1// SPDX-License-Identifier: MIT
2/*
3 * Copyright © 2014-2016 Intel Corporation
4 */
5
6#include <linux/vmalloc.h>
7
8#include <drm/drm_cache.h>
9#include <drm/drm_panic.h>
10#include <drm/drm_print.h>
11
12#include "display/intel_fb.h"
13#include "display/intel_display_types.h"
14#include "gt/intel_gt.h"
15#include "gt/intel_tlb.h"
16
17#include "i915_drv.h"
18#include "i915_gem_object.h"
19#include "i915_scatterlist.h"
20#include "i915_gem_lmem.h"
21#include "i915_gem_mman.h"
22
23void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
24 struct sg_table *pages)
25{
26 struct drm_i915_private *i915 = to_i915(dev: obj->base.dev);
27 unsigned long supported = RUNTIME_INFO(i915)->page_sizes;
28 bool shrinkable;
29 int i;
30
31 assert_object_held_shared(obj);
32
33 if (i915_gem_object_is_volatile(obj))
34 obj->mm.madv = I915_MADV_DONTNEED;
35
36 /* Make the pages coherent with the GPU (flushing any swapin). */
37 if (obj->cache_dirty) {
38 WARN_ON_ONCE(IS_DGFX(i915));
39 obj->write_domain = 0;
40 if (i915_gem_object_has_struct_page(obj))
41 drm_clflush_sg(st: pages);
42 obj->cache_dirty = false;
43 }
44
45 obj->mm.get_page.sg_pos = pages->sgl;
46 obj->mm.get_page.sg_idx = 0;
47 obj->mm.get_dma_page.sg_pos = pages->sgl;
48 obj->mm.get_dma_page.sg_idx = 0;
49
50 obj->mm.pages = pages;
51
52 obj->mm.page_sizes.phys = i915_sg_dma_sizes(sg: pages->sgl);
53 GEM_BUG_ON(!obj->mm.page_sizes.phys);
54
55 /*
56 * Calculate the supported page-sizes which fit into the given
57 * sg_page_sizes. This will give us the page-sizes which we may be able
58 * to use opportunistically when later inserting into the GTT. For
59 * example if phys=2G, then in theory we should be able to use 1G, 2M,
60 * 64K or 4K pages, although in practice this will depend on a number of
61 * other factors.
62 */
63 obj->mm.page_sizes.sg = 0;
64 for_each_set_bit(i, &supported, ilog2(I915_GTT_MAX_PAGE_SIZE) + 1) {
65 if (obj->mm.page_sizes.phys & ~0u << i)
66 obj->mm.page_sizes.sg |= BIT(i);
67 }
68 GEM_BUG_ON(!HAS_PAGE_SIZES(i915, obj->mm.page_sizes.sg));
69
70 shrinkable = i915_gem_object_is_shrinkable(obj);
71
72 if (i915_gem_object_is_tiled(obj) &&
73 i915->gem_quirks & GEM_QUIRK_PIN_SWIZZLED_PAGES) {
74 GEM_BUG_ON(i915_gem_object_has_tiling_quirk(obj));
75 i915_gem_object_set_tiling_quirk(obj);
76 GEM_BUG_ON(!list_empty(&obj->mm.link));
77 atomic_inc(v: &obj->mm.shrink_pin);
78 shrinkable = false;
79 }
80
81 if (shrinkable && !i915_gem_object_has_self_managed_shrink_list(obj)) {
82 struct list_head *list;
83 unsigned long flags;
84
85 assert_object_held(obj);
86 spin_lock_irqsave(&i915->mm.obj_lock, flags);
87
88 i915->mm.shrink_count++;
89 i915->mm.shrink_memory += obj->base.size;
90
91 if (obj->mm.madv != I915_MADV_WILLNEED)
92 list = &i915->mm.purge_list;
93 else
94 list = &i915->mm.shrink_list;
95 list_add_tail(new: &obj->mm.link, head: list);
96
97 atomic_set(v: &obj->mm.shrink_pin, i: 0);
98 spin_unlock_irqrestore(lock: &i915->mm.obj_lock, flags);
99 }
100}
101
102int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
103{
104 struct drm_i915_private *i915 = to_i915(dev: obj->base.dev);
105 int err;
106
107 assert_object_held_shared(obj);
108
109 if (unlikely(obj->mm.madv != I915_MADV_WILLNEED)) {
110 drm_dbg(&i915->drm,
111 "Attempting to obtain a purgeable object\n");
112 return -EFAULT;
113 }
114
115 err = obj->ops->get_pages(obj);
116 GEM_BUG_ON(!err && !i915_gem_object_has_pages(obj));
117
118 return err;
119}
120
121/* Ensure that the associated pages are gathered from the backing storage
122 * and pinned into our object. i915_gem_object_pin_pages() may be called
123 * multiple times before they are released by a single call to
124 * i915_gem_object_unpin_pages() - once the pages are no longer referenced
125 * either as a result of memory pressure (reaping pages under the shrinker)
126 * or as the object is itself released.
