1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  IOMMU helpers in MMU context.
4  *
5  *  Copyright (C) 2015 IBM Corp. <aik@ozlabs.ru>
6  */
7 
8 #include <linux/sched/signal.h>
9 #include <linux/slab.h>
10 #include <linux/rculist.h>
11 #include <linux/vmalloc.h>
12 #include <linux/mutex.h>
13 #include <linux/migrate.h>
14 #include <linux/hugetlb.h>
15 #include <linux/swap.h>
16 #include <linux/sizes.h>
17 #include <linux/mm.h>
18 #include <asm/mmu_context.h>
19 #include <asm/pte-walk.h>
20 #include <linux/mm_inline.h>
21 
22 static DEFINE_MUTEX(mem_list_mutex);
23 
24 #define MM_IOMMU_TABLE_GROUP_PAGE_DIRTY	0x1
25 #define MM_IOMMU_TABLE_GROUP_PAGE_MASK	~(SZ_4K - 1)
26 
27 struct mm_iommu_table_group_mem_t {
28 	struct list_head next;
29 	struct rcu_head rcu;
30 	unsigned long used;
31 	atomic64_t mapped;
32 	unsigned int pageshift;
33 	u64 ua;			/* userspace address */
34 	u64 entries;		/* number of entries in hpas/hpages[] */
35 	/*
36 	 * in mm_iommu_get we temporarily use this to store
37 	 * struct page address.
38 	 *
39 	 * We need to convert ua to hpa in real mode. Make it
40 	 * simpler by storing physical address.
41 	 */
42 	union {
43 		struct page **hpages;	/* vmalloc'ed */
44 		phys_addr_t *hpas;
45 	};
46 #define MM_IOMMU_TABLE_INVALID_HPA	((uint64_t)-1)
47 	u64 dev_hpa;		/* Device memory base address */
48 };
49 
50 bool mm_iommu_preregistered(struct mm_struct *mm)
51 {
52 	return !list_empty(&mm->context.iommu_group_mem_list);
53 }
54 EXPORT_SYMBOL_GPL(mm_iommu_preregistered);
55 
56 static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
57 			      unsigned long entries, unsigned long dev_hpa,
58 			      struct mm_iommu_table_group_mem_t **pmem)
59 {
60 	struct mm_iommu_table_group_mem_t *mem, *mem2;
61 	long i, ret, locked_entries = 0, pinned = 0;
62 	unsigned int pageshift;
63 	unsigned long entry, chunk;
64 
65 	if (dev_hpa == MM_IOMMU_TABLE_INVALID_HPA) {
66 		ret = account_locked_vm(mm, entries, true);
67 		if (ret)
68 			return ret;
69 
70 		locked_entries = entries;
71 	}
72 
73 	mem = kzalloc(sizeof(*mem), GFP_KERNEL);
74 	if (!mem) {
75 		ret = -ENOMEM;
76 		goto unlock_exit;
77 	}
78 
79 	if (dev_hpa != MM_IOMMU_TABLE_INVALID_HPA) {
80 		mem->pageshift = __ffs(dev_hpa | (entries << PAGE_SHIFT));
81 		mem->dev_hpa = dev_hpa;
82 		goto good_exit;
83 	}
84 	mem->dev_hpa = MM_IOMMU_TABLE_INVALID_HPA;
85 
86 	/*
87 	 * For a starting point for a maximum page size calculation
88 	 * we use @ua and @entries natural alignment to allow IOMMU pages
89 	 * smaller than huge pages but still bigger than PAGE_SIZE.
