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1 /*
2  * Copyright IBM Corp. 2012
3  *
4  * Author(s):
5  *   Jan Glauber <jang@linux.vnet.ibm.com>
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/slab.h>
10 #include <linux/export.h>
11 #include <linux/iommu-helper.h>
12 #include <linux/dma-mapping.h>
13 #include <linux/vmalloc.h>
14 #include <linux/pci.h>
15 #include <asm/pci_dma.h>
16 
17 static struct kmem_cache *dma_region_table_cache;
18 static struct kmem_cache *dma_page_table_cache;
19 static int s390_iommu_strict;
20 
zpci_refresh_global(struct zpci_dev * zdev)21 static int zpci_refresh_global(struct zpci_dev *zdev)
22 {
23 	return zpci_refresh_trans((u64) zdev->fh << 32, zdev->start_dma,
24 				  zdev->iommu_pages * PAGE_SIZE);
25 }
26 
dma_alloc_cpu_table(void)27 unsigned long *dma_alloc_cpu_table(void)
28 {
29 	unsigned long *table, *entry;
30 
31 	table = kmem_cache_alloc(dma_region_table_cache, GFP_ATOMIC);
32 	if (!table)
33 		return NULL;
34 
35 	for (entry = table; entry < table + ZPCI_TABLE_ENTRIES; entry++)
36 		*entry = ZPCI_TABLE_INVALID;
37 	return table;
38 }
39 
dma_free_cpu_table(void * table)40 static void dma_free_cpu_table(void *table)
41 {
42 	kmem_cache_free(dma_region_table_cache, table);
43 }
44 
dma_alloc_page_table(void)45 static unsigned long *dma_alloc_page_table(void)
46 {
47 	unsigned long *table, *entry;
48 
49 	table = kmem_cache_alloc(dma_page_table_cache, GFP_ATOMIC);
50 	if (!table)
51 		return NULL;
52 
53 	for (entry = table; entry < table + ZPCI_PT_ENTRIES; entry++)
54 		*entry = ZPCI_PTE_INVALID;
55 	return table;
56 }
57 
dma_free_page_table(void * table)58 static void dma_free_page_table(void *table)
59 {
60 	kmem_cache_free(dma_page_table_cache, table);
61 }
62 
dma_get_seg_table_origin(unsigned long * entry)63 static unsigned long *dma_get_seg_table_origin(unsigned long *entry)
64 {
65 	unsigned long *sto;
66 
67 	if (reg_entry_isvalid(*entry))
68 		sto = get_rt_sto(*entry);
69 	else {
70 		sto = dma_alloc_cpu_table();
71 		if (!sto)
72 			return NULL;
73 
74 		set_rt_sto(entry, sto);
75 		validate_rt_entry(entry);
76 		entry_clr_protected(entry);
77 	}
78 	return sto;
79 }
80 
dma_get_page_table_origin(unsigned long * entry)81 static unsigned long *dma_get_page_table_origin(unsigned long *entry)
82 {
83 	unsigned long *pto;
84 
85 	if (reg_entry_isvalid(*entry))
86 		pto = get_st_pto(*entry);
87 	else {
88 		pto = dma_alloc_page_table();
89 		if (!pto)
90 			return NULL;
91 		set_st_pto(entry, pto);
92 		validate_st_entry(entry);
93 		entry_clr_protected(entry);
94 	}
95 	return pto;
96 }
97 
dma_walk_cpu_trans(unsigned long * rto,dma_addr_t dma_addr)98 unsigned long *dma_walk_cpu_trans(unsigned long *rto, dma_addr_t dma_addr)
99 {
100 	unsigned long *sto, *pto;
101 	unsigned int rtx, sx, px;
102 
103 	rtx = calc_rtx(dma_addr);
104 	sto = dma_get_seg_table_origin(&rto[rtx]);
105 	if (!sto)
106 		return NULL;
107 
108 	sx = calc_sx(dma_addr);
109 	pto = dma_get_page_table_origin(&sto[sx]);