127 */
128int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
129{
130 int err;
131
132 assert_object_held(obj);
133
134 assert_object_held_shared(obj);
135
136 if (unlikely(!i915_gem_object_has_pages(obj))) {
137 GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));
138
139 err = ____i915_gem_object_get_pages(obj);
140 if (err)
141 return err;
142
143 smp_mb__before_atomic();
144 }
145 atomic_inc(v: &obj->mm.pages_pin_count);
146
147 return 0;
148}
149
150int i915_gem_object_pin_pages_unlocked(struct drm_i915_gem_object *obj)
151{
152 struct i915_gem_ww_ctx ww;
153 int err;
154
155 i915_gem_ww_ctx_init(ctx: &ww, intr: true);
156retry:
157 err = i915_gem_object_lock(obj, ww: &ww);
158 if (!err)
159 err = i915_gem_object_pin_pages(obj);
160
161 if (err == -EDEADLK) {
162 err = i915_gem_ww_ctx_backoff(ctx: &ww);
163 if (!err)
164 goto retry;
165 }
166 i915_gem_ww_ctx_fini(ctx: &ww);
167 return err;
168}
169
170/* Immediately discard the backing storage */
171int i915_gem_object_truncate(struct drm_i915_gem_object *obj)
172{
173 if (obj->ops->truncate)
174 return obj->ops->truncate(obj);
175
176 return 0;
177}
178
179static void __i915_gem_object_reset_page_iter(struct drm_i915_gem_object *obj)
180{
181 struct radix_tree_iter iter;
182 void __rcu **slot;
183
184 rcu_read_lock();
185 radix_tree_for_each_slot(slot, &obj->mm.get_page.radix, &iter, 0)
186 radix_tree_delete(&obj->mm.get_page.radix, iter.index);
187 radix_tree_for_each_slot(slot, &obj->mm.get_dma_page.radix, &iter, 0)
188 radix_tree_delete(&obj->mm.get_dma_page.radix, iter.index);
189 rcu_read_unlock();
190}
191
192static void unmap_object(struct drm_i915_gem_object *obj, void *ptr)
193{
194 if (is_vmalloc_addr(x: ptr))
195 vunmap(addr: ptr);
196}
197
198static void flush_tlb_invalidate(struct drm_i915_gem_object *obj)
199{
200 struct drm_i915_private *i915 = to_i915(dev: obj->base.dev);
201 struct intel_gt *gt;
202 int id;
203
204 for_each_gt(gt, i915, id) {
205 if (!obj->mm.tlb[id])
206 continue;
207
208 intel_gt_invalidate_tlb_full(gt, seqno: obj->mm.tlb[id]);
209 obj->mm.tlb[id] = 0;
210 }
211}
212
213struct sg_table *
214__i915_gem_object_unset_pages(struct drm_i915_gem_object *obj)
215{
216 struct sg_table *pages;
217
218 assert_object_held_shared(obj);
219
220 pages = fetch_and_zero(&obj->mm.pages);
221 if (IS_ERR_OR_NULL(ptr: pages))
222 return pages;
223
224 if (i915_gem_object_is_volatile(obj))
225 obj->mm.madv = I915_MADV_WILLNEED;
226
227 if (!i915_gem_object_has_self_managed_shrink_list(obj))
228 i915_gem_object_make_unshrinkable(obj);
229
230 if (obj->mm.mapping) {
231 unmap_object(obj, page_mask_bits(obj->mm.mapping));
232 obj->mm.mapping = NULL;
233 }
234
235 __i915_gem_object_reset_page_iter(obj);
236 obj->mm.page_sizes.phys = obj->mm.page_sizes.sg = 0;
237
238 flush_tlb_invalidate(obj);
239
240 return pages;
241}
242
243int __i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
244{
245 struct sg_table *pages;
246
247 if (i915_gem_object_has_pinned_pages(obj))
248 return -EBUSY;
249
250 /* May be called by shrinker from within get_pages() (on another bo) */
251 assert_object_held_shared(obj);
252
253 i915_gem_object_release_mmap_offset(obj);
254
255 /*
256 * ->put_pages might need to allocate memory for the bit17 swizzle
257 * array, hence protect them from being reaped by removing them from gtt
258 * lists early.