90 	 */
91 	mem->pageshift = __ffs(ua | (entries << PAGE_SHIFT));
92 	mem->hpas = vzalloc(array_size(entries, sizeof(mem->hpas[0])));
93 	if (!mem->hpas) {
94 		kfree(mem);
95 		ret = -ENOMEM;
96 		goto unlock_exit;
97 	}
98 
99 	down_read(&mm->mmap_sem);
100 	chunk = (1UL << (PAGE_SHIFT + MAX_ORDER - 1)) /
101 			sizeof(struct vm_area_struct *);
102 	chunk = min(chunk, entries);
103 	for (entry = 0; entry < entries; entry += chunk) {
104 		unsigned long n = min(entries - entry, chunk);
105 
106 		ret = get_user_pages(ua + (entry << PAGE_SHIFT), n,
107 				FOLL_WRITE | FOLL_LONGTERM,
108 				mem->hpages + entry, NULL);
109 		if (ret == n) {
110 			pinned += n;
111 			continue;
112 		}
113 		if (ret > 0)
114 			pinned += ret;
115 		break;
116 	}
117 	up_read(&mm->mmap_sem);
118 	if (pinned != entries) {
119 		if (!ret)
120 			ret = -EFAULT;
121 		goto free_exit;
122 	}
123 
124 	pageshift = PAGE_SHIFT;
125 	for (i = 0; i < entries; ++i) {
126 		struct page *page = mem->hpages[i];
127 
128 		/*
129 		 * Allow to use larger than 64k IOMMU pages. Only do that
130 		 * if we are backed by hugetlb.
131 		 */
132 		if ((mem->pageshift > PAGE_SHIFT) && PageHuge(page)) {
133 			struct page *head = compound_head(page);
134 
135 			pageshift = compound_order(head) + PAGE_SHIFT;
136 		}
137 		mem->pageshift = min(mem->pageshift, pageshift);
138 		/*
139 		 * We don't need struct page reference any more, switch
140 		 * to physical address.
141 		 */
142 		mem->hpas[i] = page_to_pfn(page) << PAGE_SHIFT;
143 	}
144 
145 good_exit:
146 	atomic64_set(&mem->mapped, 1);
147 	mem->used = 1;
148 	mem->ua = ua;
149 	mem->entries = entries;
150 
151 	mutex_lock(&mem_list_mutex);
152 
153 	list_for_each_entry_rcu(mem2, &mm->context.iommu_group_mem_list, next) {
154 		/* Overlap? */
155 		if ((mem2->ua < (ua + (entries << PAGE_SHIFT))) &&
156 				(ua < (mem2->ua +
157 				       (mem2->entries << PAGE_SHIFT)))) {
158 			ret = -EINVAL;
159 			mutex_unlock(&mem_list_mutex);
160 			goto free_exit;
161 		}
162 	}
163 
164 	list_add_rcu(&mem->next, &mm->context.iommu_group_mem_list);
165 
166 	mutex_unlock(&mem_list_mutex);
167 
168 	*pmem = mem;
169 
170 	return 0;
171 
172 free_exit:
173 	/* free the reference taken */
174 	for (i = 0; i < pinned; i++)
175 		put_page(mem->hpages[i]);
176 
177 	vfree(mem->hpas);
178 	kfree(mem);
179 
180 unlock_exit:
181 	account_locked_vm(mm, locked_entries, false);
182 
183 	return ret;
184 }
185 
186 long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
187 		struct mm_iommu_table_group_mem_t **pmem)
188 {
189 	return mm_iommu_do_alloc(mm, ua, entries, MM_IOMMU_TABLE_INVALID_HPA,
190 			pmem);
191 }
192 EXPORT_SYMBOL_GPL(mm_iommu_new);
193 
194 long mm_iommu_newdev(struct mm_struct *mm, unsigned long ua,
195 		unsigned long entries, unsigned long dev_hpa,
196 		struct mm_iommu_table_group_mem_t **pmem)
197 {
198 	return mm_iommu_do_alloc(mm, ua, entries, dev_hpa, pmem);
199 }
200 EXPORT_SYMBOL_GPL(mm_iommu_newdev);
201 
202 static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
203 {
204 	long i;
205 	struct page *page = NULL;
206 
207 	if (!mem->hpas)
208 		return;
209 
210 	for (i = 0; i < mem->entries; ++i) {
211 		if (!mem->hpas[i])
212 			continue;
