Merge tag 'pm+acpi-4.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management and ACPI fix from Rafael J. Wysocki:
 "Just one fix for a nasty boot failure on some systems based on Intel
  Skylake that shipped with broken firmware where enabling
  hardware-coordinated P-states management (HWP) causes a faulty
  interrupt handler in SMM to be invoked and crash the system (Srinivas
  Pandruvada)"

* tag 'pm+acpi-4.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI / processor: Request native thermal interrupt handling via _OSC

Author: torvalds

arch/x86/kernel/cpu/mcheck/therm_throt.c

@@ -384,6 +384,9 @@ static void intel_thermal_interrupt(void)
 {
 	__u64 msr_val;
 
+	if (static_cpu_has(X86_FEATURE_HWP))
+		wrmsrl_safe(MSR_HWP_STATUS, 0);
+
 	rdmsrl(MSR_IA32_THERM_STATUS, msr_val);
 
 	/* Check for violation of core thermal thresholds*/

drivers/acpi/acpi_processor.c

@@ -491,6 +491,58 @@ static void acpi_processor_remove(struct acpi_device *device)
 }
 #endif /* CONFIG_ACPI_HOTPLUG_CPU */
 
+#ifdef CONFIG_X86
+static bool acpi_hwp_native_thermal_lvt_set;
+static acpi_status __init acpi_hwp_native_thermal_lvt_osc(acpi_handle handle,
+							  u32 lvl,
+							  void *context,
+							  void **rv)
+{
+	u8 sb_uuid_str[] = "4077A616-290C-47BE-9EBD-D87058713953";
+	u32 capbuf[2];
+	struct acpi_osc_context osc_context = {
+		.uuid_str = sb_uuid_str,
+		.rev = 1,
+		.cap.length = 8,
+		.cap.pointer = capbuf,
+	};
+
+	if (acpi_hwp_native_thermal_lvt_set)
+		return AE_CTRL_TERMINATE;
+
+	capbuf[0] = 0x0000;
+	capbuf[1] = 0x1000; /* set bit 12 */
+
+	if (ACPI_SUCCESS(acpi_run_osc(handle, &osc_context))) {
+		if (osc_context.ret.pointer && osc_context.ret.length > 1) {
+			u32 *capbuf_ret = osc_context.ret.pointer;
+
+			if (capbuf_ret[1] & 0x1000) {
+				acpi_handle_info(handle,
+					"_OSC native thermal LVT Acked\n");
+				acpi_hwp_native_thermal_lvt_set = true;
+			}
+		}
+		kfree(osc_context.ret.pointer);
+	}
+
+	return AE_OK;
+}
+
+void __init acpi_early_processor_osc(void)
+{
+	if (boot_cpu_has(X86_FEATURE_HWP)) {
+		acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
+				    ACPI_UINT32_MAX,
+				    acpi_hwp_native_thermal_lvt_osc,
+				    NULL, NULL, NULL);
+		acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID,
+				 acpi_hwp_native_thermal_lvt_osc,
+				 NULL, NULL);
+	}
+}
+#endif
+
 /*
  * The following ACPI IDs are known to be suitable for representing as
  * processor devices.

drivers/acpi/bus.c

@@ -1019,6 +1019,9 @@ static int __init acpi_bus_init(void)
 		goto error1;
 	}
 
+	/* Set capability bits for _OSC under processor scope */
+	acpi_early_processor_osc();
+
 	/*
 	 * _OSC method may exist in module level code,
 	 * so it must be run after ACPI_FULL_INITIALIZATION

drivers/acpi/internal.h

@@ -145,6 +145,12 @@ void acpi_early_processor_set_pdc(void);
 static inline void acpi_early_processor_set_pdc(void) {}
 #endif
 
+#ifdef CONFIG_X86
+void acpi_early_processor_osc(void);
+#else
+static inline void acpi_early_processor_osc(void) {}
+#endif
+
 /* --------------------------------------------------------------------------
                                   Embedded Controller
    -------------------------------------------------------------------------- */