1/* SPDX-License-Identifier: GPL-2.0 OR MIT */
2/**************************************************************************
3 *
4 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
5 * All Rights Reserved.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the
9 * "Software"), to deal in the Software without restriction, including
10 * without limitation the rights to use, copy, modify, merge, publish,
11 * distribute, sub license, and/or sell copies of the Software, and to
12 * permit persons to whom the Software is furnished to do so, subject to
13 * the following conditions:
14 *
15 * The above copyright notice and this permission notice (including the
16 * next paragraph) shall be included in all copies or substantial portions
17 * of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
22 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
23 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
24 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
25 * USE OR OTHER DEALINGS IN THE SOFTWARE.
26 *
27 **************************************************************************/
28/*
29 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
30 */
31
32#define pr_fmt(fmt) "[TTM] " fmt
33
34#include <linux/export.h>
35
36#include <drm/ttm/ttm_bo.h>
37#include <drm/ttm/ttm_placement.h>
38#include <drm/ttm/ttm_tt.h>
39
40#include <drm/drm_drv.h>
41#include <drm/drm_managed.h>
42
43static vm_fault_t ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,
44 struct vm_fault *vmf)
45{
46 long err = 0;
47
48 /*
49 * Quick non-stalling check for idle.
50 */
51 if (dma_resv_test_signaled(obj: bo->base.resv, usage: DMA_RESV_USAGE_KERNEL))
52 return 0;
53
54 /*
55 * If possible, avoid waiting for GPU with mmap_lock
56 * held. We only do this if the fault allows retry and this
57 * is the first attempt.
58 */
59 if (fault_flag_allow_retry_first(flags: vmf->flags)) {
60 if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
61 return VM_FAULT_RETRY;
62
63 drm_gem_object_get(obj: &bo->base);
64 mmap_read_unlock(mm: vmf->vma->vm_mm);
65 (void)dma_resv_wait_timeout(obj: bo->base.resv,
66 usage: DMA_RESV_USAGE_KERNEL, intr: true,
67 MAX_SCHEDULE_TIMEOUT);
68 dma_resv_unlock(obj: bo->base.resv);
69 drm_gem_object_put(obj: &bo->base);
70 return VM_FAULT_RETRY;
71 }
72
73 /*
74 * Ordinary wait.
75 */
76 err = dma_resv_wait_timeout(obj: bo->base.resv, usage: DMA_RESV_USAGE_KERNEL, intr: true,
77 MAX_SCHEDULE_TIMEOUT);
78 if (unlikely(err < 0)) {
79 return (err != -ERESTARTSYS) ? VM_FAULT_SIGBUS :
80 VM_FAULT_NOPAGE;
81 }
82
83 return 0;
84}
85
86static unsigned long ttm_bo_io_mem_pfn(struct ttm_buffer_object *bo,
87 unsigned long page_offset)
88{
89 struct ttm_device *bdev = bo->bdev;
90
91 if (bdev->funcs->io_mem_pfn)
92 return bdev->funcs->io_mem_pfn(bo, page_offset);
93
94 return (bo->resource->bus.offset >> PAGE_SHIFT) + page_offset;
95}
96
97/**
98 * ttm_bo_vm_reserve - Reserve a buffer object in a retryable vm callback
99 * @bo: The buffer object
100 * @vmf: The fault structure handed to the callback
101 *
102 * vm callbacks like fault() and *_mkwrite() allow for the mmap_lock to be dropped
103 * during long waits, and after the wait the callback will be restarted. This
104 * is to allow other threads using the same virtual memory space concurrent
105 * access to map(), unmap() completely unrelated buffer objects. TTM buffer
106 * object reservations sometimes wait for GPU and should therefore be
107 * considered long waits. This function reserves the buffer object interruptibly
108 * taking this into account. Starvation is avoided by the vm system not
109 * allowing too many repeated restarts.
110 * This function is intended to be used in customized fault() and _mkwrite()
111 * handlers.
112 *
113 * Return:
114 * 0 on success and the bo was reserved.
115 * VM_FAULT_RETRY if blocking wait.
116 * VM_FAULT_NOPAGE if blocking wait and retrying was not allowed.
117 */
118vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
119 struct vm_fault *vmf)
120{
121 /*
122 * Work around locking order reversal in fault / nopfn
123 * between mmap_lock and bo_reserve: Perform a trylock operation
124 * for reserve, and if it fails, retry the fault after waiting
125 * for the buffer to become unreserved.
