Merge branch 'intel-idle-lpi' into linux-next

* intel-idle-lpi:
  intel_idle: Add ACPI _LPI support
  intel_idle: Prepare for adding ACPI _LPI support
  ACPI: processor: idle: Add switch for strict _LPI processing
  ACPI: processor: idle: Relocate acpi_processor_extract_lpi_info()
  ACPI: processor: idle: Introduce acpi_processor_extract_lpi_info()
  ACPI: processor: idle: Introduce too_many_states() for _LPI
  ACPI: processor: idle: Rework flatten_lpi_states()
  ACPI: processor: idle: Rearrange loop in acpi_processor_get_lpi_info()
  ACPI: processor: idle: Drop redundant _LPI presence checks
  ACPI: processor: idle: Rework first-level _LPI states processing
  ACPI: processor: idle: Rearrange acpi_processor_get_lpi_info()
  ACPI: processor: idle: Introduce lpi_state_debug()
  ACPI: processor: idle: Split acpi_processor_evaluate_lpi()
  ACPI: processor: idle: Rearrange acpi_processor_evaluate_lpi()
  ACPI: processor: idle: Unify debug in acpi_processor_evaluate_lpi()
  ACPI: processor: idle: Ignore _LPI states with SYSTEMIO entry method
  ACPI: processor: idle: Expand _LPI package sanity checks

