xref: /openbmc/linux/drivers/nvdimm/pfn_devs.c (revision 95b384f9)
1 /*
2  * Copyright(c) 2013-2016 Intel Corporation. All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of version 2 of the GNU General Public License as
6  * published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful, but
9  * WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  */
13 #include <linux/memremap.h>
14 #include <linux/blkdev.h>
15 #include <linux/device.h>
16 #include <linux/genhd.h>
17 #include <linux/sizes.h>
18 #include <linux/slab.h>
19 #include <linux/fs.h>
20 #include <linux/mm.h>
21 #include "nd-core.h"
22 #include "pfn.h"
23 #include "nd.h"
24 
25 static void nd_pfn_release(struct device *dev)
26 {
27 	struct nd_region *nd_region = to_nd_region(dev->parent);
28 	struct nd_pfn *nd_pfn = to_nd_pfn(dev);
29 
30 	dev_dbg(dev, "%s\n", __func__);
31 	nd_detach_ndns(&nd_pfn->dev, &nd_pfn->ndns);
32 	ida_simple_remove(&nd_region->pfn_ida, nd_pfn->id);
33 	kfree(nd_pfn->uuid);
34 	kfree(nd_pfn);
35 }
36 
37 static struct device_type nd_pfn_device_type = {
38 	.name = "nd_pfn",
39 	.release = nd_pfn_release,
40 };
41 
42 bool is_nd_pfn(struct device *dev)
43 {
44 	return dev ? dev->type == &nd_pfn_device_type : false;
45 }
46 EXPORT_SYMBOL(is_nd_pfn);
47 
48 struct nd_pfn *to_nd_pfn(struct device *dev)
49 {
50 	struct nd_pfn *nd_pfn = container_of(dev, struct nd_pfn, dev);
51 
52 	WARN_ON(!is_nd_pfn(dev));
53 	return nd_pfn;
54 }
55 EXPORT_SYMBOL(to_nd_pfn);
56 
57 static ssize_t mode_show(struct device *dev,
58 		struct device_attribute *attr, char *buf)
59 {
60 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
61 
62 	switch (nd_pfn->mode) {
63 	case PFN_MODE_RAM:
64 		return sprintf(buf, "ram\n");
65 	case PFN_MODE_PMEM:
66 		return sprintf(buf, "pmem\n");
67 	default:
68 		return sprintf(buf, "none\n");
69 	}
70 }
71 
72 static ssize_t mode_store(struct device *dev,
73 		struct device_attribute *attr, const char *buf, size_t len)
74 {
75 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
76 	ssize_t rc = 0;
77 
78 	device_lock(dev);
79 	nvdimm_bus_lock(dev);
80 	if (dev->driver)
81 		rc = -EBUSY;
82 	else {
83 		size_t n = len - 1;
84 
85 		if (strncmp(buf, "pmem\n", n) == 0
86 				|| strncmp(buf, "pmem", n) == 0) {
87 			nd_pfn->mode = PFN_MODE_PMEM;
88 		} else if (strncmp(buf, "ram\n", n) == 0
89 				|| strncmp(buf, "ram", n) == 0)
90 			nd_pfn->mode = PFN_MODE_RAM;
91 		else if (strncmp(buf, "none\n", n) == 0
92 				|| strncmp(buf, "none", n) == 0)
93 			nd_pfn->mode = PFN_MODE_NONE;
94 		else
95 			rc = -EINVAL;
96 	}
97 	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
98 			rc, buf, buf[len - 1] == '\n' ? "" : "\n");
99 	nvdimm_bus_unlock(dev);
100 	device_unlock(dev);
101 
102 	return rc ? rc : len;
103 }
104 static DEVICE_ATTR_RW(mode);
105 
106 static ssize_t align_show(struct device *dev,
107 		struct device_attribute *attr, char *buf)
108 {
109 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
110 
111 	return sprintf(buf, "%lx\n", nd_pfn->align);
112 }
113 
114 static ssize_t __align_store(struct nd_pfn *nd_pfn, const char *buf)
115 {
116 	unsigned long val;
117 	int rc;
118 
119 	rc = kstrtoul(buf, 0, &val);
120 	if (rc)
121 		return rc;
122 
123 	if (!is_power_of_2(val) || val < PAGE_SIZE || val > SZ_1G)
124 		return -EINVAL;
125 
