mitigation option similar to the one for 'retbleed=ibpb', thus re-order the code for the RETBLEED_MITIGATION_IBPB option to be less confusing by having all features enabling before the disabling of the not needed ones. For "spec_rstack_overflow=ibpb-vmexit", guard this mitigation setting with CONFIG_MITIGATION_IBPB_ENTRY to ensure UNTRAIN_RET_VM sequence is effectively compiled in. Drop instead the CONFIG_MITIGATION_SRSO guard, since none of the SRSO compile cruft is required in this configuration. Also, check only that the required microcode is present to effectively enabled the IBPB on VM-Exit. Finally, update the KConfig description for CONFIG_MITIGATION_IBPB_ENTRY to list also all SRSO config settings enabled by this guard. Fixes: 864bcaa38ee4 ("x86/cpu/kvm: Provide UNTRAIN_RET_VM") [1] Fixes: d893832d0e1e ("x86/srso: Add IBPB on VMEXIT") [2] Reported-by: Yosry Ahmed <yosryahmed@google.com> Signed-off-by: Patrick Bellasi <derkling@google.com> Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2025-02-10x86: move ZMM exclusion list into CPU feature flagEric Biggers
Lift zmm_exclusion_list in aesni-intel_glue.c into the x86 CPU setup code, and add a new x86 CPU feature flag X86_FEATURE_PREFER_YMM that is set when the CPU is on this list. This allows other code in arch/x86/, such as the CRC library code, to apply the same exclusion list when deciding whether to execute 256-bit or 512-bit optimized functions. Note that full AVX512 support including ZMM registers is still exposed to userspace and is still supported for in-kernel use. This flag just indicates whether in-kernel code should prefer to use YMM registers. Acked-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Ingo Molnar <mingo@kernel.org> Acked-by: Keith Busch <kbusch@kernel.org> Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com> Link: https://lore.kernel.org/r/20250210174540.161705-2-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com>
2025-02-04x86/cpu: Fix #define name for Intel CPU model 0x5ATony Luck
This CPU was mistakenly given the name INTEL_ATOM_AIRMONT_MID. But it uses a Silvermont core, not Airmont. Change #define name to INTEL_ATOM_SILVERMONT_MID2 Reported-by: Christian Ludloff <ludloff@gmail.com> Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/all/20241007165701.19693-1-tony.luck%40intel.com
2025-01-28treewide: const qualify ctl_tables where applicableJoel Granados
Add the const qualifier to all the ctl_tables in the tree except for watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls, loadpin_sysctl_table and the ones calling register_net_sysctl (./net, drivers/inifiniband dirs). These are special cases as they use a registration function with a non-const qualified ctl_table argument or modify the arrays before passing them on to the registration function. Constifying ctl_table structs will prevent the modification of proc_handler function pointers as the arrays would reside in .rodata. This is made possible after commit 78eb4ea25cd5 ("sysctl: treewide: constify the ctl_table argument of proc_handlers") constified all the proc_handlers. Created this by running an spatch followed by a sed command: Spatch: virtual patch @ depends on !(file in "net") disable optional_qualifier @ identifier table_name != { watchdog_hardlockup_sysctl, iwcm_ctl_table, ucma_ctl_table, memory_allocation_profiling_sysctls, loadpin_sysctl_table }; @@ + const struct ctl_table table_name [] = { ... }; sed: sed --in-place \ -e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \ kernel/utsname_sysctl.c Reviewed-by: Song Liu <song@kernel.org> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> # for kernel/trace/ Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> # SCSI Reviewed-by: Darrick J. Wong <djwong@kernel.org> # xfs Acked-by: Jani Nikula <jani.nikula@intel.com> Acked-by: Corey Minyard <cminyard@mvista.com> Acked-by: Wei Liu <wei.liu@kernel.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Bill O'Donnell <bodonnel@redhat.com> Acked-by: Baoquan He <bhe@redhat.com> Acked-by: Ashutosh Dixit <ashutosh.dixit@intel.com> Acked-by: Anna Schumaker <anna.schumaker@oracle.com> Signed-off-by: Joel Granados <joel.granados@kernel.org>
