On Mon, 7 Nov 2016, Ville Syrjälä wrote:
> I didn't manage to find a lot of time to play around with this, but it
> definitely looks like the SMM trap is the problem here. I repeated my
> pm_trace experiemnts and when it gets stuck it is trying to execute the
> _WAK ACPI method which is where the SMM trap happens.
> 
> Maybe the SMM code was written with the expectation of a periodic tick
> or something like that?

Can you try the untested hack below, please? It should confirm that.

Thanks,

	tglx

8<---------------
--- a/drivers/acpi/acpica/hwsleep.c
+++ b/drivers/acpi/acpica/hwsleep.c
@@ -269,6 +269,17 @@ acpi_status acpi_hw_legacy_wake_prep(u8
 	return_ACPI_STATUS(status);
 }
 
+static const ktime_t time10ms = { .tv64 = 10 * NSEC_PER_MSEC };
+
+static enum hrtimer_restart acpi_hw_legacy_tmr(struct hrtimer *tmr)
+{
+	hrtimer_forward_now(tmr, time10ms);
+
+	return HRTIMER_RESTART;
+}
+
+
+
 /*******************************************************************************
  *
  * FUNCTION:    acpi_hw_legacy_wake
@@ -284,6 +295,7 @@ acpi_status acpi_hw_legacy_wake_prep(u8
 
 acpi_status acpi_hw_legacy_wake(u8 sleep_state)
 {
+	struct hrtimer timer;
 	acpi_status status;
 
 	ACPI_FUNCTION_TRACE(hw_legacy_wake);
@@ -311,12 +323,18 @@ acpi_status acpi_hw_legacy_wake(u8 sleep
 		return_ACPI_STATUS(status);
 	}
 
+	hrtimer_init_on_stack(&timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	timer.function = acpi_hw_legacy_tmr;
+	hrtimer_start(&timer, time10ms, HRTIMER_MODE_REL);
+
 	/*
 	 * Now we can execute _WAK, etc. Some machines require that the GPEs
 	 * are enabled before the wake methods are executed.
 	 */
 	acpi_hw_execute_sleep_method(METHOD_PATHNAME__WAK, sleep_state);
 
+	hrtimer_cancel(&timer);
+
 	/*
 	 * Some BIOS code assumes that WAK_STS will be cleared on resume
 	 * and use it to determine whether the system is rebooting or