ACPI / idle: Implement ->enter_freeze callback routine

Add an ->enter_freeze callback routine, acpi_idle_enter_freeze(), to
the ACPI cpuidle driver and point ->enter_freeze to it for all the
C2-type and C3-type states that don't need to fall back to C1
(which may be halt-induced and that will re-enable interrupts on
exit from idle, which ->enter_freeze cannot do).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

1 files changed, 40 insertions, 8 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index c256bd7fbd78..c6bb9f1257c9 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -732,9 +732,8 @@ static int acpi_idle_play_dead(struct cpuidle_device *dev, int index)
 
 static bool acpi_idle_fallback_to_c1(struct acpi_processor *pr)
 {
-        return IS_ENABLED(CONFIG_HOTPLUG_CPU) && num_online_cpus() > 1 &&
-                !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED) &&
-                !pr->flags.has_cst;
+        return IS_ENABLED(CONFIG_HOTPLUG_CPU) && !pr->flags.has_cst &&
+                !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED);
 }
 
 static int c3_cpu_count;
@@ -744,9 +743,10 @@ static DEFINE_RAW_SPINLOCK(c3_lock);
  * acpi_idle_enter_bm - enters C3 with proper BM handling
  * @pr: Target processor
  * @cx: Target state context
+ * @timer_bc: Whether or not to change timer mode to broadcast
  */
 static void acpi_idle_enter_bm(struct acpi_processor *pr,
-                               struct acpi_processor_cx *cx)
+                               struct acpi_processor_cx *cx, bool timer_bc)
 {
         acpi_unlazy_tlb(smp_processor_id());
 
@@ -754,7 +754,8 @@ static void acpi_idle_enter_bm(struct acpi_processor *pr,
          * Must be done before busmaster disable as we might need to
          * access HPET !
          */
-        lapic_timer_state_broadcast(pr, cx, 1);
+        if (timer_bc)
+                lapic_timer_state_broadcast(pr, cx, 1);
 
         /*
          * disable bus master
@@ -784,7 +785,8 @@ static void acpi_idle_enter_bm(struct acpi_processor *pr,
                 raw_spin_unlock(&c3_lock);
         }
 
-        lapic_timer_state_broadcast(pr, cx, 0);
+        if (timer_bc)
+                lapic_timer_state_broadcast(pr, cx, 0);
 }
 
 static int acpi_idle_enter(struct cpuidle_device *dev,
@@ -798,12 +800,12 @@ static int acpi_idle_enter(struct cpuidle_device *dev,
                 return -EINVAL;
 
         if (cx->type != ACPI_STATE_C1) {
-                if (acpi_idle_fallback_to_c1(pr)) {
+                if (acpi_idle_fallback_to_c1(pr) && num_online_cpus() > 1) {
                         index = CPUIDLE_DRIVER_STATE_START;
                         cx = per_cpu(acpi_cstate[index], dev->cpu);
                 } else if (cx->type == ACPI_STATE_C3 && pr->flags.bm_check) {
                         if (cx->bm_sts_skip || !acpi_idle_bm_check()) {
-                                acpi_idle_enter_bm(pr, cx);
+                                acpi_idle_enter_bm(pr, cx, true);
                                 return index;
                         } else if (drv->safe_state_index >= 0) {
                                 index = drv->safe_state_index;
@@ -827,6 +829,27 @@ static int acpi_idle_enter(struct cpuidle_device *dev,
         return index;
 }
 
+static void acpi_idle_enter_freeze(struct cpuidle_device *dev,
+                                   struct cpuidle_driver *drv, int index)
+{
+        struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
+
+        if (cx->type == ACPI_STATE_C3) {
+                struct acpi_processor *pr = __this_cpu_read(processors);
+
+                if (unlikely(!pr))
+                        return;
+
+                if (pr->flags.bm_check) {
+                        acpi_idle_enter_bm(pr, cx, false);
+                        return;
+                } else {
+                        ACPI_FLUSH_CPU_CACHE();
+                }
+        }
+        acpi_idle_do_entry(cx);
+}
+
 struct cpuidle_driver acpi_idle_driver = {
         .name =         "acpi_idle",
         .owner =        THIS_MODULE,
@@ -925,6 +948,15 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
                         state->enter_dead = acpi_idle_play_dead;
                         drv->safe_state_index = count;
                 }
+                /*
+                 * Halt-induced C1 is not good for ->enter_freeze, because it
+                 * re-enables interrupts on exit.  Moreover, C1 is generally not
+                 * particularly interesting from the suspend-to-idle angle, so
+                 * avoid C1 and the situations in which we may need to fall back
+                 * to it altogether.
+                 */
+                if (cx->type != ACPI_STATE_C1 && !acpi_idle_fallback_to_c1(pr))
+                        state->enter_freeze = acpi_idle_enter_freeze;
 
                 count++;
                 if (count == CPUIDLE_STATE_MAX)