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--- b/arch/x86/kernel/cpu/bugs.c
+++ a/arch/x86/kernel/cpu/bugs.c
@@ -61,7 +61,7 @@
* identify_boot_cpu() initialized SMT support information, let the
* core code know.
*/
+ cpu_smt_check_topology();
- cpu_smt_check_topology_early();
if (!IS_ENABLED(CONFIG_SMP)) {
pr_info("CPU: ");
--- b/include/linux/cpu.h
+++ a/include/linux/cpu.h
@@ -267,12 +267,10 @@
#if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_SMT)
extern enum cpuhp_smt_control cpu_smt_control;
extern void cpu_smt_disable(bool force);
-extern void cpu_smt_check_topology_early(void);
extern void cpu_smt_check_topology(void);
#else
# define cpu_smt_control (CPU_SMT_ENABLED)
static inline void cpu_smt_disable(bool force) { }
-static inline void cpu_smt_check_topology_early(void) { }
static inline void cpu_smt_check_topology(void) { }
#endif
--- b/kernel/cpu.c
+++ a/kernel/cpu.c
@@ -360,8 +360,6 @@
enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED;
EXPORT_SYMBOL_GPL(cpu_smt_control);
-static bool cpu_smt_available __read_mostly;
-
void __init cpu_smt_disable(bool force)
{
if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||
@@ -378,28 +376,14 @@
/*
* The decision whether SMT is supported can only be done after the full
+ * CPU identification. Called from architecture code.
- * CPU identification. Called from architecture code before non boot CPUs
- * are brought up.
*/
+void __init cpu_smt_check_topology(void)
-void __init cpu_smt_check_topology_early(void)
{
if (!topology_smt_supported())
cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
}
-/*
- * If SMT was disabled by BIOS, detect it here, after the CPUs have been
- * brought online. This ensures the smt/l1tf sysfs entries are consistent
- * with reality. cpu_smt_available is set to true during the bringup of non
- * boot CPUs when a SMT sibling is detected. Note, this may overwrite
- * cpu_smt_control's previous setting.
- */
-void __init cpu_smt_check_topology(void)
-{
- if (!cpu_smt_available)
- cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
-}
-
static int __init smt_cmdline_disable(char *str)
{
cpu_smt_disable(str && !strcmp(str, "force"));
@@ -409,18 +393,10 @@
static inline bool cpu_smt_allowed(unsigned int cpu)
{
+ if (cpu_smt_control == CPU_SMT_ENABLED)
- if (topology_is_primary_thread(cpu))
return true;
+ if (topology_is_primary_thread(cpu))
- /*
- * If the CPU is not a 'primary' thread and the booted_once bit is
- * set then the processor has SMT support. Store this information
- * for the late check of SMT support in cpu_smt_check_topology().
- */
- if (per_cpu(cpuhp_state, cpu).booted_once)
- cpu_smt_available = true;
-
- if (cpu_smt_control == CPU_SMT_ENABLED)
return true;
/*
@@ -2087,6 +2063,15 @@
static int __init cpu_smt_state_init(void)
{
+ /*
+ * If SMT was disabled by BIOS, detect it here, after the CPUs have
+ * been brought online. This ensures the smt/l1tf sysfs entries are
+ * consistent with reality. Note this may overwrite cpu_smt_control's
+ * previous setting.
+ */
+ if (topology_max_smt_threads() == 1)
+ cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
+
return sysfs_create_group(&cpu_subsys.dev_root->kobj,
&cpuhp_smt_attr_group);
}
--- b/kernel/smp.c
+++ a/kernel/smp.c
@@ -564,8 +564,6 @@
cpu_up(cpu);
}
- /* Final decision about SMT support */
- cpu_smt_check_topology();
/* Any cleanup work */
smp_announce();
smp_cpus_done(setup_max_cpus);
|