4 files changed, 529 insertions, 302 deletions

diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index 00775b91bd41..5fbab54171b7 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -994,3 +994,357 @@ end:
 }
 EXPORT_SYMBOL_NS_GPL(acpi_processor_evaluate_cst, "ACPI_PROCESSOR_IDLE");
 #endif /* CONFIG_ACPI_PROCESSOR_CSTATE */
+
+#ifdef CONFIG_ACPI_PROCESSOR_IDLE
+struct acpi_lpi_states_array {
+	unsigned int size;
+	unsigned int composite_states_size;
+	struct acpi_lpi_state *entries;
+	struct acpi_lpi_state *composite_states[ACPI_PROCESSOR_MAX_POWER];
+};
+
+static int obj_get_integer(union acpi_object *obj, u32 *value)
+{
+	if (obj->type != ACPI_TYPE_INTEGER)
+		return -EINVAL;
+
+	*value = obj->integer.value;
+	return 0;
+}
+
+#define lpi_state_debug(handle, message, state_idx)	\
+	acpi_handle_debug(handle, message " for _LPI state %u\n", state_idx)
+
+static void process_lpi_state_package(union acpi_object *lpi_pkg,
+				      struct acpi_lpi_state *lpi_state,
+				      acpi_handle handle,
+				      unsigned int state_idx, bool strict)
+{
+	union acpi_object *lpi_pkg_elem, *obj;
+
+	if (lpi_pkg->type != ACPI_TYPE_PACKAGE || lpi_pkg->package.count < 7)
+		return;
+
+	lpi_pkg_elem = lpi_pkg->package.elements;
+
+	/* Get the entry method first and skip the state if that fails. */
+	obj = &lpi_pkg_elem[6];
+	if (obj->type == ACPI_TYPE_BUFFER) {
+		struct acpi_power_register *reg;
+
+		if (obj->buffer.length < sizeof(*reg)) {
+			lpi_state_debug(handle, "Invalid register data", state_idx);
+			return;
+		}
+
+		reg = (struct acpi_power_register *)obj->buffer.pointer;
+		if (reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE) {
+			lpi_state_debug(handle, "Unsupported entry method", state_idx);
+			return;
+		}
+
+		lpi_state->entry_method = ACPI_CSTATE_FFH;
+		lpi_state->address = reg->address;
+	} else if (obj->type == ACPI_TYPE_INTEGER) {
+		lpi_state->entry_method = ACPI_CSTATE_INTEGER;
+		lpi_state->address = obj->integer.value;
+	} else {
+		lpi_state_debug(handle, "Invalid entry method", state_idx);
+		return;
+	}
+
+	if (obj_get_integer(&lpi_pkg_elem[0], &lpi_state->min_residency)) {
+		if (strict) {
+			lpi_state_debug(handle, "No min. residency", state_idx);
+			return;
+		}
+
+		lpi_state_debug(handle, "Assuming 10 us min. residency", state_idx);
+		lpi_state->min_residency = 10;
+	}
+
+	if (obj_get_integer(&lpi_pkg_elem[1], &lpi_state->wake_latency)) {
+		if (strict) {
+			lpi_state_debug(handle, "No wake latency", state_idx);
+			return;
+		}
+
+		lpi_state_debug(handle, "Assuming 10 us wake latency", state_idx);
+		lpi_state->wake_latency = 10;
+	}
+
+	if (obj_get_integer(&lpi_pkg_elem[2], &lpi_state->flags))
+		lpi_state->flags = 0;
+
+	if (obj_get_integer(&lpi_pkg_elem[3], &lpi_state->arch_flags))
+		lpi_state->arch_flags = 0;
+
+	if (obj_get_integer(&lpi_pkg_elem[4], &lpi_state->res_cnt_freq))
+		lpi_state->res_cnt_freq = 1;
+
+	if (obj_get_integer(&lpi_pkg_elem[5], &lpi_state->enable_parent_state))
+		lpi_state->enable_parent_state = 0;
+
+	/* Skip elements [7-8] i.e. Residency/Usage counters. */
+
+	/*
+	 * Avoid out-of-bounds access if the size of the package is less than
+	 * expected.
+	 */
+	if (lpi_pkg->package.count < 10)
+		return;
+
+	obj = &lpi_pkg_elem[9];
+	if (obj->type == ACPI_TYPE_STRING)
+		strscpy(lpi_state->desc, obj->string.pointer, ACPI_CX_DESC_LEN);
+}
+
+static int acpi_processor_evaluate_lpi(acpi_handle handle,
+				       struct acpi_lpi_states_array *info,
+				       bool strict)
+{
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *lpi_data, *lpi_pkg;
+	unsigned int lpi_pkg_count, state_idx;
+	struct acpi_lpi_state *lpi_state;
+	acpi_status status;
+	int ret = 0;
+
+	status = acpi_evaluate_object(handle, "_LPI", NULL, &buffer);
+	if (ACPI_FAILURE(status)) {
+		acpi_handle_debug(handle, "No _LPI, giving up\n");
+		return -ENODEV;
+	}
+
+	lpi_data = buffer.pointer;
+
+	/* There must be at least 4 elements = 3 elements + 1 package */
+	if (!lpi_data || lpi_data->type != ACPI_TYPE_PACKAGE ||
+	    lpi_data->package.count < 4) {
+		acpi_handle_debug(handle, "Not enough elements in _LPI\n");
+		ret = -ENODATA;
+		goto end;
+	}
+
+	lpi_pkg_count = lpi_data->package.elements[2].integer.value;
+
+	/* Validate number of power states. */
+	if (!lpi_pkg_count || lpi_pkg_count != lpi_data->package.count - 3) {
+		acpi_handle_debug(handle, "Invalid _LPI state count\n");
+		ret = -ENODATA;
+		goto end;
+	}
+
+	lpi_state = kzalloc_objs(*lpi_state, lpi_pkg_count);
+	if (!lpi_state) {
+		ret = -ENOMEM;
+		goto end;
+	}
+
+	info->size = lpi_pkg_count;
+	info->entries = lpi_state;
+
+	/* _LPI State packages start at index 3. */
+	lpi_pkg = &lpi_data->package.elements[3];
+
+	for (state_idx = 1; state_idx <= lpi_pkg_count; state_idx++) {
+		lpi_state->index = state_idx;
+		process_lpi_state_package(lpi_pkg++, lpi_state++, handle,
+					  state_idx, strict);
+	}
+
+	acpi_handle_debug(handle, "Found %u power states\n", lpi_pkg_count);
+end:
+	kfree(buffer.pointer);
+	return ret;
+}
+
+/**
+ * combine_lpi_states - combine local and parent LPI states to form a composite LPI state
+ *
+ * @local: local LPI state
