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2024-05-14Merge tag 'x86_apic_for_6.10' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 APIC update from Dave Hansen: "Coccinelle complained about some 64-bit divisions, but the divisor was really just a 32-bit value being stored as 'unsigned long'. Fixing the types fixes the warning" * tag 'x86_apic_for_6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/apic: Improve data types to fix Coccinelle warnings
2024-05-13Merge tag 'x86-cpu-2024-05-13' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 cpu updates from Ingo Molnar: - Rework the x86 CPU vendor/family/model code: introduce the 'VFM' value that is an 8+8+8 bit concatenation of the vendor/family/model value, and add macros that work on VFM values. This simplifies the addition of new Intel models & families, and simplifies existing enumeration & quirk code. - Add support for the AMD 0x80000026 leaf, to better parse topology information - Optimize the NUMA allocation layout of more per-CPU data structures - Improve the workaround for AMD erratum 1386 - Clear TME from /proc/cpuinfo as well, when disabled by the firmware - Improve x86 self-tests - Extend the mce_record tracepoint with the ::ppin and ::microcode fields - Implement recovery for MCE errors in TDX/SEAM non-root mode - Misc cleanups and fixes * tag 'x86-cpu-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits) x86/mm: Switch to new Intel CPU model defines x86/tsc_msr: Switch to new Intel CPU model defines x86/tsc: Switch to new Intel CPU model defines x86/cpu: Switch to new Intel CPU model defines x86/resctrl: Switch to new Intel CPU model defines x86/microcode/intel: Switch to new Intel CPU model defines x86/mce: Switch to new Intel CPU model defines x86/cpu: Switch to new Intel CPU model defines x86/cpu/intel_epb: Switch to new Intel CPU model defines x86/aperfmperf: Switch to new Intel CPU model defines x86/apic: Switch to new Intel CPU model defines perf/x86/msr: Switch to new Intel CPU model defines perf/x86/intel/uncore: Switch to new Intel CPU model defines perf/x86/intel/pt: Switch to new Intel CPU model defines perf/x86/lbr: Switch to new Intel CPU model defines perf/x86/intel/cstate: Switch to new Intel CPU model defines x86/bugs: Switch to new Intel CPU model defines x86/bugs: Switch to new Intel CPU model defines x86/cpu/vfm: Update arch/x86/include/asm/intel-family.h x86/cpu/vfm: Add new macros to work with (vendor/family/model) values ...
2024-04-30x86/apic: Don't access the APIC when disabling x2APICThomas Gleixner
With 'iommu=off' on the kernel command line and x2APIC enabled by the BIOS the code which disables the x2APIC triggers an unchecked MSR access error: RDMSR from 0x802 at rIP: 0xffffffff94079992 (native_apic_msr_read+0x12/0x50) This is happens because default_acpi_madt_oem_check() selects an x2APIC driver before the x2APIC is disabled. When the x2APIC is disabled because interrupt remapping cannot be enabled due to 'iommu=off' on the command line, x2apic_disable() invokes apic_set_fixmap() which in turn tries to read the APIC ID. This triggers the MSR warning because x2APIC is disabled, but the APIC driver is still x2APIC based. Prevent that by adding an argument to apic_set_fixmap() which makes the APIC ID read out conditional and set it to false from the x2APIC disable path. That's correct as the APIC ID has already been read out during early discovery. Fixes: d10a904435fa ("x86/apic: Consolidate boot_cpu_physical_apicid initialization sites") Reported-by: Adrian Huang <ahuang12@lenovo.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Adrian Huang <ahuang12@lenovo.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/875xw5t6r7.ffs@tglx
2024-04-30x86/irq: Factor out common code for checking pending interruptsJacob Pan
Use a common function for checking pending interrupt vector in APIC IRR instead of duplicated open coding them. Additional checks for posted MSI vectors can then be contained in this function. Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20240423174114.526704-10-jacob.jun.pan@linux.intel.com
2024-04-29x86/apic: Switch to new Intel CPU model definesTony Luck
New CPU #defines encode vendor and family as well as model. Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/all/20240424181504.41634-1-tony.luck%40intel.com
2024-04-12Merge branch 'x86/urgent' into x86/cpu, to resolve conflictIngo Molnar
There's a new conflict between this commit pending in x86/cpu: 63edbaa48a57 x86/cpu/topology: Add support for the AMD 0x80000026 leaf And these fixes in x86/urgent: c064b536a8f9 x86/cpu/amd: Make the NODEID_MSR union actually work 1b3108f6898e x86/cpu/amd: Make the CPUID 0x80000008 parser correct Resolve them. Conflicts: arch/x86/kernel/cpu/topology_amd.c Signed-off-by: Ingo Molnar <mingo@kernel.org>
2024-04-11x86/bugs: Rename various 'ia32_cap' variables to 'x86_arch_cap_msr'Ingo Molnar
