xref: /linux/drivers/gpu/drm/ttm/ttm_bo_vm.c (revision 9208c05f9fdfd927ea160b97dfef3c379049fff2)
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 <drm/ttm/ttm_bo.h>
35 #include <drm/ttm/ttm_placement.h>
36 #include <drm/ttm/ttm_tt.h>
37 
38 #include <drm/drm_drv.h>
39 #include <drm/drm_managed.h>
40 
41 static vm_fault_t ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,
42 				struct vm_fault *vmf)
43 {
44 	long err = 0;
45 
46 	/*
47 	 * Quick non-stalling check for idle.
48 	 */
49 	if (dma_resv_test_signaled(bo->base.resv, DMA_RESV_USAGE_KERNEL))
50 		return 0;
51 
52 	/*
53 	 * If possible, avoid waiting for GPU with mmap_lock
54 	 * held.  We only do this if the fault allows retry and this
55 	 * is the first attempt.
56 	 */
57 	if (fault_flag_allow_retry_first(vmf->flags)) {
58 		if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
59 			return VM_FAULT_RETRY;
60 
61 		ttm_bo_get(bo);
62 		mmap_read_unlock(vmf->vma->vm_mm);
63 		(void)dma_resv_wait_timeout(bo->base.resv,
64 					    DMA_RESV_USAGE_KERNEL, true,
65 					    MAX_SCHEDULE_TIMEOUT);
66 		dma_resv_unlock(bo->base.resv);
67 		ttm_bo_put(bo);
68 		return VM_FAULT_RETRY;
69 	}
70 
71 	/*
72 	 * Ordinary wait.
73 	 */
74 	err = dma_resv_wait_timeout(bo->base.resv, DMA_RESV_USAGE_KERNEL, true,
75 				    MAX_SCHEDULE_TIMEOUT);
76 	if (unlikely(err < 0)) {
77 		return (err != -ERESTARTSYS) ? VM_FAULT_SIGBUS :
78 			VM_FAULT_NOPAGE;
79 	}
80 
81 	return 0;
82 }
83 
84 static unsigned long ttm_bo_io_mem_pfn(struct ttm_buffer_object *bo,
85 				       unsigned long page_offset)
86 {
87 	struct ttm_device *bdev = bo->bdev;
88 
89 	if (bdev->funcs->io_mem_pfn)
90 		return bdev->funcs->io_mem_pfn(bo, page_offset);
91 
92 	return (bo->resource->bus.offset >> PAGE_SHIFT) + page_offset;
93 }
94 
95 /**
96  * ttm_bo_vm_reserve - Reserve a buffer object in a retryable vm callback
97  * @bo: The buffer object
98  * @vmf: The fault structure handed to the callback
99  *
100  * vm callbacks like fault() and *_mkwrite() allow for the mmap_lock to be dropped
101  * during long waits, and after the wait the callback will be restarted. This
102  * is to allow other threads using the same virtual memory space concurrent
103  * access to map(), unmap() completely unrelated buffer objects. TTM buffer
104  * object reservations sometimes wait for GPU and should therefore be
105  * considered long waits. This function reserves the buffer object interruptibly
106  * taking this into account. Starvation is avoided by the vm system not
107  * allowing too many repeated restarts.
108  * This function is intended to be used in customized fault() and _mkwrite()
109  * handlers.
110  *
111  * Return:
112  *    0 on success and the bo was reserved.
113  *    VM_FAULT_RETRY if blocking wait.
114  *    VM_FAULT_NOPAGE if blocking wait and retrying was not allowed.
115  */
116 vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
117 			     struct vm_fault *vmf)
118 {
119 	/*
120 	 * Work around locking order reversal in fault / nopfn
121 	 * between mmap_lock and bo_reserve: Perform a trylock operation
122 	 * for reserve, and if it fails, retry the fault after waiting
123 	 * for the buffer to become unreserved.
