1 // SPDX-License-Identifier: GPL-2.0-only OR MIT
2 /*
3 * Copyright © 2024-2025 Intel Corporation
4 */
5
6 #include <linux/dma-mapping.h>
7 #include <linux/migrate.h>
8 #include <linux/pagemap.h>
9 #include <drm/drm_drv.h>
10 #include <drm/drm_pagemap.h>
11
12 /**
13 * DOC: Overview
14 *
15 * The DRM pagemap layer is intended to augment the dev_pagemap functionality by
16 * providing a way to populate a struct mm_struct virtual range with device
17 * private pages and to provide helpers to abstract device memory allocations,
18 * to migrate memory back and forth between device memory and system RAM and
19 * to handle access (and in the future migration) between devices implementing
20 * a fast interconnect that is not necessarily visible to the rest of the
21 * system.
22 *
23 * Typically the DRM pagemap receives requests from one or more DRM GPU SVM
24 * instances to populate struct mm_struct virtual ranges with memory, and the
25 * migration is best effort only and may thus fail. The implementation should
26 * also handle device unbinding by blocking (return an -ENODEV) error for new
27 * population requests and after that migrate all device pages to system ram.
28 */
29
30 /**
31 * DOC: Migration
32 *
33 * Migration granularity typically follows the GPU SVM range requests, but
34 * if there are clashes, due to races or due to the fact that multiple GPU
35 * SVM instances have different views of the ranges used, and because of that
36 * parts of a requested range is already present in the requested device memory,
37 * the implementation has a variety of options. It can fail and it can choose
38 * to populate only the part of the range that isn't already in device memory,
39 * and it can evict the range to system before trying to migrate. Ideally an
40 * implementation would just try to migrate the missing part of the range and
41 * allocate just enough memory to do so.
42 *
43 * When migrating to system memory as a response to a cpu fault or a device
44 * memory eviction request, currently a full device memory allocation is
45 * migrated back to system. Moving forward this might need improvement for
46 * situations where a single page needs bouncing between system memory and
47 * device memory due to, for example, atomic operations.
48 *
49 * Key DRM pagemap components:
50 *
51 * - Device Memory Allocations:
52 * Embedded structure containing enough information for the drm_pagemap to
53 * migrate to / from device memory.
54 *
55 * - Device Memory Operations:
56 * Define the interface for driver-specific device memory operations
57 * release memory, populate pfns, and copy to / from device memory.
58 */
59
60 /**
61 * struct drm_pagemap_zdd - GPU SVM zone device data
62 *
63 * @refcount: Reference count for the zdd
64 * @devmem_allocation: device memory allocation
65 * @device_private_page_owner: Device private pages owner
66 *
67 * This structure serves as a generic wrapper installed in
68 * page->zone_device_data. It provides infrastructure for looking up a device
69 * memory allocation upon CPU page fault and asynchronously releasing device
70 * memory once the CPU has no page references. Asynchronous release is useful
71 * because CPU page references can be dropped in IRQ contexts, while releasing
72 * device memory likely requires sleeping locks.
73 */
74 struct drm_pagemap_zdd {
75 struct kref refcount;
76 struct drm_pagemap_devmem *devmem_allocation;
77 void *device_private_page_owner;
78 };
79
80 /**
81 * drm_pagemap_zdd_alloc() - Allocate a zdd structure.
82 * @device_private_page_owner: Device private pages owner
83 *
84 * This function allocates and initializes a new zdd structure. It sets up the
85 * reference count and initializes the destroy work.
86 *
87 * Return: Pointer to the allocated zdd on success, ERR_PTR() on failure.
88 */
89 static struct drm_pagemap_zdd *
drm_pagemap_zdd_alloc(void * device_private_page_owner)90 drm_pagemap_zdd_alloc(void *device_private_page_owner)
91 {
92 struct drm_pagemap_zdd *zdd;
93
94 zdd = kmalloc(sizeof(*zdd), GFP_KERNEL);
95 if (!zdd)
96 return NULL;
97
98 kref_init(&zdd->refcount);
99 zdd->devmem_allocation = NULL;
100 zdd->device_private_page_owner = device_private_page_owner;
101
102 return zdd;
103 }
104
105 /**
106 * drm_pagemap_zdd_get() - Get a reference to a zdd structure.