So we are using the 'ia32_cap' value in a number of places, which got its name from MSR_IA32_ARCH_CAPABILITIES MSR register. But there's very little 'IA32' about it - this isn't 32-bit only code, nor does it originate from there, it's just a historic quirk that many Intel MSR names are prefixed with IA32_. This is already clear from the helper method around the MSR: x86_read_arch_cap_msr(), which doesn't have the IA32 prefix. So rename 'ia32_cap' to 'x86_arch_cap_msr' to be consistent with its role and with the naming of the helper function. Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Nikolay Borisov <nik.borisov@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/r/9592a18a814368e75f8f4b9d74d3883aa4fd1eaf.1712813475.git.jpoimboe@kernel.org
2024-04-10x86/cpu: Improve readability of per-CPU cpumask initialization codeIngo Molnar
In smp_prepare_cpus_common() and x2apic_prepare_cpu(): - use 'cpu' instead of 'i' - use 'node' instead of 'n' - use vertical alignment to improve readability - better structure basic blocks - reduce col80 checkpatch damage Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: linux-kernel@vger.kernel.org
2024-04-10x86/cpu: Take NUMA node into account when allocating per-CPU cpumasksLi RongQing
per-CPU cpumasks are dominantly accessed from their own local CPUs, so allocate them node-local to improve performance. [ mingo: Rewrote the changelog. ] Signed-off-by: Li RongQing <lirongqing@baidu.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20240410030114.6201-1-lirongqing@baidu.com
2024-04-03x86/apic: Improve data types to fix Coccinelle warningsThorsten Blum
Given that acpi_pm_read_early() returns a u32 (masked to 24 bits), several variables that store its return value are improved by adjusting their data types from unsigned long to u32. Specifically, change deltapm's type from long to u32 because its value fits into 32 bits and it cannot be negative. These data type improvements resolve the following two Coccinelle/ coccicheck warnings reported by do_div.cocci: arch/x86/kernel/apic/apic.c:734:1-7: WARNING: do_div() does a 64-by-32 division, please consider using div64_long instead. arch/x86/kernel/apic/apic.c:742:2-8: WARNING: do_div() does a 64-by-32 division, please consider using div64_long instead. Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/all/20240318104721.117741-3-thorsten.blum%40toblux.com
2024-03-11Merge tag 'x86-apic-2024-03-10' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 APIC updates from Thomas Gleixner: "Rework of APIC enumeration and topology evaluation. The current implementation has a couple of shortcomings: - It fails to handle hybrid systems correctly. - The APIC registration code which handles CPU number assignents is in the middle of the APIC code and detached from the topology evaluation. - The various mechanisms which enumerate APICs, ACPI, MPPARSE and guest specific ones, tweak global variables as they see fit or in case of XENPV just hack around the generic mechanisms completely. - The CPUID topology evaluation code is sprinkled all over the vendor code and reevaluates global variables on every hotplug operation. - There is no way to analyze topology on the boot CPU before bringing up the APs. This causes problems for infrastructure like PERF which needs to size certain aspects upfront or could be simplified if that would be possible. - The APIC admission and CPU number association logic is incomprehensible and overly complex and needs to be kept around after boot instead of completing this right after the APIC enumeration. This update addresses these shortcomings with the following changes: - Rework the CPUID evaluation code so it is common for all vendors and provides information about the APIC ID segments in a uniform way independent of the number of segments (Thread, Core, Module, ..., Die, Package) so that this information can be computed instead of rewriting global variables of dubious value over and over. - A few cleanups and simplifcations of the APIC, IO/APIC and related interfaces to prepare for the topology evaluation changes. - Seperation of the parser stages so the early evaluation which tries to find the APIC address can be seperately overridden from the late evaluation which enumerates and registers the local APIC as further preparation for sanitizing the topology evaluation. - A new registration and admission logic which - encapsulates the inner workings so that parsers and guest logic cannot longer fiddle in it - uses the APIC ID segments to build topology bitmaps at registration time - provides a sane admission logic - allows to detect the crash kernel case, where CPU0 does not run on the real BSP, automatically. This is required to prevent sending INIT/SIPI sequences to the real BSP which would reset the whole machine. This was so far handled by a tedious command line parameter, which does not even work in nested crash scenarios. - Associates CPU number after the enumeration completed and prevents the late registration of APICs, which was somehow tolerated before. - Converting all parsers and guest enumeration mechanisms over to the new interfaces. This allows to get rid of all global variable tweaking from the parsers and enumeration mechanisms and sanitizes the XEN[PV] handling so it can use CPUID evaluation for the first time. - Mopping up existing sins by taking the information from the APIC ID segment bitmaps. This evaluates hybrid systems correctly on the boot CPU and allows for cleanups and fixes in the related drivers, e.g. PERF. The series has been extensively tested and the minimal