110 	if (!pto)
111 		return NULL;
112 
113 	px = calc_px(dma_addr);
114 	return &pto[px];
115 }
116 
dma_update_cpu_trans(unsigned long * entry,void * page_addr,int flags)117 void dma_update_cpu_trans(unsigned long *entry, void *page_addr, int flags)
118 {
119 	if (flags & ZPCI_PTE_INVALID) {
120 		invalidate_pt_entry(entry);
121 	} else {
122 		set_pt_pfaa(entry, page_addr);
123 		validate_pt_entry(entry);
124 	}
125 
126 	if (flags & ZPCI_TABLE_PROTECTED)
127 		entry_set_protected(entry);
128 	else
129 		entry_clr_protected(entry);
130 }
131 
dma_update_trans(struct zpci_dev * zdev,unsigned long pa,dma_addr_t dma_addr,size_t size,int flags)132 static int dma_update_trans(struct zpci_dev *zdev, unsigned long pa,
133 			    dma_addr_t dma_addr, size_t size, int flags)
134 {
135 	unsigned int nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
136 	u8 *page_addr = (u8 *) (pa & PAGE_MASK);
137 	dma_addr_t start_dma_addr = dma_addr;
138 	unsigned long irq_flags;
139 	unsigned long *entry;
140 	int i, rc = 0;
141 
142 	if (!nr_pages)
143 		return -EINVAL;
144 
145 	spin_lock_irqsave(&zdev->dma_table_lock, irq_flags);
146 	if (!zdev->dma_table) {
147 		rc = -EINVAL;
148 		goto no_refresh;
149 	}
150 
151 	for (i = 0; i < nr_pages; i++) {
152 		entry = dma_walk_cpu_trans(zdev->dma_table, dma_addr);
153 		if (!entry) {
154 			rc = -ENOMEM;
155 			goto undo_cpu_trans;
156 		}
157 		dma_update_cpu_trans(entry, page_addr, flags);
158 		page_addr += PAGE_SIZE;
159 		dma_addr += PAGE_SIZE;
160 	}
161 
162 	/*
163 	 * With zdev->tlb_refresh == 0, rpcit is not required to establish new
164 	 * translations when previously invalid translation-table entries are
165 	 * validated. With lazy unmap, it also is skipped for previously valid
166 	 * entries, but a global rpcit is then required before any address can
167 	 * be re-used, i.e. after each iommu bitmap wrap-around.
168 	 */
169 	if (!zdev->tlb_refresh &&
170 			(!s390_iommu_strict ||
171 			((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID)))
172 		goto no_refresh;
173 
174 	rc = zpci_refresh_trans((u64) zdev->fh << 32, start_dma_addr,
175 				nr_pages * PAGE_SIZE);
176 undo_cpu_trans:
177 	if (rc && ((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID)) {
178 		flags = ZPCI_PTE_INVALID;
179 		while (i-- > 0) {
180 			page_addr -= PAGE_SIZE;
181 			dma_addr -= PAGE_SIZE;
182 			entry = dma_walk_cpu_trans(zdev->dma_table, dma_addr);
183 			if (!entry)
184 				break;
185 			dma_update_cpu_trans(entry, page_addr, flags);
186 		}
187 	}
188 
189 no_refresh:
190 	spin_unlock_irqrestore(&zdev->dma_table_lock, irq_flags);
191 	return rc;
192 }
193 
dma_free_seg_table(unsigned long entry)194 void dma_free_seg_table(unsigned long entry)
195 {
196 	unsigned long *sto = get_rt_sto(entry);
197 	int sx;
198 
199 	for (sx = 0; sx < ZPCI_TABLE_ENTRIES; sx++)
200 		if (reg_entry_isvalid(sto[sx]))
201 			dma_free_page_table(get_st_pto(sto[sx]));
202 
203 	dma_free_cpu_table(sto);
204 }
205 
