1 /*
2  * Copyright (c) 2014 Mellanox Technologies. All rights reserved.
3  *
4  * This software is available to you under a choice of one of two
5  * licenses.  You may choose to be licensed under the terms of the GNU
6  * General Public License (GPL) Version 2, available from the file
7  * COPYING in the main directory of this source tree, or the
8  * OpenIB.org BSD license below:
9  *
10  *     Redistribution and use in source and binary forms, with or
11  *     without modification, are permitted provided that the following
12  *     conditions are met:
13  *
14  *      - Redistributions of source code must retain the above
15  *        copyright notice, this list of conditions and the following
16  *        disclaimer.
17  *
18  *      - Redistributions in binary form must reproduce the above
19  *        copyright notice, this list of conditions and the following
20  *        disclaimer in the documentation and/or other materials
21  *        provided with the distribution.
22  *
23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30  * SOFTWARE.
31  */
32 
33 #include <linux/types.h>
34 #include <linux/sched.h>
35 #include <linux/sched/mm.h>
36 #include <linux/sched/task.h>
37 #include <linux/pid.h>
38 #include <linux/slab.h>
39 #include <linux/export.h>
40 #include <linux/vmalloc.h>
41 #include <linux/hugetlb.h>
42 #include <linux/interval_tree.h>
43 #include <linux/hmm.h>
44 #include <linux/pagemap.h>
45 
46 #include <rdma/ib_umem_odp.h>
47 
48 #include "uverbs.h"
49 
50 static inline int ib_init_umem_odp(struct ib_umem_odp *umem_odp,
51 				   const struct mmu_interval_notifier_ops *ops)
52 {
53 	int ret;
54 
55 	umem_odp->umem.is_odp = 1;
56 	mutex_init(&umem_odp->umem_mutex);
57 
58 	if (!umem_odp->is_implicit_odp) {
59 		size_t page_size = 1UL << umem_odp->page_shift;
60 		unsigned long start;
61 		unsigned long end;
62 		size_t ndmas, npfns;
63 
64 		start = ALIGN_DOWN(umem_odp->umem.address, page_size);
65 		if (check_add_overflow(umem_odp->umem.address,
66 				       (unsigned long)umem_odp->umem.length,
67 				       &end))
68 			return -EOVERFLOW;
69 		end = ALIGN(end, page_size);
70 		if (unlikely(end < page_size))
71 			return -EOVERFLOW;
72 
73 		ndmas = (end - start) >> umem_odp->page_shift;
74 		if (!ndmas)
75 			return -EINVAL;
76 
77 		npfns = (end - start) >> PAGE_SHIFT;
78 		umem_odp->pfn_list = kvcalloc(
79 			npfns, sizeof(*umem_odp->pfn_list), GFP_KERNEL);
80 		if (!umem_odp->pfn_list)
81 			return -ENOMEM;
82 
83 		umem_odp->dma_list = kvcalloc(
84 			ndmas, sizeof(*umem_odp->dma_list), GFP_KERNEL);
85 		if (!umem_odp->dma_list) {
86 			ret = -ENOMEM;
87 			goto out_pfn_list;
88 		}
89 
90 		ret = mmu_interval_notifier_insert(&umem_odp->notifier,
91 						   umem_odp->umem.owning_mm,
92 						   start, end - start, ops);
93 		if (ret)
94 			goto out_dma_list;
95 	}
96 
97 	return 0;
98 
99 out_dma_list:
100 	kvfree(umem_odp->dma_list);
101 out_pfn_list:
102 	kvfree(umem_odp->pfn_list);
103 	return ret;
104 }
105 
106 /**
107  * ib_umem_odp_alloc_implicit - Allocate a parent implicit ODP umem
108  *
109  * Implicit ODP umems do not have a VA range and do not have any page lists.
110  * They exist only to hold the per_mm reference to help the driver create
111  * children umems.