late fallout due to a broken ACPI/MADT table has been addressed by tightening the admission logic further" * tag 'x86-apic-2024-03-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (76 commits) x86/topology: Ignore non-present APIC IDs in a present package x86/apic: Build the x86 topology enumeration functions on UP APIC builds too smp: Provide 'setup_max_cpus' definition on UP too smp: Avoid 'setup_max_cpus' namespace collision/shadowing x86/bugs: Use fixed addressing for VERW operand x86/cpu/topology: Get rid of cpuinfo::x86_max_cores x86/cpu/topology: Provide __num_[cores|threads]_per_package x86/cpu/topology: Rename topology_max_die_per_package() x86/cpu/topology: Rename smp_num_siblings x86/cpu/topology: Retrieve cores per package from topology bitmaps x86/cpu/topology: Use topology logical mapping mechanism x86/cpu/topology: Provide logical pkg/die mapping x86/cpu/topology: Simplify cpu_mark_primary_thread() x86/cpu/topology: Mop up primary thread mask handling x86/cpu/topology: Use topology bitmaps for sizing x86/cpu/topology: Let XEN/PV use topology from CPUID/MADT x86/xen/smp_pv: Count number of vCPUs early x86/cpu/topology: Assign hotpluggable CPUIDs during init x86/cpu/topology: Reject unknown APIC IDs on ACPI hotplug x86/topology: Add a mechanism to track topology via APIC IDs ...
2024-02-25x86/apic/msi: Use DOMAIN_BUS_GENERIC_MSI for HPET/IO-APIC domain searchThomas Gleixner
The recent restriction to invoke irqdomain_ops::select() only when the domain bus token is not DOMAIN_BUS_ANY breaks the search for the parent MSI domain of HPET and IO-APIC. The latter causes a full boot fail. The restriction itself makes sense to avoid adding DOMAIN_BUS_ANY matches into the various ARM specific select() callbacks. Reverting this change would obviously break ARM platforms again and require DOMAIN_BUS_ANY matches added to various places. A simpler solution is to use the DOMAIN_BUS_GENERIC_MSI token for the HPET and IO-APIC parent domain search. This works out of the box because the affected parent domains check only for the firmware specification content and not for the bus token. Fixes: 5aa3c0cf5bba ("genirq/irqdomain: Don't call ops->select for DOMAIN_BUS_ANY tokens") Reported-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/878r38cy8n.ffs@tglx
2024-02-15x86/cpu/topology: Confine topology informationThomas Gleixner
Now that all external fiddling with num_processors and disabled_cpus is gone, move the last user prefill_possible_map() into the topology code too and remove the global visibility of these variables. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240213210251.994756960@linutronix.de
2024-02-15x86/cpu/topology: Move registration out of APIC codeThomas Gleixner
The APIC/CPU registration sits in the middle of the APIC code. In fact this is a topology evaluation function and has nothing to do with the inner workings of the local APIC. Move it out into a file which reflects what this is about. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240213210251.543948812@linutronix.de
2024-02-15x86/apic: Use a proper define for invalid ACPI CPU IDThomas Gleixner
The ACPI ID for CPUs is preset with U32_MAX which is completely non obvious. Use a proper define for it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240212154640.177504138@linutronix.de
2024-02-15x86/apic: Remove yet another dubious callbackThomas Gleixner
Paranoia is not wrong, but having an APIC callback which is in most implementations a complete NOOP and in one actually looking whether the APICID of an upcoming CPU has been registered. The same APICID which was used to bring the CPU out of wait for startup. That's paranoia for the paranoia sake. Remove the voodoo. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240212154640.116510935@linutronix.de
2024-02-15x86/apic: Remove the pointless writeback of boot_cpu_physical_apicidThomas Gleixner
There is absolutely no point to write the APIC ID which was read from the local APIC earlier, back into the local APIC for the 64-bit UP case. Remove that along with the apic callback which is solely there for this pointless exercise. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240212154640.055288922@linutronix.de
2024-02-15x86/mpparse: Remove the physid_t bitmap wrapperThomas Gleixner
physid_t is a wrapper around bitmap. Just remove the onion layer and use bitmap functionality directly. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240212154639.994904510@linutronix.de
2024-02-15x86/apic: Remove check_apicid_used() and ioapic_phys_id_map()Thomas Gleixner
No more users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240212154639.243307499@linutronix.de
2024-02-15x86/ioapic: Simplify setup_ioapic_ids_from_mpc_nocheck()Thomas Gleixner
No need to go through APIC callbacks. It's already established that this is an ancient APIC. So just copy the present mask and use the direct physid* functions all over the place. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240212154639.181901887@linutronix.de
2024-02-15x86/ioapic: Make io_apic_get_unique_id() simplerThomas Gleixner
No need to go through APIC callbacks. It's already established that this is an ancient APIC. So just copy the present mask and use the direct physid* functions all over the place. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240212154639.119261725@linutronix.de
