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authorThomas Gleixner <tglx@linutronix.de>2018-05-29 17:50:22 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-08-15 18:14:45 +0200
commit7b69a96e5a328f17fe33f3826d7e8349ab59015d (patch)
treea8f09be1ff2ed4561a1511e4efa7de3183e26568 /arch/x86/include/asm
parent1ac1dc14671f531134f29755f98386f8e168b810 (diff)
x86/smp: Provide topology_is_primary_thread()
commit 6a4d2657e048f096c7ffcad254010bd94891c8c0 upstream 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> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/include/asm')
-rw-r--r--arch/x86/include/asm/apic.h7
-rw-r--r--arch/x86/include/asm/topology.h4
2 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index f5aaf6c83222..20eed46c5827 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -633,6 +633,13 @@ extern int default_check_phys_apicid_present(int phys_apicid);
#endif
#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 cf75871d2f81..e5e6c02c203f 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -129,13 +129,15 @@ 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)