xref: /openbmc/linux/drivers/acpi/pptt.c (revision ba61bb17)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * pptt.c - parsing of Processor Properties Topology Table (PPTT)
4  *
5  * Copyright (C) 2018, ARM
6  *
7  * This file implements parsing of the Processor Properties Topology Table
8  * which is optionally used to describe the processor and cache topology.
9  * Due to the relative pointers used throughout the table, this doesn't
10  * leverage the existing subtable parsing in the kernel.
11  *
12  * The PPTT structure is an inverted tree, with each node potentially
13  * holding one or two inverted tree data structures describing
14  * the caches available at that level. Each cache structure optionally
15  * contains properties describing the cache at a given level which can be
16  * used to override hardware probed values.
17  */
18 #define pr_fmt(fmt) "ACPI PPTT: " fmt
19 
20 #include <linux/acpi.h>
21 #include <linux/cacheinfo.h>
22 #include <acpi/processor.h>
23 
24 static struct acpi_subtable_header *fetch_pptt_subtable(struct acpi_table_header *table_hdr,
25 							u32 pptt_ref)
26 {
27 	struct acpi_subtable_header *entry;
28 
29 	/* there isn't a subtable at reference 0 */
30 	if (pptt_ref < sizeof(struct acpi_subtable_header))
31 		return NULL;
32 
33 	if (pptt_ref + sizeof(struct acpi_subtable_header) > table_hdr->length)
34 		return NULL;
35 
36 	entry = ACPI_ADD_PTR(struct acpi_subtable_header, table_hdr, pptt_ref);
37 
38 	if (entry->length == 0)
39 		return NULL;
40 
41 	if (pptt_ref + entry->length > table_hdr->length)
42 		return NULL;
43 
44 	return entry;
45 }
46 
47 static struct acpi_pptt_processor *fetch_pptt_node(struct acpi_table_header *table_hdr,
48 						   u32 pptt_ref)
49 {
50 	return (struct acpi_pptt_processor *)fetch_pptt_subtable(table_hdr, pptt_ref);
51 }
52 
53 static struct acpi_pptt_cache *fetch_pptt_cache(struct acpi_table_header *table_hdr,
54 						u32 pptt_ref)
55 {
56 	return (struct acpi_pptt_cache *)fetch_pptt_subtable(table_hdr, pptt_ref);
57 }
58 
59 static struct acpi_subtable_header *acpi_get_pptt_resource(struct acpi_table_header *table_hdr,
60 							   struct acpi_pptt_processor *node,
61 							   int resource)
62 {
63 	u32 *ref;
64 
65 	if (resource >= node->number_of_priv_resources)
66 		return NULL;
67 
68 	ref = ACPI_ADD_PTR(u32, node, sizeof(struct acpi_pptt_processor));
69 	ref += resource;
70 
71 	return fetch_pptt_subtable(table_hdr, *ref);
72 }
73 
74 static inline bool acpi_pptt_match_type(int table_type, int type)
75 {
76 	return ((table_type & ACPI_PPTT_MASK_CACHE_TYPE) == type ||
77 		table_type & ACPI_PPTT_CACHE_TYPE_UNIFIED & type);
78 }
79 
80 /**
81  * acpi_pptt_walk_cache() - Attempt to find the requested acpi_pptt_cache
82  * @table_hdr: Pointer to the head of the PPTT table
83  * @local_level: passed res reflects this cache level
84  * @res: cache resource in the PPTT we want to walk
85  * @found: returns a pointer to the requested level if found
86  * @level: the requested cache level
87  * @type: the requested cache type
88  *
89  * Attempt to find a given cache level, while counting the max number
90  * of cache levels for the cache node.
91  *
92  * Given a pptt resource, verify that it is a cache node, then walk
93  * down each level of caches, counting how many levels are found
94  * as well as checking the cache type (icache, dcache, unified). If a
95  * level & type match, then we set found, and continue the search.
96  * Once the entire cache branch has been walked return its max
97  * depth.
98  *
99  * Return: The cache structure and the level we terminated with.