213 
214 		page = pfn_to_page(mem->hpas[i] >> PAGE_SHIFT);
215 		if (!page)
216 			continue;
217 
218 		if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)
219 			SetPageDirty(page);
220 
221 		put_page(page);
222 		mem->hpas[i] = 0;
223 	}
224 }
225 
226 static void mm_iommu_do_free(struct mm_iommu_table_group_mem_t *mem)
227 {
228 
229 	mm_iommu_unpin(mem);
230 	vfree(mem->hpas);
231 	kfree(mem);
232 }
233 
234 static void mm_iommu_free(struct rcu_head *head)
235 {
236 	struct mm_iommu_table_group_mem_t *mem = container_of(head,
237 			struct mm_iommu_table_group_mem_t, rcu);
238 
239 	mm_iommu_do_free(mem);
240 }
241 
242 static void mm_iommu_release(struct mm_iommu_table_group_mem_t *mem)
243 {
244 	list_del_rcu(&mem->next);
245 	call_rcu(&mem->rcu, mm_iommu_free);
246 }
247 
248 long mm_iommu_put(struct mm_struct *mm, struct mm_iommu_table_group_mem_t *mem)
249 {
250 	long ret = 0;
251 	unsigned long unlock_entries = 0;
252 
253 	mutex_lock(&mem_list_mutex);
254 
255 	if (mem->used == 0) {
256 		ret = -ENOENT;
257 		goto unlock_exit;
258 	}
259 
260 	--mem->used;
261 	/* There are still users, exit */
262 	if (mem->used)
263 		goto unlock_exit;
264 
265 	/* Are there still mappings? */
266 	if (atomic_cmpxchg(&mem->mapped, 1, 0) != 1) {
267 		++mem->used;
268 		ret = -EBUSY;
269 		goto unlock_exit;
270 	}
271 
272 	if (mem->dev_hpa == MM_IOMMU_TABLE_INVALID_HPA)
273 		unlock_entries = mem->entries;
274 
275 	/* @mapped became 0 so now mappings are disabled, release the region */
276 	mm_iommu_release(mem);
277 
278 unlock_exit:
279 	mutex_unlock(&mem_list_mutex);
280 
281 	account_locked_vm(mm, unlock_entries, false);
282 
283 	return ret;
284 }
285 EXPORT_SYMBOL_GPL(mm_iommu_put);
286 
287 struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct *mm,
288 		unsigned long ua, unsigned long size)
289 {
290 	struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
291 
292 	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
293 		if ((mem->ua <= ua) &&
294 				(ua + size <= mem->ua +
295 				 (mem->entries << PAGE_SHIFT))) {
296 			ret = mem;
297 			break;
298 		}
299 	}
300 
301 	return ret;
302 }
303 EXPORT_SYMBOL_GPL(mm_iommu_lookup);
304 
305 struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(struct mm_struct *mm,
306 		unsigned long ua, unsigned long size)
307 {
308 	struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
309 
310 	list_for_each_entry_lockless(mem, &mm->context.iommu_group_mem_list,
311 			next) {
312 		if ((mem->ua <= ua) &&
313 				(ua + size <= mem->ua +
314 				 (mem->entries << PAGE_SHIFT))) {
315 			ret = mem;
316 			break;
317 		}
318 	}
319 
320 	return ret;
321 }
322 
323 struct mm_iommu_table_group_mem_t *mm_iommu_get(struct mm_struct *mm,
324 		unsigned long ua, unsigned long entries)
325 {
326 	struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
327 
328 	mutex_lock(&mem_list_mutex);
329 
330 	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
331 		if ((mem->ua == ua) && (mem->entries == entries)) {
332 			ret = mem;
333 			++mem->used;
334 			break;
335 		}
336 	}
337 
338 	mutex_unlock(&mem_list_mutex);
339 
340 	return ret;
341 }
342 EXPORT_SYMBOL_GPL(mm_iommu_get);
343 
