x86/apic: Ignore secondary threads if nosmt=force

[platform/kernel/linux-rpi.git] / arch / x86 / kernel / apic / apic.c

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 0a10d3e..828ee43 100644 (file)
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2107,6 +2107,16 @@ bool apic_id_is_primary_thread(unsigned int apicid)
        return !(apicid & mask);
 }
 
+/**
+ * apic_id_disabled - Check whether APIC ID is disabled via SMT control
+ * @id:        APIC ID to check
+ */
+bool apic_id_disabled(unsigned int id)
+{
+       return (cpu_smt_control == CPU_SMT_FORCE_DISABLED &&
+               !apic_id_is_primary_thread(id));
+}
+
 /*
  * Should use this API to allocate logical CPU IDs to keep nr_logical_cpuids
  * and cpuid_to_apicid[] synchronized.
@@ -2202,6 +2212,15 @@ int generic_processor_info(int apicid, int version)
                return -EINVAL;
        }
 
+       /*
+        * If SMT is force disabled and the APIC ID belongs to
+        * a secondary thread, ignore it.
+        */
+       if (apic_id_disabled(apicid)) {
+               pr_info_once("Ignoring secondary SMT threads\n");
+               return -EINVAL;
+       }
+
        if (apicid == boot_cpu_physical_apicid) {
                /*
                 * x86_bios_cpu_apicid is required to have processors listed