112  *
113  * @device: IB device to create UMEM
114  * @access: ib_reg_mr access flags
115  */
116 struct ib_umem_odp *ib_umem_odp_alloc_implicit(struct ib_device *device,
117 					       int access)
118 {
119 	struct ib_umem *umem;
120 	struct ib_umem_odp *umem_odp;
121 	int ret;
122 
123 	if (access & IB_ACCESS_HUGETLB)
124 		return ERR_PTR(-EINVAL);
125 
126 	umem_odp = kzalloc(sizeof(*umem_odp), GFP_KERNEL);
127 	if (!umem_odp)
128 		return ERR_PTR(-ENOMEM);
129 	umem = &umem_odp->umem;
130 	umem->ibdev = device;
131 	umem->writable = ib_access_writable(access);
132 	umem->owning_mm = current->mm;
133 	umem_odp->is_implicit_odp = 1;
134 	umem_odp->page_shift = PAGE_SHIFT;
135 
136 	umem_odp->tgid = get_task_pid(current->group_leader, PIDTYPE_PID);
137 	ret = ib_init_umem_odp(umem_odp, NULL);
138 	if (ret) {
139 		put_pid(umem_odp->tgid);
140 		kfree(umem_odp);
141 		return ERR_PTR(ret);
142 	}
143 	return umem_odp;
144 }
145 EXPORT_SYMBOL(ib_umem_odp_alloc_implicit);
146 
147 /**
148  * ib_umem_odp_alloc_child - Allocate a child ODP umem under an implicit
149  *                           parent ODP umem
150  *
151  * @root: The parent umem enclosing the child. This must be allocated using
152  *        ib_alloc_implicit_odp_umem()
153  * @addr: The starting userspace VA
154  * @size: The length of the userspace VA
155  * @ops: MMU interval ops, currently only @invalidate
156  */
157 struct ib_umem_odp *
158 ib_umem_odp_alloc_child(struct ib_umem_odp *root, unsigned long addr,
159 			size_t size,
160 			const struct mmu_interval_notifier_ops *ops)
161 {
162 	/*
163 	 * Caller must ensure that root cannot be freed during the call to
164 	 * ib_alloc_odp_umem.
165 	 */
166 	struct ib_umem_odp *odp_data;
167 	struct ib_umem *umem;
168 	int ret;
169 
170 	if (WARN_ON(!root->is_implicit_odp))
171 		return ERR_PTR(-EINVAL);
172 
173 	odp_data = kzalloc(sizeof(*odp_data), GFP_KERNEL);
174 	if (!odp_data)
175 		return ERR_PTR(-ENOMEM);
176 	umem = &odp_data->umem;
177 	umem->ibdev = root->umem.ibdev;
178 	umem->length     = size;
179 	umem->address    = addr;
180 	umem->writable   = root->umem.writable;
181 	umem->owning_mm  = root->umem.owning_mm;
182 	odp_data->page_shift = PAGE_SHIFT;
183 	odp_data->notifier.ops = ops;
184 
185 	/*
186 	 * A mmget must be held when registering a notifier, the owming_mm only
187 	 * has a mm_grab at this point.
188 	 */
189 	if (!mmget_not_zero(umem->owning_mm)) {
190 		ret = -EFAULT;
191 		goto out_free;
192 	}
193 
194 	odp_data->tgid = get_pid(root->tgid);
195 	ret = ib_init_umem_odp(odp_data, ops);
196 	if (ret)
197 		goto out_tgid;
198 	mmput(umem->owning_mm);
199 	return odp_data;
200 
201 out_tgid:
202 	put_pid(odp_data->tgid);
203 	mmput(umem->owning_mm);
204 out_free:
205 	kfree(odp_data);
206 	return ERR_PTR(ret);
207 }
208 EXPORT_SYMBOL(ib_umem_odp_alloc_child);
209 
210 /**
211  * ib_umem_odp_get - Create a umem_odp for a userspace va
212  *
213  * @device: IB device struct to get UMEM
214  * @addr: userspace virtual address to start at
215  * @size: length of region to pin
216  * @access: IB_ACCESS_xxx flags for memory being pinned
217  * @ops: MMU interval ops, currently only @invalidate
218  *
219  * The driver should use when the access flags indicate ODP memory. It avoids
220  * pinning, instead, stores the mm for future page fault handling in
221  * conjunction with MMU notifiers.
