summaryrefslogtreecommitdiff
path: root/drivers/dax/device.c
blob: 8465d12fecba9d3b06c3116ebd7614697becf409 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2016-2018 Intel Corporation. All rights reserved. */
#include <linux/memremap.h>
#include <linux/pagemap.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/pfn_t.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/dax.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include "dax-private.h"
#include "bus.h"

static struct dev_dax *ref_to_dev_dax(struct percpu_ref *ref)
{
	return container_of(ref, struct dev_dax, ref);
}

static void dev_dax_percpu_release(struct percpu_ref *ref)
{
	struct dev_dax *dev_dax = ref_to_dev_dax(ref);

	dev_dbg(&dev_dax->dev, "%s\n", __func__);
	complete(&dev_dax->cmp);
}

static void dev_dax_percpu_exit(struct percpu_ref *ref)
{
	struct dev_dax *dev_dax = ref_to_dev_dax(ref);

	dev_dbg(&dev_dax->dev, "%s\n", __func__);
	wait_for_completion(&dev_dax->cmp);
	percpu_ref_exit(ref);
}

static void dev_dax_percpu_kill(struct percpu_ref *data)
{
	struct percpu_ref *ref = data;
	struct dev_dax *dev_dax = ref_to_dev_dax(ref);

	dev_dbg(&dev_dax->dev, "%s\n", __func__);
	percpu_ref_kill(ref);
}

static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
		const char *func)
{
	struct dax_region *dax_region = dev_dax->region;
	struct device *dev = &dev_dax->dev;
	unsigned long mask;

	if (!dax_alive(dev_dax->dax_dev))
		return -ENXIO;

	/* prevent private mappings from being established */
	if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
		dev_info_ratelimited(dev,
				"%s: %s: fail, attempted private mapping\n",
				current->comm, func);
		return -EINVAL;
	}

	mask = dax_region->align - 1;
	if (vma->vm_start & mask || vma->vm_end & mask) {
		dev_info_ratelimited(dev,
				"%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
				current->comm, func, vma->vm_start, vma->vm_end,
				mask);
		return -EINVAL;
	}

	if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
			&& (vma->vm_flags & VM_DONTCOPY) == 0) {
		dev_info_ratelimited(dev,
				"%s: %s: fail, dax range requires MADV_DONTFORK\n",
				current->comm, func);
		return -EINVAL;
	}

	if (!vma_is_dax(vma)) {
		dev_info_ratelimited(dev,
				"%s: %s: fail, vma is not DAX capable\n",
				current->comm, func);
		return -EINVAL;
	}

	return 0;
}

/* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
__weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
		unsigned long size)
{
	struct resource *res = &dev_dax->region->res;
	phys_addr_t phys;

	phys = pgoff * PAGE_SIZE + res->start;
	if (phys >= res->start && phys <= res->end) {
		if (phys + size - 1 <= res->end)
			return phys;
	}

	return -1;
}

static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
				struct vm_fault *vmf, pfn_t *pfn)
{
	struct device *dev = &dev_dax->dev;
	struct dax_region *dax_region;
	phys_addr_t phys;
	unsigned int fault_size = PAGE_SIZE;

	if (check_vma(dev_dax, vmf->vma, __func__))
		return VM_FAULT_SIGBUS;

	dax_region = dev_dax->region;
	if (dax_region->align > PAGE_SIZE) {
		dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
			dax_region->align, fault_size);
		return VM_FAULT_SIGBUS;
	}

	if (fault_size != dax_region->align)
		return VM_FAULT_SIGBUS;

	phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
	if (phys == -1) {
		dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", vmf->pgoff);
		return VM_FAULT_SIGBUS;
	}