+ * @parent: parent LPI state
+ * @result: composite LPI state
+ */
+static bool combine_lpi_states(struct acpi_lpi_state *local,
+			       struct acpi_lpi_state *parent,
+			       struct acpi_lpi_state *result)
+{
+	if (parent->entry_method == ACPI_CSTATE_INTEGER) {
+		if (!parent->address) /* 0 means autopromotable */
+			return false;
+		result->address = local->address + parent->address;
+	} else {
+		result->address = parent->address;
+	}
+
+	result->min_residency = max(local->min_residency, parent->min_residency);
+	result->wake_latency = local->wake_latency + parent->wake_latency;
+	result->enable_parent_state = parent->enable_parent_state;
+	result->entry_method = local->entry_method;
+
+	result->flags = parent->flags;
+	result->arch_flags = parent->arch_flags;
+	result->index = parent->index;
+
+	scnprintf(result->desc, ACPI_CX_DESC_LEN, "%s+%s", local->desc, parent->desc);
+	return true;
+}
+
+#define ACPI_LPI_STATE_FLAGS_ENABLED			BIT(0)
+
+static void stash_composite_state(struct acpi_lpi_states_array *curr_level,
+				  struct acpi_lpi_state *t)
+{
+	curr_level->composite_states[curr_level->composite_states_size++] = t;
+}
+
+static bool too_many_states(acpi_handle handle, unsigned int state_count)
+{
+	if (state_count < ACPI_PROCESSOR_MAX_POWER)
+		return false;
+
+	acpi_handle_info(handle, "No space for more _LPI states than %d\n",
+			 ACPI_PROCESSOR_MAX_POWER);
+	return true;
+}
+
+static unsigned int flatten_lpi_states(acpi_handle handle,
+				       struct acpi_lpi_state *lpi_states,
+				       unsigned int state_count,
+				       struct acpi_lpi_states_array *curr,
+				       struct acpi_lpi_states_array *prev)
+{
+	struct acpi_lpi_state *parent_lpi = curr->entries;
+	unsigned int j;
+
+	/*
+	 * Combine each of the "raw" _LPI states from the current (processor
+	 * container) level with all of the composite _LPI states from the
+	 * previous (processor or processor container) level.
+	 */
+	for (j = 0; j < curr->size; j++, parent_lpi++) {
+		struct acpi_lpi_state *flpi;
+		int i;
+
+		if (!(parent_lpi->flags & ACPI_LPI_STATE_FLAGS_ENABLED))
+			continue;
+
+		if (too_many_states(handle, state_count))
+			break;
+
+		flpi = &lpi_states[state_count];
+
+		for (i = 0; i < prev->composite_states_size; i++) {
+			struct acpi_lpi_state *local_lpi = prev->composite_states[i];
+
+			if (parent_lpi->index > local_lpi->enable_parent_state)
+				continue;
+
+			if (!combine_lpi_states(local_lpi, parent_lpi, flpi))
+				continue;
+
+			stash_composite_state(curr, flpi);
+			state_count++;
+			flpi++;
+
+			if (state_count >= ACPI_PROCESSOR_MAX_POWER)
+				break;
+		}
+	}
+
+	return state_count;
+}
+
+int acpi_processor_extract_lpi_info(acpi_handle pr_handle,
+				    struct acpi_processor_power *pr_power,
+				    bool strict)
+{
+	struct acpi_lpi_states_array info[2], *prev, *curr;
+	acpi_handle handle = pr_handle;
+	unsigned int state_count = 0;
+	unsigned int i;
+	int ret;
+
+	if (!osc_pc_lpi_support_confirmed)
+		return -EOPNOTSUPP;
+
+	curr = &info[0];
+	curr->composite_states_size = 0;
+
+	ret = acpi_processor_evaluate_lpi(handle, curr, strict);
+	if (ret)
+		return ret;
+
+	/* Copy all of the usable first-level states to power.lpi_states[]. */
+	for (i = 0; i < curr->size; i++) {
+		struct acpi_lpi_state *lpi = &curr->entries[i];
+		struct acpi_lpi_state *flpi;
+
+		/*
+		 * Skip states that are not enabled or have an inadequate entry
+		 * method for this level.
+		 */
+		if (!(lpi->flags & ACPI_LPI_STATE_FLAGS_ENABLED) ||
+		    lpi->entry_method == ACPI_CSTATE_INTEGER)
+			continue;
+
+		if (too_many_states(pr_handle, state_count))
+			break;
+
+		flpi = &pr_power->lpi_states[state_count++];
+		memcpy(flpi, lpi, sizeof(*lpi));
+		stash_composite_state(curr, flpi);
+	}
+
+	kfree(curr->entries);
+
+	/*
+	 * If there are no _LPI states at the first level, there are no _LPI
+	 * states at all.
+	 */
+	if (!state_count)
+		return -ENODATA;
+
+	prev = curr;
+	curr = &info[1];
+
+	for (;;) {
+		struct acpi_lpi_states_array *tmp;
+		struct acpi_device *d;
+
+		if (ACPI_FAILURE(acpi_get_parent(handle, &handle)))
+			break;
+
+		d = acpi_fetch_acpi_dev(handle);
+		if (!d)
+			break;
+
+		if (strcmp(acpi_device_hid(d), ACPI_PROCESSOR_CONTAINER_HID))
+			break;
+
+		curr->composite_states_size = 0;
+
+		ret = acpi_processor_evaluate_lpi(handle, curr, strict);
+		if (ret)
+			break;
+
+		/* flatten all the LPI states in this level of hierarchy */
+		state_count = flatten_lpi_states(pr_handle, pr_power->lpi_states,
+						 state_count, curr, prev);
+
+		kfree(curr->entries);
+
+		tmp = prev, prev = curr, curr = tmp;
+	}
+
+	/* reset the index after flattening */
+	for (i = 0; i < state_count; i++)
+		pr_power->lpi_states[i].index = i;
+
+	pr_power->count = state_count;
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(acpi_processor_extract_lpi_info, "ACPI_PROCESSOR_IDLE");
+#endif /* CONFIG_ACPI_PROCESSOR_IDLE */
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 4482cf28f56a..e113bcbbb882 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -853,223 +853,6 @@ static int acpi_processor_setup_cstates(struct acpi_processor *pr)
 