259 */
260 pages = __i915_gem_object_unset_pages(obj);
261
262 /*
263 * XXX Temporary hijinx to avoid updating all backends to handle
264 * NULL pages. In the future, when we have more asynchronous
265 * get_pages backends we should be better able to handle the
266 * cancellation of the async task in a more uniform manner.
267 */
268 if (!IS_ERR_OR_NULL(ptr: pages))
269 obj->ops->put_pages(obj, pages);
270
271 return 0;
272}
273
274/* The 'mapping' part of i915_gem_object_pin_map() below */
275static void *i915_gem_object_map_page(struct drm_i915_gem_object *obj,
276 enum i915_map_type type)
277{
278 unsigned long n_pages = obj->base.size >> PAGE_SHIFT, i;
279 struct page *stack[32], **pages = stack, *page;
280 struct sgt_iter iter;
281 pgprot_t pgprot;
282 void *vaddr;
283
284 switch (type) {
285 default:
286 MISSING_CASE(type);
287 fallthrough; /* to use PAGE_KERNEL anyway */
288 case I915_MAP_WB:
289 /*
290 * On 32b, highmem using a finite set of indirect PTE (i.e.
291 * vmap) to provide virtual mappings of the high pages.
292 * As these are finite, map_new_virtual() must wait for some
293 * other kmap() to finish when it runs out. If we map a large
294 * number of objects, there is no method for it to tell us
295 * to release the mappings, and we deadlock.
296 *
297 * However, if we make an explicit vmap of the page, that
298 * uses a larger vmalloc arena, and also has the ability
299 * to tell us to release unwanted mappings. Most importantly,
300 * it will fail and propagate an error instead of waiting
301 * forever.
302 *
303 * So if the page is beyond the 32b boundary, make an explicit
304 * vmap.
305 */
306 if (n_pages == 1 && !PageHighMem(page: sg_page(sg: obj->mm.pages->sgl)))
307 return page_address(sg_page(obj->mm.pages->sgl));
308 pgprot = PAGE_KERNEL;
309 break;
310 case I915_MAP_WC:
311 pgprot = pgprot_writecombine(PAGE_KERNEL_IO);
312 break;
313 }
314
315 if (n_pages > ARRAY_SIZE(stack)) {
316 /* Too big for stack -- allocate temporary array instead */
317 pages = kvmalloc_array(n_pages, sizeof(*pages), GFP_KERNEL);
318 if (!pages)
319 return ERR_PTR(error: -ENOMEM);
320 }
321
322 i = 0;
323 for_each_sgt_page(page, iter, obj->mm.pages)
324 pages[i++] = page;
325 vaddr = vmap(pages, count: n_pages, flags: 0, prot: pgprot);
326 if (pages != stack)
327 kvfree(addr: pages);
328
329 return vaddr ?: ERR_PTR(error: -ENOMEM);
330}
331
332static void *i915_gem_object_map_pfn(struct drm_i915_gem_object *obj,
333 enum i915_map_type type)
334{
335 resource_size_t iomap = obj->mm.region->iomap.base -
336 obj->mm.region->region.start;
337 unsigned long n_pfn = obj->base.size >> PAGE_SHIFT;
338 unsigned long stack[32], *pfns = stack, i;
339 struct sgt_iter iter;
340 dma_addr_t addr;
341 void *vaddr;
342
343 GEM_BUG_ON(type != I915_MAP_WC);
344
345 if (n_pfn > ARRAY_SIZE(stack)) {
346 /* Too big for stack -- allocate temporary array instead */