100  */
101 static int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
102 				int local_level,
103 				struct acpi_subtable_header *res,
104 				struct acpi_pptt_cache **found,
105 				int level, int type)
106 {
107 	struct acpi_pptt_cache *cache;
108 
109 	if (res->type != ACPI_PPTT_TYPE_CACHE)
110 		return 0;
111 
112 	cache = (struct acpi_pptt_cache *) res;
113 	while (cache) {
114 		local_level++;
115 
116 		if (local_level == level &&
117 		    cache->flags & ACPI_PPTT_CACHE_TYPE_VALID &&
118 		    acpi_pptt_match_type(cache->attributes, type)) {
119 			if (*found != NULL && cache != *found)
120 				pr_warn("Found duplicate cache level/type unable to determine uniqueness\n");
121 
122 			pr_debug("Found cache @ level %d\n", level);
123 			*found = cache;
124 			/*
125 			 * continue looking at this node's resource list
126 			 * to verify that we don't find a duplicate
127 			 * cache node.
128 			 */
129 		}
130 		cache = fetch_pptt_cache(table_hdr, cache->next_level_of_cache);
131 	}
132 	return local_level;
133 }
134 
135 static struct acpi_pptt_cache *acpi_find_cache_level(struct acpi_table_header *table_hdr,
136 						     struct acpi_pptt_processor *cpu_node,
137 						     int *starting_level, int level,
138 						     int type)
139 {
140 	struct acpi_subtable_header *res;
141 	int number_of_levels = *starting_level;
142 	int resource = 0;
143 	struct acpi_pptt_cache *ret = NULL;
144 	int local_level;
145 
146 	/* walk down from processor node */
147 	while ((res = acpi_get_pptt_resource(table_hdr, cpu_node, resource))) {
148 		resource++;
149 
150 		local_level = acpi_pptt_walk_cache(table_hdr, *starting_level,
151 						   res, &ret, level, type);
152 		/*
153 		 * we are looking for the max depth. Since its potentially
154 		 * possible for a given node to have resources with differing
155 		 * depths verify that the depth we have found is the largest.
156 		 */
157 		if (number_of_levels < local_level)
158 			number_of_levels = local_level;
159 	}
160 	if (number_of_levels > *starting_level)
161 		*starting_level = number_of_levels;
162 
163 	return ret;
164 }
165 
166 /**
167  * acpi_count_levels() - Given a PPTT table, and a cpu node, count the caches
168  * @table_hdr: Pointer to the head of the PPTT table
169  * @cpu_node: processor node we wish to count caches for
170  *
171  * Given a processor node containing a processing unit, walk into it and count
172  * how many levels exist solely for it, and then walk up each level until we hit
173  * the root node (ignore the package level because it may be possible to have
174  * caches that exist across packages). Count the number of cache levels that
175  * exist at each level on the way up.
176  *
177  * Return: Total number of levels found.
178  */
179 static int acpi_count_levels(struct acpi_table_header *table_hdr,
180 			     struct acpi_pptt_processor *cpu_node)
181 {
182 	int total_levels = 0;
183 
184 	do {
185 		acpi_find_cache_level(table_hdr, cpu_node, &total_levels, 0, 0);
186 		cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
187 	} while (cpu_node);
188 
189 	return total_levels;
190 }
191 
192 /**
193  * acpi_pptt_leaf_node() - Given a processor node, determine if its a leaf
194  * @table_hdr: Pointer to the head of the PPTT table
195  * @node: passed node is checked to see if its a leaf
196  *
197  * Determine if the *node parameter is a leaf node by iterating the
198  * PPTT table, looking for nodes which reference it.
199  *
200  * Return: 0 if we find a node referencing the passed node (or table error),
201  * or 1 if we don't.
202  */
203 static int acpi_pptt_leaf_node(struct acpi_table_header *table_hdr,
204 			       struct acpi_pptt_processor *node)
205 {
206 	struct acpi_subtable_header *entry;
207 	unsigned long table_end;
208 	u32 node_entry;
209 	struct acpi_pptt_processor *cpu_node;
210 	u32 proc_sz;
211 
212 	table_end = (unsigned long)table_hdr + table_hdr->length;
213 	node_entry = ACPI_PTR_DIFF(node, table_hdr);
214 	entry = ACPI_ADD_PTR(struct acpi_subtable_header, table_hdr,
215 			     sizeof(struct acpi_table_pptt));
216 	proc_sz = sizeof(struct acpi_pptt_processor *);
217 
218 	while ((unsigned long)entry + proc_sz < table_end) {
219 		cpu_node = (struct acpi_pptt_processor *)entry;
220 		if (entry->type == ACPI_PPTT_TYPE_PROCESSOR &&
221 		    cpu_node->parent == node_entry)
222 			return 0;
223 		if (entry->length == 0)
224 			return 0;
225 		entry = ACPI_ADD_PTR(struct acpi_subtable_header, entry,
226 				     entry->length);
227 
228 	}
229 	return 1;
230 }
231 
232 /**
233  * acpi_find_processor_node() - Given a PPTT table find the requested processor
234  * @table_hdr:  Pointer to the head of the PPTT table
235  * @acpi_cpu_id: cpu we are searching for
236  *
237  * Find the subtable entry describing the provided processor.
