Power management and ACPI fixes for v4.3-rc6

- Fix a regression introduced by a recent ACPICA cleanup that
    uncovered a latent bug (Lv Zheng).
 
  - Fix a recent regression in the generic power domains framework
    that may cause it to violate PM QoS latency constraints in some
    cases (Ulf Hansson).
 
  - Fix an intel_pstate driver crash on the Knights Landing chips
    that do not update the MPERF counter as often as expected by the
    driver which may result in a divide by 0 (Srinivas Pandruvada).
 
 /
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Merge tag 'pm+acpi-4.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management and ACPI fixes from Rafael Wysocki:
 "These fix two recent regressions (ACPICA, the generic power domains
  framework) and one crash that may happen on specific hardware
  supported since 4.1 (intel_pstate).

  Specifics:

   - Fix a regression introduced by a recent ACPICA cleanup that
     uncovered a latent bug (Lv Zheng).

   - Fix a recent regression in the generic power domains framework that
     may cause it to violate PM QoS latency constraints in some cases
     (Ulf Hansson).

   - Fix an intel_pstate driver crash on the Knights Landing chips that
     do not update the MPERF counter as often as expected by the driver
     which may result in a divide by 0 (Srinivas Pandruvada)"

* tag 'pm+acpi-4.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: intel_pstate: Fix divide by zero on Knights Landing (KNL)
  ACPICA: Tables: Fix FADT dependency regression
  PM / Domains: Fix validation of latency constraints in genpd governor

drivers/acpi/acpica/acglobal.h

@@ -61,6 +61,7 @@ ACPI_GLOBAL(struct acpi_table_header, acpi_gbl_original_dsdt_header);
 ACPI_INIT_GLOBAL(u32, acpi_gbl_dsdt_index, ACPI_INVALID_TABLE_INDEX);
 ACPI_INIT_GLOBAL(u32, acpi_gbl_facs_index, ACPI_INVALID_TABLE_INDEX);
 ACPI_INIT_GLOBAL(u32, acpi_gbl_xfacs_index, ACPI_INVALID_TABLE_INDEX);
+ACPI_INIT_GLOBAL(u32, acpi_gbl_fadt_index, ACPI_INVALID_TABLE_INDEX);
 
 #if (!ACPI_REDUCED_HARDWARE)
 ACPI_GLOBAL(struct acpi_table_facs *, acpi_gbl_FACS);

drivers/acpi/acpica/actables.h

@@ -85,7 +85,7 @@ void acpi_tb_set_table_loaded_flag(u32 table_index, u8 is_loaded);
 /*
  * tbfadt - FADT parse/convert/validate
  */
-void acpi_tb_parse_fadt(u32 table_index);
+void acpi_tb_parse_fadt(void);
 
 void acpi_tb_create_local_fadt(struct acpi_table_header *table, u32 length);
 
@@ -138,8 +138,6 @@ acpi_status acpi_tb_get_owner_id(u32 table_index, acpi_owner_id *owner_id);
  */
 acpi_status acpi_tb_initialize_facs(void);
 
-u8 acpi_tb_tables_loaded(void);
-
 void
 acpi_tb_print_table_header(acpi_physical_address address,
 			   struct acpi_table_header *header);

drivers/acpi/acpica/evxfevnt.c

@@ -71,7 +71,7 @@ acpi_status acpi_enable(void)
 
 	/* ACPI tables must be present */
 
-	if (!acpi_tb_tables_loaded()) {
+	if (acpi_gbl_fadt_index == ACPI_INVALID_TABLE_INDEX) {
 		return_ACPI_STATUS(AE_NO_ACPI_TABLES);
 	}
 

drivers/acpi/acpica/tbfadt.c

@@ -298,7 +298,7 @@ acpi_tb_select_address(char *register_name, u32 address32, u64 address64)
  *
  * FUNCTION:    acpi_tb_parse_fadt
  *
- * PARAMETERS:  table_index         - Index for the FADT
+ * PARAMETERS:  None
  *
  * RETURN:      None
  *
@@ -307,7 +307,7 @@ acpi_tb_select_address(char *register_name, u32 address32, u64 address64)
  *
  ******************************************************************************/
 