347 pfns = kvmalloc_array(n_pfn, sizeof(*pfns), GFP_KERNEL);
348 if (!pfns)
349 return ERR_PTR(error: -ENOMEM);
350 }
351
352 i = 0;
353 for_each_sgt_daddr(addr, iter, obj->mm.pages)
354 pfns[i++] = (iomap + addr) >> PAGE_SHIFT;
355 vaddr = vmap_pfn(pfns, count: n_pfn, pgprot_writecombine(PAGE_KERNEL_IO));
356 if (pfns != stack)
357 kvfree(addr: pfns);
358
359 return vaddr ?: ERR_PTR(error: -ENOMEM);
360}
361
362struct intel_panic {
363 struct page **pages;
364 int page;
365 void *vaddr;
366};
367
368static void i915_panic_kunmap(struct intel_panic *panic)
369{
370 if (panic->vaddr) {
371 drm_clflush_virt_range(addr: panic->vaddr, PAGE_SIZE);
372 kunmap_local(panic->vaddr);
373 panic->vaddr = NULL;
374 }
375}
376
377static struct page **i915_gem_object_panic_pages(struct drm_i915_gem_object *obj)
378{
379 unsigned long n_pages = obj->base.size >> PAGE_SHIFT, i;
380 struct page *page;
381 struct page **pages;
382 struct sgt_iter iter;
383
384 /* For a 3840x2160 32 bits Framebuffer, this should require ~64K */
385 pages = kmalloc_array(n_pages, sizeof(*pages), GFP_ATOMIC);
386 if (!pages)
387 return NULL;
388
389 i = 0;
390 for_each_sgt_page(page, iter, obj->mm.pages)
391 pages[i++] = page;
392 return pages;
393}
394
395static void i915_gem_object_panic_map_set_pixel(struct drm_scanout_buffer *sb, unsigned int x,
396 unsigned int y, u32 color)
397{
398 struct intel_framebuffer *fb = (struct intel_framebuffer *)sb->private;
399 unsigned int offset = fb->panic_tiling(sb->width, x, y);
400
401 iosys_map_wr(&sb->map[0], offset, u32, color);
402}
403
404/*
405 * The scanout buffer pages are not mapped, so for each pixel,
406 * use kmap_local_page_try_from_panic() to map the page, and write the pixel.
407 * Try to keep the map from the previous pixel, to avoid too much map/unmap.
408 */
409static void i915_gem_object_panic_page_set_pixel(struct drm_scanout_buffer *sb, unsigned int x,
410 unsigned int y, u32 color)
411{
412 unsigned int new_page;
413 unsigned int offset;
414 struct intel_framebuffer *fb = (struct intel_framebuffer *)sb->private;
415 struct intel_panic *panic = fb->panic;
416
417 if (fb->panic_tiling)
418 offset = fb->panic_tiling(sb->width, x, y);
419 else
420 offset = y * sb->pitch[0] + x * sb->format->cpp[0];
421
422 new_page = offset >> PAGE_SHIFT;
423 offset = offset % PAGE_SIZE;
424 if (new_page != panic->page) {
425 i915_panic_kunmap(panic);
426 panic->page = new_page;
427 panic->vaddr =
428 kmap_local_page_try_from_panic(page: panic->pages[panic->page]);
429 }
430 if (panic->vaddr) {
431 u32 *pix = panic->vaddr + offset;
432 *pix = color;
433 }
434}
435
436struct intel_panic *i915_gem_object_alloc_panic(void)
437{
438 struct intel_panic *panic;
439
440 panic = kzalloc(sizeof(*panic), GFP_KERNEL);
441
442 return panic;
443}
444
445/*
446 * Setup the gem framebuffer for drm_panic access.