2024-02-15x86/apic: Get rid of get_physical_broadcast()Thomas Gleixner
There is no point for this function. The only case where this is used is when there is no XAPIC available, which means the broadcast address is 0xF. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240212154639.057209154@linutronix.de
2024-02-15x86/ioapic: Replace some more set bit nonsenseThomas Gleixner
Yet another set_bit() operation wrapped in oring a mask. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240212154638.995080989@linutronix.de
2024-02-15x86/platform/ce4100: Dont override x86_init.mpparse.setup_ioapic_idsThomas Gleixner
There is no point to do that. The ATOMs have an XAPIC for which this function is a pointless exercise. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240212154638.931617775@linutronix.de
2024-02-15x86/apic/uv: Remove the private leaf 0xb parserThomas Gleixner
The package shift has been already evaluated by the early CPU init. Put the mindless copy right next to the original leaf 0xb parser. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Zhang Rui <rui.zhang@intel.com> Tested-by: Wang Wendy <wendy.wang@intel.com> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20240212153625.637385562@linutronix.de
2024-02-15x86/apic: Remove unused phys_pkg_id() callbackThomas Gleixner
Now that the core code does not use this monstrosity anymore, it's time to put it to rest. The only real purpose was to read the APIC ID on UV and VSMP systems for the actual evaluation. That's what the core code does now. For doing the actual shift operation there is truly no APIC callback required. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Zhang Rui <rui.zhang@intel.com> Tested-by: Wang Wendy <wendy.wang@intel.com> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20240212153625.516536121@linutronix.de
2024-01-08Merge tag 'x86-cleanups-2024-01-08' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 cleanups from Ingo Molnar: - Change global variables to local - Add missing kernel-doc function parameter descriptions - Remove unused parameter from a macro - Remove obsolete Kconfig entry - Fix comments - Fix typos, mostly scripted, manually reviewed and a micro-optimization got misplaced as a cleanup: - Micro-optimize the asm code in secondary_startup_64_no_verify() * tag 'x86-cleanups-2024-01-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: arch/x86: Fix typos x86/head_64: Use TESTB instead of TESTL in secondary_startup_64_no_verify() x86/docs: Remove reference to syscall trampoline in PTI x86/Kconfig: Remove obsolete config X86_32_SMP x86/io: Remove the unused 'bw' parameter from the BUILDIO() macro x86/mtrr: Document missing function parameters in kernel-doc x86/setup: Make relocated_ramdisk a local variable of relocate_initrd()
2024-01-03arch/x86: Fix typosBjorn Helgaas
Fix typos, most reported by "codespell arch/x86". Only touches comments, no code changes. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Link: https://lore.kernel.org/r/20240103004011.1758650-1-helgaas@kernel.org
2023-11-23x86/ioapic: Remove unfinished sentence from commentAdrian Huang
[ mingo: Refine changelog. ] Signed-off-by: Adrian Huang <ahuang12@lenovo.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: linux-kernel@vger.kernel.org
2023-11-21x86/apic: Drop apic::delivery_modeAndrew Cooper
This field is set to APIC_DELIVERY_MODE_FIXED in all cases, and is read exactly once. Fold the constant in uv_program_mmr() and drop the field. Searching for the origin of the stale HyperV comment reveals commit a31e58e129f7 ("x86/apic: Switch all APICs to Fixed delivery mode") which notes: As a consequence of this change, the apic::irq_delivery_mode field is now pointless, but this needs to be cleaned up in a separate patch. 6 years is long enough for this technical debt to have survived. [ bp: Fold in https://lore.kernel.org/r/20231121123034.1442059-1-andrew.cooper3@citrix.com ] Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Steve Wahl <steve.wahl@hpe.com> Link: https://lore.kernel.org/r/20231102-x86-apic-v1-1-bf049a2a0ed6@citrix.com
2023-11-04Merge tag 'x86_microcode_for_v6.7_rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 microcode loading updates from Borislac Petkov: "Major microcode loader restructuring, cleanup and improvements by Thomas Gleixner: - Restructure the code needed for it and add a temporary initrd mapping on 32-bit so that the loader can access the microcode blobs. This in itself is a preparation for the next major improvement: - Do not load microcode on 32-bit before paging has been enabled. Handling this has caused an endless stream of headaches, issues, ugly code and unnecessary hacks in the past. And there really wasn't any sensible reason to do that in the first place. So switch the 32-bit loading to happen after paging has been enabled and turn the loader code "real purrty" again - Drop mixed microcode steppings loading on Intel - there, a single patch loaded on the whole system is sufficient - Rework late loading to track which CPUs have updated microcode successfully and which haven't, act accordingly - Move late