cpu/SMT: create and export cpu_smt_possible()

KVM needs to know if SMT is theoretically possible, this means it is
supported and not forcefully disabled ('nosmt=force'). Create and
export cpu_smt_possible() answering this question.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index e1967e9eddc2..fc28e17940e0 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -392,8 +392,7 @@ enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED;
 
 void __init cpu_smt_disable(bool force)
 {
-        if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||
-                cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
+        if (!cpu_smt_possible())
                 return;
 
         if (force) {
@@ -438,6 +437,14 @@ static inline bool cpu_smt_allowed(unsigned int cpu)
          */
         return !cpumask_test_cpu(cpu, &cpus_booted_once_mask);
 }
+
+/* Returns true if SMT is not supported of forcefully (irreversibly) disabled */
+bool cpu_smt_possible(void)
+{
+        return cpu_smt_control != CPU_SMT_FORCE_DISABLED &&
+                cpu_smt_control != CPU_SMT_NOT_SUPPORTED;
+}
+EXPORT_SYMBOL_GPL(cpu_smt_possible);
 #else
 static inline bool cpu_smt_allowed(unsigned int cpu) { return true; }
 #endif