447 * Use current vaddr if it exists, or setup a list of pages.
448 * pfn is not supported yet.
449 */
450int i915_gem_object_panic_setup(struct intel_panic *panic, struct drm_scanout_buffer *sb,
451 struct drm_gem_object *_obj, bool panic_tiling)
452{
453 enum i915_map_type has_type;
454 struct drm_i915_gem_object *obj = to_intel_bo(gem: _obj);
455 void *ptr;
456
457 ptr = page_unpack_bits(obj->mm.mapping, &has_type);
458 if (ptr) {
459 if (i915_gem_object_has_iomem(obj))
460 iosys_map_set_vaddr_iomem(map: &sb->map[0], vaddr_iomem: (void __iomem *)ptr);
461 else
462 iosys_map_set_vaddr(map: &sb->map[0], vaddr: ptr);
463
464 if (panic_tiling)
465 sb->set_pixel = i915_gem_object_panic_map_set_pixel;
466 return 0;
467 }
468 if (i915_gem_object_has_struct_page(obj)) {
469 panic->pages = i915_gem_object_panic_pages(obj);
470 if (!panic->pages)
471 return -ENOMEM;
472 panic->page = -1;
473 sb->set_pixel = i915_gem_object_panic_page_set_pixel;
474 return 0;
475 }
476 return -EOPNOTSUPP;
477}
478
479void i915_gem_object_panic_finish(struct intel_panic *panic)
480{
481 i915_panic_kunmap(panic);
482 panic->page = -1;
483 kfree(objp: panic->pages);
484 panic->pages = NULL;
485}
486
487/* get, pin, and map the pages of the object into kernel space */
488void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
489 enum i915_map_type type)
490{
491 enum i915_map_type has_type;
492 bool pinned;
493 void *ptr;
494 int err;
495
496 if (!i915_gem_object_has_struct_page(obj) &&
497 !i915_gem_object_has_iomem(obj))
498 return ERR_PTR(error: -ENXIO);
499
500 if (WARN_ON_ONCE(obj->flags & I915_BO_ALLOC_GPU_ONLY))
501 return ERR_PTR(error: -EINVAL);
502
503 assert_object_held(obj);
504
505 pinned = !(type & I915_MAP_OVERRIDE);
506 type &= ~I915_MAP_OVERRIDE;
507
508 if (!atomic_inc_not_zero(v: &obj->mm.pages_pin_count)) {
509 if (unlikely(!i915_gem_object_has_pages(obj))) {
510 GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));
511
512 err = ____i915_gem_object_get_pages(obj);
513 if (err)
514 return ERR_PTR(error: err);
515
516 smp_mb__before_atomic();
517 }
518 atomic_inc(v: &obj->mm.pages_pin_count);
519 pinned = false;
520 }
521 GEM_BUG_ON(!i915_gem_object_has_pages(obj));
522
523 /*
524 * For discrete our CPU mappings needs to be consistent in order to
525 * function correctly on !x86. When mapping things through TTM, we use
526 * the same rules to determine the caching type.
527 *
528 * The caching rules, starting from DG1:
529 *
530 * - If the object can be placed in device local-memory, then the
531 * pages should be allocated and mapped as write-combined only.
532 *
533 * - Everything else is always allocated and mapped as write-back,
534 * with the guarantee that everything is also coherent with the
535 * GPU.
536 *
537 * Internal users of lmem are already expected to get this right, so no
538 * fudging needed there.