2025-01-25Merge tag 'hyperv-next-signed-20250123' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux Pull hyperv updates from Wei Liu: - Introduce a new set of Hyper-V headers in include/hyperv and replace the old hyperv-tlfs.h with the new headers (Nuno Das Neves) - Fixes for the Hyper-V VTL mode (Roman Kisel) - Fixes for cpu mask usage in Hyper-V code (Michael Kelley) - Document the guest VM hibernation behaviour (Michael Kelley) - Miscellaneous fixes and cleanups (Jacob Pan, John Starks, Naman Jain) * tag 'hyperv-next-signed-20250123' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: Documentation: hyperv: Add overview of guest VM hibernation hyperv: Do not overlap the hvcall IO areas in hv_vtl_apicid_to_vp_id() hyperv: Do not overlap the hvcall IO areas in get_vtl() hyperv: Enable the hypercall output page for the VTL mode hv_balloon: Fallback to generic_online_page() for non-HV hot added mem Drivers: hv: vmbus: Log on missing offers if any Drivers: hv: vmbus: Wait for boot-time offers during boot and resume uio_hv_generic: Add a check for HV_NIC for send, receive buffers setup iommu/hyper-v: Don't assume cpu_possible_mask is dense Drivers: hv: Don't assume cpu_possible_mask is dense x86/hyperv: Don't assume cpu_possible_mask is dense hyperv: Remove the now unused hyperv-tlfs.h files hyperv: Switch from hyperv-tlfs.h to hyperv/hvhdk.h hyperv: Add new Hyper-V headers in include/hyperv hyperv: Clean up unnecessary #includes hyperv: Move hv_connection_id to hyperv-tlfs.h
2025-01-21Merge tag 'x86-cleanups-2025-01-21' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 cleanups from Ingo Molnar: "Miscellaneous x86 cleanups and typo fixes, and also the removal of the 'disablelapic' boot parameter" * tag 'x86-cleanups-2025-01-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/ioapic: Remove a stray tab in the IO-APIC type string x86/cpufeatures: Remove "AMD" from the comments to the AMD-specific leaf Documentation/kernel-parameters: Fix a typo in kvm.enable_virt_at_load text x86/cpu: Fix typo in x86_match_cpu()'s doc x86/apic: Remove "disablelapic" cmdline option Documentation: Merge x86-specific boot options doc into kernel-parameters.txt x86/ioremap: Remove unused size parameter in remapping functions x86/ioremap: Simplify setup_data mapping variants x86/boot/compressed: Remove unused header includes from kaslr.c
2025-01-21Merge tag 'perf-core-2025-01-20' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull performance events updates from Ingo Molnar: "Seqlock optimizations that arose in a perf context and were merged into the perf tree: - seqlock: Add raw_seqcount_try_begin (Suren Baghdasaryan) - mm: Convert mm_lock_seq to a proper seqcount (Suren Baghdasaryan) - mm: Introduce mmap_lock_speculate_{try_begin|retry} (Suren Baghdasaryan) - mm/gup: Use raw_seqcount_try_begin() (Peter Zijlstra) Core perf enhancements: - Reduce 'struct page' footprint of perf by mapping pages in advance (Lorenzo Stoakes) - Save raw sample data conditionally based on sample type (Yabin Cui) - Reduce sampling overhead by checking sample_type in perf_sample_save_callchain() and perf_sample_save_brstack() (Yabin Cui) - Export perf_exclude_event() (Namhyung Kim) Uprobes scalability enhancements: (Andrii Nakryiko) - Simplify find_active_uprobe_rcu() VMA checks - Add speculative lockless VMA-to-inode-to-uprobe resolution - Simplify session consumer tracking - Decouple return_instance list traversal and freeing - Ensure return_instance is detached from the list before freeing - Reuse return_instances between multiple uretprobes within task - Guard against kmemdup() failing in dup_return_instance() AMD core PMU driver enhancements: - Relax privilege filter restriction on AMD IBS (Namhyung Kim) AMD RAPL energy counters support: (Dhananjay Ugwekar) - Introduce topology_logical_core_id() (K Prateek