void lockdep_assert_cpus_held(void)
{
+ /*
+ * We can't have hotplug operations before userspace starts running,
+ * and some init codepaths will knowingly not take the hotplug lock.
+ * This is all valid, so mute lockdep until it makes sense to report
+ * unheld locks.
+ */
+ if (system_state < SYSTEM_RUNNING)
+ return;
+
percpu_rwsem_assert_held(&cpu_hotplug_lock);
}
#ifdef CONFIG_HOTPLUG_SMT
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)
{
pr_info("SMT: Force disabled\n");
cpu_smt_control = CPU_SMT_FORCE_DISABLED;
} else {
+ pr_info("SMT: disabled\n");
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.
+ * CPU identification. Called from architecture code.
*/
void __init cpu_smt_check_topology(void)
{
- if (!cpu_smt_available)
+ if (!topology_smt_supported())
cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
}
static inline bool cpu_smt_allowed(unsigned int cpu)
{
- if (topology_is_primary_thread(cpu))
+ if (cpu_smt_control == CPU_SMT_ENABLED)
return true;
- /*
- * 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)
+ if (topology_is_primary_thread(cpu))
return true;
/*
}
}
+static inline bool can_rollback_cpu(struct cpuhp_cpu_state *st)
+{
+ if (IS_ENABLED(CONFIG_HOTPLUG_CPU))
+ return true;
+ /*
+ * When CPU hotplug is disabled, then taking the CPU down is not
+ * possible because takedown_cpu() and the architecture and
+ * subsystem specific mechanisms are not available. So the CPU
+ * which would be completely unplugged again needs to stay around
+ * in the current state.
+ */
+ return st->state <= CPUHP_BRINGUP_CPU;
+}
+
static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
enum cpuhp_state target)
{
st->state++;
ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL);
if (ret) {
- st->target = prev_state;
- undo_cpu_up(cpu, st);
+ if (can_rollback_cpu(st)) {
+ st->target = prev_state;
+ undo_cpu_up(cpu, st);
+ }
break;
}
}
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);
}
if (ret)
return ret;
+ if (fail < CPUHP_OFFLINE || fail > CPUHP_ONLINE)
+ return -EINVAL;
+
/*
* Cannot fail STARTING/DYING callbacks.
*/
kobject_uevent(&dev->kobj, KOBJ_ONLINE);
}
-static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
+int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
{
int cpu, ret = 0;
return ret;
}
-static int cpuhp_smt_enable(void)
+int cpuhp_smt_enable(void)
{
int cpu, ret = 0;
per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE;
}
-enum cpu_mitigations cpu_mitigations __ro_after_init = CPU_MITIGATIONS_AUTO;
+/*
+ * These are used for a global "mitigations=" cmdline option for toggling
+ * optional CPU mitigations.
+ */
+enum cpu_mitigations {
+ CPU_MITIGATIONS_OFF,
+ CPU_MITIGATIONS_AUTO,
+ CPU_MITIGATIONS_AUTO_NOSMT,
+};
+
+static enum cpu_mitigations cpu_mitigations __ro_after_init =
+ CPU_MITIGATIONS_AUTO;
static int __init mitigations_parse_cmdline(char *arg)
{
cpu_mitigations = CPU_MITIGATIONS_AUTO;
else if (!strcmp(arg, "auto,nosmt"))
cpu_mitigations = CPU_MITIGATIONS_AUTO_NOSMT;
+ else
+ pr_crit("Unsupported mitigations=%s, system may still be vulnerable\n",
+ arg);
return 0;
}
early_param("mitigations", mitigations_parse_cmdline);
+
+/* mitigations=off */
+bool cpu_mitigations_off(void)
+{
+ return cpu_mitigations == CPU_MITIGATIONS_OFF;
+}
+EXPORT_SYMBOL_GPL(cpu_mitigations_off);
+
+/* mitigations=auto,nosmt */
+bool cpu_mitigations_auto_nosmt(void)
+{
+ return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT;
+}
+EXPORT_SYMBOL_GPL(cpu_mitigations_auto_nosmt);
projects / mirror_ubuntu-bionic-kernel.git / blobdiff