 #endif /* CONFIG_ACPI_PROCESSOR_CSTATE */
 
-struct acpi_lpi_states_array {
-	unsigned int size;
-	unsigned int composite_states_size;
-	struct acpi_lpi_state *entries;
-	struct acpi_lpi_state *composite_states[ACPI_PROCESSOR_MAX_POWER];
-};
-
-static int obj_get_integer(union acpi_object *obj, u32 *value)
-{
-	if (obj->type != ACPI_TYPE_INTEGER)
-		return -EINVAL;
-
-	*value = obj->integer.value;
-	return 0;
-}
-
-static int acpi_processor_evaluate_lpi(acpi_handle handle,
-				       struct acpi_lpi_states_array *info)
-{
-	acpi_status status;
-	int ret = 0;
-	int pkg_count, state_idx = 1, loop;
-	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
-	union acpi_object *lpi_data;
-	struct acpi_lpi_state *lpi_state;
-
-	status = acpi_evaluate_object(handle, "_LPI", NULL, &buffer);
-	if (ACPI_FAILURE(status)) {
-		acpi_handle_debug(handle, "No _LPI, giving up\n");
-		return -ENODEV;
-	}
-
-	lpi_data = buffer.pointer;
-
-	/* There must be at least 4 elements = 3 elements + 1 package */
-	if (!lpi_data || lpi_data->type != ACPI_TYPE_PACKAGE ||
-	    lpi_data->package.count < 4) {
-		pr_debug("not enough elements in _LPI\n");
-		ret = -ENODATA;
-		goto end;
-	}
-
-	pkg_count = lpi_data->package.elements[2].integer.value;
-
-	/* Validate number of power states. */
-	if (pkg_count < 1 || pkg_count != lpi_data->package.count - 3) {
-		pr_debug("count given by _LPI is not valid\n");
-		ret = -ENODATA;
-		goto end;
-	}
-
-	lpi_state = kzalloc_objs(*lpi_state, pkg_count);
-	if (!lpi_state) {
-		ret = -ENOMEM;
-		goto end;
-	}
-
-	info->size = pkg_count;
-	info->entries = lpi_state;
-
-	/* LPI States start at index 3 */
-	for (loop = 3; state_idx <= pkg_count; loop++, state_idx++, lpi_state++) {
-		union acpi_object *element, *pkg_elem, *obj;
-
-		element = &lpi_data->package.elements[loop];
-		if (element->type != ACPI_TYPE_PACKAGE || element->package.count < 7)
-			continue;
-
-		pkg_elem = element->package.elements;
-
-		obj = pkg_elem + 6;
-		if (obj->type == ACPI_TYPE_BUFFER) {
-			struct acpi_power_register *reg;
-
-			reg = (struct acpi_power_register *)obj->buffer.pointer;
-			if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO &&
-			    reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE)
-				continue;
-
-			lpi_state->address = reg->address;
-			lpi_state->entry_method =
-				reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE ?
-				ACPI_CSTATE_FFH : ACPI_CSTATE_SYSTEMIO;
-		} else if (obj->type == ACPI_TYPE_INTEGER) {
-			lpi_state->entry_method = ACPI_CSTATE_INTEGER;
-			lpi_state->address = obj->integer.value;
-		} else {
-			pr_debug("Entry method of state-%d is invalid, disable it.\n",
-				 state_idx);
-			continue;
-		}
-
-		/* elements[7,8] skipped for now i.e. Residency/Usage counter*/
-
-		obj = pkg_elem + 9;
-		if (obj->type == ACPI_TYPE_STRING)
-			strscpy(lpi_state->desc, obj->string.pointer,
-				ACPI_CX_DESC_LEN);
-
-		lpi_state->index = state_idx;
-		if (obj_get_integer(pkg_elem + 0, &lpi_state->min_residency)) {
-			pr_debug("No min. residency found, assuming 10 us\n");
-			lpi_state->min_residency = 10;
-		}
-
-		if (obj_get_integer(pkg_elem + 1, &lpi_state->wake_latency)) {
-			pr_debug("No wakeup residency found, assuming 10 us\n");
-			lpi_state->wake_latency = 10;
-		}
-
-		if (obj_get_integer(pkg_elem + 2, &lpi_state->flags))
-			lpi_state->flags = 0;
-
-		if (obj_get_integer(pkg_elem + 3, &lpi_state->arch_flags))
-			lpi_state->arch_flags = 0;