107 * @zdd: Pointer to the zdd structure.
108 *
109 * This function increments the reference count of the provided zdd structure.
110 *
111 * Return: Pointer to the zdd structure.
112 */
drm_pagemap_zdd_get(struct drm_pagemap_zdd * zdd)113 static struct drm_pagemap_zdd *drm_pagemap_zdd_get(struct drm_pagemap_zdd *zdd)
114 {
115 kref_get(&zdd->refcount);
116 return zdd;
117 }
118
119 /**
120 * drm_pagemap_zdd_destroy() - Destroy a zdd structure.
121 * @ref: Pointer to the reference count structure.
122 *
123 * This function queues the destroy_work of the zdd for asynchronous destruction.
124 */
drm_pagemap_zdd_destroy(struct kref * ref)125 static void drm_pagemap_zdd_destroy(struct kref *ref)
126 {
127 struct drm_pagemap_zdd *zdd =
128 container_of(ref, struct drm_pagemap_zdd, refcount);
129 struct drm_pagemap_devmem *devmem = zdd->devmem_allocation;
130
131 if (devmem) {
132 complete_all(&devmem->detached);
133 if (devmem->ops->devmem_release)
134 devmem->ops->devmem_release(devmem);
135 }
136 kfree(zdd);
137 }
138
139 /**
140 * drm_pagemap_zdd_put() - Put a zdd reference.
141 * @zdd: Pointer to the zdd structure.
142 *
143 * This function decrements the reference count of the provided zdd structure
144 * and schedules its destruction if the count drops to zero.
145 */
drm_pagemap_zdd_put(struct drm_pagemap_zdd * zdd)146 static void drm_pagemap_zdd_put(struct drm_pagemap_zdd *zdd)
147 {
148 kref_put(&zdd->refcount, drm_pagemap_zdd_destroy);
149 }
150
151 /**
152 * drm_pagemap_migration_unlock_put_page() - Put a migration page
153 * @page: Pointer to the page to put
154 *
155 * This function unlocks and puts a page.
156 */
drm_pagemap_migration_unlock_put_page(struct page * page)157 static void drm_pagemap_migration_unlock_put_page(struct page *page)
158 {
159 unlock_page(page);
160 put_page(page);
161 }
162
163 /**
164 * drm_pagemap_migration_unlock_put_pages() - Put migration pages
165 * @npages: Number of pages
166 * @migrate_pfn: Array of migrate page frame numbers
167 *
168 * This function unlocks and puts an array of pages.
169 */
drm_pagemap_migration_unlock_put_pages(unsigned long npages,unsigned long * migrate_pfn)170 static void drm_pagemap_migration_unlock_put_pages(unsigned long npages,
171 unsigned long *migrate_pfn)
172 {
173 unsigned long i;
174
175 for (i = 0; i < npages; ++i) {
176 struct page *page;
177
178 if (!migrate_pfn[i])
179 continue;
180
181 page = migrate_pfn_to_page(migrate_pfn[i]);
182 drm_pagemap_migration_unlock_put_page(page);
183 migrate_pfn[i] = 0;
184 }
185 }
186
187 /**
188 * drm_pagemap_get_devmem_page() - Get a reference to a device memory page
189 * @page: Pointer to the page
190 * @zdd: Pointer to the GPU SVM zone device data
191 *
192 * This function associates the given page with the specified GPU SVM zone
193 * device data and initializes it for zone device usage.
194 */
drm_pagemap_get_devmem_page(struct page * page,struct drm_pagemap_zdd * zdd)195 static void drm_pagemap_get_devmem_page(struct page *page,
196 struct drm_pagemap_zdd *zdd)
197 {
198 page->zone_device_data = drm_pagemap_zdd_get(zdd);
199 zone_device_page_init(page);
200 }
201
202 /**
203 * drm_pagemap_migrate_map_pages() - Map migration pages for GPU SVM migration
204 * @dev: The device for which the pages are being mapped
205 * @dma_addr: Array to store DMA addresses corresponding to mapped pages
206 * @migrate_pfn: Array of migrate page frame numbers to map
207 * @npages: Number of pages to map
208 * @dir: Direction of data transfer (e.g., DMA_BIDIRECTIONAL)
209 *
210 * This function maps pages of memory for migration usage in GPU SVM. It
211 * iterates over each page frame number provided in @migrate_pfn, maps the
212 * corresponding page, and stores the DMA address in the provided @dma_addr
213 * array.