238  * This is done by iterating the PPTT table looking for processor nodes
239  * which have an acpi_processor_id that matches the acpi_cpu_id parameter
240  * passed into the function. If we find a node that matches this criteria
241  * we verify that its a leaf node in the topology rather than depending
242  * on the valid flag, which doesn't need to be set for leaf nodes.
243  *
244  * Return: NULL, or the processors acpi_pptt_processor*
245  */
246 static struct acpi_pptt_processor *acpi_find_processor_node(struct acpi_table_header *table_hdr,
247 							    u32 acpi_cpu_id)
248 {
249 	struct acpi_subtable_header *entry;
250 	unsigned long table_end;
251 	struct acpi_pptt_processor *cpu_node;
252 	u32 proc_sz;
253 
254 	table_end = (unsigned long)table_hdr + table_hdr->length;
255 	entry = ACPI_ADD_PTR(struct acpi_subtable_header, table_hdr,
256 			     sizeof(struct acpi_table_pptt));
257 	proc_sz = sizeof(struct acpi_pptt_processor *);
258 
259 	/* find the processor structure associated with this cpuid */
260 	while ((unsigned long)entry + proc_sz < table_end) {
261 		cpu_node = (struct acpi_pptt_processor *)entry;
262 
263 		if (entry->length == 0) {
264 			pr_warn("Invalid zero length subtable\n");
265 			break;
266 		}
267 		if (entry->type == ACPI_PPTT_TYPE_PROCESSOR &&
268 		    acpi_cpu_id == cpu_node->acpi_processor_id &&
269 		     acpi_pptt_leaf_node(table_hdr, cpu_node)) {
270 			return (struct acpi_pptt_processor *)entry;
271 		}
272 
273 		entry = ACPI_ADD_PTR(struct acpi_subtable_header, entry,
274 				     entry->length);
275 	}
276 
277 	return NULL;
278 }
279 
280 static int acpi_find_cache_levels(struct acpi_table_header *table_hdr,
281 				  u32 acpi_cpu_id)
282 {
283 	int number_of_levels = 0;
284 	struct acpi_pptt_processor *cpu;
285 
286 	cpu = acpi_find_processor_node(table_hdr, acpi_cpu_id);
287 	if (cpu)
288 		number_of_levels = acpi_count_levels(table_hdr, cpu);
289 
290 	return number_of_levels;
291 }
292 
293 static u8 acpi_cache_type(enum cache_type type)
294 {
295 	switch (type) {
296 	case CACHE_TYPE_DATA:
297 		pr_debug("Looking for data cache\n");
298 		return ACPI_PPTT_CACHE_TYPE_DATA;
299 	case CACHE_TYPE_INST:
300 		pr_debug("Looking for instruction cache\n");
301 		return ACPI_PPTT_CACHE_TYPE_INSTR;
302 	default:
303 	case CACHE_TYPE_UNIFIED:
304 		pr_debug("Looking for unified cache\n");
305 		/*
306 		 * It is important that ACPI_PPTT_CACHE_TYPE_UNIFIED
307 		 * contains the bit pattern that will match both
308 		 * ACPI unified bit patterns because we use it later
309 		 * to match both cases.