124 	 */
125 	if (unlikely(!dma_resv_trylock(bo->base.resv))) {
126 		/*
127 		 * If the fault allows retry and this is the first
128 		 * fault attempt, we try to release the mmap_lock
129 		 * before waiting
130 		 */
131 		if (fault_flag_allow_retry_first(vmf->flags)) {
132 			if (!(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
133 				ttm_bo_get(bo);
134 				mmap_read_unlock(vmf->vma->vm_mm);
135 				if (!dma_resv_lock_interruptible(bo->base.resv,
136 								 NULL))
137 					dma_resv_unlock(bo->base.resv);
138 				ttm_bo_put(bo);
139 			}
140 
141 			return VM_FAULT_RETRY;
142 		}
143 
144 		if (dma_resv_lock_interruptible(bo->base.resv, NULL))
145 			return VM_FAULT_NOPAGE;
146 	}
147 
148 	/*
149 	 * Refuse to fault imported pages. This should be handled
150 	 * (if at all) by redirecting mmap to the exporter.
151 	 */
152 	if (bo->ttm && (bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL)) {
153 		if (!(bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL_MAPPABLE)) {
154 			dma_resv_unlock(bo->base.resv);
155 			return VM_FAULT_SIGBUS;
156 		}
157 	}
158 
159 	return 0;
160 }
161 EXPORT_SYMBOL(ttm_bo_vm_reserve);
162 
163 /**
164  * ttm_bo_vm_fault_reserved - TTM fault helper
165  * @vmf: The struct vm_fault given as argument to the fault callback
166  * @prot: The page protection to be used for this memory area.
167  * @num_prefault: Maximum number of prefault pages. The caller may want to
168  * specify this based on madvice settings and the size of the GPU object
169  * backed by the memory.
170  *
171  * This function inserts one or more page table entries pointing to the
172  * memory backing the buffer object, and then returns a return code
173  * instructing the caller to retry the page access.
174  *
175  * Return:
176  *   VM_FAULT_NOPAGE on success or pending signal
177  *   VM_FAULT_SIGBUS on unspecified error
178  *   VM_FAULT_OOM on out-of-memory
179  *   VM_FAULT_RETRY if retryable wait
180  */
181 vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
182 				    pgprot_t prot,
183 				    pgoff_t num_prefault)
184 {
185 	struct vm_area_struct *vma = vmf->vma;
186 	struct ttm_buffer_object *bo = vma->vm_private_data;
187 	struct ttm_device *bdev = bo->bdev;
188 	unsigned long page_offset;
189 	unsigned long page_last;
190 	unsigned long pfn;
191 	struct ttm_tt *ttm = NULL;
192 	struct page *page;
193 	int err;
194 	pgoff_t i;
195 	vm_fault_t ret = VM_FAULT_NOPAGE;
196 	unsigned long address = vmf->address;
197 
198 	/*
199 	 * Wait for buffer data in transit, due to a pipelined
200 	 * move.
201 	 */
202 	ret = ttm_bo_vm_fault_idle(bo, vmf);
203 	if (unlikely(ret != 0))
204 		return ret;
205 
206 	err = ttm_mem_io_reserve(bdev, bo->resource);
207 	if (unlikely(err != 0))
208 		return VM_FAULT_SIGBUS;
209 
210 	page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
211 		vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node);
212 	page_last = vma_pages(vma) + vma->vm_pgoff -
213 		drm_vma_node_start(&bo->base.vma_node);
214 
215 	if (unlikely(page_offset >= PFN_UP(bo->base.size)))
216 		return VM_FAULT_SIGBUS;
217 
218 	prot = ttm_io_prot(bo, bo->resource, prot);
219 	if (!bo->resource->bus.is_iomem) {
220 		struct ttm_operation_ctx ctx = {
221 			.interruptible = true,
222 			.no_wait_gpu = false,
223 			.force_alloc = true
224 		};
225 
226 		ttm = bo->ttm;
227 		err = ttm_bo_populate(bo, &ctx);
228 		if (err) {
229 			if (err == -EINTR || err == -ERESTARTSYS ||
230 			    err == -EAGAIN)
231 				return VM_FAULT_NOPAGE;
232 
233 			pr_debug("TTM fault hit %pe.\n", ERR_PTR(err));
234 			return VM_FAULT_SIGBUS;
235 		}
236 	} else {
237 		/* Iomem should not be marked encrypted */
238 		prot = pgprot_decrypted(prot);
239 	}
240 
241 	/*
242 	 * Speculatively prefault a number of pages. Only error on
243 	 * first page.
