#ifdef CONFIG_HOTPLUG_SMT
enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED;
+EXPORT_SYMBOL_GPL(cpu_smt_control);
-static int __init smt_cmdline_disable(char *str)
+static bool cpu_smt_available __read_mostly;
+
+void __init cpu_smt_disable(bool force)
{
- cpu_smt_control = CPU_SMT_DISABLED;
- if (str && !strcmp(str, "force")) {
+ if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||
+ cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
+ return;
+
+ if (force) {
pr_info("SMT: Force disabled\n");
cpu_smt_control = CPU_SMT_FORCE_DISABLED;
+ } else {
+ cpu_smt_control = CPU_SMT_DISABLED;
}
+}
+
+/*
+ * The decision whether SMT is supported can only be done after the full
+ * CPU identification. Called from architecture code before non boot CPUs
+ * are brought up.
+ */
+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"));
return 0;
}
early_param("nosmt", smt_cmdline_disable);
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);
}
kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
}
+static void cpuhp_online_cpu_device(unsigned int cpu)
+{
+ struct device *dev = get_cpu_device(cpu);
+
+ dev->offline = false;
+ /* Tell user space about the state change */
+ kobject_uevent(&dev->kobj, KOBJ_ONLINE);
+}
+
static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
{
int cpu, ret = 0;
return ret;
}
-static void cpuhp_smt_enable(void)
+static int cpuhp_smt_enable(void)
{
+ int cpu, ret = 0;
+
cpu_maps_update_begin();
cpu_smt_control = CPU_SMT_ENABLED;
+ for_each_present_cpu(cpu) {
+ /* Skip online CPUs and CPUs on offline nodes */
+ if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
+ continue;
+ ret = _cpu_up(cpu, 0, CPUHP_ONLINE);
+ if (ret)
+ break;
+ /* See comment in cpuhp_smt_disable() */
+ cpuhp_online_cpu_device(cpu);
+ }
cpu_maps_update_done();
+ return ret;
}
static ssize_t
if (ctrlval != cpu_smt_control) {
switch (ctrlval) {
case CPU_SMT_ENABLED:
- cpuhp_smt_enable();
+ ret = cpuhp_smt_enable();
break;
case CPU_SMT_DISABLED:
case CPU_SMT_FORCE_DISABLED:
static int __init cpu_smt_state_init(void)
{
- if (!topology_smt_supported())
- 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);
}