dma_cleanup_tables(unsigned long * table)206 void dma_cleanup_tables(unsigned long *table)
207 {
208 	int rtx;
209 
210 	if (!table)
211 		return;
212 
213 	for (rtx = 0; rtx < ZPCI_TABLE_ENTRIES; rtx++)
214 		if (reg_entry_isvalid(table[rtx]))
215 			dma_free_seg_table(table[rtx]);
216 
217 	dma_free_cpu_table(table);
218 }
219 
__dma_alloc_iommu(struct zpci_dev * zdev,unsigned long start,int size)220 static unsigned long __dma_alloc_iommu(struct zpci_dev *zdev,
221 				       unsigned long start, int size)
222 {
223 	unsigned long boundary_size;
224 
225 	boundary_size = ALIGN(dma_get_seg_boundary(&zdev->pdev->dev) + 1,
226 			      PAGE_SIZE) >> PAGE_SHIFT;
227 	return iommu_area_alloc(zdev->iommu_bitmap, zdev->iommu_pages,
228 				start, size, 0, boundary_size, 0);
229 }
230 
dma_alloc_iommu(struct zpci_dev * zdev,int size)231 static unsigned long dma_alloc_iommu(struct zpci_dev *zdev, int size)
232 {
233 	unsigned long offset, flags;
234 	int wrap = 0;
235 
236 	spin_lock_irqsave(&zdev->iommu_bitmap_lock, flags);
237 	offset = __dma_alloc_iommu(zdev, zdev->next_bit, size);
238 	if (offset == -1) {
239 		/* wrap-around */
240 		offset = __dma_alloc_iommu(zdev, 0, size);
241 		wrap = 1;
242 	}
243 
244 	if (offset != -1) {
245 		zdev->next_bit = offset + size;
246 		if (!zdev->tlb_refresh && !s390_iommu_strict && wrap)
247 			/* global flush after wrap-around with lazy unmap */
248 			zpci_refresh_global(zdev);
249 	}
250 	spin_unlock_irqrestore(&zdev->iommu_bitmap_lock, flags);
251 	return offset;
252 }
253 
dma_free_iommu(struct zpci_dev * zdev,unsigned long offset,int size)254 static void dma_free_iommu(struct zpci_dev *zdev, unsigned long offset, int size)
255 {
256 	unsigned long flags;
257 
258 	spin_lock_irqsave(&zdev->iommu_bitmap_lock, flags);
259 	if (!zdev->iommu_bitmap)
260 		goto out;
261 	bitmap_clear(zdev->iommu_bitmap, offset, size);
262 	/*
263 	 * Lazy flush for unmap: need to move next_bit to avoid address re-use
264 	 * until wrap-around.
265 	 */
266 	if (!s390_iommu_strict && offset >= zdev->next_bit)
267 		zdev->next_bit = offset + size;
268 out:
269 	spin_unlock_irqrestore(&zdev->iommu_bitmap_lock, flags);
270 }
271 
zpci_err_dma(unsigned long rc,unsigned long addr)272 static inline void zpci_err_dma(unsigned long rc, unsigned long addr)
273 {
274 	struct {
275 		unsigned long rc;
276 		unsigned long addr;
277 	} __packed data = {rc, addr};
278 
279 	zpci_err_hex(&data, sizeof(data));
280 }
281 
s390_dma_map_pages(struct device * dev,struct page * page,unsigned long offset,size_t size,enum dma_data_direction direction,struct dma_attrs * attrs)282 static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
283 				     unsigned long offset, size_t size,
284 				     enum dma_data_direction direction,
285 				     struct dma_attrs *attrs)
286 {
287 	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
288 	unsigned long nr_pages, iommu_page_index;
289 	unsigned long pa = page_to_phys(page) + offset;
290 	int flags = ZPCI_PTE_VALID;