222  */
223 struct ib_umem_odp *ib_umem_odp_get(struct ib_device *device,
224 				    unsigned long addr, size_t size, int access,
225 				    const struct mmu_interval_notifier_ops *ops)
226 {
227 	struct ib_umem_odp *umem_odp;
228 	int ret;
229 
230 	if (WARN_ON_ONCE(!(access & IB_ACCESS_ON_DEMAND)))
231 		return ERR_PTR(-EINVAL);
232 
233 	umem_odp = kzalloc(sizeof(struct ib_umem_odp), GFP_KERNEL);
234 	if (!umem_odp)
235 		return ERR_PTR(-ENOMEM);
236 
237 	umem_odp->umem.ibdev = device;
238 	umem_odp->umem.length = size;
239 	umem_odp->umem.address = addr;
240 	umem_odp->umem.writable = ib_access_writable(access);
241 	umem_odp->umem.owning_mm = current->mm;
242 	umem_odp->notifier.ops = ops;
243 
244 	umem_odp->page_shift = PAGE_SHIFT;
245 #ifdef CONFIG_HUGETLB_PAGE
246 	if (access & IB_ACCESS_HUGETLB)
247 		umem_odp->page_shift = HPAGE_SHIFT;
248 #endif
249 
250 	umem_odp->tgid = get_task_pid(current->group_leader, PIDTYPE_PID);
251 	ret = ib_init_umem_odp(umem_odp, ops);
252 	if (ret)
253 		goto err_put_pid;
254 	return umem_odp;
255 
256 err_put_pid:
257 	put_pid(umem_odp->tgid);
258 	kfree(umem_odp);
259 	return ERR_PTR(ret);
260 }
261 EXPORT_SYMBOL(ib_umem_odp_get);
262 
263 void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
264 {
265 	/*
266 	 * Ensure that no more pages are mapped in the umem.
267 	 *
268 	 * It is the driver's responsibility to ensure, before calling us,
269 	 * that the hardware will not attempt to access the MR any more.
270 	 */
271 	if (!umem_odp->is_implicit_odp) {
272 		mutex_lock(&umem_odp->umem_mutex);
273 		ib_umem_odp_unmap_dma_pages(umem_odp, ib_umem_start(umem_odp),
274 					    ib_umem_end(umem_odp));
275 		mutex_unlock(&umem_odp->umem_mutex);
276 		mmu_interval_notifier_remove(&umem_odp->notifier);
277 		kvfree(umem_odp->dma_list);
278 		kvfree(umem_odp->pfn_list);
279 	}
280 	put_pid(umem_odp->tgid);
281 	kfree(umem_odp);
282 }
283 EXPORT_SYMBOL(ib_umem_odp_release);
284 
285 /*
286  * Map for DMA and insert a single page into the on-demand paging page tables.
287  *
288  * @umem: the umem to insert the page to.
289  * @dma_index: index in the umem to add the dma to.
290  * @page: the page struct to map and add.
291  * @access_mask: access permissions needed for this page.
292  *
293  * The function returns -EFAULT if the DMA mapping operation fails.
294  *
295  */
296 static int ib_umem_odp_map_dma_single_page(
297 		struct ib_umem_odp *umem_odp,
298 		unsigned int dma_index,
299 		struct page *page,
300 		u64 access_mask)
301 {
302 	struct ib_device *dev = umem_odp->umem.ibdev;
303 	dma_addr_t *dma_addr = &umem_odp->dma_list[dma_index];
304 
305 	if (*dma_addr) {
306 		/*
307 		 * If the page is already dma mapped it means it went through
308 		 * a non-invalidating trasition, like read-only to writable.
309 		 * Resync the flags.
310 		 */
311 		*dma_addr = (*dma_addr & ODP_DMA_ADDR_MASK) | access_mask;
312 		return 0;
313 	}
314 
315 	*dma_addr = ib_dma_map_page(dev, page, 0, 1 << umem_odp->page_shift,
316 				    DMA_BIDIRECTIONAL);
317 	if (ib_dma_mapping_error(dev, *dma_addr)) {
318 		*dma_addr = 0;
319 		return -EFAULT;
320 	}
321 	umem_odp->npages++;
322 	*dma_addr |= access_mask;
323 	return 0;
324 }
325 
326 /**
327  * ib_umem_odp_map_dma_and_lock - DMA map userspace memory in an ODP MR and lock it.