214 *
215 * Returns: 0 on success, -EFAULT if an error occurs during mapping.
216 */
drm_pagemap_migrate_map_pages(struct device * dev,dma_addr_t * dma_addr,unsigned long * migrate_pfn,unsigned long npages,enum dma_data_direction dir)217 static int drm_pagemap_migrate_map_pages(struct device *dev,
218 dma_addr_t *dma_addr,
219 unsigned long *migrate_pfn,
220 unsigned long npages,
221 enum dma_data_direction dir)
222 {
223 unsigned long i;
224
225 for (i = 0; i < npages; ++i) {
226 struct page *page = migrate_pfn_to_page(migrate_pfn[i]);
227
228 if (!page)
229 continue;
230
231 if (WARN_ON_ONCE(is_zone_device_page(page)))
232 return -EFAULT;
233
234 dma_addr[i] = dma_map_page(dev, page, 0, PAGE_SIZE, dir);
235 if (dma_mapping_error(dev, dma_addr[i]))
236 return -EFAULT;
237 }
238
239 return 0;
240 }
241
242 /**
243 * drm_pagemap_migrate_unmap_pages() - Unmap pages previously mapped for GPU SVM migration
244 * @dev: The device for which the pages were mapped
245 * @dma_addr: Array of DMA addresses corresponding to mapped pages
246 * @npages: Number of pages to unmap
247 * @dir: Direction of data transfer (e.g., DMA_BIDIRECTIONAL)
248 *
249 * This function unmaps previously mapped pages of memory for GPU Shared Virtual
250 * Memory (SVM). It iterates over each DMA address provided in @dma_addr, checks
251 * if it's valid and not already unmapped, and unmaps the corresponding page.
252 */
drm_pagemap_migrate_unmap_pages(struct device * dev,dma_addr_t * dma_addr,unsigned long npages,enum dma_data_direction dir)253 static void drm_pagemap_migrate_unmap_pages(struct device *dev,
254 dma_addr_t *dma_addr,
255 unsigned long npages,
256 enum dma_data_direction dir)
257 {
258 unsigned long i;
259
260 for (i = 0; i < npages; ++i) {
261 if (!dma_addr[i] || dma_mapping_error(dev, dma_addr[i]))
262 continue;
263
264 dma_unmap_page(dev, dma_addr[i], PAGE_SIZE, dir);
265 }
266 }
267
268 static unsigned long
npages_in_range(unsigned long start,unsigned long end)269 npages_in_range(unsigned long start, unsigned long end)
270 {
271 return (end - start) >> PAGE_SHIFT;
272 }
273
274 /**
275 * drm_pagemap_migrate_to_devmem() - Migrate a struct mm_struct range to device memory
276 * @devmem_allocation: The device memory allocation to migrate to.
277 * The caller should hold a reference to the device memory allocation,
278 * and the reference is consumed by this function unless it returns with
279 * an error.
280 * @mm: Pointer to the struct mm_struct.
281 * @start: Start of the virtual address range to migrate.
282 * @end: End of the virtual address range to migrate.
283 * @timeslice_ms: The time requested for the migrated pagemap pages to
284 * be present in @mm before being allowed to be migrated back.
285 * @pgmap_owner: Not used currently, since only system memory is considered.
286 *
287 * This function migrates the specified virtual address range to device memory.
288 * It performs the necessary setup and invokes the driver-specific operations for
289 * migration to device memory. Expected to be called while holding the mmap lock in
290 * at least read mode.
291 *
292 * Note: The @timeslice_ms parameter can typically be used to force data to
293 * remain in pagemap pages long enough for a GPU to perform a task and to prevent
294 * a migration livelock. One alternative would be for the GPU driver to block
295 * in a mmu_notifier for the specified amount of time, but adding the
296 * functionality to the pagemap is likely nicer to the system as a whole.
297 *
298 * Return: %0 on success, negative error code on failure.