291 	dma_addr_t dma_addr;
292 	int ret;
293 
294 	/* This rounds up number of pages based on size and offset */
295 	nr_pages = iommu_num_pages(pa, size, PAGE_SIZE);
296 	iommu_page_index = dma_alloc_iommu(zdev, nr_pages);
297 	if (iommu_page_index == -1) {
298 		ret = -ENOSPC;
299 		goto out_err;
300 	}
301 
302 	/* Use rounded up size */
303 	size = nr_pages * PAGE_SIZE;
304 
305 	dma_addr = zdev->start_dma + iommu_page_index * PAGE_SIZE;
306 	if (dma_addr + size > zdev->end_dma) {
307 		ret = -ERANGE;
308 		goto out_free;
309 	}
310 
311 	if (direction == DMA_NONE || direction == DMA_TO_DEVICE)
312 		flags |= ZPCI_TABLE_PROTECTED;
313 
314 	ret = dma_update_trans(zdev, pa, dma_addr, size, flags);
315 	if (ret)
316 		goto out_free;
317 
318 	atomic64_add(nr_pages, &zdev->mapped_pages);
319 	return dma_addr + (offset & ~PAGE_MASK);
320 
321 out_free:
322 	dma_free_iommu(zdev, iommu_page_index, nr_pages);
323 out_err:
324 	zpci_err("map error:\n");
325 	zpci_err_dma(ret, pa);
326 	return DMA_ERROR_CODE;
327 }
328 
s390_dma_unmap_pages(struct device * dev,dma_addr_t dma_addr,size_t size,enum dma_data_direction direction,struct dma_attrs * attrs)329 static void s390_dma_unmap_pages(struct device *dev, dma_addr_t dma_addr,
330 				 size_t size, enum dma_data_direction direction,
331 				 struct dma_attrs *attrs)
332 {
333 	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
334 	unsigned long iommu_page_index;
335 	int npages, ret;
336 
337 	npages = iommu_num_pages(dma_addr, size, PAGE_SIZE);
338 	dma_addr = dma_addr & PAGE_MASK;
339 	ret = dma_update_trans(zdev, 0, dma_addr, npages * PAGE_SIZE,
340 			       ZPCI_PTE_INVALID);
341 	if (ret) {
342 		zpci_err("unmap error:\n");
343 		zpci_err_dma(ret, dma_addr);
344 		return;
345 	}
346 
347 	atomic64_add(npages, &zdev->unmapped_pages);
348 	iommu_page_index = (dma_addr - zdev->start_dma) >> PAGE_SHIFT;
349 	dma_free_iommu(zdev, iommu_page_index, npages);
350 }
351 
s390_dma_alloc(struct device * dev,size_t size,dma_addr_t * dma_handle,gfp_t flag,struct dma_attrs * attrs)352 static void *s390_dma_alloc(struct device *dev, size_t size,
353 			    dma_addr_t *dma_handle, gfp_t flag,
354 			    struct dma_attrs *attrs)
355 {
356 	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
357 	struct page *page;
358 	unsigned long pa;
359 	dma_addr_t map;
360 
361 	size = PAGE_ALIGN(size);
362 	page = alloc_pages(flag, get_order(size));
363 	if (!page)
364 		return NULL;
365 
366 	pa = page_to_phys(page);
367 	memset((void *) pa, 0, size);
368 
369 	map = s390_dma_map_pages(dev, page, pa % PAGE_SIZE,
370 				 size, DMA_BIDIRECTIONAL, NULL);
371 	if (dma_mapping_error(dev, map)) {
372 		free_pages(pa, get_order(size));
373 		return NULL;
374 	}
375 
376 	atomic64_add(size / PAGE_SIZE, &zdev->allocated_pages);
377 	if (dma_handle)
378 		*dma_handle = map;
379 	return (void *) pa;
380 }
381 
s390_dma_free(struct device * dev,size_t size,void * pa,dma_addr_t dma_handle,struct dma_attrs * attrs)382 static void s390_dma_free(struct device *dev, size_t size,