126 */
127 if (unlikely(!dma_resv_trylock(bo->base.resv))) {
128 /*
129 * If the fault allows retry and this is the first
130 * fault attempt, we try to release the mmap_lock
131 * before waiting
132 */
133 if (fault_flag_allow_retry_first(flags: vmf->flags)) {
134 if (!(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
135 drm_gem_object_get(obj: &bo->base);
136 mmap_read_unlock(mm: vmf->vma->vm_mm);
137 if (!dma_resv_lock_interruptible(obj: bo->base.resv,
138 NULL))
139 dma_resv_unlock(obj: bo->base.resv);
140 drm_gem_object_put(obj: &bo->base);
141 }
142
143 return VM_FAULT_RETRY;
144 }
145
146 if (dma_resv_lock_interruptible(obj: bo->base.resv, NULL))
147 return VM_FAULT_NOPAGE;
148 }
149
150 /*
151 * Refuse to fault imported pages. This should be handled
152 * (if at all) by redirecting mmap to the exporter.
153 */
154 if (bo->ttm && (bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL)) {
155 if (!(bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL_MAPPABLE)) {
156 dma_resv_unlock(obj: bo->base.resv);
157 return VM_FAULT_SIGBUS;
158 }
159 }
160
161 return 0;
162}
163EXPORT_SYMBOL(ttm_bo_vm_reserve);
164
165/**
166 * ttm_bo_vm_fault_reserved - TTM fault helper
167 * @vmf: The struct vm_fault given as argument to the fault callback
168 * @prot: The page protection to be used for this memory area.
169 * @num_prefault: Maximum number of prefault pages. The caller may want to
170 * specify this based on madvice settings and the size of the GPU object
171 * backed by the memory.
172 *
173 * This function inserts one or more page table entries pointing to the
174 * memory backing the buffer object, and then returns a return code
175 * instructing the caller to retry the page access.
176 *
177 * Return:
178 * VM_FAULT_NOPAGE on success or pending signal
179 * VM_FAULT_SIGBUS on unspecified error
180 * VM_FAULT_OOM on out-of-memory
181 * VM_FAULT_RETRY if retryable wait
182 */
183vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
184 pgprot_t prot,
185 pgoff_t num_prefault)
186{
187 struct vm_area_struct *vma = vmf->vma;
188 struct ttm_buffer_object *bo = vma->vm_private_data;
189 struct ttm_device *bdev = bo->bdev;
190 unsigned long page_offset;
191 unsigned long page_last;
192 unsigned long pfn;
193 struct ttm_tt *ttm = NULL;
194 struct page *page;
195 int err;
196 pgoff_t i;
197 vm_fault_t ret = VM_FAULT_NOPAGE;
198 unsigned long address = vmf->address;
199
200 /*
201 * Wait for buffer data in transit, due to a pipelined
202 * move.
203 */
204 ret = ttm_bo_vm_fault_idle(bo, vmf);
205 if (unlikely(ret != 0))
206 return ret;
207
208 err = ttm_mem_io_reserve(bdev, mem: bo->resource);
209 if (unlikely(err != 0))
210 return VM_FAULT_SIGBUS;
211
212 page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
213 vma->vm_pgoff - drm_vma_node_start(node: &bo->base.vma_node);
214 page_last = vma_pages(vma) + vma->vm_pgoff -
215 drm_vma_node_start(node: &bo->base.vma_node);
216
217 if (unlikely(page_offset >= PFN_UP(bo->base.size)))
218 return VM_FAULT_SIGBUS;
219
220 prot = ttm_io_prot(bo, res: bo->resource, tmp: prot);
221 if (!bo->resource->bus.is_iomem) {
222 struct ttm_operation_ctx ctx = {
223 .interruptible = true,
224 .no_wait_gpu = false,
225 };
226
227 ttm = bo->ttm;
228 err = ttm_bo_populate(bo, ctx: &ctx);
229 if (err) {
230 if (err == -EINTR || err == -ERESTARTSYS ||
231 err == -EAGAIN)
232 return VM_FAULT_NOPAGE;
233
234 pr_debug("TTM fault hit %pe.\n", ERR_PTR(err));
235 return VM_FAULT_SIGBUS;
236 }
237 } else {
238 /* Iomem should not be marked encrypted */
239 prot = pgprot_decrypted(prot);
240 }
241
242 /*
243 * Speculatively prefault a number of pages. Only error on
244 * first page.