328  *
329  * Maps the range passed in the argument to DMA addresses.
330  * The DMA addresses of the mapped pages is updated in umem_odp->dma_list.
331  * Upon success the ODP MR will be locked to let caller complete its device
332  * page table update.
333  *
334  * Returns the number of pages mapped in success, negative error code
335  * for failure.
336  * @umem_odp: the umem to map and pin
337  * @user_virt: the address from which we need to map.
338  * @bcnt: the minimal number of bytes to pin and map. The mapping might be
339  *        bigger due to alignment, and may also be smaller in case of an error
340  *        pinning or mapping a page. The actual pages mapped is returned in
341  *        the return value.
342  * @access_mask: bit mask of the requested access permissions for the given
343  *               range.
344  * @fault: is faulting required for the given range
345  */
346 int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
347 				 u64 bcnt, u64 access_mask, bool fault)
348 			__acquires(&umem_odp->umem_mutex)
349 {
350 	struct task_struct *owning_process  = NULL;
351 	struct mm_struct *owning_mm = umem_odp->umem.owning_mm;
352 	int pfn_index, dma_index, ret = 0, start_idx;
353 	unsigned int page_shift, hmm_order, pfn_start_idx;
354 	unsigned long num_pfns, current_seq;
355 	struct hmm_range range = {};
356 	unsigned long timeout;
357 
358 	if (access_mask == 0)
359 		return -EINVAL;
360 
361 	if (user_virt < ib_umem_start(umem_odp) ||
362 	    user_virt + bcnt > ib_umem_end(umem_odp))
363 		return -EFAULT;
364 
365 	page_shift = umem_odp->page_shift;
366 
367 	/*
368 	 * owning_process is allowed to be NULL, this means somehow the mm is
369 	 * existing beyond the lifetime of the originating process.. Presumably
370 	 * mmget_not_zero will fail in this case.
371 	 */
372 	owning_process = get_pid_task(umem_odp->tgid, PIDTYPE_PID);
373 	if (!owning_process || !mmget_not_zero(owning_mm)) {
374 		ret = -EINVAL;
375 		goto out_put_task;
376 	}
377 
378 	range.notifier = &umem_odp->notifier;
379 	range.start = ALIGN_DOWN(user_virt, 1UL << page_shift);
380 	range.end = ALIGN(user_virt + bcnt, 1UL << page_shift);
381 	pfn_start_idx = (range.start - ib_umem_start(umem_odp)) >> PAGE_SHIFT;
382 	num_pfns = (range.end - range.start) >> PAGE_SHIFT;
383 	if (fault) {
384 		range.default_flags = HMM_PFN_REQ_FAULT;
385 
386 		if (access_mask & ODP_WRITE_ALLOWED_BIT)
387 			range.default_flags |= HMM_PFN_REQ_WRITE;
388 	}
389 
390 	range.hmm_pfns = &(umem_odp->pfn_list[pfn_start_idx]);
391 	timeout = jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
392 
393 retry:
394 	current_seq = range.notifier_seq =
395 		mmu_interval_read_begin(&umem_odp->notifier);
396 
397 	mmap_read_lock(owning_mm);
398 	ret = hmm_range_fault(&range);
399 	mmap_read_unlock(owning_mm);
400 	if (unlikely(ret)) {
401 		if (ret == -EBUSY && !time_after(jiffies, timeout))
402 			goto retry;
403 		goto out_put_mm;
404 	}
405 
406 	start_idx = (range.start - ib_umem_start(umem_odp)) >> page_shift;
407 	dma_index = start_idx;
408 
409 	mutex_lock(&umem_odp->umem_mutex);
410 	if (mmu_interval_read_retry(&umem_odp->notifier, current_seq)) {
411 		mutex_unlock(&umem_odp->umem_mutex);
412 		goto retry;
413 	}
414 
415 	for (pfn_index = 0; pfn_index < num_pfns;
416 		pfn_index += 1 << (page_shift - PAGE_SHIFT), dma_index++) {
417 
418 		if (fault) {
419 			/*
420 			 * Since we asked for hmm_range_fault() to populate
421 			 * pages it shouldn't return an error entry on success.