244 	 */
245 	for (i = 0; i < num_prefault; ++i) {
246 		if (bo->resource->bus.is_iomem) {
247 			pfn = ttm_bo_io_mem_pfn(bo, page_offset);
248 		} else {
249 			page = ttm->pages[page_offset];
250 			if (unlikely(!page && i == 0)) {
251 				return VM_FAULT_OOM;
252 			} else if (unlikely(!page)) {
253 				break;
254 			}
255 			pfn = page_to_pfn(page);
256 		}
257 
258 		/*
259 		 * Note that the value of @prot at this point may differ from
260 		 * the value of @vma->vm_page_prot in the caching- and
261 		 * encryption bits. This is because the exact location of the
262 		 * data may not be known at mmap() time and may also change
263 		 * at arbitrary times while the data is mmap'ed.
264 		 * See vmf_insert_pfn_prot() for a discussion.
265 		 */
266 		ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
267 
268 		/* Never error on prefaulted PTEs */
269 		if (unlikely((ret & VM_FAULT_ERROR))) {
270 			if (i == 0)
271 				return VM_FAULT_NOPAGE;
272 			else
273 				break;
274 		}
275 
276 		address += PAGE_SIZE;
277 		if (unlikely(++page_offset >= page_last))
278 			break;
279 	}
280 	return ret;
281 }
282 EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);
283 
284 static void ttm_bo_release_dummy_page(struct drm_device *dev, void *res)
285 {
286 	struct page *dummy_page = (struct page *)res;
287 
288 	__free_page(dummy_page);
289 }
290 
291 vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot)
292 {
293 	struct vm_area_struct *vma = vmf->vma;
294 	struct ttm_buffer_object *bo = vma->vm_private_data;
295 	struct drm_device *ddev = bo->base.dev;
296 	vm_fault_t ret = VM_FAULT_NOPAGE;
297 	unsigned long address;
298 	unsigned long pfn;
299 	struct page *page;
300 
301 	/* Allocate new dummy page to map all the VA range in this VMA to it*/
302 	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
303 	if (!page)
304 		return VM_FAULT_OOM;
305 
306 	/* Set the page to be freed using drmm release action */
307 	if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page, page))
308 		return VM_FAULT_OOM;
309 
310 	pfn = page_to_pfn(page);
311 
312 	/* Prefault the entire VMA range right away to avoid further faults */
313 	for (address = vma->vm_start; address < vma->vm_end;
314 	     address += PAGE_SIZE)
315 		ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
316 
317 	return ret;
318 }
319 EXPORT_SYMBOL(ttm_bo_vm_dummy_page);
320 
321 vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
322 {
323 	struct vm_area_struct *vma = vmf->vma;
324 	pgprot_t prot;
325 	struct ttm_buffer_object *bo = vma->vm_private_data;
326 	struct drm_device *ddev = bo->base.dev;
327 	vm_fault_t ret;
328 	int idx;
329 
330 	ret = ttm_bo_vm_reserve(bo, vmf);
331 	if (ret)
332 		return ret;
333 
334 	prot = vma->vm_page_prot;
335 	if (drm_dev_enter(ddev, &idx)) {
336 		ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT);
337 		drm_dev_exit(idx);
338 	} else {
339 		ret = ttm_bo_vm_dummy_page(vmf, prot);
340 	}
341 	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
342 		return ret;
343 
344 	dma_resv_unlock(bo->base.resv);
345 
346 	return ret;
347 }
348 EXPORT_SYMBOL(ttm_bo_vm_fault);
349 
350 void ttm_bo_vm_open(struct vm_area_struct *vma)
351 {
352 	struct ttm_buffer_object *bo = vma->vm_private_data;
353 
354 	WARN_ON(bo->bdev->dev_mapping != vma->vm_file->f_mapping);