245 */
246 for (i = 0; i < num_prefault; ++i) {
247 if (bo->resource->bus.is_iomem) {
248 pfn = ttm_bo_io_mem_pfn(bo, page_offset);
249 } else {
250 page = ttm->pages[page_offset];
251 if (unlikely(!page && i == 0)) {
252 return VM_FAULT_OOM;
253 } else if (unlikely(!page)) {
254 break;
255 }
256 pfn = page_to_pfn(page);
257 }
258
259 /*
260 * Note that the value of @prot at this point may differ from
261 * the value of @vma->vm_page_prot in the caching- and
262 * encryption bits. This is because the exact location of the
263 * data may not be known at mmap() time and may also change
264 * at arbitrary times while the data is mmap'ed.
265 * See vmf_insert_pfn_prot() for a discussion.
266 */
267 ret = vmf_insert_pfn_prot(vma, addr: address, pfn, pgprot: prot);
268
269 /* Never error on prefaulted PTEs */
270 if (unlikely((ret & VM_FAULT_ERROR))) {
271 if (i == 0)
272 return VM_FAULT_NOPAGE;
273 else
274 break;
275 }
276
277 address += PAGE_SIZE;
278 if (unlikely(++page_offset >= page_last))
279 break;
280 }
281 return ret;
282}
283EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);
284
285static void ttm_bo_release_dummy_page(struct drm_device *dev, void *res)
286{
287 struct page *dummy_page = (struct page *)res;
288
289 __free_page(dummy_page);
290}
291
292vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot)
293{
294 struct vm_area_struct *vma = vmf->vma;
295 struct ttm_buffer_object *bo = vma->vm_private_data;
296 struct drm_device *ddev = bo->base.dev;
297 vm_fault_t ret = VM_FAULT_NOPAGE;
298 unsigned long address;
299 unsigned long pfn;
300 struct page *page;
301
302 /* Allocate new dummy page to map all the VA range in this VMA to it*/
303 page = alloc_page(GFP_KERNEL | __GFP_ZERO);
304 if (!page)
305 return VM_FAULT_OOM;
306
307 /* Set the page to be freed using drmm release action */
308 if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page, page))
309 return VM_FAULT_OOM;
310
311 pfn = page_to_pfn(page);
312
313 /* Prefault the entire VMA range right away to avoid further faults */
314 for (address = vma->vm_start; address < vma->vm_end;
315 address += PAGE_SIZE)
316 ret = vmf_insert_pfn_prot(vma, addr: address, pfn, pgprot: prot);
317
318 return ret;
319}
320EXPORT_SYMBOL(ttm_bo_vm_dummy_page);
321
322vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
323{
324 struct vm_area_struct *vma = vmf->vma;
325 pgprot_t prot;
326 struct ttm_buffer_object *bo = vma->vm_private_data;
327 struct drm_device *ddev = bo->base.dev;
328 vm_fault_t ret;
329 int idx;
330
331 ret = ttm_bo_vm_reserve(bo, vmf);
332 if (ret)
333 return ret;
334
335 prot = vma->vm_page_prot;
336 if (drm_dev_enter(dev: ddev, idx: &idx)) {
337 ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT);
338 drm_dev_exit(idx);
339 } else {
340 ret = ttm_bo_vm_dummy_page(vmf, prot);
341 }
342 if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
343 return ret;
344
345 dma_resv_unlock(obj: bo->base.resv);
346
347 return ret;
348}
349EXPORT_SYMBOL(ttm_bo_vm_fault);
350
351void ttm_bo_vm_open(struct vm_area_struct *vma)
352{
353 struct ttm_buffer_object *bo = vma->vm_private_data;
354
355 WARN_ON(bo->bdev->dev_mapping != vma->vm_file->f_mapping);
356
357 drm_gem_object_get(obj: &bo->base);
358}
359EXPORT_SYMBOL(ttm_bo_vm_open);
360
361void ttm_bo_vm_close(struct vm_area_struct *vma)
362{
363 struct ttm_buffer_object *bo = vma->vm_private_data;
364
365 drm_gem_object_put(obj: &bo->base);
366 vma->vm_private_data = NULL;
367}
368EXPORT_SYMBOL(ttm_bo_vm_close);
369
370static int ttm_bo_vm_access_kmap(struct ttm_buffer_object *bo,
371 unsigned long offset,
372 uint8_t *buf, int len, int write)
373{
374 unsigned long page = offset >> PAGE_SHIFT;
375 unsigned long bytes_left = len;
376 int ret;
377
378 /* Copy a page at a time, that way no extra virtual address
379 * mapping is needed
380 */
381 offset -= page << PAGE_SHIFT;
382 do {
383 unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
384 struct ttm_bo_kmap_obj map;
385 void *ptr;
386 bool is_iomem;
387
388 ret = ttm_bo_kmap(bo, start_page: page, num_pages: 1, map: &map);
389 if (ret)
390 return ret;
391
392 ptr = (uint8_t *)ttm_kmap_obj_virtual(map: &map, is_iomem: &is_iomem) + offset;
393 WARN_ON_ONCE(is_iomem);
394 if (write)
395 memcpy(ptr, buf, bytes);
396 else
397 memcpy(buf, ptr, bytes);
398 ttm_bo_kunmap(map: &map);
399
400 page++;
401 buf += bytes;
402 bytes_left -= bytes;
403 offset = 0;
404 } while (bytes_left);
405
406 return len;
407}
408
409/**
410 * ttm_bo_access - Helper to access a buffer object
411 *
412 * @bo: ttm buffer object
413 * @offset: access offset into buffer object
414 * @buf: pointer to caller memory to read into or write from
415 * @len: length of access
416 * @write: write access
417 *
418 * Utility function to access a buffer object. Useful when buffer object cannot
419 * be easily mapped (non-contiguous, non-visible, etc...). Should not directly
420 * be exported to user space via a peak / poke interface.