microcode loading on Intel in NMI context in order to guarantee concurrent loading on all threads - Make the late loading CPU-hotplug-safe and have the offlined threads be woken up for the purpose of the update - Add support for a minimum revision which determines whether late microcode loading is safe on a machine and the microcode does not change software visible features which the machine cannot use anyway since feature detection has happened already. Roughly, the minimum revision is the smallest revision number which must be loaded currently on the system so that late updates can be allowed - Other nice leanups, fixess, etc all over the place" * tag 'x86_microcode_for_v6.7_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits) x86/microcode/intel: Add a minimum required revision for late loading x86/microcode: Prepare for minimal revision check x86/microcode: Handle "offline" CPUs correctly x86/apic: Provide apic_force_nmi_on_cpu() x86/microcode: Protect against instrumentation x86/microcode: Rendezvous and load in NMI x86/microcode: Replace the all-in-one rendevous handler x86/microcode: Provide new control functions x86/microcode: Add per CPU control field x86/microcode: Add per CPU result state x86/microcode: Sanitize __wait_for_cpus() x86/microcode: Clarify the late load logic x86/microcode: Handle "nosmt" correctly x86/microcode: Clean up mc_cpu_down_prep() x86/microcode: Get rid of the schedule work indirection x86/microcode: Mop up early loading leftovers x86/microcode/amd: Use cached microcode for AP load x86/microcode/amd: Cache builtin/initrd microcode early x86/microcode/amd: Cache builtin microcode too x86/microcode/amd: Use correct per CPU ucode_cpu_info ...
2023-10-30Merge tag 'x86-core-2023-10-29-v2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 core updates from Thomas Gleixner: - Limit the hardcoded topology quirk for Hygon CPUs to those which have a model ID less than 4. The newer models have the topology CPUID leaf 0xB correctly implemented and are not affected. - Make SMT control more robust against enumeration failures SMT control was added to allow controlling SMT at boottime or runtime. The primary purpose was to provide a simple mechanism to disable SMT in the light of speculation attack vectors. It turned out that the code is sensible to enumeration failures and worked only by chance for XEN/PV. XEN/PV has no real APIC enumeration which means the primary thread mask is not set up correctly. By chance a XEN/PV boot ends up with smp_num_siblings == 2, which makes the hotplug control stay at its default value "enabled". So the mask is never evaluated. The ongoing rework of the topology evaluation caused XEN/PV to end up with smp_num_siblings == 1, which sets the SMT control to "not supported" and the empty primary thread mask causes the hotplug core to deny the bringup of the APS. Make the decision logic more robust and take 'not supported' and 'not implemented' into account for the decision whether a CPU should be booted or not. - Fake primary thread mask for XEN/PV Pretend that all XEN/PV vCPUs are primary threads, which makes the usage of the primary thread mask valid on XEN/PV. That is consistent with because all of the topology information on XEN/PV is fake or even non-existent. - Encapsulate topology information in cpuinfo_x86 Move the randomly scattered topology data into a separate data structure for readability and as a preparatory step for the topology evaluation overhaul. - Consolidate APIC ID data type to u32 It's fixed width hardware data and not randomly u16, int, unsigned long or whatever developers decided to use. - Cure the abuse of cpuinfo for persisting logical IDs. Per CPU cpuinfo is used to persist the logical package and die IDs. That's really not the right place simply because cpuinfo is subject to be reinitialized when a CPU goes through an offline/online cycle. Use separate per CPU data for the persisting to enable the further topology management rework. It will be removed once the new topology management is in place. - Provide a debug interface for inspecting topology information Useful in general and extremly helpful for validating the topology management rework in terms of correctness or "bug" compatibility. * tag 'x86-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits) x86/apic, x86/hyperv: Use u32 in hv_snp_boot_ap() too x86/cpu: Provide debug interface x86/cpu/topology: Cure the abuse of cpuinfo for persisting logical ids x86/apic: Use u32 for wakeup_secondary_cpu[_64]() x86/apic: Use u32 for [gs]et_apic_id() x86/apic: Use u32 for phys_pkg_id() x86/apic: Use u32 for cpu_present_to_apicid() x86/apic: Use u32 for check_apicid_used() x86/apic: Use u32 for APIC IDs in global data x86/apic: Use BAD_APICID consistently x86/cpu: Move cpu_l[l2]c_id into topology info x86/cpu: Move logical package and die IDs into topology info x86/cpu: Remove pointless evaluation of x86_coreid_bits x86/cpu: Move cu_id into topology info x86/cpu: Move cpu_core_id into topology info hwmon: (fam15h_power) Use topology_core_id() scsi: lpfc: Use topology_core_id() x86/cpu: Move cpu_die_id into topology info x86/cpu: Move phys_proc_id into topology info x86/cpu: Encapsulate topology information in cpuinfo_x86 ...