299 */
drm_pagemap_migrate_to_devmem(struct drm_pagemap_devmem * devmem_allocation,struct mm_struct * mm,unsigned long start,unsigned long end,unsigned long timeslice_ms,void * pgmap_owner)300 int drm_pagemap_migrate_to_devmem(struct drm_pagemap_devmem *devmem_allocation,
301 struct mm_struct *mm,
302 unsigned long start, unsigned long end,
303 unsigned long timeslice_ms,
304 void *pgmap_owner)
305 {
306 const struct drm_pagemap_devmem_ops *ops = devmem_allocation->ops;
307 struct migrate_vma migrate = {
308 .start = start,
309 .end = end,
310 .pgmap_owner = pgmap_owner,
311 .flags = MIGRATE_VMA_SELECT_SYSTEM,
312 };
313 unsigned long i, npages = npages_in_range(start, end);
314 struct vm_area_struct *vas;
315 struct drm_pagemap_zdd *zdd = NULL;
316 struct page **pages;
317 dma_addr_t *dma_addr;
318 void *buf;
319 int err;
320
321 mmap_assert_locked(mm);
322
323 if (!ops->populate_devmem_pfn || !ops->copy_to_devmem ||
324 !ops->copy_to_ram)
325 return -EOPNOTSUPP;
326
327 vas = vma_lookup(mm, start);
328 if (!vas) {
329 err = -ENOENT;
330 goto err_out;
331 }
332
333 if (end > vas->vm_end || start < vas->vm_start) {
334 err = -EINVAL;
335 goto err_out;
336 }
337
338 if (!vma_is_anonymous(vas)) {
339 err = -EBUSY;
340 goto err_out;
341 }
342
343 buf = kvcalloc(npages, 2 * sizeof(*migrate.src) + sizeof(*dma_addr) +
344 sizeof(*pages), GFP_KERNEL);
345 if (!buf) {
346 err = -ENOMEM;
347 goto err_out;
348 }
349 dma_addr = buf + (2 * sizeof(*migrate.src) * npages);
350 pages = buf + (2 * sizeof(*migrate.src) + sizeof(*dma_addr)) * npages;
351
352 zdd = drm_pagemap_zdd_alloc(pgmap_owner);
353 if (!zdd) {
354 err = -ENOMEM;
355 goto err_free;
356 }
357
358 migrate.vma = vas;
359 migrate.src = buf;
360 migrate.dst = migrate.src + npages;
361
362 err = migrate_vma_setup(&migrate);
363 if (err)
364 goto err_free;
365
366 if (!migrate.cpages) {
367 err = -EFAULT;
368 goto err_free;
369 }
370
371 if (migrate.cpages != npages) {
372 err = -EBUSY;
373 goto err_finalize;
374 }
375
376 err = ops->populate_devmem_pfn(devmem_allocation, npages, migrate.dst);
377 if (err)
378 goto err_finalize;
379
380 err = drm_pagemap_migrate_map_pages(devmem_allocation->dev, dma_addr,
381 migrate.src, npages, DMA_TO_DEVICE);
382 if (err)
383 goto err_finalize;
384
385 for (i = 0; i < npages; ++i) {
386 struct page *page = pfn_to_page(migrate.dst[i]);
387
388 pages[i] = page;
389 migrate.dst[i] = migrate_pfn(migrate.dst[i]);
390 drm_pagemap_get_devmem_page(page, zdd);
391 }
392
393 err = ops->copy_to_devmem(pages, dma_addr, npages);
394 if (err)
395 goto err_finalize;
396
397 /* Upon success bind devmem allocation to range and zdd */
398 devmem_allocation->timeslice_expiration = get_jiffies_64() +
399 msecs_to_jiffies(timeslice_ms);
400 zdd->devmem_allocation = devmem_allocation; /* Owns ref */
401
402 err_finalize:
403 if (err)
404 drm_pagemap_migration_unlock_put_pages(npages, migrate.dst);
405 migrate_vma_pages(&migrate);
406 migrate_vma_finalize(&migrate);
407 drm_pagemap_migrate_unmap_pages(devmem_allocation->dev, dma_addr, npages,
408 DMA_TO_DEVICE);
409 err_free:
410 if (zdd)
411 drm_pagemap_zdd_put(zdd);
412 kvfree(buf);
413 err_out:
414 return err;
415 }
416 EXPORT_SYMBOL_GPL(drm_pagemap_migrate_to_devmem);
417
418 /**
419 * drm_pagemap_migrate_populate_ram_pfn() - Populate RAM PFNs for a VM area
420 * @vas: Pointer to the VM area structure, can be NULL
421 * @fault_page: Fault page
422 * @npages: Number of pages to populate
423 * @mpages: Number of pages to migrate
424 * @src_mpfn: Source array of migrate PFNs
425 * @mpfn: Array of migrate PFNs to populate
426 * @addr: Start address for PFN allocation
427 *
428 * This function populates the RAM migrate page frame numbers (PFNs) for the
429 * specified VM area structure. It allocates and locks pages in the VM area for
430 * RAM usage. If vas is non-NULL use alloc_page_vma for allocation, if NULL use
431 * alloc_page for allocation.