421 *
422 * Returns:
423 * @len if successful, negative error code on failure.
424 */
425int ttm_bo_access(struct ttm_buffer_object *bo, unsigned long offset,
426 void *buf, int len, int write)
427{
428 int ret;
429
430 if (len < 1 || (offset + len) > bo->base.size)
431 return -EIO;
432
433 ret = ttm_bo_reserve(bo, interruptible: true, no_wait: false, NULL);
434 if (ret)
435 return ret;
436
437 if (!bo->resource) {
438 ret = -ENODATA;
439 goto unlock;
440 }
441
442 switch (bo->resource->mem_type) {
443 case TTM_PL_SYSTEM:
444 fallthrough;
445 case TTM_PL_TT:
446 ret = ttm_bo_vm_access_kmap(bo, offset, buf, len, write);
447 break;
448 default:
449 if (bo->bdev->funcs->access_memory)
450 ret = bo->bdev->funcs->access_memory
451 (bo, offset, buf, len, write);
452 else
453 ret = -EIO;
454 }
455
456unlock:
457 ttm_bo_unreserve(bo);
458
459 return ret;
460}
461EXPORT_SYMBOL(ttm_bo_access);
462
463int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
464 void *buf, int len, int write)
465{
466 struct ttm_buffer_object *bo = vma->vm_private_data;
467 unsigned long offset = (addr) - vma->vm_start +
468 ((vma->vm_pgoff - drm_vma_node_start(node: &bo->base.vma_node))
469 << PAGE_SHIFT);
470
471 return ttm_bo_access(bo, offset, buf, len, write);
472}
473EXPORT_SYMBOL(ttm_bo_vm_access);
474
475static const struct vm_operations_struct ttm_bo_vm_ops = {
476 .fault = ttm_bo_vm_fault,
477 .open = ttm_bo_vm_open,
478 .close = ttm_bo_vm_close,
479 .access = ttm_bo_vm_access,
480};
481
482/**
483 * ttm_bo_mmap_obj - mmap memory backed by a ttm buffer object.
484 *
485 * @vma: vma as input from the fbdev mmap method.
486 * @bo: The bo backing the address space.
487 *
488 * Maps a buffer object.
489 */
490int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
491{
492 /* Enforce no COW since would have really strange behavior with it. */
493 if (is_cow_mapping(flags: vma->vm_flags))
494 return -EINVAL;
495
496 drm_gem_object_get(obj: &bo->base);
497
498 /*
499 * Drivers may want to override the vm_ops field. Otherwise we
500 * use TTM's default callbacks.
501 */
502 if (!vma->vm_ops)
503 vma->vm_ops = &ttm_bo_vm_ops;
504
505 /*
506 * Note: We're transferring the bo reference to
507 * vma->vm_private_data here.
508 */
509
510 vma->vm_private_data = bo;
511
512 vm_flags_set(vma, VM_PFNMAP | VM_IO | VM_DONTEXPAND | VM_DONTDUMP);
513 return 0;
514}
515EXPORT_SYMBOL(ttm_bo_mmap_obj);
516

source code of linux/drivers/gpu/drm/ttm/ttm_bo_vm.c