344 long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
345 		unsigned long ua, unsigned int pageshift, unsigned long *hpa)
346 {
347 	const long entry = (ua - mem->ua) >> PAGE_SHIFT;
348 	u64 *va;
349 
350 	if (entry >= mem->entries)
351 		return -EFAULT;
352 
353 	if (pageshift > mem->pageshift)
354 		return -EFAULT;
355 
356 	if (!mem->hpas) {
357 		*hpa = mem->dev_hpa + (ua - mem->ua);
358 		return 0;
359 	}
360 
361 	va = &mem->hpas[entry];
362 	*hpa = (*va & MM_IOMMU_TABLE_GROUP_PAGE_MASK) | (ua & ~PAGE_MASK);
363 
364 	return 0;
365 }
366 EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa);
367 
368 long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
369 		unsigned long ua, unsigned int pageshift, unsigned long *hpa)
370 {
371 	const long entry = (ua - mem->ua) >> PAGE_SHIFT;
372 	unsigned long *pa;
373 
374 	if (entry >= mem->entries)
375 		return -EFAULT;
376 
377 	if (pageshift > mem->pageshift)
378 		return -EFAULT;
379 
380 	if (!mem->hpas) {
381 		*hpa = mem->dev_hpa + (ua - mem->ua);
382 		return 0;
383 	}
384 
385 	pa = (void *) vmalloc_to_phys(&mem->hpas[entry]);
386 	if (!pa)
387 		return -EFAULT;
388 
389 	*hpa = (*pa & MM_IOMMU_TABLE_GROUP_PAGE_MASK) | (ua & ~PAGE_MASK);
390 
391 	return 0;
392 }
393 
394 extern void mm_iommu_ua_mark_dirty_rm(struct mm_struct *mm, unsigned long ua)
395 {
396 	struct mm_iommu_table_group_mem_t *mem;
397 	long entry;
398 	void *va;
399 	unsigned long *pa;
400 
401 	mem = mm_iommu_lookup_rm(mm, ua, PAGE_SIZE);
402 	if (!mem)
403 		return;
404 
405 	if (mem->dev_hpa != MM_IOMMU_TABLE_INVALID_HPA)
406 		return;
407 
408 	entry = (ua - mem->ua) >> PAGE_SHIFT;
409 	va = &mem->hpas[entry];
410 
411 	pa = (void *) vmalloc_to_phys(va);
412 	if (!pa)
413 		return;
414 
415 	*pa |= MM_IOMMU_TABLE_GROUP_PAGE_DIRTY;
416 }
417 
418 bool mm_iommu_is_devmem(struct mm_struct *mm, unsigned long hpa,
419 		unsigned int pageshift, unsigned long *size)
420 {
421 	struct mm_iommu_table_group_mem_t *mem;
422 	unsigned long end;
423 
424 	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
425 		if (mem->dev_hpa == MM_IOMMU_TABLE_INVALID_HPA)
426 			continue;
427 
428 		end = mem->dev_hpa + (mem->entries << PAGE_SHIFT);
429 		if ((mem->dev_hpa <= hpa) && (hpa < end)) {
430 			/*
431 			 * Since the IOMMU page size might be bigger than
432 			 * PAGE_SIZE, the amount of preregistered memory
433 			 * starting from @hpa might be smaller than 1<<pageshift
434 			 * and the caller needs to distinguish this situation.
435 			 */
436 			*size = min(1UL << pageshift, end - hpa);
437 			return true;
438 		}
439 	}
440 
441 	return false;
442 }
443 EXPORT_SYMBOL_GPL(mm_iommu_is_devmem);
444 
445 long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem)
446 {
447 	if (atomic64_inc_not_zero(&mem->mapped))
448 		return 0;
449 
450 	/* Last mm_iommu_put() has been called, no more mappings allowed() */
451 	return -ENXIO;
452 }
453 EXPORT_SYMBOL_GPL(mm_iommu_mapped_inc);
454 
455 void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem)
456 {
457 	atomic64_add_unless(&mem->mapped, -1, 1);
458 }
459 EXPORT_SYMBOL_GPL(mm_iommu_mapped_dec);
460 
461 void mm_iommu_init(struct mm_struct *mm)
462 {
463 	INIT_LIST_HEAD_RCU(&mm->context.iommu_group_mem_list);
464 }
465