2023-10-26x86/apic/msi: Fix misconfigured non-maskable MSI quirkKoichiro Den
commit ef8dd01538ea ("genirq/msi: Make interrupt allocation less convoluted"), reworked the code so that the x86 specific quirk for affinity setting of non-maskable PCI/MSI interrupts is not longer activated if necessary. This could be solved by restoring the original logic in the core MSI code, but after a deeper analysis it turned out that the quirk flag is not required at all. The quirk is only required when the PCI/MSI device cannot mask the MSI interrupts, which in turn also prevents reservation mode from being enabled for the affected interrupt. This allows ot remove the NOMASK quirk bit completely as msi_set_affinity() can instead check whether reservation mode is enabled for the interrupt, which gives exactly the same answer. Even in the momentary non-existing case that the reservation mode would be not set for a maskable MSI interrupt this would not cause any harm as it just would cause msi_set_affinity() to go needlessly through the functionaly equivalent slow path, which works perfectly fine with maskable interrupts as well. Rework msi_set_affinity() to query the reservation mode and remove all NOMASK quirk logic from the core code. [ tglx: Massaged changelog ] Fixes: ef8dd01538ea ("genirq/msi: Make interrupt allocation less convoluted") Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Koichiro Den <den@valinux.co.jp> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20231026032036.2462428-1-den@valinux.co.jp
2023-10-24x86/apic: Provide apic_force_nmi_on_cpu()Thomas Gleixner
When SMT siblings are soft-offlined and parked in one of the play_dead() variants they still react on NMI, which is problematic on affected Intel CPUs. The default play_dead() variant uses MWAIT on modern CPUs, which is not guaranteed to be safe when updated concurrently. Right now late loading is prevented when not all SMT siblings are online, but as they still react on NMI, it is possible to bring them out of their park position into a trivial rendezvous handler. Provide a function which allows to do that. I does sanity checks whether the target is in the cpus_booted_once_mask and whether the APIC driver supports it. Mark X2APIC and XAPIC as capable, but exclude 32bit and the UV and NUMACHIP variants as that needs feedback from the relevant experts. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20231002115903.603100036@linutronix.de
2023-10-10x86/apic: Use u32 for wakeup_secondary_cpu[_64]()Thomas Gleixner
APIC IDs are used with random data types u16, u32, int, unsigned int, unsigned long. Make it all consistently use u32 because that reflects the hardware register width. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Reviewed-by: Arjan van de Ven <arjan@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230814085113.233274223@linutronix.de
2023-10-10x86/apic: Use u32 for [gs]et_apic_id()Thomas Gleixner
APIC IDs are used with random data types u16, u32, int, unsigned int, unsigned long. Make it all consistently use u32 because that reflects the hardware register width. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230814085113.172569282@linutronix.de
2023-10-10x86/apic: Use u32 for phys_pkg_id()Thomas Gleixner
APIC IDs are used with random data types u16, u32, int, unsigned int, unsigned long. Make it all consistently use u32 because that reflects the hardware register width even if that callback going to be removed soonish. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Reviewed-by: Arjan van de Ven <arjan@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230814085113.113097126@linutronix.de
2023-10-10x86/apic: Use u32 for cpu_present_to_apicid()Thomas Gleixner
APIC IDs are used with random data types u16, u32, int, unsigned int, unsigned long. Make it all consistently use u32 because that reflects the hardware register width and fixup a few related usage sites for consistency sake. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Reviewed-by: Arjan van de Ven <arjan@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230814085113.054064391@linutronix.de
2023-10-10x86/apic: Use u32 for check_apicid_used()Thomas Gleixner
APIC IDs are used with random data types u16, u32, int, unsigned int, unsigned long. Make it all consistently use u32 because that reflects the hardware register width and move the default implementation to local.h as there are no users outside the apic directory. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Reviewed-by: Arjan van de Ven <arjan@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230814085112.981956102@linutronix.de
2023-10-10x86/apic: Use u32 for APIC IDs in global dataThomas Gleixner
APIC IDs are used with random data types u16, u32, int, unsigned int, unsigned long. Make it all consistently use u32 because that reflects the hardware register width and fixup the most obvious usage sites of that. The APIC callbacks will be addressed separately. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Reviewed-by: Arjan van de Ven <arjan@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230814085112.922905727@linutronix.de
2023-10-10x86/apic: Use BAD_APICID consistentlyThomas Gleixner
APIC ID checks compare with BAD_APICID all over the place, but some initializers and some code which fiddles with global data structure use -1[U] instead. That simply cannot work at all. Fix it up and use BAD_APICID consistently all over the place. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230814085112.862835121@linutronix.de