539 */
540 if (i915_gem_object_placement_possible(obj, type: INTEL_MEMORY_LOCAL)) {
541 if (type != I915_MAP_WC && !obj->mm.n_placements) {
542 ptr = ERR_PTR(error: -ENODEV);
543 goto err_unpin;
544 }
545
546 type = I915_MAP_WC;
547 } else if (IS_DGFX(to_i915(obj->base.dev))) {
548 type = I915_MAP_WB;
549 }
550
551 ptr = page_unpack_bits(obj->mm.mapping, &has_type);
552 if (ptr && has_type != type) {
553 if (pinned) {
554 ptr = ERR_PTR(error: -EBUSY);
555 goto err_unpin;
556 }
557
558 unmap_object(obj, ptr);
559
560 ptr = obj->mm.mapping = NULL;
561 }
562
563 if (!ptr) {
564 err = i915_gem_object_wait_moving_fence(obj, intr: true);
565 if (err) {
566 ptr = ERR_PTR(error: err);
567 goto err_unpin;
568 }
569
570 if (GEM_WARN_ON(type == I915_MAP_WC && !pat_enabled()))
571 ptr = ERR_PTR(error: -ENODEV);
572 else if (i915_gem_object_has_struct_page(obj))
573 ptr = i915_gem_object_map_page(obj, type);
574 else
575 ptr = i915_gem_object_map_pfn(obj, type);
576 if (IS_ERR(ptr))
577 goto err_unpin;
578
579 obj->mm.mapping = page_pack_bits(ptr, type);
580 }
581
582 return ptr;
583
584err_unpin:
585 atomic_dec(v: &obj->mm.pages_pin_count);
586 return ptr;
587}
588
589void *i915_gem_object_pin_map_unlocked(struct drm_i915_gem_object *obj,
590 enum i915_map_type type)
591{
592 void *ret;
593
594 i915_gem_object_lock(obj, NULL);
595 ret = i915_gem_object_pin_map(obj, type);
596 i915_gem_object_unlock(obj);
597
598 return ret;
599}
600
601void __i915_gem_object_flush_map(struct drm_i915_gem_object *obj,
602 unsigned long offset,
603 unsigned long size)
604{
605 enum i915_map_type has_type;
606 void *ptr;
607
608 GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
609 GEM_BUG_ON(range_overflows_t(typeof(obj->base.size),
610 offset, size, obj->base.size));
611
612 wmb(); /* let all previous writes be visible to coherent partners */
613 obj->mm.dirty = true;
614
615 if (obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_WRITE)
616 return;
617
618 ptr = page_unpack_bits(obj->mm.mapping, &has_type);
619 if (has_type == I915_MAP_WC)
620 return;
621
622 drm_clflush_virt_range(addr: ptr + offset, length: size);
623 if (size == obj->base.size) {
624 obj->write_domain &= ~I915_GEM_DOMAIN_CPU;
625 obj->cache_dirty = false;
626 }
627}
628
629void __i915_gem_object_release_map(struct drm_i915_gem_object *obj)
630{
631 GEM_BUG_ON(!obj->mm.mapping);
632
633 /*
634 * We allow removing the mapping from underneath pinned pages!
635 *
636 * Furthermore, since this is an unsafe operation reserved only
637 * for construction time manipulation, we ignore locking prudence.
638 */
639 unmap_object(obj, page_mask_bits(fetch_and_zero(&obj->mm.mapping)));
640
641 i915_gem_object_unpin_map(obj);
642}
643
644struct scatterlist *
645__i915_gem_object_page_iter_get_sg(struct drm_i915_gem_object *obj,
646 struct i915_gem_object_page_iter *iter,
647 pgoff_t n,
648 unsigned int *offset)
649
650{
651 const bool dma = iter == &obj->mm.get_dma_page ||
652 iter == &obj->ttm.get_io_page;
653 unsigned int idx, count;
654 struct scatterlist *sg;
655
656 might_sleep();
657 GEM_BUG_ON(n >= obj->base.size >> PAGE_SHIFT);
658 if (!i915_gem_object_has_pinned_pages(obj))
659 assert_object_held(obj);
660
661 /* As we iterate forward through the sg, we record each entry in a
662 * radixtree for quick repeated (backwards) lookups. If we have seen
663 * this index previously, we will have an entry for it.
664 *
665 * Initial lookup is O(N), but this is amortized to O(1) for
666 * sequential page access (where each new request is consecutive
667 * to the previous one). Repeated lookups are O(lg(obj->base.size)),
668 * i.e. O(1) with a large constant!
669 */
670 if (n < READ_ONCE(iter->sg_idx))
671 goto lookup;
672
673 mutex_lock(&iter->lock);
674
675 /* We prefer to reuse the last sg so that repeated lookup of this
676 * (or the subsequent) sg are fast - comparing against the last
677 * sg is faster than going through the radixtree.
