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 ||
/*
* 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"));
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;
/*
bool bringup = st->bringup;
enum cpuhp_state state;
+ if (WARN_ON_ONCE(!st->should_run))
+ return;
+
/*
* ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures
* that if we see ->should_run we also see the rest of the state.
*/
smp_mb();
- if (WARN_ON_ONCE(!st->should_run))
- return;
-
cpuhp_lock_acquire(bringup);
if (st->single) {
ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);
if (ret) {
st->target = prev_state;
- undo_cpu_down(cpu, st);
+ if (st->state < prev_state)
+ undo_cpu_down(cpu, st);
break;
}
}
* to do the further cleanups.
*/
ret = cpuhp_down_callbacks(cpu, st, target);
- if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) {
+ if (ret && st->state == CPUHP_TEARDOWN_CPU && st->state < prev_state) {
cpuhp_reset_state(st, prev_state);
__cpuhp_kick_ap(st);
}
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);
}
*/
void __init boot_cpu_hotplug_init(void)
{
+#ifdef CONFIG_SMP
this_cpu_write(cpuhp_state.booted_once, true);
+#endif
this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);
}