Nayak) - Remove the unused get_rapl_pmu_cpumask() function - Remove the cpu_to_rapl_pmu() function - Rename rapl_pmu variables - Make rapl_model struct global - Add arguments to the init and cleanup functions - Modify the generic variable names to *_pkg* - Remove the global variable rapl_msrs - Move the cntr_mask to rapl_pmus struct - Add core energy counter support for AMD CPUs Intel core PMU driver enhancements: - Support RDPMC 'metrics clear mode' feature (Kan Liang) - Clarify adaptive PEBS processing (Kan Liang) - Factor out functions for PEBS records processing (Kan Liang) - Simplify the PEBS records processing for adaptive PEBS (Kan Liang) Intel uncore driver enhancements: (Kan Liang) - Convert buggy pmu->func_id use to pmu->registered - Support more units on Granite Rapids" * tag 'perf-core-2025-01-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits) perf: map pages in advance perf/x86/intel/uncore: Support more units on Granite Rapids perf/x86/intel/uncore: Clean up func_id perf/x86/intel: Support RDPMC metrics clear mode uprobes: Guard against kmemdup() failing in dup_return_instance() perf/x86: Relax privilege filter restriction on AMD IBS perf/core: Export perf_exclude_event() uprobes: Reuse return_instances between multiple uretprobes within task uprobes: Ensure return_instance is detached from the list before freeing uprobes: Decouple return_instance list traversal and freeing uprobes: Simplify session consumer tracking uprobes: add speculative lockless VMA-to-inode-to-uprobe resolution uprobes: simplify find_active_uprobe_rcu() VMA checks mm: introduce mmap_lock_speculate_{try_begin|retry} mm: convert mm_lock_seq to a proper seqcount mm/gup: Use raw_seqcount_try_begin() seqlock: add raw_seqcount_try_begin perf/x86/rapl: Add core energy counter support for AMD CPUs perf/x86/rapl: Move the cntr_mask to rapl_pmus struct perf/x86/rapl: Remove the global variable rapl_msrs ...
2025-01-21Merge tag 'x86_misc_for_v6.14_rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull misc x86 updates from Borislav Petkov: - The first part of a restructuring of AMD's representation of a northbridge which is legacy now, and the creation of the new AMD node concept which represents the Zen architecture of having a collection of I/O devices within an SoC. Those nodes comprise the so-called data fabric on Zen. This has at least one practical advantage of not having to add a PCI ID each time a new data fabric PCI device releases. Eventually, the lot more uniform provider of data fabric functionality amd_node.c will be used by all the drivers which need it - Smaller cleanups * tag 'x86_misc_for_v6.14_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/amd_node: Use defines for SMN register offsets x86/amd_node: Remove dependency on AMD_NB x86/amd_node: Update __amd_smn_rw() error paths x86/amd_nb: Move SMN access code to a new amd_node driver x86/amd_nb, hwmon: (k10temp): Simplify amd_pci_dev_to_node_id() x86/amd_nb: Simplify function 3 search x86/amd_nb: Use topology info to get AMD node count x86/amd_nb: Simplify root device search x86/amd_nb: Simplify function 4 search x86: Start moving AMD node functionality out of AMD_NB x86/amd_nb: Clean up early_is_amd_nb() x86/amd_nb: Restrict init function to AMD-based systems x86/mtrr: Rename mtrr_overwrite_state() to guest_force_mtrr_state()
2025-01-21Merge tag 'x86_cpu_for_v6.14_rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 cpuid updates from Borislav Petkov: - Remove the less generic CPU matching infra around struct x86_cpu_desc and use the generic struct x86_cpu_id thing - Remove magic naked numbers for CPUID functions and use proper defines of the prefix CPUID_LEAF_*. Consolidate some of the crazy use around the tree - Smaller cleanups and improvements * tag 'x86_cpu_for_v6.14_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/cpu: Make all all CPUID leaf names consistent x86/fpu: Remove unnecessary CPUID level check x86/fpu: Move CPUID leaf definitions to common code x86/tsc: Remove CPUID "frequency" leaf magic numbers. x86/tsc: Move away from TSC leaf magic numbers x86/cpu: Move TSC CPUID leaf definition x86/cpu: Refresh DCA leaf reading code x86/cpu: Remove unnecessary MwAIT leaf checks x86/cpu: Use MWAIT leaf definition x86/cpu: Move MWAIT leaf definition to common header x86/cpu: Remove 'x86_cpu_desc' infrastructure x86/cpu: Move AMD erratum 1386 table over to 'x86_cpu_id' x86/cpu: Replace PEBS use of 'x86_cpu_desc' use with 'x86_cpu_id' x86/cpu: Expose only stepping min/max interface x86/cpu: Introduce new microcode matching helper x86/cpufeature: Document cpu_feature_enabled() as the default to use x86/paravirt: Remove the WBINVD callback x86/cpufeatures: Free up unused feature bits
2025-01-21Merge tag 'x86_sev_for_v6.14_rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 SEV updates from Borislav Petkov: - A segmented Reverse Map table (RMP) is a across-nodes distributed table of sorts which contains per-node descriptors of each node-local 4K page, denoting its ownership (hypervisor, guest, etc) in the realm of confidential computing. Add support for such a table in order to improve referential locality when accessing or modifying RMP table entries - Add support for reading the TSC in SNP guests by removing any interference or influence the hypervisor might have, with the goal of making a confidential guest even more independent from the hypervisor * tag 'x86_sev_for_v6.14_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/sev: Add the Secure TSC feature for SNP guests x86/tsc: Init the TSC for Secure TSC guests x86/sev: Mark the TSC in a secure TSC guest as reliable x86/sev: Prevent RDTSC/RDTSCP interception for Secure TSC enabled guests x86/sev: Prevent GUEST_TSC_FREQ MSR interception for Secure TSC enabled guests x86/sev: Change TSC MSR behavior for Secure TSC enabled guests x86/sev: Add Secure TSC support for SNP guests x86/sev: Relocate SNP guest messaging routines to common code x86/sev: Carve out and export SNP guest messaging init routines virt: sev-guest: Replace GFP_KERNEL_ACCOUNT with GFP_KERNEL virt: sev-guest: Remove is_vmpck_empty() helper x86/sev/docs: Document the SNP Reverse Map Table (RMP) x86/sev: Add full support for a segmented RMP table x86/sev: Treat the contiguous RMP table as a single RMP segment x86/sev: Map only the RMP table entries instead of the full RMP range x86/sev: Move the SNP probe routine out of the way x86/sev: Require the RMPREAD instruction after Zen4 x86/sev: Add support for the RMPREAD instruction x86/sev: Prepare for using the RMPREAD instruction to access the RMP
2025-01-21Merge tag 'x86_microcode_for_v6.14_rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 microcode loader updates from Borislav Petkov: - A bunch of minor cleanups * tag 'x86_microcode_for_v6.14_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/microcode/AMD: Remove ret local var in early_apply_microcode() x86/microcode/AMD: Have __apply_microcode_amd() return bool x86/microcode/AMD: Make __verify_patch_size() return bool x86/microcode/AMD: Remove bogus comment from parse_container() x86/microcode/AMD: Return bool from find_blobs_in_containers()
2025-01-21Merge tag 'x86_cache_for_v6.14_rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 resource control updates from Borislav Petkov: - Extend resctrl with the capability of total memory bandwidth monitoring, thus accomodating systems which support only total but not local memory bandwidth monitoring. Add the respective new mount options - The usual cleanups * tag 'x86_cache_for_v6.14_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/resctrl: Document the new "mba_MBps_event" file x86/resctrl: Add write option to "mba_MBps_event" file x86/resctrl: Add "mba_MBps_event" file to CTRL_MON directories x86/resctrl: Make mba_sc use total bandwidth if local is not supported x86/resctrl: Compute memory bandwidth for all supported events x86/resctrl: Modify update_mba_bw() to use per CTRL_MON group event x86/resctrl: Prepare for per-CTRL_MON group mba_MBps control x86/resctrl: Introduce resctrl_file_fflags_init() to initialize fflags x86/resctrl: Use kthread_run_on_cpu()