310 		 */
311 		return ACPI_PPTT_CACHE_TYPE_UNIFIED;
312 	}
313 }
314 
315 static struct acpi_pptt_cache *acpi_find_cache_node(struct acpi_table_header *table_hdr,
316 						    u32 acpi_cpu_id,
317 						    enum cache_type type,
318 						    unsigned int level,
319 						    struct acpi_pptt_processor **node)
320 {
321 	int total_levels = 0;
322 	struct acpi_pptt_cache *found = NULL;
323 	struct acpi_pptt_processor *cpu_node;
324 	u8 acpi_type = acpi_cache_type(type);
325 
326 	pr_debug("Looking for CPU %d's level %d cache type %d\n",
327 		 acpi_cpu_id, level, acpi_type);
328 
329 	cpu_node = acpi_find_processor_node(table_hdr, acpi_cpu_id);
330 
331 	while (cpu_node && !found) {
332 		found = acpi_find_cache_level(table_hdr, cpu_node,
333 					      &total_levels, level, acpi_type);
334 		*node = cpu_node;
335 		cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
336 	}
337 
338 	return found;
339 }
340 
341 /* total number of attributes checked by the properties code */
342 #define PPTT_CHECKED_ATTRIBUTES 4
343 
344 /**
345  * update_cache_properties() - Update cacheinfo for the given processor
346  * @this_leaf: Kernel cache info structure being updated
347  * @found_cache: The PPTT node describing this cache instance
348  * @cpu_node: A unique reference to describe this cache instance
349  *
350  * The ACPI spec implies that the fields in the cache structures are used to
351  * extend and correct the information probed from the hardware. Lets only
352  * set fields that we determine are VALID.
353  *
354  * Return: nothing. Side effect of updating the global cacheinfo
355  */
356 static void update_cache_properties(struct cacheinfo *this_leaf,
357 				    struct acpi_pptt_cache *found_cache,
358 				    struct acpi_pptt_processor *cpu_node)
359 {
360 	int valid_flags = 0;
361 
362 	this_leaf->fw_token = cpu_node;
363 	if (found_cache->flags & ACPI_PPTT_SIZE_PROPERTY_VALID) {
364 		this_leaf->size = found_cache->size;
365 		valid_flags++;
366 	}
367 	if (found_cache->flags & ACPI_PPTT_LINE_SIZE_VALID) {
368 		this_leaf->coherency_line_size = found_cache->line_size;
369 		valid_flags++;
370 	}
371 	if (found_cache->flags & ACPI_PPTT_NUMBER_OF_SETS_VALID) {
372 		this_leaf->number_of_sets = found_cache->number_of_sets;
373 		valid_flags++;
374 	}
375 	if (found_cache->flags & ACPI_PPTT_ASSOCIATIVITY_VALID) {
376 		this_leaf->ways_of_associativity = found_cache->associativity;
377 		valid_flags++;
378 	}
379 	if (found_cache->flags & ACPI_PPTT_WRITE_POLICY_VALID) {
380 		switch (found_cache->attributes & ACPI_PPTT_MASK_WRITE_POLICY) {
381 		case ACPI_PPTT_CACHE_POLICY_WT:
382 			this_leaf->attributes = CACHE_WRITE_THROUGH;
383 			break;
384 		case ACPI_PPTT_CACHE_POLICY_WB:
385 			this_leaf->attributes = CACHE_WRITE_BACK;
386 			break;
387 		}
388 	}
389 	if (found_cache->flags & ACPI_PPTT_ALLOCATION_TYPE_VALID) {
390 		switch (found_cache->attributes & ACPI_PPTT_MASK_ALLOCATION_TYPE) {
391 		case ACPI_PPTT_CACHE_READ_ALLOCATE:
392 			this_leaf->attributes |= CACHE_READ_ALLOCATE;
393 			break;
394 		case ACPI_PPTT_CACHE_WRITE_ALLOCATE:
395 			this_leaf->attributes |= CACHE_WRITE_ALLOCATE;
396 			break;
397 		case ACPI_PPTT_CACHE_RW_ALLOCATE:
398 		case ACPI_PPTT_CACHE_RW_ALLOCATE_ALT:
399 			this_leaf->attributes |=
400 				CACHE_READ_ALLOCATE | CACHE_WRITE_ALLOCATE;
401 			break;
402 		}
403 	}
404 	/*
405 	 * If the above flags are valid, and the cache type is NOCACHE
406 	 * update the cache type as well.