126 	if (nd_pfn->dev.driver)
127 		return -EBUSY;
128 	else
129 		nd_pfn->align = val;
130 
131 	return 0;
132 }
133 
134 static ssize_t align_store(struct device *dev,
135 		struct device_attribute *attr, const char *buf, size_t len)
136 {
137 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
138 	ssize_t rc;
139 
140 	device_lock(dev);
141 	nvdimm_bus_lock(dev);
142 	rc = __align_store(nd_pfn, buf);
143 	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
144 			rc, buf, buf[len - 1] == '\n' ? "" : "\n");
145 	nvdimm_bus_unlock(dev);
146 	device_unlock(dev);
147 
148 	return rc ? rc : len;
149 }
150 static DEVICE_ATTR_RW(align);
151 
152 static ssize_t uuid_show(struct device *dev,
153 		struct device_attribute *attr, char *buf)
154 {
155 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
156 
157 	if (nd_pfn->uuid)
158 		return sprintf(buf, "%pUb\n", nd_pfn->uuid);
159 	return sprintf(buf, "\n");
160 }
161 
162 static ssize_t uuid_store(struct device *dev,
163 		struct device_attribute *attr, const char *buf, size_t len)
164 {
165 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
166 	ssize_t rc;
167 
168 	device_lock(dev);
169 	rc = nd_uuid_store(dev, &nd_pfn->uuid, buf, len);
170 	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
171 			rc, buf, buf[len - 1] == '\n' ? "" : "\n");
172 	device_unlock(dev);
173 
174 	return rc ? rc : len;
175 }
176 static DEVICE_ATTR_RW(uuid);
177 
178 static ssize_t namespace_show(struct device *dev,
179 		struct device_attribute *attr, char *buf)
180 {
181 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
182 	ssize_t rc;
183 
184 	nvdimm_bus_lock(dev);
185 	rc = sprintf(buf, "%s\n", nd_pfn->ndns
186 			? dev_name(&nd_pfn->ndns->dev) : "");
187 	nvdimm_bus_unlock(dev);
188 	return rc;
189 }
190 
191 static ssize_t namespace_store(struct device *dev,
192 		struct device_attribute *attr, const char *buf, size_t len)
193 {
194 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
195 	ssize_t rc;
196 
197 	device_lock(dev);
198 	nvdimm_bus_lock(dev);
199 	rc = nd_namespace_store(dev, &nd_pfn->ndns, buf, len);
200 	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
201 			rc, buf, buf[len - 1] == '\n' ? "" : "\n");
202 	nvdimm_bus_unlock(dev);
203 	device_unlock(dev);
204 
205 	return rc;
206 }
207 static DEVICE_ATTR_RW(namespace);
208 
209 static ssize_t resource_show(struct device *dev,
210 		struct device_attribute *attr, char *buf)
211 {
212 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
213 	ssize_t rc;
214 
215 	device_lock(dev);
216 	if (dev->driver) {
217 		struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
218 		u64 offset = __le64_to_cpu(pfn_sb->dataoff);
219 		struct nd_namespace_common *ndns = nd_pfn->ndns;
220 		u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
221 		struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
222 
223 		rc = sprintf(buf, "%#llx\n", (unsigned long long) nsio->res.start
224 				+ start_pad + offset);
225 	} else {
226 		/* no address to convey if the pfn instance is disabled */
227 		rc = -ENXIO;
228 	}
229 	device_unlock(dev);
230 
231 	return rc;
232 }
233 static DEVICE_ATTR_RO(resource);
234 
235 static ssize_t size_show(struct device *dev,
236 		struct device_attribute *attr, char *buf)
237 {
238 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