432 *
433 * Return: 0 on success, negative error code on failure.
434 */
drm_pagemap_migrate_populate_ram_pfn(struct vm_area_struct * vas,struct page * fault_page,unsigned long npages,unsigned long * mpages,unsigned long * src_mpfn,unsigned long * mpfn,unsigned long addr)435 static int drm_pagemap_migrate_populate_ram_pfn(struct vm_area_struct *vas,
436 struct page *fault_page,
437 unsigned long npages,
438 unsigned long *mpages,
439 unsigned long *src_mpfn,
440 unsigned long *mpfn,
441 unsigned long addr)
442 {
443 unsigned long i;
444
445 for (i = 0; i < npages; ++i, addr += PAGE_SIZE) {
446 struct page *page, *src_page;
447
448 if (!(src_mpfn[i] & MIGRATE_PFN_MIGRATE))
449 continue;
450
451 src_page = migrate_pfn_to_page(src_mpfn[i]);
452 if (!src_page)
453 continue;
454
455 if (fault_page) {
456 if (src_page->zone_device_data !=
457 fault_page->zone_device_data)
458 continue;
459 }
460
461 if (vas)
462 page = alloc_page_vma(GFP_HIGHUSER, vas, addr);
463 else
464 page = alloc_page(GFP_HIGHUSER);
465
466 if (!page)
467 goto free_pages;
468
469 mpfn[i] = migrate_pfn(page_to_pfn(page));
470 }
471
472 for (i = 0; i < npages; ++i) {
473 struct page *page = migrate_pfn_to_page(mpfn[i]);
474
475 if (!page)
476 continue;
477
478 WARN_ON_ONCE(!trylock_page(page));
479 ++*mpages;
480 }
481
482 return 0;
483
484 free_pages:
485 for (i = 0; i < npages; ++i) {
486 struct page *page = migrate_pfn_to_page(mpfn[i]);
487
488 if (!page)
489 continue;
490
491 put_page(page);
492 mpfn[i] = 0;
493 }
494 return -ENOMEM;
495 }
496
497 /**
498 * drm_pagemap_evict_to_ram() - Evict GPU SVM range to RAM
499 * @devmem_allocation: Pointer to the device memory allocation
500 *
501 * Similar to __drm_pagemap_migrate_to_ram but does not require mmap lock and
502 * migration done via migrate_device_* functions.
503 *
504 * Return: 0 on success, negative error code on failure.