407 	 */
408 	if (this_leaf->type == CACHE_TYPE_NOCACHE &&
409 	    valid_flags == PPTT_CHECKED_ATTRIBUTES)
410 		this_leaf->type = CACHE_TYPE_UNIFIED;
411 }
412 
413 static void cache_setup_acpi_cpu(struct acpi_table_header *table,
414 				 unsigned int cpu)
415 {
416 	struct acpi_pptt_cache *found_cache;
417 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
418 	u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);
419 	struct cacheinfo *this_leaf;
420 	unsigned int index = 0;
421 	struct acpi_pptt_processor *cpu_node = NULL;
422 
423 	while (index < get_cpu_cacheinfo(cpu)->num_leaves) {
424 		this_leaf = this_cpu_ci->info_list + index;
425 		found_cache = acpi_find_cache_node(table, acpi_cpu_id,
426 						   this_leaf->type,
427 						   this_leaf->level,
428 						   &cpu_node);
429 		pr_debug("found = %p %p\n", found_cache, cpu_node);
430 		if (found_cache)
431 			update_cache_properties(this_leaf,
432 						found_cache,
433 						cpu_node);
434 
435 		index++;
436 	}
437 }
438 
439 /* Passing level values greater than this will result in search termination */
440 #define PPTT_ABORT_PACKAGE 0xFF
441 
442 static struct acpi_pptt_processor *acpi_find_processor_package_id(struct acpi_table_header *table_hdr,
443 								  struct acpi_pptt_processor *cpu,
444 								  int level, int flag)
445 {
446 	struct acpi_pptt_processor *prev_node;
447 
448 	while (cpu && level) {
449 		if (cpu->flags & flag)
450 			break;
451 		pr_debug("level %d\n", level);
452 		prev_node = fetch_pptt_node(table_hdr, cpu->parent);
453 		if (prev_node == NULL)
454 			break;
455 		cpu = prev_node;
456 		level--;
457 	}
458 	return cpu;
459 }
460 
461 /**
462  * topology_get_acpi_cpu_tag() - Find a unique topology value for a feature
463  * @table: Pointer to the head of the PPTT table
464  * @cpu: Kernel logical cpu number
465  * @level: A level that terminates the search
466  * @flag: A flag which terminates the search
467  *
468  * Get a unique value given a cpu, and a topology level, that can be
469  * matched to determine which cpus share common topological features
470  * at that level.
471  *
472  * Return: Unique value, or -ENOENT if unable to locate cpu
473  */
474 static int topology_get_acpi_cpu_tag(struct acpi_table_header *table,
475 				     unsigned int cpu, int level, int flag)
476 {
477 	struct acpi_pptt_processor *cpu_node;
478 	u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);
479 
480 	cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
481 	if (cpu_node) {
482 		cpu_node = acpi_find_processor_package_id(table, cpu_node,
483 							  level, flag);
484 		/* Only the first level has a guaranteed id */
485 		if (level == 0)
486 			return cpu_node->acpi_processor_id;
487 		return ACPI_PTR_DIFF(cpu_node, table);
488 	}
489 	pr_warn_once("PPTT table found, but unable to locate core %d (%d)\n",
490 		    cpu, acpi_cpu_id);
491 	return -ENOENT;
492 }
493 
494 static int find_acpi_cpu_topology_tag(unsigned int cpu, int level, int flag)
495 {
496 	struct acpi_table_header *table;
497 	acpi_status status;
498 	int retval;
499 
500 	status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
501 	if (ACPI_FAILURE(status)) {
502 		pr_warn_once("No PPTT table found, cpu topology may be inaccurate\n");
503 		return -ENOENT;
504 	}
505 	retval = topology_get_acpi_cpu_tag(table, cpu, level, flag);
506 	pr_debug("Topology Setup ACPI cpu %d, level %d ret = %d\n",
507 		 cpu, level, retval);
508 	acpi_put_table(table);
509 
510 	return retval;
511 }
512 
513 /**
514  * acpi_find_last_cache_level() - Determines the number of cache levels for a PE
515  * @cpu: Kernel logical cpu number
516  *
517  * Given a logical cpu number, returns the number of levels of cache represented
518  * in the PPTT. Errors caused by lack of a PPTT table, or otherwise, return 0
519  * indicating we didn't find any cache levels.
520  *
521  * Return: Cache levels visible to this core.
522  */
523 int acpi_find_last_cache_level(unsigned int cpu)
524 {
525 	u32 acpi_cpu_id;
526 	struct acpi_table_header *table;
527 	int number_of_levels = 0;
528 	acpi_status status;
529 
530 	pr_debug("Cache Setup find last level cpu=%d\n", cpu);
531 
532 	acpi_cpu_id = get_acpi_id_for_cpu(cpu);
533 	status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
534 	if (ACPI_FAILURE(status)) {
535 		pr_warn_once("No PPTT table found, cache topology may be inaccurate\n");
536 	} else {
537 		number_of_levels = acpi_find_cache_levels(table, acpi_cpu_id);
538 		acpi_put_table(table);
539 	}
540 	pr_debug("Cache Setup find last level level=%d\n", number_of_levels);
541 
542 	return number_of_levels;
543 }
544 
545 /**
546  * cache_setup_acpi() - Override CPU cache topology with data from the PPTT
547  * @cpu: Kernel logical cpu number
548  *
549  * Updates the global cache info provided by cpu_get_cacheinfo()
550  * when there are valid properties in the acpi_pptt_cache nodes. A
551  * successful parse may not result in any updates if none of the
552  * cache levels have any valid flags set.  Futher, a unique value is
553  * associated with each known CPU cache entry. This unique value
554  * can be used to determine whether caches are shared between cpus.