239 	ssize_t rc;
240 
241 	device_lock(dev);
242 	if (dev->driver) {
243 		struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
244 		u64 offset = __le64_to_cpu(pfn_sb->dataoff);
245 		struct nd_namespace_common *ndns = nd_pfn->ndns;
246 		u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
247 		u32 end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
248 		struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
249 
250 		rc = sprintf(buf, "%llu\n", (unsigned long long)
251 				resource_size(&nsio->res) - start_pad
252 				- end_trunc - offset);
253 	} else {
254 		/* no size to convey if the pfn instance is disabled */
255 		rc = -ENXIO;
256 	}
257 	device_unlock(dev);
258 
259 	return rc;
260 }
261 static DEVICE_ATTR_RO(size);
262 
263 static struct attribute *nd_pfn_attributes[] = {
264 	&dev_attr_mode.attr,
265 	&dev_attr_namespace.attr,
266 	&dev_attr_uuid.attr,
267 	&dev_attr_align.attr,
268 	&dev_attr_resource.attr,
269 	&dev_attr_size.attr,
270 	NULL,
271 };
272 
273 struct attribute_group nd_pfn_attribute_group = {
274 	.attrs = nd_pfn_attributes,
275 };
276 
277 static const struct attribute_group *nd_pfn_attribute_groups[] = {
278 	&nd_pfn_attribute_group,
279 	&nd_device_attribute_group,
280 	&nd_numa_attribute_group,
281 	NULL,
282 };
283 
284 struct device *nd_pfn_devinit(struct nd_pfn *nd_pfn,
285 		struct nd_namespace_common *ndns)
286 {
287 	struct device *dev = &nd_pfn->dev;
288 
289 	if (!nd_pfn)
290 		return NULL;
291 
292 	nd_pfn->mode = PFN_MODE_NONE;
293 	nd_pfn->align = HPAGE_SIZE;
294 	dev = &nd_pfn->dev;
295 	device_initialize(&nd_pfn->dev);
296 	if (ndns && !__nd_attach_ndns(&nd_pfn->dev, ndns, &nd_pfn->ndns)) {
297 		dev_dbg(&ndns->dev, "%s failed, already claimed by %s\n",
298 				__func__, dev_name(ndns->claim));
299 		put_device(dev);
300 		return NULL;
301 	}
302 	return dev;
303 }
304 
305 static struct nd_pfn *nd_pfn_alloc(struct nd_region *nd_region)
306 {
307 	struct nd_pfn *nd_pfn;
308 	struct device *dev;
309 
310 	nd_pfn = kzalloc(sizeof(*nd_pfn), GFP_KERNEL);
311 	if (!nd_pfn)
312 		return NULL;
313 
314 	nd_pfn->id = ida_simple_get(&nd_region->pfn_ida, 0, 0, GFP_KERNEL);
315 	if (nd_pfn->id < 0) {
316 		kfree(nd_pfn);
317 		return NULL;
318 	}
319 
320 	dev = &nd_pfn->dev;
321 	dev_set_name(dev, "pfn%d.%d", nd_region->id, nd_pfn->id);
322 	dev->groups = nd_pfn_attribute_groups;
323 	dev->type = &nd_pfn_device_type;
324 	dev->parent = &nd_region->dev;
325 
326 	return nd_pfn;
327 }
328 
329 struct device *nd_pfn_create(struct nd_region *nd_region)
330 {
331 	struct nd_pfn *nd_pfn;
332 	struct device *dev;
333 
334 	if (!is_nd_pmem(&nd_region->dev))
335 		return NULL;
336 
337 	nd_pfn = nd_pfn_alloc(nd_region);
338 	dev = nd_pfn_devinit(nd_pfn, NULL);
339 
340 	__nd_device_register(dev);
341 	return dev;
342 }
343 
344 int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
345 {
346 	u64 checksum, offset;
347 	struct nd_namespace_io *nsio;
348 	struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
349 	struct nd_namespace_common *ndns = nd_pfn->ndns;
350 	const u8 *parent_uuid = nd_dev_to_uuid(&ndns->dev);
351 
352 	if (!pfn_sb || !ndns)
353 		return -ENODEV;
354 
355 	if (!is_nd_pmem(nd_pfn->dev.parent))
356 		return -ENODEV;
357 
358 	if (nvdimm_read_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb)))