2023-10-10x86/cpu: Move cpu_l[l2]c_id into topology infoThomas Gleixner
The topology IDs which identify the LLC and L2 domains clearly belong to the per CPU topology information. Move them into cpuinfo_x86::cpuinfo_topo and get rid of the extra per CPU data and the related exports. This also paves the way to do proper topology evaluation during early boot because it removes the only per CPU dependency for that. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Reviewed-by: Arjan van de Ven <arjan@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230814085112.803864641@linutronix.de
2023-10-10x86/cpu: Move phys_proc_id into topology infoThomas Gleixner
Rename it to pkg_id which is the terminology used in the kernel. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230814085112.329006989@linutronix.de
2023-10-10x86/apic: Fake primary thread mask for XEN/PVThomas Gleixner
The SMT control mechanism got added as speculation attack vector mitigation. The implemented logic relies on the primary thread mask to be set up properly. This turns out to be an issue with XEN/PV guests because their CPU hotplug mechanics do not enumerate APICs and therefore the mask is never correctly populated. This went unnoticed so far because by chance XEN/PV ends up with smp_num_siblings == 2. So cpu_smt_control stays at its default value CPU_SMT_ENABLED and the primary thread mask is never evaluated in the context of CPU hotplug. This stopped "working" with the upcoming overhaul of the topology evaluation which legitimately provides a fake topology for XEN/PV. That sets smp_num_siblings to 1, which causes the core CPU hot-plug core to refuse to bring up the APs. This happens because cpu_smt_control is set to CPU_SMT_NOT_SUPPORTED which causes cpu_bootable() to evaluate the unpopulated primary thread mask with the conclusion that all non-boot CPUs are not valid to be plugged. The core code has already been made more robust against this kind of fail, but the primary thread mask really wants to be populated to avoid other issues all over the place. Just fake the mask by pretending that all XEN/PV vCPUs are primary threads, which is consistent because all of XEN/PVs topology is fake or non-existent. Fixes: 6a4d2657e048 ("x86/smp: Provide topology_is_primary_thread()") Fixes: f54d4434c281 ("x86/apic: Provide cpu_primary_thread mask") Reported-by: Juergen Gross <jgross@suse.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230814085112.210011520@linutronix.de
2023-09-21x86/platform/uv/apic: Clean up inconsistent indentingYang Li
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230816003842.116574-1-yang.lee@linux.alibaba.com
2023-09-11x86/platform/uv: Use alternate source for socket to node dataSteve Wahl
The UV code attempts to build a set of tables to allow it to do bidirectional socket<=>node lookups. But when nr_cpus is set to a smaller number than actually present, the cpu_to_node() mapping information for unused CPUs is not available to build_socket_tables(). This results in skipping some nodes or sockets when creating the tables and leaving some -1's for later code to trip. over, causing oopses. The problem is that the socket<=>node lookups are created by doing a loop over all CPUs, then looking up the CPU's APICID and socket. But if a CPU is not present, there is no way to start this lookup. Instead of looping over all CPUs, take CPUs out of the equation entirely. Loop over all APICIDs which are mapped to a valid NUMA node. Then just extract the socket-id from the APICID. This avoid tripping over disabled CPUs. Fixes: 8a50c5851927 ("x86/platform/uv: UV support for sub-NUMA clustering") Signed-off-by: Steve Wahl <steve.wahl@hpe.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20230807141730.1117278-1-steve.wahl%40hpe.com
2023-08-30Merge tag 'x86_apic_for_6.6-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 apic updates from Dave Hansen: "This includes a very thorough rework of the 'struct apic' handlers. Quite a variety of them popped up over the years, especially in the 32-bit days when odd apics were much more in vogue. The end result speaks for itself, which is a removal of a ton of code and static calls to replace indirect calls. If there's any breakage here, it's likely to be around the 32-bit museum pieces that get light to no testing these days. Summary: - Rework apic callbacks, getting rid of unnecessary ones and coalescing lots of silly duplicates. - Use static_calls() instead of indirect calls for apic->foo() - Tons of cleanups an crap removal along the way" * tag 'x86_apic_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits) x86/apic: Turn on static calls x86/apic: Provide static call infrastructure for APIC callbacks x86/apic: Wrap IPI calls into helper functions x86/apic: Mark all hotpath APIC callback wrappers __always_inline x86/xen/apic: Mark apic __ro_after_init x86/apic: Convert other overrides to apic_update_callback() x86/apic: Replace acpi_wake_cpu_handler_update() and apic_set_eoi_cb() x86/apic: Provide apic_update_callback() x86/xen/apic: Use standard apic driver mechanism for Xen PV x86/apic: Provide common init infrastructure x86/apic: Wrap apic->native_eoi() into a helper x86/apic: Nuke ack_APIC_irq() x86/apic: Remove pointless arguments from [native_]eoi_write() x86/apic/noop: Tidy up the code x86/apic: Remove pointless NULL initializations x86/apic: Sanitize APIC ID range validation x86/apic: Prepare x2APIC for using apic::max_apic_id x86/apic: Simplify X2APIC ID validation x86/apic: Add max_apic_id member x86/apic: Wrap APIC ID validation into an inline ...