505 */
drm_pagemap_evict_to_ram(struct drm_pagemap_devmem * devmem_allocation)506 int drm_pagemap_evict_to_ram(struct drm_pagemap_devmem *devmem_allocation)
507 {
508 const struct drm_pagemap_devmem_ops *ops = devmem_allocation->ops;
509 unsigned long npages, mpages = 0;
510 struct page **pages;
511 unsigned long *src, *dst;
512 dma_addr_t *dma_addr;
513 void *buf;
514 int i, err = 0;
515 unsigned int retry_count = 2;
516
517 npages = devmem_allocation->size >> PAGE_SHIFT;
518
519 retry:
520 if (!mmget_not_zero(devmem_allocation->mm))
521 return -EFAULT;
522
523 buf = kvcalloc(npages, 2 * sizeof(*src) + sizeof(*dma_addr) +
524 sizeof(*pages), GFP_KERNEL);
525 if (!buf) {
526 err = -ENOMEM;
527 goto err_out;
528 }
529 src = buf;
530 dst = buf + (sizeof(*src) * npages);
531 dma_addr = buf + (2 * sizeof(*src) * npages);
532 pages = buf + (2 * sizeof(*src) + sizeof(*dma_addr)) * npages;
533
534 err = ops->populate_devmem_pfn(devmem_allocation, npages, src);
535 if (err)
536 goto err_free;
537
538 err = migrate_device_pfns(src, npages);
539 if (err)
540 goto err_free;
541
542 err = drm_pagemap_migrate_populate_ram_pfn(NULL, NULL, npages, &mpages,
543 src, dst, 0);
544 if (err || !mpages)
545 goto err_finalize;
546
547 err = drm_pagemap_migrate_map_pages(devmem_allocation->dev, dma_addr,
548 dst, npages, DMA_FROM_DEVICE);
549 if (err)
550 goto err_finalize;
551
552 for (i = 0; i < npages; ++i)
553 pages[i] = migrate_pfn_to_page(src[i]);
554
555 err = ops->copy_to_ram(pages, dma_addr, npages);
556 if (err)
557 goto err_finalize;
558
559 err_finalize:
560 if (err)
561 drm_pagemap_migration_unlock_put_pages(npages, dst);
562 migrate_device_pages(src, dst, npages);
563 migrate_device_finalize(src, dst, npages);
564 drm_pagemap_migrate_unmap_pages(devmem_allocation->dev, dma_addr, npages,
565 DMA_FROM_DEVICE);
566 err_free:
567 kvfree(buf);
568 err_out:
569 mmput_async(devmem_allocation->mm);
570
571 if (completion_done(&devmem_allocation->detached))
572 return 0;
573
574 if (retry_count--) {
575 cond_resched();
576 goto retry;
577 }
578
579 return err ?: -EBUSY;
580 }
581 EXPORT_SYMBOL_GPL(drm_pagemap_evict_to_ram);
582
583 /**
584 * __drm_pagemap_migrate_to_ram() - Migrate GPU SVM range to RAM (internal)
585 * @vas: Pointer to the VM area structure
586 * @device_private_page_owner: Device private pages owner
587 * @page: Pointer to the page for fault handling (can be NULL)
588 * @fault_addr: Fault address
589 * @size: Size of migration
590 *
591 * This internal function performs the migration of the specified GPU SVM range
592 * to RAM. It sets up the migration, populates + dma maps RAM PFNs, and
593 * invokes the driver-specific operations for migration to RAM.
594 *
595 * Return: 0 on success, negative error code on failure.
596 */
__drm_pagemap_migrate_to_ram(struct vm_area_struct * vas,void * device_private_page_owner,struct page * page,unsigned long fault_addr,unsigned long size)597 static int __drm_pagemap_migrate_to_ram(struct vm_area_struct *vas,
598 void *device_private_page_owner,
599 struct page *page,
600 unsigned long fault_addr,
601 unsigned long size)
602 {
603 struct migrate_vma migrate = {
604 .vma = vas,
605 .pgmap_owner = device_private_page_owner,
606 .flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE |
607 MIGRATE_VMA_SELECT_DEVICE_COHERENT,
608 .fault_page = page,
609 };
610 struct drm_pagemap_zdd *zdd;
611 const struct drm_pagemap_devmem_ops *ops;
612 struct device *dev = NULL;
613 unsigned long npages, mpages = 0;
614 struct page **pages;
615 dma_addr_t *dma_addr;
616 unsigned long start, end;
617 void *buf;
618 int i, err = 0;
619
620 if (page) {
621 zdd = page->zone_device_data;
622 if (time_before64(get_jiffies_64(),
623 zdd->devmem_allocation->timeslice_expiration))