359 		return -ENXIO;
360 
361 	if (memcmp(pfn_sb->signature, sig, PFN_SIG_LEN) != 0)
362 		return -ENODEV;
363 
364 	checksum = le64_to_cpu(pfn_sb->checksum);
365 	pfn_sb->checksum = 0;
366 	if (checksum != nd_sb_checksum((struct nd_gen_sb *) pfn_sb))
367 		return -ENODEV;
368 	pfn_sb->checksum = cpu_to_le64(checksum);
369 
370 	if (memcmp(pfn_sb->parent_uuid, parent_uuid, 16) != 0)
371 		return -ENODEV;
372 
373 	if (__le16_to_cpu(pfn_sb->version_minor) < 1) {
374 		pfn_sb->start_pad = 0;
375 		pfn_sb->end_trunc = 0;
376 	}
377 
378 	if (__le16_to_cpu(pfn_sb->version_minor) < 2)
379 		pfn_sb->align = 0;
380 
381 	switch (le32_to_cpu(pfn_sb->mode)) {
382 	case PFN_MODE_RAM:
383 	case PFN_MODE_PMEM:
384 		break;
385 	default:
386 		return -ENXIO;
387 	}
388 
389 	if (!nd_pfn->uuid) {
390 		/* from probe we allocate */
391 		nd_pfn->uuid = kmemdup(pfn_sb->uuid, 16, GFP_KERNEL);
392 		if (!nd_pfn->uuid)
393 			return -ENOMEM;
394 	} else {
395 		/* from init we validate */
396 		if (memcmp(nd_pfn->uuid, pfn_sb->uuid, 16) != 0)
397 			return -ENODEV;
398 	}
399 
400 	if (nd_pfn->align == 0)
401 		nd_pfn->align = le32_to_cpu(pfn_sb->align);
402 	if (nd_pfn->align > nvdimm_namespace_capacity(ndns)) {
403 		dev_err(&nd_pfn->dev, "alignment: %lx exceeds capacity %llx\n",
404 				nd_pfn->align, nvdimm_namespace_capacity(ndns));
405 		return -EINVAL;
406 	}
407 
408 	/*
409 	 * These warnings are verbose because they can only trigger in
410 	 * the case where the physical address alignment of the
411 	 * namespace has changed since the pfn superblock was
412 	 * established.
413 	 */
414 	offset = le64_to_cpu(pfn_sb->dataoff);
415 	nsio = to_nd_namespace_io(&ndns->dev);
416 	if (offset >= resource_size(&nsio->res)) {
417 		dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s\n",
418 				dev_name(&ndns->dev));
419 		return -EBUSY;
420 	}
421 
422 	if ((nd_pfn->align && !IS_ALIGNED(offset, nd_pfn->align))
423 			|| !IS_ALIGNED(offset, PAGE_SIZE)) {
424 		dev_err(&nd_pfn->dev, "bad offset: %#llx dax disabled\n",
425 				offset);
426 		return -ENXIO;
427 	}
428 
429 	return 0;
430 }
431 EXPORT_SYMBOL(nd_pfn_validate);
432 
433 int nd_pfn_probe(struct device *dev, struct nd_namespace_common *ndns)
434 {
435 	int rc;
436 	struct nd_pfn *nd_pfn;
437 	struct device *pfn_dev;
438 	struct nd_pfn_sb *pfn_sb;
439 	struct nd_region *nd_region = to_nd_region(ndns->dev.parent);
440 
441 	if (ndns->force_raw)
442 		return -ENODEV;
443 
444 	nvdimm_bus_lock(&ndns->dev);
445 	nd_pfn = nd_pfn_alloc(nd_region);
446 	pfn_dev = nd_pfn_devinit(nd_pfn, ndns);
447 	nvdimm_bus_unlock(&ndns->dev);
448 	if (!pfn_dev)
449 		return -ENOMEM;
450 	pfn_sb = devm_kzalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
451 	nd_pfn = to_nd_pfn(pfn_dev);
452 	nd_pfn->pfn_sb = pfn_sb;
453 	rc = nd_pfn_validate(nd_pfn, PFN_SIG);
454 	dev_dbg(dev, "%s: pfn: %s\n", __func__,
455 			rc == 0 ? dev_name(pfn_dev) : "<none>");
456 	if (rc < 0) {
457 		__nd_detach_ndns(pfn_dev, &nd_pfn->ndns);
458 		put_device(pfn_dev);
459 	} else
460 		__nd_device_register(pfn_dev);
461 
462 	return rc;
463 }
464 EXPORT_SYMBOL(nd_pfn_probe);
465 
466 /*
467  * We hotplug memory at section granularity, pad the reserved area from
468  * the previous section base to the namespace base address.