2023-08-29Merge tag 'mm-nonmm-stable-2023-08-28-22-48' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull non-MM updates from Andrew Morton: - An extensive rework of kexec and crash Kconfig from Eric DeVolder ("refactor Kconfig to consolidate KEXEC and CRASH options") - kernel.h slimming work from Andy Shevchenko ("kernel.h: Split out a couple of macros to args.h") - gdb feature work from Kuan-Ying Lee ("Add GDB memory helper commands") - vsprintf inclusion rationalization from Andy Shevchenko ("lib/vsprintf: Rework header inclusions") - Switch the handling of kdump from a udev scheme to in-kernel handling, by Eric DeVolder ("crash: Kernel handling of CPU and memory hot un/plug") - Many singleton patches to various parts of the tree * tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (81 commits) document while_each_thread(), change first_tid() to use for_each_thread() drivers/char/mem.c: shrink character device's devlist[] array x86/crash: optimize CPU changes crash: change crash_prepare_elf64_headers() to for_each_possible_cpu() crash: hotplug support for kexec_load() x86/crash: add x86 crash hotplug support crash: memory and CPU hotplug sysfs attributes kexec: exclude elfcorehdr from the segment digest crash: add generic infrastructure for crash hotplug support crash: move a few code bits to setup support of crash hotplug kstrtox: consistently use _tolower() kill do_each_thread() nilfs2: fix WARNING in mark_buffer_dirty due to discarded buffer reuse scripts/bloat-o-meter: count weak symbol sizes treewide: drop CONFIG_EMBEDDED lockdep: fix static memory detection even more lib/vsprintf: declare no_hash_pointers in sprintf.h lib/vsprintf: split out sprintf() and friends kernel/fork: stop playing lockless games for exe_file replacement adfs: delete unused "union adfs_dirtail" definition ...
2023-08-24x86/platform/uv: Refactor code using deprecated strncpy() interface to use ↵Justin Stitt
strscpy() `strncpy` is deprecated for use on NUL-terminated destination strings [1]. A suitable replacement is `strscpy` [2] due to the fact that it guarantees NUL-termination on its destination buffer argument which is _not_ the case for `strncpy`! In this case, it means we can drop the `...-1` from: | strncpy(to, from, len-1); as well as remove the comment mentioning NUL-termination as `strscpy` implicitly grants us this behavior. There should be no functional change as I don't believe the padding from `strncpy` is needed here. If it turns out that the padding is necessary we should use `strscpy_pad` as a direct replacement. Signed-off-by: Justin Stitt <justinstitt@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: Kees Cook <keescook@chromium.org> Cc: Dimitri Sivanich <sivanich@hpe.com> Link: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings[1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Link: https://lore.kernel.org/r/20230822-strncpy-arch-x86-kernel-apic-x2apic_uv_x-v1-1-91d681d0b3f3@google.com
2023-08-18nmi_backtrace: allow excluding an arbitrary CPUDouglas Anderson
The APIs that allow backtracing across CPUs have always had a way to exclude the current CPU. This convenience means callers didn't need to find a place to allocate a CPU mask just to handle the common case. Let's extend the API to take a CPU ID to exclude instead of just a boolean. This isn't any more complex for the API to handle and allows the hardlockup detector to exclude a different CPU (the one it already did a trace for) without needing to find space for a CPU mask. Arguably, this new API also encourages safer behavior. Specifically if the caller wants to avoid tracing the current CPU (maybe because they already traced the current CPU) this makes it more obvious to the caller that they need to make sure that the current CPU ID can't change. [akpm@linux-foundation.org: fix trigger_allbutcpu_cpu_backtrace() stub] Link: https://lkml.kernel.org/r/20230804065935.v4.1.Ia35521b91fc781368945161d7b28538f9996c182@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: kernel test robot <lkp@intel.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>