2025-01-21Merge tag 'x86_bugs_for_v6.14_rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 CPU speculation update from Borislav Petkov: - Add support for AMD hardware which is not affected by SRSO on the user/kernel attack vector and advertise it to guest userspace * tag 'x86_bugs_for_v6.14_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: KVM: x86: Advertise SRSO_USER_KERNEL_NO to userspace x86/bugs: Add SRSO_USER_KERNEL_NO support
2025-01-10hyperv: Switch from hyperv-tlfs.h to hyperv/hvhdk.hNuno Das Neves
Switch to using hvhdk.h everywhere in the kernel. This header includes all the new Hyper-V headers in include/hyperv, which form a superset of the definitions found in hyperv-tlfs.h. This makes it easier to add new Hyper-V interfaces without being restricted to those in the TLFS doc (reflected in hyperv-tlfs.h). To be more consistent with the original Hyper-V code, the names of some definitions are changed slightly. Update those where needed. Update comments in mshyperv.h files to point to include/hyperv for adding new definitions. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com> Signed-off-by: Roman Kisel <romank@linux.microsoft.com> Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com> Link: https://lore.kernel.org/r/1732577084-2122-5-git-send-email-nunodasneves@linux.microsoft.com Link: https://lore.kernel.org/r/20250108222138.1623703-3-romank@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2025-01-03x86/mce/amd: Remove shared threshold bank plumbingYazen Ghannam
Legacy AMD systems include an integrated Northbridge that is represented by MCA bank 4. This is the only non-core MCA bank in legacy systems. The Northbridge is physically shared by all the CPUs within an AMD "Node". However, in practice the "shared" MCA bank can only by managed by a single CPU within that AMD Node. This is known as the "Node Base Core" (NBC). For example, only the NBC will be able to read the MCA bank 4 registers; they will be Read-as-Zero for other CPUs. Also, the MCA Thresholding interrupt will only signal the NBC; the other CPUs will not receive it. This is enforced by hardware, and it should not be managed by software. The current AMD Thresholding code attempts to deal with the "shared" MCA bank by micromanaging the bank's sysfs kobjects. However, this does not follow the intended kobject use cases. It is also fragile, and it has caused bugs in the past. Modern AMD systems do not need this shared MCA bank support, and it should not be needed on legacy systems either. Remove the shared threshold bank code. Also, move the threshold struct definitions to mce/amd.c, since they are no longer needed in amd_nb.c. Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20241206161210.163701-2-yazen.ghannam@amd.com
2024-12-31x86/microcode/AMD: Remove ret local var in early_apply_microcode()Borislav Petkov (AMD)
No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
2024-12-31x86/microcode/AMD: Have __apply_microcode_amd() return boolBorislav Petkov (AMD)
This is the natural thing to do anyway. No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
2024-12-31x86/microcode/AMD: Make __verify_patch_size() return boolNikolay Borisov
The result of that function is in essence boolean, so simplify to return the result of the relevant expression. It also makes it follow the convention used by __verify_patch_section(). No functional changes. Signed-off-by: Nikolay Borisov <nik.borisov@suse.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20241018155151.702350-3-nik.borisov@suse.com
2024-12-31x86/microcode/AMD: Remove bogus comment from parse_container()Nikolay Borisov
The function doesn't return an equivalence ID, remove the false comment. Signed-off-by: Nikolay Borisov <nik.borisov@suse.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20241018155151.702350-4-nik.borisov@suse.com
generated by cgit (git 2.34.1) at 2025-07-16 00:40:01 +0000