383 			  void *pa, dma_addr_t dma_handle,
384 			  struct dma_attrs *attrs)
385 {
386 	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
387 
388 	size = PAGE_ALIGN(size);
389 	atomic64_sub(size / PAGE_SIZE, &zdev->allocated_pages);
390 	s390_dma_unmap_pages(dev, dma_handle, size, DMA_BIDIRECTIONAL, NULL);
391 	free_pages((unsigned long) pa, get_order(size));
392 }
393 
s390_dma_map_sg(struct device * dev,struct scatterlist * sg,int nr_elements,enum dma_data_direction dir,struct dma_attrs * attrs)394 static int s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
395 			   int nr_elements, enum dma_data_direction dir,
396 			   struct dma_attrs *attrs)
397 {
398 	int mapped_elements = 0;
399 	struct scatterlist *s;
400 	int i;
401 
402 	for_each_sg(sg, s, nr_elements, i) {
403 		struct page *page = sg_page(s);
404 		s->dma_address = s390_dma_map_pages(dev, page, s->offset,
405 						    s->length, dir, NULL);
406 		if (!dma_mapping_error(dev, s->dma_address)) {
407 			s->dma_length = s->length;
408 			mapped_elements++;
409 		} else
410 			goto unmap;
411 	}
412 out:
413 	return mapped_elements;
414 
415 unmap:
416 	for_each_sg(sg, s, mapped_elements, i) {
417 		if (s->dma_address)
418 			s390_dma_unmap_pages(dev, s->dma_address, s->dma_length,
419 					     dir, NULL);
420 		s->dma_address = 0;
421 		s->dma_length = 0;
422 	}
423 	mapped_elements = 0;
424 	goto out;
425 }
426 
s390_dma_unmap_sg(struct device * dev,struct scatterlist * sg,int nr_elements,enum dma_data_direction dir,struct dma_attrs * attrs)427 static void s390_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
428 			      int nr_elements, enum dma_data_direction dir,
429 			      struct dma_attrs *attrs)
430 {
431 	struct scatterlist *s;
432 	int i;
433 
434 	for_each_sg(sg, s, nr_elements, i) {
435 		s390_dma_unmap_pages(dev, s->dma_address, s->dma_length, dir, NULL);
436 		s->dma_address = 0;
437 		s->dma_length = 0;
438 	}
439 }
440 
zpci_dma_init_device(struct zpci_dev * zdev)441 int zpci_dma_init_device(struct zpci_dev *zdev)
442 {
443 	int rc;
444 
445 	/*
446 	 * At this point, if the device is part of an IOMMU domain, this would
447 	 * be a strong hint towards a bug in the IOMMU API (common) code and/or
448 	 * simultaneous access via IOMMU and DMA API. So let's issue a warning.
449 	 */
450 	WARN_ON(zdev->s390_domain);
451 
452 	spin_lock_init(&zdev->iommu_bitmap_lock);
453 	spin_lock_init(&zdev->dma_table_lock);
454 
455 	zdev->dma_table = dma_alloc_cpu_table();
456 	if (!zdev->dma_table) {
457 		rc = -ENOMEM;
458 		goto out;
459 	}
460 
461 	/*
462 	 * Restrict the iommu bitmap size to the minimum of the following:
463 	 * - main memory size
464 	 * - 3-level pagetable address limit minus start_dma offset
465 	 * - DMA address range allowed by the hardware (clp query pci fn)
466 	 *
467 	 * Also set zdev->end_dma to the actual end address of the usable
468 	 * range, instead of the theoretical maximum as reported by hardware.