-void acpi_tb_parse_fadt(u32 table_index)
+void acpi_tb_parse_fadt(void)
 {
 	u32 length;
 	struct acpi_table_header *table;
@@ -319,11 +319,11 @@ void acpi_tb_parse_fadt(u32 table_index)
 	 * Get a local copy of the FADT and convert it to a common format
 	 * Map entire FADT, assumed to be smaller than one page.
 	 */
-	length = acpi_gbl_root_table_list.tables[table_index].length;
+	length = acpi_gbl_root_table_list.tables[acpi_gbl_fadt_index].length;
 
 	table =
-	    acpi_os_map_memory(acpi_gbl_root_table_list.tables[table_index].
-			       address, length);
+	    acpi_os_map_memory(acpi_gbl_root_table_list.
+			       tables[acpi_gbl_fadt_index].address, length);
 	if (!table) {
 		return;
 	}

drivers/acpi/acpica/tbutils.c

@@ -97,29 +97,6 @@ acpi_status acpi_tb_initialize_facs(void)
 }
 #endif				/* !ACPI_REDUCED_HARDWARE */
 
-/*******************************************************************************
- *
- * FUNCTION:    acpi_tb_tables_loaded
- *
- * PARAMETERS:  None
- *
- * RETURN:      TRUE if required ACPI tables are loaded
- *
- * DESCRIPTION: Determine if the minimum required ACPI tables are present
- *              (FADT, FACS, DSDT)
- *
- ******************************************************************************/
-
-u8 acpi_tb_tables_loaded(void)
-{
-
-	if (acpi_gbl_root_table_list.current_table_count >= 4) {
-		return (TRUE);
-	}
-
-	return (FALSE);
-}
-
 /*******************************************************************************
  *
  * FUNCTION:    acpi_tb_check_dsdt_header
@@ -392,7 +369,8 @@ acpi_status __init acpi_tb_parse_root_table(acpi_physical_address rsdp_address)
 		    ACPI_COMPARE_NAME(&acpi_gbl_root_table_list.
 				      tables[table_index].signature,
 				      ACPI_SIG_FADT)) {
-			acpi_tb_parse_fadt(table_index);
+			acpi_gbl_fadt_index = table_index;
+			acpi_tb_parse_fadt();
 		}
 
 next_table:

drivers/base/power/domain_governor.c

@@ -77,13 +77,16 @@ static bool default_stop_ok(struct device *dev)
 				      dev_update_qos_constraint);
 
 	if (constraint_ns > 0) {
-		constraint_ns -= td->start_latency_ns;
+		constraint_ns -= td->save_state_latency_ns +
+				td->stop_latency_ns +
+				td->start_latency_ns +
+				td->restore_state_latency_ns;
 		if (constraint_ns == 0)
 			return false;
 	}
 	td->effective_constraint_ns = constraint_ns;
-	td->cached_stop_ok = constraint_ns > td->stop_latency_ns ||
-				constraint_ns == 0;
+	td->cached_stop_ok = constraint_ns >= 0;
+
 	/*
 	 * The children have been suspended already, so we don't need to take
 	 * their stop latencies into account here.
@@ -126,18 +129,6 @@ static bool default_power_down_ok(struct dev_pm_domain *pd)
 
 	off_on_time_ns = genpd->power_off_latency_ns +
 				genpd->power_on_latency_ns;
-	/*
-	 * It doesn't make sense to remove power from the domain if saving
-	 * the state of all devices in it and the power off/power on operations
-	 * take too much time.
-	 *
-	 * All devices in this domain have been stopped already at this point.
-	 */
-	list_for_each_entry(pdd, &genpd->dev_list, list_node) {
-		if (pdd->dev->driver)
-			off_on_time_ns +=
-				to_gpd_data(pdd)->td.save_state_latency_ns;
-	}
 
 	min_off_time_ns = -1;
 	/*
@@ -193,7 +184,6 @@ static bool default_power_down_ok(struct dev_pm_domain *pd)
 		 * constraint_ns cannot be negative here, because the device has
 		 * been suspended.
 		 */
-		constraint_ns -= td->restore_state_latency_ns;
 		if (constraint_ns <= off_on_time_ns)
 			return false;
 

drivers/cpufreq/intel_pstate.c

@@ -776,6 +776,11 @@ static inline void intel_pstate_sample(struct cpudata *cpu)
 	local_irq_save(flags);
 	rdmsrl(MSR_IA32_APERF, aperf);
 	rdmsrl(MSR_IA32_MPERF, mperf);
+	if (cpu->prev_mperf == mperf) {
+		local_irq_restore(flags);
+		return;
+	}
+
 	tsc = rdtsc();
 	local_irq_restore(flags);