678 */
679
680 sg = iter->sg_pos;
681 idx = iter->sg_idx;
682 count = dma ? __sg_dma_page_count(sg) : __sg_page_count(sg);
683
684 while (idx + count <= n) {
685 void *entry;
686 unsigned long i;
687 int ret;
688
689 /* If we cannot allocate and insert this entry, or the
690 * individual pages from this range, cancel updating the
691 * sg_idx so that on this lookup we are forced to linearly
692 * scan onwards, but on future lookups we will try the
693 * insertion again (in which case we need to be careful of
694 * the error return reporting that we have already inserted
695 * this index).
696 */
697 ret = radix_tree_insert(&iter->radix, index: idx, sg);
698 if (ret && ret != -EEXIST)
699 goto scan;
700
701 entry = xa_mk_value(v: idx);
702 for (i = 1; i < count; i++) {
703 ret = radix_tree_insert(&iter->radix, index: idx + i, entry);
704 if (ret && ret != -EEXIST)
705 goto scan;
706 }
707
708 idx += count;
709 sg = ____sg_next(sg);
710 count = dma ? __sg_dma_page_count(sg) : __sg_page_count(sg);
711 }
712
713scan:
714 iter->sg_pos = sg;
715 iter->sg_idx = idx;
716
717 mutex_unlock(lock: &iter->lock);
718
719 if (unlikely(n < idx)) /* insertion completed by another thread */
720 goto lookup;
721
722 /* In case we failed to insert the entry into the radixtree, we need
723 * to look beyond the current sg.
724 */
725 while (idx + count <= n) {
726 idx += count;
727 sg = ____sg_next(sg);
728 count = dma ? __sg_dma_page_count(sg) : __sg_page_count(sg);
729 }
730
731 *offset = n - idx;
732 return sg;
733
734lookup:
735 rcu_read_lock();
736
737 sg = radix_tree_lookup(&iter->radix, n);
738 GEM_BUG_ON(!sg);
739
740 /* If this index is in the middle of multi-page sg entry,
741 * the radix tree will contain a value entry that points
742 * to the start of that range. We will return the pointer to
743 * the base page and the offset of this page within the
744 * sg entry's range.
745 */
746 *offset = 0;
747 if (unlikely(xa_is_value(sg))) {
748 unsigned long base = xa_to_value(entry: sg);
749
750 sg = radix_tree_lookup(&iter->radix, base);
751 GEM_BUG_ON(!sg);
752
753 *offset = n - base;
754 }
755
756 rcu_read_unlock();
757
758 return sg;
759}
760
761struct page *
762__i915_gem_object_get_page(struct drm_i915_gem_object *obj, pgoff_t n)
763{
764 struct scatterlist *sg;
765 unsigned int offset;
766
767 GEM_BUG_ON(!i915_gem_object_has_struct_page(obj));
768
769 sg = i915_gem_object_get_sg(obj, n, &offset);
770 return sg_page(sg) + offset;
771}
772
773/* Like i915_gem_object_get_page(), but mark the returned page dirty */
774struct page *
775__i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, pgoff_t n)
776{
777 struct page *page;
778
779 page = i915_gem_object_get_page(obj, n);
780 if (!obj->mm.dirty)
781 set_page_dirty(page);
782
783 return page;
784}
785
786dma_addr_t
787__i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj,
788 pgoff_t n, unsigned int *len)
789{
790 struct scatterlist *sg;
791 unsigned int offset;
792
793 sg = i915_gem_object_get_sg_dma(obj, n, &offset);
794
795 if (len)
796 *len = sg_dma_len(sg) - (offset << PAGE_SHIFT);
797
798 return sg_dma_address(sg) + (offset << PAGE_SHIFT);
799}
800
801dma_addr_t
802__i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj, pgoff_t n)
803{
804 return i915_gem_object_get_dma_address_len(obj, n, NULL);
805}
806

source code of linux/drivers/gpu/drm/i915/gem/i915_gem_pages.c