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Fix a CPU topology code regression that caused the mishandling 

of certain boot command line options, and re-enable CONFIG_PTDUMP
 on i386 that was mistakenly turned off in the Kconfig.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-urgent-2025-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:
 "Fix a CPU topology code regression that caused the mishandling of
  certain boot command line options, and re-enable CONFIG_PTDUMP on i386
  that was mistakenly turned off in the Kconfig"

* tag 'x86-urgent-2025-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/topology: Implement topology_is_core_online() to address SMT regression
  x86/Kconfig: Reenable PTDUMP on i386
This commit is contained in:
Linus Torvalds 2025-09-26 13:44:21 -07:00
parent 083fc6d7fa 2066f00e5b
commit d4df17482e
3 changed files with 24 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/Kconfig
View File

@ -26,7 +26,6 @@ config X86_64
depends on 64BIT
# Options that are inherently 64-bit kernel only:
select ARCH_HAS_GIGANTIC_PAGE
select ARCH_HAS_PTDUMP
select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS
select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
select ARCH_SUPPORTS_PER_VMA_LOCK
@ -99,6 +98,7 @@ config X86
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
select ARCH_HAS_PMEM_API if X86_64
select ARCH_HAS_PREEMPT_LAZY
select ARCH_HAS_PTDUMP
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_HW_PTE_YOUNG
select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2

10
arch/x86/include/asm/topology.h
View File

@ -231,6 +231,16 @@ static inline bool topology_is_primary_thread(unsigned int cpu)
}
#define topology_is_primary_thread topology_is_primary_thread
int topology_get_primary_thread(unsigned int cpu);
static inline bool topology_is_core_online(unsigned int cpu)
{
int pcpu = topology_get_primary_thread(cpu);
return pcpu >= 0 ? cpu_online(pcpu) : false;
}
#define topology_is_core_online topology_is_core_online
#else /* CONFIG_SMP */
static inline int topology_phys_to_logical_pkg(unsigned int pkg) { return 0; }
static inline int topology_max_smt_threads(void) { return 1; }

13
arch/x86/kernel/cpu/topology.c
View File

@ -372,6 +372,19 @@ unsigned int topology_unit_count(u32 apicid, enum x86_topology_domains which_uni
return topo_unit_count(lvlid, at_level, apic_maps[which_units].map);
}
#ifdef CONFIG_SMP
int topology_get_primary_thread(unsigned int cpu)
{
u32 apic_id = cpuid_to_apicid[cpu];
/*
* Get the core domain level APIC id, which is the primary thread
* and return the CPU number assigned to it.
*/
return topo_lookup_cpuid(topo_apicid(apic_id, TOPO_CORE_DOMAIN));
}
#endif
#ifdef CONFIG_ACPI_HOTPLUG_CPU
/**
* topology_hotplug_apic - Handle a physical hotplugged APIC after boot