-
-		if (obj_get_integer(pkg_elem + 4, &lpi_state->res_cnt_freq))
-			lpi_state->res_cnt_freq = 1;
-
-		if (obj_get_integer(pkg_elem + 5, &lpi_state->enable_parent_state))
-			lpi_state->enable_parent_state = 0;
-	}
-
-	acpi_handle_debug(handle, "Found %d power states\n", state_idx);
-end:
-	kfree(buffer.pointer);
-	return ret;
-}
-
-/**
- * combine_lpi_states - combine local and parent LPI states to form a composite LPI state
- *
- * @local: local LPI state
- * @parent: parent LPI state
- * @result: composite LPI state
- */
-static bool combine_lpi_states(struct acpi_lpi_state *local,
-			       struct acpi_lpi_state *parent,
-			       struct acpi_lpi_state *result)
-{
-	if (parent->entry_method == ACPI_CSTATE_INTEGER) {
-		if (!parent->address) /* 0 means autopromotable */
-			return false;
-		result->address = local->address + parent->address;
-	} else {
-		result->address = parent->address;
-	}
-
-	result->min_residency = max(local->min_residency, parent->min_residency);
-	result->wake_latency = local->wake_latency + parent->wake_latency;
-	result->enable_parent_state = parent->enable_parent_state;
-	result->entry_method = local->entry_method;
-
-	result->flags = parent->flags;
-	result->arch_flags = parent->arch_flags;
-	result->index = parent->index;
-
-	scnprintf(result->desc, ACPI_CX_DESC_LEN, "%s+%s", local->desc, parent->desc);
-	return true;
-}
-
-#define ACPI_LPI_STATE_FLAGS_ENABLED			BIT(0)
-
-static void stash_composite_state(struct acpi_lpi_states_array *curr_level,
-				  struct acpi_lpi_state *t)
-{
-	curr_level->composite_states[curr_level->composite_states_size++] = t;
-}
-
-static unsigned int flatten_lpi_states(struct acpi_processor *pr,
-				       unsigned int flat_state_cnt,
-				       struct acpi_lpi_states_array *curr_level,
-				       struct acpi_lpi_states_array *prev_level)
-{
-	int i, j, state_count = curr_level->size;
-	struct acpi_lpi_state *p, *t = curr_level->entries;
-
-	curr_level->composite_states_size = 0;
-	for (j = 0; j < state_count; j++, t++) {
-		struct acpi_lpi_state *flpi;
-
-		if (!(t->flags & ACPI_LPI_STATE_FLAGS_ENABLED))
-			continue;
-
-		if (flat_state_cnt >= ACPI_PROCESSOR_MAX_POWER) {
-			pr_warn("Limiting number of LPI states to max (%d)\n",
-				ACPI_PROCESSOR_MAX_POWER);
-			pr_warn("Please increase ACPI_PROCESSOR_MAX_POWER if needed.\n");
-			break;
-		}
-
-		flpi = &pr->power.lpi_states[flat_state_cnt];
-
-		if (!prev_level) { /* leaf/processor node */
-			memcpy(flpi, t, sizeof(*t));
-			stash_composite_state(curr_level, flpi);
-			flat_state_cnt++;
-			continue;
-		}
-
-		for (i = 0; i < prev_level->composite_states_size; i++) {
-			p = prev_level->composite_states[i];
-			if (t->index <= p->enable_parent_state &&
-			    combine_lpi_states(p, t, flpi)) {
-				stash_composite_state(curr_level, flpi);
-				flat_state_cnt++;
-				flpi++;
-				if (flat_state_cnt >= ACPI_PROCESSOR_MAX_POWER)
-					break;
-			}
-		}
-	}
-
-	kfree(curr_level->entries);
-	return flat_state_cnt;
-}
-
 int __weak acpi_processor_ffh_lpi_probe(unsigned int cpu)
 {
 	return -EOPNOTSUPP;
@@ -1077,64 +860,16 @@ int __weak acpi_processor_ffh_lpi_probe(unsigned int cpu)
 
 static int acpi_processor_get_lpi_info(struct acpi_processor *pr)
 {
-	int ret, i;
-	acpi_status status;
-	acpi_handle handle = pr->handle, pr_ahandle;
-	struct acpi_device *d = NULL;
-	struct acpi_lpi_states_array info[2], *tmp, *prev, *curr;
-	unsigned int state_count;
+	int ret;
 