555  *
556  * Return: -ENOENT on failure to find table, or 0 on success
557  */
558 int cache_setup_acpi(unsigned int cpu)
559 {
560 	struct acpi_table_header *table;
561 	acpi_status status;
562 
563 	pr_debug("Cache Setup ACPI cpu %d\n", cpu);
564 
565 	status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
566 	if (ACPI_FAILURE(status)) {
567 		pr_warn_once("No PPTT table found, cache topology may be inaccurate\n");
568 		return -ENOENT;
569 	}
570 
571 	cache_setup_acpi_cpu(table, cpu);
572 	acpi_put_table(table);
573 
574 	return status;
575 }
576 
577 /**
578  * find_acpi_cpu_topology() - Determine a unique topology value for a given cpu
579  * @cpu: Kernel logical cpu number
580  * @level: The topological level for which we would like a unique ID
581  *
582  * Determine a topology unique ID for each thread/core/cluster/mc_grouping
583  * /socket/etc. This ID can then be used to group peers, which will have
584  * matching ids.
585  *
586  * The search terminates when either the requested level is found or
587  * we reach a root node. Levels beyond the termination point will return the
588  * same unique ID. The unique id for level 0 is the acpi processor id. All
589  * other levels beyond this use a generated value to uniquely identify
590  * a topological feature.
591  *
592  * Return: -ENOENT if the PPTT doesn't exist, or the cpu cannot be found.
593  * Otherwise returns a value which represents a unique topological feature.
594  */
595 int find_acpi_cpu_topology(unsigned int cpu, int level)
596 {
597 	return find_acpi_cpu_topology_tag(cpu, level, 0);
598 }
599 
600 /**
601  * find_acpi_cpu_cache_topology() - Determine a unique cache topology value
602  * @cpu: Kernel logical cpu number
603  * @level: The cache level for which we would like a unique ID
604  *
605  * Determine a unique ID for each unified cache in the system
606  *
607  * Return: -ENOENT if the PPTT doesn't exist, or the cpu cannot be found.
608  * Otherwise returns a value which represents a unique topological feature.
609  */
610 int find_acpi_cpu_cache_topology(unsigned int cpu, int level)
611 {
612 	struct acpi_table_header *table;
613 	struct acpi_pptt_cache *found_cache;
614 	acpi_status status;
615 	u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);
616 	struct acpi_pptt_processor *cpu_node = NULL;
617 	int ret = -1;
618 
619 	status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
620 	if (ACPI_FAILURE(status)) {
621 		pr_warn_once("No PPTT table found, topology may be inaccurate\n");
622 		return -ENOENT;
623 	}
624 
625 	found_cache = acpi_find_cache_node(table, acpi_cpu_id,
626 					   CACHE_TYPE_UNIFIED,
627 					   level,
628 					   &cpu_node);
629 	if (found_cache)
630 		ret = ACPI_PTR_DIFF(cpu_node, table);
631 
632 	acpi_put_table(table);
633 
634 	return ret;
635 }
636 
637 
638 /**
639  * find_acpi_cpu_topology_package() - Determine a unique cpu package value
640  * @cpu: Kernel logical cpu number
641  *
642  * Determine a topology unique package ID for the given cpu.
643  * This ID can then be used to group peers, which will have matching ids.
644  *
645  * The search terminates when either a level is found with the PHYSICAL_PACKAGE
646  * flag set or we reach a root node.
647  *
648  * Return: -ENOENT if the PPTT doesn't exist, or the cpu cannot be found.
649  * Otherwise returns a value which represents the package for this cpu.
650  */
651 int find_acpi_cpu_topology_package(unsigned int cpu)
652 {
653 	return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE,
654 					  ACPI_PPTT_PHYSICAL_PACKAGE);
655 }
656