624 return 0;
625 }
626
627 start = ALIGN_DOWN(fault_addr, size);
628 end = ALIGN(fault_addr + 1, size);
629
630 /* Corner where VMA area struct has been partially unmapped */
631 if (start < vas->vm_start)
632 start = vas->vm_start;
633 if (end > vas->vm_end)
634 end = vas->vm_end;
635
636 migrate.start = start;
637 migrate.end = end;
638 npages = npages_in_range(start, end);
639
640 buf = kvcalloc(npages, 2 * sizeof(*migrate.src) + sizeof(*dma_addr) +
641 sizeof(*pages), GFP_KERNEL);
642 if (!buf) {
643 err = -ENOMEM;
644 goto err_out;
645 }
646 dma_addr = buf + (2 * sizeof(*migrate.src) * npages);
647 pages = buf + (2 * sizeof(*migrate.src) + sizeof(*dma_addr)) * npages;
648
649 migrate.vma = vas;
650 migrate.src = buf;
651 migrate.dst = migrate.src + npages;
652
653 err = migrate_vma_setup(&migrate);
654 if (err)
655 goto err_free;
656
657 /* Raced with another CPU fault, nothing to do */
658 if (!migrate.cpages)
659 goto err_free;
660
661 if (!page) {
662 for (i = 0; i < npages; ++i) {
663 if (!(migrate.src[i] & MIGRATE_PFN_MIGRATE))
664 continue;
665
666 page = migrate_pfn_to_page(migrate.src[i]);
667 break;
668 }
669
670 if (!page)
671 goto err_finalize;
672 }
673 zdd = page->zone_device_data;
674 ops = zdd->devmem_allocation->ops;
675 dev = zdd->devmem_allocation->dev;
676
677 err = drm_pagemap_migrate_populate_ram_pfn(vas, page, npages, &mpages,
678 migrate.src, migrate.dst,
679 start);
680 if (err)
681 goto err_finalize;
682
683 err = drm_pagemap_migrate_map_pages(dev, dma_addr, migrate.dst, npages,
684 DMA_FROM_DEVICE);
685 if (err)
686 goto err_finalize;
687
688 for (i = 0; i < npages; ++i)
689 pages[i] = migrate_pfn_to_page(migrate.src[i]);
690
691 err = ops->copy_to_ram(pages, dma_addr, npages);
692 if (err)
693 goto err_finalize;
694
695 err_finalize:
696 if (err)
697 drm_pagemap_migration_unlock_put_pages(npages, migrate.dst);
698 migrate_vma_pages(&migrate);
699 migrate_vma_finalize(&migrate);
700 if (dev)
701 drm_pagemap_migrate_unmap_pages(dev, dma_addr, npages,
702 DMA_FROM_DEVICE);
703 err_free:
704 kvfree(buf);
705 err_out:
706
707 return err;
708 }
709
710 /**
711 * drm_pagemap_page_free() - Put GPU SVM zone device data associated with a page
712 * @page: Pointer to the page
713 *
714 * This function is a callback used to put the GPU SVM zone device data
715 * associated with a page when it is being released.
716 */
drm_pagemap_page_free(struct page * page)717 static void drm_pagemap_page_free(struct page *page)
718 {
719 drm_pagemap_zdd_put(page->zone_device_data);
720 }
721
722 /**
723 * drm_pagemap_migrate_to_ram() - Migrate a virtual range to RAM (page fault handler)
724 * @vmf: Pointer to the fault information structure
725 *
726 * This function is a page fault handler used to migrate a virtual range
727 * to ram. The device memory allocation in which the device page is found is
728 * migrated in its entirety.
729 *
730 * Returns:
731 * VM_FAULT_SIGBUS on failure, 0 on success.
732 */
drm_pagemap_migrate_to_ram(struct vm_fault * vmf)733 static vm_fault_t drm_pagemap_migrate_to_ram(struct vm_fault *vmf)
734 {
735 struct drm_pagemap_zdd *zdd = vmf->page->zone_device_data;
736 int err;
737
738 err = __drm_pagemap_migrate_to_ram(vmf->vma,
739 zdd->device_private_page_owner,
740 vmf->page, vmf->address,
741 zdd->devmem_allocation->size);
742
743 return err ? VM_FAULT_SIGBUS : 0;
744 }
745
746 static const struct dev_pagemap_ops drm_pagemap_pagemap_ops = {
747 .page_free = drm_pagemap_page_free,
748 .migrate_to_ram = drm_pagemap_migrate_to_ram,
749 };
750
751 /**
752 * drm_pagemap_pagemap_ops_get() - Retrieve GPU SVM device page map operations
753 *
754 * Returns:
755 * Pointer to the GPU SVM device page map operations structure.