 	/* make sure our architecture has support */
 	ret = acpi_processor_ffh_lpi_probe(pr->id);
 	if (ret == -EOPNOTSUPP)
 		return ret;
 
-	if (!osc_pc_lpi_support_confirmed)
-		return -EOPNOTSUPP;
-
-	if (!acpi_has_method(handle, "_LPI"))
-		return -EINVAL;
-
-	prev = &info[0];
-	curr = &info[1];
-	handle = pr->handle;
-	ret = acpi_processor_evaluate_lpi(handle, prev);
+	ret = acpi_processor_extract_lpi_info(pr->handle, &pr->power, false);
 	if (ret)
 		return ret;
-	state_count = flatten_lpi_states(pr, 0, prev, NULL);
-
-	status = acpi_get_parent(handle, &pr_ahandle);
-	while (ACPI_SUCCESS(status)) {
-		d = acpi_fetch_acpi_dev(pr_ahandle);
-		if (!d)
-			break;
-
-		handle = pr_ahandle;
-
-		if (strcmp(acpi_device_hid(d), ACPI_PROCESSOR_CONTAINER_HID))
-			break;
-
-		/* can be optional ? */
-		if (!acpi_has_method(handle, "_LPI"))
-			break;
-
-		ret = acpi_processor_evaluate_lpi(handle, curr);
-		if (ret)
-			break;
-
-		/* flatten all the LPI states in this level of hierarchy */
-		state_count = flatten_lpi_states(pr, state_count, curr, prev);
-
-		tmp = prev, prev = curr, curr = tmp;
-
-		status = acpi_get_parent(handle, &pr_ahandle);
-	}
-
-	/* reset the index after flattening */
-	for (i = 0; i < state_count; i++)
-		pr->power.lpi_states[i].index = i;
-
-	pr->power.count = state_count;
 
 	/* Tell driver that _LPI is supported. */
 	pr->flags.has_lpi = 1;
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index d74b478db280..bcc2725769c5 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -1779,6 +1779,7 @@ module_param_named(no_native, no_native, bool, 0444);
 MODULE_PARM_DESC(no_native, "Ignore cpu specific (native) idle states in lieu of ACPI idle states");
 
 static struct acpi_processor_power acpi_state_table __initdata;
+static bool acpi_lpi_available __initdata;
 
 /**
  * intel_idle_cst_usable - Check if the _CST information can be used.
@@ -1803,18 +1804,37 @@ static bool __init intel_idle_cst_usable(void)
 	return true;
 }
 
-static bool __init intel_idle_acpi_cst_extract(void)
+static bool __init intel_idle_acpi_extract_lpi_cstates(void)
 {
 	unsigned int cpu;
 
-	if (no_acpi) {
-		pr_debug("Not allowed to use ACPI _CST\n");
-		return false;
+	for_each_possible_cpu(cpu) {
+		struct acpi_processor *pr;
+
+		pr = per_cpu(processors, cpu);
+		if (!pr)
+			continue;
+
+		if (acpi_processor_extract_lpi_info(pr->handle,
+						    &acpi_state_table, true))
+			continue;
+
+		acpi_lpi_available = true;
+		return true;
 	}
 
+	pr_debug("No ACPI _LPI idle states\n");
+	return false;
+}
+
+static bool __init intel_idle_acpi_extract_cst_cstates(void)
+{
+	unsigned int cpu;
+
 	for_each_possible_cpu(cpu) {
-		struct acpi_processor *pr = per_cpu(processors, cpu);
+		struct acpi_processor *pr;
 
+		pr = per_cpu(processors, cpu);
 		if (!pr)
 			continue;
 
@@ -1826,18 +1846,96 @@ static bool __init intel_idle_acpi_cst_extract(void)
 		if (!intel_idle_cst_usable())
 			continue;
 
-		if (!acpi_processor_claim_cst_control())
-			break;
+		return true;
+	}
+
+	pr_debug("ACPI _CST not found or not usable\n");
+	return false;
+}
+
+static bool __init intel_idle_acpi_extract_cstates(void)
+{
+	if (intel_idle_acpi_extract_lpi_cstates())
+		return true;
 