422 			 */
423 			WARN_ON(range.hmm_pfns[pfn_index] & HMM_PFN_ERROR);
424 			WARN_ON(!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID));
425 		} else {
426 			if (!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID)) {
427 				WARN_ON(umem_odp->dma_list[dma_index]);
428 				continue;
429 			}
430 			access_mask = ODP_READ_ALLOWED_BIT;
431 			if (range.hmm_pfns[pfn_index] & HMM_PFN_WRITE)
432 				access_mask |= ODP_WRITE_ALLOWED_BIT;
433 		}
434 
435 		hmm_order = hmm_pfn_to_map_order(range.hmm_pfns[pfn_index]);
436 		/* If a hugepage was detected and ODP wasn't set for, the umem
437 		 * page_shift will be used, the opposite case is an error.
438 		 */
439 		if (hmm_order + PAGE_SHIFT < page_shift) {
440 			ret = -EINVAL;
441 			ibdev_dbg(umem_odp->umem.ibdev,
442 				  "%s: un-expected hmm_order %u, page_shift %u\n",
443 				  __func__, hmm_order, page_shift);
444 			break;
445 		}
446 
447 		ret = ib_umem_odp_map_dma_single_page(
448 				umem_odp, dma_index, hmm_pfn_to_page(range.hmm_pfns[pfn_index]),
449 				access_mask);
450 		if (ret < 0) {
451 			ibdev_dbg(umem_odp->umem.ibdev,
452 				  "ib_umem_odp_map_dma_single_page failed with error %d\n", ret);
453 			break;
454 		}
455 	}
456 	/* upon success lock should stay on hold for the callee */
457 	if (!ret)
458 		ret = dma_index - start_idx;
459 	else
460 		mutex_unlock(&umem_odp->umem_mutex);
461 
462 out_put_mm:
463 	mmput_async(owning_mm);
464 out_put_task:
465 	if (owning_process)
466 		put_task_struct(owning_process);
467 	return ret;
468 }
469 EXPORT_SYMBOL(ib_umem_odp_map_dma_and_lock);
470 
471 void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
472 				 u64 bound)
473 {
474 	dma_addr_t dma_addr;
475 	dma_addr_t dma;
476 	int idx;
477 	u64 addr;
478 	struct ib_device *dev = umem_odp->umem.ibdev;
479 
480 	lockdep_assert_held(&umem_odp->umem_mutex);
481 
482 	virt = max_t(u64, virt, ib_umem_start(umem_odp));
483 	bound = min_t(u64, bound, ib_umem_end(umem_odp));
484 	for (addr = virt; addr < bound; addr += BIT(umem_odp->page_shift)) {
485 		idx = (addr - ib_umem_start(umem_odp)) >> umem_odp->page_shift;
486 		dma = umem_odp->dma_list[idx];
487 
488 		/* The access flags guaranteed a valid DMA address in case was NULL */
489 		if (dma) {
490 			unsigned long pfn_idx = (addr - ib_umem_start(umem_odp)) >> PAGE_SHIFT;
491 			struct page *page = hmm_pfn_to_page(umem_odp->pfn_list[pfn_idx]);
492 
493 			dma_addr = dma & ODP_DMA_ADDR_MASK;
494 			ib_dma_unmap_page(dev, dma_addr,
495 					  BIT(umem_odp->page_shift),
496 					  DMA_BIDIRECTIONAL);
497 			if (dma & ODP_WRITE_ALLOWED_BIT) {
498 				struct page *head_page = compound_head(page);
499 				/*
500 				 * set_page_dirty prefers being called with
501 				 * the page lock. However, MMU notifiers are
502 				 * called sometimes with and sometimes without
503 				 * the lock. We rely on the umem_mutex instead
504 				 * to prevent other mmu notifiers from
505 				 * continuing and allowing the page mapping to
506 				 * be removed.
507 				 */
508 				set_page_dirty(head_page);
509 			}
510 			umem_odp->dma_list[idx] = 0;
511 			umem_odp->npages--;
512 		}
513 	}
514 }
515 EXPORT_SYMBOL(ib_umem_odp_unmap_dma_pages);
516