	*pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);

	return vmf_insert_mixed(vmf->vma, vmf->address, *pfn);
}

static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
				struct vm_fault *vmf, pfn_t *pfn)
{
	unsigned long pmd_addr = vmf->address & PMD_MASK;
	struct device *dev = &dev_dax->dev;
	struct dax_region *dax_region;
	phys_addr_t phys;
	pgoff_t pgoff;
	unsigned int fault_size = PMD_SIZE;

	if (check_vma(dev_dax, vmf->vma, __func__))
		return VM_FAULT_SIGBUS;

	dax_region = dev_dax->region;
	if (dax_region->align > PMD_SIZE) {
		dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
			dax_region->align, fault_size);
		return VM_FAULT_SIGBUS;
	}

	/* dax pmd mappings require pfn_t_devmap() */
	if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
		dev_dbg(dev, "region lacks devmap flags\n");
		return VM_FAULT_SIGBUS;
	}

	if (fault_size < dax_region->align)
		return VM_FAULT_SIGBUS;
	else if (fault_size > dax_region->align)
		return VM_FAULT_FALLBACK;

	/* if we are outside of the VMA */
	if (pmd_addr < vmf->vma->vm_start ||
			(pmd_addr + PMD_SIZE) > vmf->vma->vm_end)
		return VM_FAULT_SIGBUS;

	pgoff = linear_page_index(vmf->vma, pmd_addr);
	phys = dax_pgoff_to_phys(dev_dax, pgoff, PMD_SIZE);
	if (phys == -1) {
		dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
		return VM_FAULT_SIGBUS;
	}

	*pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);

	return vmf_insert_pfn_pmd(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
}

#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
				struct vm_fault *vmf, pfn_t *pfn)
{
	unsigned long pud_addr = vmf->address & PUD_MASK;
	struct device *dev = &dev_dax->dev;
	struct dax_region *dax_region;
	phys_addr_t phys;
	pgoff_t pgoff;
	unsigned int fault_size = PUD_SIZE;


	if (check_vma(dev_dax, vmf->vma, __func__))
		return VM_FAULT_SIGBUS;

	dax_region = dev_dax->region;
	if (dax_region->align > PUD_SIZE) {
		dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
			dax_region->align, fault_size);
		return VM_FAULT_SIGBUS;
	}

	/* dax pud mappings require pfn_t_devmap() */
	if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
		dev_dbg(dev, "region lacks devmap flags\n");
		return VM_FAULT_SIGBUS;
	}

	if (fault_size < dax_region->align)
		return VM_FAULT_SIGBUS;
	else if (fault_size > dax_region->align)
		return VM_FAULT_FALLBACK;

	/* if we are outside of the VMA */
	if (pud_addr < vmf->vma->vm_start ||
			(pud_addr + PUD_SIZE) > vmf->vma->vm_end)
		return VM_FAULT_SIGBUS;

	pgoff = linear_page_index(vmf->vma, pud_addr);
	phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
	if (phys == -1) {
		dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
		return VM_FAULT_SIGBUS;
	}

	*pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);

	return vmf_insert_pfn_pud(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
}
#else
static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
				struct vm_fault *vmf, pfn_t *pfn)
{
	return VM_FAULT_FALLBACK;
}
#endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */

static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
		enum page_entry_size pe_size)
{
	struct file *filp = vmf->vma->vm_file;
	unsigned long fault_size;
	vm_fault_t rc = VM_FAULT_SIGBUS;
	int id;
	pfn_t pfn;
	struct dev_dax *dev_dax = filp->private_data;

	dev_dbg(&dev_dax->dev, "%s: %s (%#lx - %#lx) size = %d\n", current->comm,
			(vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read",
			vmf->vma->vm_start, vmf->vma->vm_end, pe_size);

	id = dax_read_lock();
	switch (pe_size) {
	case PE_SIZE_PTE:
		fault_size = PAGE_SIZE;
		rc = __dev_dax_pte_fault(dev_dax, vmf, &pfn);
		break;
	case PE_SIZE_PMD:
		fault_size = PMD_SIZE;
		rc = __dev_dax_pmd_fault(dev_dax, vmf, &pfn);
		break;
	case PE_SIZE_PUD:
		fault_size = PUD_SIZE;
		rc = __dev_dax_pud_fault(dev_dax, vmf, &pfn);
		break;
	default:
		rc = VM_FAULT_SIGBUS;
	}

	if (rc == VM_FAULT_NOPAGE) {
		unsigned long i;
		pgoff_t pgoff;