+	if (intel_idle_acpi_extract_cst_cstates())
 		return true;
+
+	return false;
+}
+
+static bool __init intel_idle_acpi_probe(void)
+{
+	if (no_acpi) {
+		pr_debug("Not allowed to use ACPI for C-states extraction\n");
+		return false;
 	}
 
+	if (intel_idle_acpi_extract_cstates() &&
+	    acpi_processor_claim_cst_control())
+		return true;
+
 	acpi_state_table.count = 0;
-	pr_debug("ACPI _CST not found or not usable\n");
 	return false;
 }
 
-static void __init intel_idle_init_cstates_acpi(struct cpuidle_driver *drv)
+static void __init intel_idle_complete_state_init(struct cpuidle_state *state)
+{
+	if (intel_idle_state_needs_timer_stop(state))
+		state->flags |= CPUIDLE_FLAG_TIMER_STOP;
+
+	state->enter = intel_idle;
+	state->enter_dead = intel_idle_enter_dead;
+	state->enter_s2idle = intel_idle_s2idle;
+}
+
+static void __init intel_idle_init_cstates_acpi_lpi(struct cpuidle_driver *drv)
+{
+	int index;
+
+	for (index = 0; index < acpi_state_table.count; index++) {
+		struct acpi_lpi_state *lpi_state;
+		struct cpuidle_state *state;
+
+		if (intel_idle_max_cstate_reached(index))
+			break;
+
+		lpi_state = &acpi_state_table.lpi_states[index];
+
+		state = &drv->states[drv->state_count++];
+
+		scnprintf(state->name, CPUIDLE_NAME_LEN, "C%d_LPI", index + 1);
+		strscpy(state->desc, lpi_state->desc, CPUIDLE_DESC_LEN);
+		state->exit_latency = lpi_state->wake_latency;
+		state->target_residency = lpi_state->min_residency;
+		state->flags = MWAIT2flg(lpi_state->address);
+		/*
+		 * Assume that entering any of the idle states extracted from
+		 * _LPI except for the first two will cause the TLB to be
+		 * flushed and let the core call leave_mm() for them upfront
+		 * to avoid unnecessary wakeups due to TLB shootdowns.
+		 */
+		if (index > 1)
+			state->flags |= CPUIDLE_FLAG_TLB_FLUSHED;
+
+		if (disabled_states_mask & BIT(index + 1))
+			state->flags |= CPUIDLE_FLAG_OFF;
+
+		intel_idle_complete_state_init(state);
+
+		pr_info("%s: MWAIT hint 0x%x\n", state->name, flg2MWAIT(state->flags));
+	}
+
+	/*
+	 * Assume the first idle state in the table to be C1 and if any deeper
+	 * idle states are exposed while X86_FEATURE_NONSTOP_TSC is unset, mark
+	 * the TSC as unstable.
+	 */
+	if (index > 1 && !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
+		mark_tsc_unstable("TSC halts in idle");
+}
+
+static void __init intel_idle_init_cstates_acpi_cst(struct cpuidle_driver *drv)
 {
 	int cstate, limit = min_t(int, CPUIDLE_STATE_MAX, acpi_state_table.count);
 
@@ -1879,49 +1977,76 @@ static void __init intel_idle_init_cstates_acpi(struct cpuidle_driver *drv)
 		if (disabled_states_mask & BIT(cstate))
 			state->flags |= CPUIDLE_FLAG_OFF;
 
-		if (intel_idle_state_needs_timer_stop(state))
-			state->flags |= CPUIDLE_FLAG_TIMER_STOP;
-
 		if (cx->type > ACPI_STATE_C1 && !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 			mark_tsc_unstable("TSC halts in idle");
 
-		state->enter = intel_idle;
-		state->enter_dead = intel_idle_enter_dead;
-		state->enter_s2idle = intel_idle_s2idle;
+		intel_idle_complete_state_init(state);
 	}
 }
 
-static bool __init intel_idle_off_by_default(unsigned int flags, u32 mwait_hint)
+static void __init intel_idle_init_cstates_acpi(struct cpuidle_driver *drv)
 {
-	int cstate, limit;
+	if (acpi_lpi_available)
+		intel_idle_init_cstates_acpi_lpi(drv);
+	else
+		intel_idle_init_cstates_acpi_cst(drv);
+}
 
