x86/topology: Provide topology_smt_supported()

Provide information whether SMT is supoorted by the CPUs. Preparatory patch
for SMT control mechanism.

Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index 661e361a12a6acf76abcd22d97668252ca74d409..453cf38a1c33d5b2452dff29be06ce52b5b30ffb 100644 (file)
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -125,6 +125,7 @@ static inline int topology_max_smt_threads(void)
 int topology_update_package_map(unsigned int apicid, unsigned int cpu);
 int topology_phys_to_logical_pkg(unsigned int pkg);
 bool topology_is_primary_thread(unsigned int cpu);
+bool topology_smt_supported(void);
 #else
 #define topology_max_packages()                        (1)
 static inline int
@@ -132,6 +133,7 @@ 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; }
+static inline bool topology_smt_supported(void) { return false; }
 #endif
 
 static inline void arch_fix_phys_package_id(int num, u32 slot)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index f9c731240142193905f04c39bd3e79a799986f64..7f7def989fb04ed1ac5b3bb711c731b09375c6b6 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -274,6 +274,14 @@ bool topology_is_primary_thread(unsigned int cpu)
        return apic_id_is_primary_thread(per_cpu(x86_cpu_to_apicid, cpu));
 }
 
+/**
+ * topology_smt_supported - Check whether SMT is supported by the CPUs
+ */
+bool topology_smt_supported(void)
+{
+       return smp_num_siblings > 1;
+}
+
 /**
  * topology_phys_to_logical_pkg - Map a physical package id to a logical
  *