		/*
		 * In the device-dax case the only possibility for a
		 * VM_FAULT_NOPAGE result is when device-dax capacity is
		 * mapped. No need to consider the zero page, or racing
		 * conflicting mappings.
		 */
		pgoff = linear_page_index(vmf->vma, vmf->address
				& ~(fault_size - 1));
		for (i = 0; i < fault_size / PAGE_SIZE; i++) {
			struct page *page;

			page = pfn_to_page(pfn_t_to_pfn(pfn) + i);
			if (page->mapping)
				continue;
			page->mapping = filp->f_mapping;
			page->index = pgoff + i;
		}
	}
	dax_read_unlock(id);

	return rc;
}

static vm_fault_t dev_dax_fault(struct vm_fault *vmf)
{
	return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
}

static int dev_dax_split(struct vm_area_struct *vma, unsigned long addr)
{
	struct file *filp = vma->vm_file;
	struct dev_dax *dev_dax = filp->private_data;
	struct dax_region *dax_region = dev_dax->region;

	if (!IS_ALIGNED(addr, dax_region->align))
		return -EINVAL;
	return 0;
}

static unsigned long dev_dax_pagesize(struct vm_area_struct *vma)
{
	struct file *filp = vma->vm_file;
	struct dev_dax *dev_dax = filp->private_data;
	struct dax_region *dax_region = dev_dax->region;

	return dax_region->align;
}

static const struct vm_operations_struct dax_vm_ops = {
	.fault = dev_dax_fault,
	.huge_fault = dev_dax_huge_fault,
	.split = dev_dax_split,
	.pagesize = dev_dax_pagesize,
};

static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
{
	struct dev_dax *dev_dax = filp->private_data;
	int rc, id;

	dev_dbg(&dev_dax->dev, "trace\n");

	/*
	 * We lock to check dax_dev liveness and will re-check at
	 * fault time.
	 */
	id = dax_read_lock();
	rc = check_vma(dev_dax, vma, __func__);
	dax_read_unlock(id);
	if (rc)
		return rc;

	vma->vm_ops = &dax_vm_ops;
	vma->vm_flags |= VM_HUGEPAGE;
	return 0;
}

/* return an unmapped area aligned to the dax region specified alignment */
static unsigned long dax_get_unmapped_area(struct file *filp,
		unsigned long addr, unsigned long len, unsigned long pgoff,
		unsigned long flags)
{
	unsigned long off, off_end, off_align, len_align, addr_align, align;
	struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
	struct dax_region *dax_region;

	if (!dev_dax || addr)
		goto out;

	dax_region = dev_dax->region;
	align = dax_region->align;
	off = pgoff << PAGE_SHIFT;
	off_end = off + len;
	off_align = round_up(off, align);

	if ((off_end <= off_align) || ((off_end - off_align) < align))
		goto out;

	len_align = len + align;
	if ((off + len_align) < off)
		goto out;

	addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
			pgoff, flags);
	if (!IS_ERR_VALUE(addr_align)) {
		addr_align += (off - addr_align) & (align - 1);
		return addr_align;
	}
 out:
	return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
}

static const struct address_space_operations dev_dax_aops = {
	.set_page_dirty		= noop_set_page_dirty,
	.invalidatepage		= noop_invalidatepage,
};

static int dax_open(struct inode *inode, struct file *filp)
{
	struct dax_device *dax_dev = inode_dax(inode);
	struct inode *__dax_inode = dax_inode(dax_dev);
	struct dev_dax *dev_dax = dax_get_private(dax_dev);