469 	 */
470 	zdev->iommu_size = min3((u64) high_memory,
471 				ZPCI_TABLE_SIZE_RT - zdev->start_dma,
472 				zdev->end_dma - zdev->start_dma + 1);
473 	zdev->end_dma = zdev->start_dma + zdev->iommu_size - 1;
474 	zdev->iommu_pages = zdev->iommu_size >> PAGE_SHIFT;
475 	zdev->iommu_bitmap = vzalloc(zdev->iommu_pages / 8);
476 	if (!zdev->iommu_bitmap) {
477 		rc = -ENOMEM;
478 		goto free_dma_table;
479 	}
480 
481 	rc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
482 				(u64) zdev->dma_table);
483 	if (rc)
484 		goto free_bitmap;
485 
486 	return 0;
487 free_bitmap:
488 	vfree(zdev->iommu_bitmap);
489 	zdev->iommu_bitmap = NULL;
490 free_dma_table:
491 	dma_free_cpu_table(zdev->dma_table);
492 	zdev->dma_table = NULL;
493 out:
494 	return rc;
495 }
496 
zpci_dma_exit_device(struct zpci_dev * zdev)497 void zpci_dma_exit_device(struct zpci_dev *zdev)
498 {
499 	/*
500 	 * At this point, if the device is part of an IOMMU domain, this would
501 	 * be a strong hint towards a bug in the IOMMU API (common) code and/or
502 	 * simultaneous access via IOMMU and DMA API. So let's issue a warning.
503 	 */
504 	WARN_ON(zdev->s390_domain);
505 
506 	zpci_unregister_ioat(zdev, 0);
507 	dma_cleanup_tables(zdev->dma_table);
508 	zdev->dma_table = NULL;
509 	vfree(zdev->iommu_bitmap);
510 	zdev->iommu_bitmap = NULL;
511 	zdev->next_bit = 0;
512 }
513 
dma_alloc_cpu_table_caches(void)514 static int __init dma_alloc_cpu_table_caches(void)
515 {
516 	dma_region_table_cache = kmem_cache_create("PCI_DMA_region_tables",
517 					ZPCI_TABLE_SIZE, ZPCI_TABLE_ALIGN,
518 					0, NULL);
519 	if (!dma_region_table_cache)
520 		return -ENOMEM;
521 
522 	dma_page_table_cache = kmem_cache_create("PCI_DMA_page_tables",
523 					ZPCI_PT_SIZE, ZPCI_PT_ALIGN,
524 					0, NULL);
525 	if (!dma_page_table_cache) {
526 		kmem_cache_destroy(dma_region_table_cache);
527 		return -ENOMEM;
528 	}
529 	return 0;
530 }
531 
zpci_dma_init(void)532 int __init zpci_dma_init(void)
533 {
534 	return dma_alloc_cpu_table_caches();
535 }
536 
zpci_dma_exit(void)537 void zpci_dma_exit(void)
538 {
539 	kmem_cache_destroy(dma_page_table_cache);
540 	kmem_cache_destroy(dma_region_table_cache);
541 }
542 
543 #define PREALLOC_DMA_DEBUG_ENTRIES	(1 << 16)
544 
dma_debug_do_init(void)545 static int __init dma_debug_do_init(void)
546 {
547 	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
548 	return 0;
549 }
550 fs_initcall(dma_debug_do_init);
551 
552 struct dma_map_ops s390_dma_ops = {
553 	.alloc		= s390_dma_alloc,
554 	.free		= s390_dma_free,
555 	.map_sg		= s390_dma_map_sg,
556 	.unmap_sg	= s390_dma_unmap_sg,
557 	.map_page	= s390_dma_map_pages,
558 	.unmap_page	= s390_dma_unmap_pages,
559 	/* if we support direct DMA this must be conditional */
560 	.is_phys	= 0,
561 	/* dma_supported is unconditionally true without a callback */
562 };
563 EXPORT_SYMBOL_GPL(s390_dma_ops);
564 
s390_iommu_setup(char * str)565 static int __init s390_iommu_setup(char *str)
566 {
567 	if (!strncmp(str, "strict", 6))
568 		s390_iommu_strict = 1;
569 	return 0;
570 }
571 
572 __setup("s390_iommu=", s390_iommu_setup);
573