469  */
470 static unsigned long init_altmap_base(resource_size_t base)
471 {
472 	unsigned long base_pfn = PHYS_PFN(base);
473 
474 	return PFN_SECTION_ALIGN_DOWN(base_pfn);
475 }
476 
477 static unsigned long init_altmap_reserve(resource_size_t base)
478 {
479 	unsigned long reserve = PHYS_PFN(SZ_8K);
480 	unsigned long base_pfn = PHYS_PFN(base);
481 
482 	reserve += base_pfn - PFN_SECTION_ALIGN_DOWN(base_pfn);
483 	return reserve;
484 }
485 
486 static struct vmem_altmap *__nvdimm_setup_pfn(struct nd_pfn *nd_pfn,
487 		struct resource *res, struct vmem_altmap *altmap)
488 {
489 	struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
490 	u64 offset = le64_to_cpu(pfn_sb->dataoff);
491 	u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
492 	u32 end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
493 	struct nd_namespace_common *ndns = nd_pfn->ndns;
494 	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
495 	resource_size_t base = nsio->res.start + start_pad;
496 	struct vmem_altmap __altmap = {
497 		.base_pfn = init_altmap_base(base),
498 		.reserve = init_altmap_reserve(base),
499 	};
500 
501 	memcpy(res, &nsio->res, sizeof(*res));
502 	res->start += start_pad;
503 	res->end -= end_trunc;
504 
505 	nd_pfn->mode = le32_to_cpu(nd_pfn->pfn_sb->mode);
506 	if (nd_pfn->mode == PFN_MODE_RAM) {
507 		if (offset < SZ_8K)
508 			return ERR_PTR(-EINVAL);
509 		nd_pfn->npfns = le64_to_cpu(pfn_sb->npfns);
510 		altmap = NULL;
511 	} else if (nd_pfn->mode == PFN_MODE_PMEM) {
512 		nd_pfn->npfns = (resource_size(res) - offset) / PAGE_SIZE;
513 		if (le64_to_cpu(nd_pfn->pfn_sb->npfns) > nd_pfn->npfns)
514 			dev_info(&nd_pfn->dev,
515 					"number of pfns truncated from %lld to %ld\n",
516 					le64_to_cpu(nd_pfn->pfn_sb->npfns),
517 					nd_pfn->npfns);
518 		memcpy(altmap, &__altmap, sizeof(*altmap));
519 		altmap->free = PHYS_PFN(offset - SZ_8K);
520 		altmap->alloc = 0;
521 	} else
522 		return ERR_PTR(-ENXIO);
523 
524 	return altmap;
525 }
526 
527 static int nd_pfn_init(struct nd_pfn *nd_pfn)
528 {
529 	u32 dax_label_reserve = is_nd_dax(&nd_pfn->dev) ? SZ_128K : 0;
530 	struct nd_namespace_common *ndns = nd_pfn->ndns;
531 	u32 start_pad = 0, end_trunc = 0;
532 	resource_size_t start, size;
533 	struct nd_namespace_io *nsio;
534 	struct nd_region *nd_region;
535 	struct nd_pfn_sb *pfn_sb;
536 	unsigned long npfns;
537 	phys_addr_t offset;
538 	const char *sig;
539 	u64 checksum;
540 	int rc;
541 
542 	pfn_sb = devm_kzalloc(&nd_pfn->dev, sizeof(*pfn_sb), GFP_KERNEL);
543 	if (!pfn_sb)
544 		return -ENOMEM;
545 
546 	nd_pfn->pfn_sb = pfn_sb;
547 	if (is_nd_dax(&nd_pfn->dev))
548 		sig = DAX_SIG;
549 	else
550 		sig = PFN_SIG;
551 	rc = nd_pfn_validate(nd_pfn, sig);
552 	if (rc != -ENODEV)
553 		return rc;
554 
555 	/* no info block, do init */;
556 	nd_region = to_nd_region(nd_pfn->dev.parent);
557 	if (nd_region->ro) {
558 		dev_info(&nd_pfn->dev,
559 				"%s is read-only, unable to init metadata\n",
560 				dev_name(&nd_region->dev));
561 		return -ENXIO;
562 	}
563 
564 	memset(pfn_sb, 0, sizeof(*pfn_sb));
565 
566 	/*
567 	 * Check if pmem collides with 'System RAM' when section aligned and
568 	 * trim it accordingly
569 	 */
570 	nsio = to_nd_namespace_io(&ndns->dev);
571 	start = PHYS_SECTION_ALIGN_DOWN(nsio->res.start);
572 	size = resource_size(&nsio->res);
573 	if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
574 				IORES_DESC_NONE) == REGION_MIXED) {
575 		start = nsio->res.start;
576 		start_pad = PHYS_SECTION_ALIGN_UP(start) - start;
577 	}
578 
579 	start = nsio->res.start;
580 	size = PHYS_SECTION_ALIGN_UP(start + size) - start;
581 	if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
582 				IORES_DESC_NONE) == REGION_MIXED) {
583 		size = resource_size(&nsio->res);
584 		end_trunc = start + size - PHYS_SECTION_ALIGN_DOWN(start + size);
585 	}
586 
587 	if (start_pad + end_trunc)
588 		dev_info(&nd_pfn->dev, "%s section collision, truncate %d bytes\n",
589 				dev_name(&ndns->dev), start_pad + end_trunc);
590 
591 	/*
592 	 * Note, we use 64 here for the standard size of struct page,
593 	 * debugging options may cause it to be larger in which case the
594 	 * implementation will limit the pfns advertised through
595 	 * ->direct_access() to those that are included in the memmap.