756 */
drm_pagemap_pagemap_ops_get(void)757 const struct dev_pagemap_ops *drm_pagemap_pagemap_ops_get(void)
758 {
759 return &drm_pagemap_pagemap_ops;
760 }
761 EXPORT_SYMBOL_GPL(drm_pagemap_pagemap_ops_get);
762
763 /**
764 * drm_pagemap_devmem_init() - Initialize a drm_pagemap device memory allocation
765 *
766 * @devmem_allocation: The struct drm_pagemap_devmem to initialize.
767 * @dev: Pointer to the device structure which device memory allocation belongs to
768 * @mm: Pointer to the mm_struct for the address space
769 * @ops: Pointer to the operations structure for GPU SVM device memory
770 * @dpagemap: The struct drm_pagemap we're allocating from.
771 * @size: Size of device memory allocation
772 */
drm_pagemap_devmem_init(struct drm_pagemap_devmem * devmem_allocation,struct device * dev,struct mm_struct * mm,const struct drm_pagemap_devmem_ops * ops,struct drm_pagemap * dpagemap,size_t size)773 void drm_pagemap_devmem_init(struct drm_pagemap_devmem *devmem_allocation,
774 struct device *dev, struct mm_struct *mm,
775 const struct drm_pagemap_devmem_ops *ops,
776 struct drm_pagemap *dpagemap, size_t size)
777 {
778 init_completion(&devmem_allocation->detached);
779 devmem_allocation->dev = dev;
780 devmem_allocation->mm = mm;
781 devmem_allocation->ops = ops;
782 devmem_allocation->dpagemap = dpagemap;
783 devmem_allocation->size = size;
784 }
785 EXPORT_SYMBOL_GPL(drm_pagemap_devmem_init);
786
787 /**
788 * drm_pagemap_page_to_dpagemap() - Return a pointer the drm_pagemap of a page
789 * @page: The struct page.
790 *
791 * Return: A pointer to the struct drm_pagemap of a device private page that
792 * was populated from the struct drm_pagemap. If the page was *not* populated
793 * from a struct drm_pagemap, the result is undefined and the function call
794 * may result in dereferencing and invalid address.
795 */
drm_pagemap_page_to_dpagemap(struct page * page)796 struct drm_pagemap *drm_pagemap_page_to_dpagemap(struct page *page)
797 {
798 struct drm_pagemap_zdd *zdd = page->zone_device_data;
799
800 return zdd->devmem_allocation->dpagemap;
801 }
802 EXPORT_SYMBOL_GPL(drm_pagemap_page_to_dpagemap);
803
804 /**
805 * drm_pagemap_populate_mm() - Populate a virtual range with device memory pages
806 * @dpagemap: Pointer to the drm_pagemap managing the device memory
807 * @start: Start of the virtual range to populate.
808 * @end: End of the virtual range to populate.
809 * @mm: Pointer to the virtual address space.
810 * @timeslice_ms: The time requested for the migrated pagemap pages to
811 * be present in @mm before being allowed to be migrated back.
812 *
813 * Attempt to populate a virtual range with device memory pages,
814 * clearing them or migrating data from the existing pages if necessary.
815 * The function is best effort only, and implementations may vary
816 * in how hard they try to satisfy the request.
817 *
818 * Return: %0 on success, negative error code on error. If the hardware
819 * device was removed / unbound the function will return %-ENODEV.
820 */
drm_pagemap_populate_mm(struct drm_pagemap * dpagemap,unsigned long start,unsigned long end,struct mm_struct * mm,unsigned long timeslice_ms)821 int drm_pagemap_populate_mm(struct drm_pagemap *dpagemap,
822 unsigned long start, unsigned long end,
823 struct mm_struct *mm,
824 unsigned long timeslice_ms)
825 {
826 int err;
827
828 if (!mmget_not_zero(mm))
829 return -EFAULT;
830 mmap_read_lock(mm);
831 err = dpagemap->ops->populate_mm(dpagemap, start, end, mm,
832 timeslice_ms);
833 mmap_read_unlock(mm);
834 mmput(mm);
835
836 return err;
837 }
838 EXPORT_SYMBOL(drm_pagemap_populate_mm);
839