	dev_dbg(&dev_dax->dev, "trace\n");
	inode->i_mapping = __dax_inode->i_mapping;
	inode->i_mapping->host = __dax_inode;
	inode->i_mapping->a_ops = &dev_dax_aops;
	filp->f_mapping = inode->i_mapping;
	filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
	filp->private_data = dev_dax;
	inode->i_flags = S_DAX;

	return 0;
}

static int dax_release(struct inode *inode, struct file *filp)
{
	struct dev_dax *dev_dax = filp->private_data;

	dev_dbg(&dev_dax->dev, "trace\n");
	return 0;
}

static const struct file_operations dax_fops = {
	.llseek = noop_llseek,
	.owner = THIS_MODULE,
	.open = dax_open,
	.release = dax_release,
	.get_unmapped_area = dax_get_unmapped_area,
	.mmap = dax_mmap,
	.mmap_supported_flags = MAP_SYNC,
};

static void dev_dax_cdev_del(void *cdev)
{
	cdev_del(cdev);
}

static void dev_dax_kill(void *dev_dax)
{
	kill_dev_dax(dev_dax);
}

int dev_dax_probe(struct device *dev)
{
	struct dev_dax *dev_dax = to_dev_dax(dev);
	struct dax_device *dax_dev = dev_dax->dax_dev;
	struct resource *res = &dev_dax->region->res;
	struct inode *inode;
	struct cdev *cdev;
	void *addr;
	int rc;

	/* 1:1 map region resource range to device-dax instance range */
	if (!devm_request_mem_region(dev, res->start, resource_size(res),
				dev_name(dev))) {
		dev_warn(dev, "could not reserve region %pR\n", res);
		return -EBUSY;
	}

	init_completion(&dev_dax->cmp);
	rc = percpu_ref_init(&dev_dax->ref, dev_dax_percpu_release, 0,
			GFP_KERNEL);
	if (rc)
		return rc;

	dev_dax->pgmap.ref = &dev_dax->ref;
	dev_dax->pgmap.kill = dev_dax_percpu_kill;
	dev_dax->pgmap.cleanup = dev_dax_percpu_exit;
	addr = devm_memremap_pages(dev, &dev_dax->pgmap);
	if (IS_ERR(addr))
		return PTR_ERR(addr);

	inode = dax_inode(dax_dev);
	cdev = inode->i_cdev;
	cdev_init(cdev, &dax_fops);
	if (dev->class) {
		/* for the CONFIG_DEV_DAX_PMEM_COMPAT case */
		cdev->owner = dev->parent->driver->owner;
	} else
		cdev->owner = dev->driver->owner;
	cdev_set_parent(cdev, &dev->kobj);
	rc = cdev_add(cdev, dev->devt, 1);
	if (rc)
		return rc;

	rc = devm_add_action_or_reset(dev, dev_dax_cdev_del, cdev);
	if (rc)
		return rc;

	run_dax(dax_dev);
	return devm_add_action_or_reset(dev, dev_dax_kill, dev_dax);
}
EXPORT_SYMBOL_GPL(dev_dax_probe);

static int dev_dax_remove(struct device *dev)
{
	/* all probe actions are unwound by devm */
	return 0;
}

static struct dax_device_driver device_dax_driver = {
	.drv = {
		.probe = dev_dax_probe,
		.remove = dev_dax_remove,
	},
	.match_always = 1,
};

static int __init dax_init(void)
{
	return dax_driver_register(&device_dax_driver);
}

static void __exit dax_exit(void)
{
	dax_driver_unregister(&device_dax_driver);
}

MODULE_AUTHOR("Intel Corporation");
MODULE_LICENSE("GPL v2");
module_init(dax_init);
module_exit(dax_exit);
MODULE_ALIAS_DAX_DEVICE(0);