1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 5b6a9865300e..83fd1b6c10c4 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -280,6 +280,16 @@ static void acpi_processor_idle(void)
 
         cx->usage++;
 
+#ifdef CONFIG_HOTPLUG_CPU
+        /*
+         * Check for P_LVL2_UP flag before entering C2 and above on
+         * an SMP system. We do it here instead of doing it at _CST/P_LVL
+         * detection phase, to work cleanly with logical CPU hotplug.
+         */
+        if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) && 
+            !pr->flags.has_cst && acpi_fadt.plvl2_up)
+                cx->type = ACPI_STATE_C1;
+#endif
         /*
          * Sleep:
          * ------
@@ -534,6 +544,15 @@ static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
         pr->power.states[ACPI_STATE_C0].valid = 1;
         pr->power.states[ACPI_STATE_C1].valid = 1;
 
+#ifndef CONFIG_HOTPLUG_CPU
+        /*
+         * Check for P_LVL2_UP flag before entering C2 and above on
+         * an SMP system. 
+         */
+        if ((num_online_cpus() > 1) && acpi_fadt.plvl2_up)
+                return_VALUE(-ENODEV);
+#endif
+
         /* determine C2 and C3 address from pblk */
         pr->power.states[ACPI_STATE_C2].address = pr->pblk + 4;
         pr->power.states[ACPI_STATE_C3].address = pr->pblk + 5;