596 	 */
597 	start += start_pad;
598 	size = resource_size(&nsio->res);
599 	npfns = (size - start_pad - end_trunc - SZ_8K) / SZ_4K;
600 	if (nd_pfn->mode == PFN_MODE_PMEM) {
601 		unsigned long memmap_size;
602 
603 		/*
604 		 * vmemmap_populate_hugepages() allocates the memmap array in
605 		 * HPAGE_SIZE chunks.
606 		 */
607 		memmap_size = ALIGN(64 * npfns, HPAGE_SIZE);
608 		offset = ALIGN(start + SZ_8K + memmap_size + dax_label_reserve,
609 				nd_pfn->align) - start;
610 	} else if (nd_pfn->mode == PFN_MODE_RAM)
611 		offset = ALIGN(start + SZ_8K + dax_label_reserve,
612 				nd_pfn->align) - start;
613 	else
614 		return -ENXIO;
615 
616 	if (offset + start_pad + end_trunc >= size) {
617 		dev_err(&nd_pfn->dev, "%s unable to satisfy requested alignment\n",
618 				dev_name(&ndns->dev));
619 		return -ENXIO;
620 	}
621 
622 	npfns = (size - offset - start_pad - end_trunc) / SZ_4K;
623 	pfn_sb->mode = cpu_to_le32(nd_pfn->mode);
624 	pfn_sb->dataoff = cpu_to_le64(offset);
625 	pfn_sb->npfns = cpu_to_le64(npfns);
626 	memcpy(pfn_sb->signature, sig, PFN_SIG_LEN);
627 	memcpy(pfn_sb->uuid, nd_pfn->uuid, 16);
628 	memcpy(pfn_sb->parent_uuid, nd_dev_to_uuid(&ndns->dev), 16);
629 	pfn_sb->version_major = cpu_to_le16(1);
630 	pfn_sb->version_minor = cpu_to_le16(2);
631 	pfn_sb->start_pad = cpu_to_le32(start_pad);
632 	pfn_sb->end_trunc = cpu_to_le32(end_trunc);
633 	pfn_sb->align = cpu_to_le32(nd_pfn->align);
634 	checksum = nd_sb_checksum((struct nd_gen_sb *) pfn_sb);
635 	pfn_sb->checksum = cpu_to_le64(checksum);
636 
637 	return nvdimm_write_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb));
638 }
639 
640 /*
641  * Determine the effective resource range and vmem_altmap from an nd_pfn
642  * instance.
643  */
644 struct vmem_altmap *nvdimm_setup_pfn(struct nd_pfn *nd_pfn,
645 		struct resource *res, struct vmem_altmap *altmap)
646 {
647 	int rc;
648 
649 	if (!nd_pfn->uuid || !nd_pfn->ndns)
650 		return ERR_PTR(-ENODEV);
651 
652 	rc = nd_pfn_init(nd_pfn);
653 	if (rc)
654 		return ERR_PTR(rc);
655 
656 	/* we need a valid pfn_sb before we can init a vmem_altmap */
657 	return __nvdimm_setup_pfn(nd_pfn, res, altmap);
658 }
659 EXPORT_SYMBOL_GPL(nvdimm_setup_pfn);
660