-	/*
-	 * If there are no _CST C-states, do not disable any C-states by
-	 * default.
-	 */
-	if (!acpi_state_table.count)
-		return false;
+static bool __init intel_idle_acpi_hint_match(unsigned int flags, u32 acpi_hint,
+					      u32 table_hint)
+{
+	if (flags & CPUIDLE_FLAG_PARTIAL_HINT_MATCH) {
+		acpi_hint &= ~MWAIT_SUBSTATE_MASK;
+		table_hint &= ~MWAIT_SUBSTATE_MASK;
+	}
+	return acpi_hint == table_hint;
+}
+
+static bool __init intel_idle_off_by_default_lpi(unsigned int flags, u32 mwait_hint)
+{
+	int index;
+
+	for (index = 0; index < acpi_state_table.count; index++) {
+		u32 acpi_hint = acpi_state_table.lpi_states[index].address;
+
+		if (intel_idle_acpi_hint_match(flags, acpi_hint, mwait_hint))
+			return false;
+	}
+	return true;
+}
+
+static bool __init intel_idle_off_by_default_cst(unsigned int flags, u32 mwait_hint)
+{
+	int cstate, limit = min_t(int, CPUIDLE_STATE_MAX, acpi_state_table.count);
 
-	limit = min_t(int, CPUIDLE_STATE_MAX, acpi_state_table.count);
 	/*
 	 * If limit > 0, intel_idle_cst_usable() has returned 'true', so all of
 	 * the interesting states are ACPI_CSTATE_FFH.
 	 */
 	for (cstate = 1; cstate < limit; cstate++) {
 		u32 acpi_hint = acpi_state_table.states[cstate].address;
-		u32 table_hint = mwait_hint;
 
-		if (flags & CPUIDLE_FLAG_PARTIAL_HINT_MATCH) {
-			acpi_hint &= ~MWAIT_SUBSTATE_MASK;
-			table_hint &= ~MWAIT_SUBSTATE_MASK;
-		}
-
-		if (acpi_hint == table_hint)
+		if (intel_idle_acpi_hint_match(flags, acpi_hint, mwait_hint))
 			return false;
 	}
 	return true;
 }
 
+static bool __init intel_idle_off_by_default(unsigned int flags, u32 mwait_hint)
+{
+	/*
+	 * If there is no C-states information in the ACPI tables, do not
+	 * disable any C-states by default.
+	 */
+	if (!acpi_state_table.count)
+		return false;
+
+	if (acpi_lpi_available)
+		return intel_idle_off_by_default_lpi(flags, mwait_hint);
+
+	return intel_idle_off_by_default_cst(flags, mwait_hint);
+}
+
 static inline bool ignore_native(void)
 {
 	return no_native && !no_acpi;
@@ -1929,7 +2054,7 @@ static inline bool ignore_native(void)
 #else /* !CONFIG_ACPI_PROCESSOR_CSTATE */
 #define force_use_acpi	(false)
 
-static inline bool intel_idle_acpi_cst_extract(void) { return false; }
+static inline bool intel_idle_acpi_probe(void) { return false; }
 static inline void intel_idle_init_cstates_acpi(struct cpuidle_driver *drv) { }
 static inline bool intel_idle_off_by_default(unsigned int flags, u32 mwait_hint)
 {
@@ -2741,7 +2866,7 @@ static int __init intel_idle_init(void)
 	if (icpu) {
 		if (icpu->state_table)
 			cpuidle_state_table = icpu->state_table;
-		else if (!intel_idle_acpi_cst_extract())
+		else if (!intel_idle_acpi_probe())
 			return -ENODEV;
 
 		auto_demotion_disable_flags = icpu->auto_demotion_disable_flags;
@@ -2750,8 +2875,8 @@ static int __init intel_idle_init(void)
 		if (icpu->c1_demotion_supported)
 			c1_demotion_supported = true;
 		if (icpu->use_acpi || force_use_acpi)
-			intel_idle_acpi_cst_extract();
-	} else if (!intel_idle_acpi_cst_extract()) {
+			intel_idle_acpi_probe();
+	} else if (!intel_idle_acpi_probe()) {
 		return -ENODEV;
 	}
 
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 899dc00b4b01..8d20a25f1a62 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -321,6 +321,19 @@ static inline int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu,
 }
 #endif
 
+#ifdef CONFIG_ACPI_PROCESSOR_IDLE
+int acpi_processor_extract_lpi_info(acpi_handle pr_handle,
+				    struct acpi_processor_power *pr_power,
+				    bool strict);
+#else
+static inline int acpi_processor_extract_lpi_info(acpi_handle pr_handle,
+				    struct acpi_processor_power *pr_power,
+				    bool strict)
+{
+	return -ENODEV;
+}
+#endif
+
 #ifdef CONFIG_ACPI_HOTPLUG_CPU
 /* Arch dependent functions for cpu hotplug support */
 int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, u32 acpi_id,