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| author | Thomas Gleixner <tglx@linutronix.de> | 2018-05-29 17:50:22 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-06-21 14:20:57 +0200 |
| commit | 6a4d2657e048f096c7ffcad254010bd94891c8c0 (patch) | |
| tree | 20d72fc0fdc2d6a5903ed7f0681dbc50e5c93d66 /arch/x86/include | |
| parent | sched/smt: Update sched_smt_present at runtime (diff) | |
| download | linux-6a4d2657e048f096c7ffcad254010bd94891c8c0.tar.xz linux-6a4d2657e048f096c7ffcad254010bd94891c8c0.zip | |
x86/smp: Provide topology_is_primary_thread()
If the CPU is supporting SMT then the primary thread can be found by
checking the lower APIC ID bits for zero. smp_num_siblings is used to build
the mask for the APIC ID bits which need to be taken into account.
This uses the MPTABLE or ACPI/MADT supplied APIC ID, which can be different
than the initial APIC ID in CPUID. But according to AMD the lower bits have
to be consistent. Intel gave a tentative confirmation as well.
Preparatory patch to support disabling SMT at boot/runtime.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/apic.h | 6 | ||||
| -rw-r--r-- | arch/x86/include/asm/topology.h | 4 |
2 files changed, 9 insertions, 1 deletions
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index 74a9e06b6cfd..9362a3aae927 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -502,6 +502,12 @@ extern int default_check_phys_apicid_present(int phys_apicid); #endif /* CONFIG_X86_LOCAL_APIC */ +#ifdef CONFIG_SMP +bool apic_id_is_primary_thread(unsigned int id); +#else +static inline bool apic_id_is_primary_thread(unsigned int id) { return false; } +#endif + extern void irq_enter(void); extern void irq_exit(void); diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index c1d2a9892352..661e361a12a6 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -123,13 +123,15 @@ static inline int topology_max_smt_threads(void) } int topology_update_package_map(unsigned int apicid, unsigned int cpu); -extern int topology_phys_to_logical_pkg(unsigned int pkg); +int topology_phys_to_logical_pkg(unsigned int pkg); +bool topology_is_primary_thread(unsigned int cpu); #else #define topology_max_packages() (1) static inline int topology_update_package_map(unsigned int apicid, unsigned int cpu) { return 0; } static inline int topology_phys_to_logical_pkg(unsigned int pkg) { return 0; } static inline int topology_max_smt_threads(void) { return 1; } +static inline bool topology_is_primary_thread(unsigned int cpu) { return true; } #endif static inline void arch_fix_phys_package_id(int num, u32 slot) |