355 
356 	ttm_bo_get(bo);
357 }
358 EXPORT_SYMBOL(ttm_bo_vm_open);
359 
360 void ttm_bo_vm_close(struct vm_area_struct *vma)
361 {
362 	struct ttm_buffer_object *bo = vma->vm_private_data;
363 
364 	ttm_bo_put(bo);
365 	vma->vm_private_data = NULL;
366 }
367 EXPORT_SYMBOL(ttm_bo_vm_close);
368 
369 static int ttm_bo_vm_access_kmap(struct ttm_buffer_object *bo,
370 				 unsigned long offset,
371 				 uint8_t *buf, int len, int write)
372 {
373 	unsigned long page = offset >> PAGE_SHIFT;
374 	unsigned long bytes_left = len;
375 	int ret;
376 
377 	/* Copy a page at a time, that way no extra virtual address
378 	 * mapping is needed
379 	 */
380 	offset -= page << PAGE_SHIFT;
381 	do {
382 		unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
383 		struct ttm_bo_kmap_obj map;
384 		void *ptr;
385 		bool is_iomem;
386 
387 		ret = ttm_bo_kmap(bo, page, 1, &map);
388 		if (ret)
389 			return ret;
390 
391 		ptr = (uint8_t *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;
392 		WARN_ON_ONCE(is_iomem);
393 		if (write)
394 			memcpy(ptr, buf, bytes);
395 		else
396 			memcpy(buf, ptr, bytes);
397 		ttm_bo_kunmap(&map);
398 
399 		page++;
400 		buf += bytes;
401 		bytes_left -= bytes;
402 		offset = 0;
403 	} while (bytes_left);
404 
405 	return len;
406 }
407 
408 int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
409 		     void *buf, int len, int write)
410 {
411 	struct ttm_buffer_object *bo = vma->vm_private_data;
412 	unsigned long offset = (addr) - vma->vm_start +
413 		((vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node))
414 		 << PAGE_SHIFT);
415 	int ret;
416 
417 	if (len < 1 || (offset + len) > bo->base.size)
418 		return -EIO;
419 
420 	ret = ttm_bo_reserve(bo, true, false, NULL);
421 	if (ret)
422 		return ret;
423 
424 	switch (bo->resource->mem_type) {
425 	case TTM_PL_SYSTEM:
426 		fallthrough;
427 	case TTM_PL_TT:
428 		ret = ttm_bo_vm_access_kmap(bo, offset, buf, len, write);
429 		break;
430 	default:
431 		if (bo->bdev->funcs->access_memory)
432 			ret = bo->bdev->funcs->access_memory(
433 				bo, offset, buf, len, write);
434 		else
435 			ret = -EIO;
436 	}
437 
438 	ttm_bo_unreserve(bo);
439 
440 	return ret;
441 }
442 EXPORT_SYMBOL(ttm_bo_vm_access);
443 
444 static const struct vm_operations_struct ttm_bo_vm_ops = {
445 	.fault = ttm_bo_vm_fault,
446 	.open = ttm_bo_vm_open,
447 	.close = ttm_bo_vm_close,
448 	.access = ttm_bo_vm_access,
449 };
450 
451 /**
452  * ttm_bo_mmap_obj - mmap memory backed by a ttm buffer object.
453  *
454  * @vma:       vma as input from the fbdev mmap method.
455  * @bo:        The bo backing the address space.
456  *
457  * Maps a buffer object.
458  */
459 int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
460 {
461 	/* Enforce no COW since would have really strange behavior with it. */
462 	if (is_cow_mapping(vma->vm_flags))
463 		return -EINVAL;
464 
465 	ttm_bo_get(bo);
466 
467 	/*
468 	 * Drivers may want to override the vm_ops field. Otherwise we
469 	 * use TTM's default callbacks.
470 	 */
471 	if (!vma->vm_ops)
472 		vma->vm_ops = &ttm_bo_vm_ops;
473 
474 	/*
475 	 * Note: We're transferring the bo reference to
476 	 * vma->vm_private_data here.
477 	 */
478 
479 	vma->vm_private_data = bo;
480 
481 	vm_flags_set(vma, VM_PFNMAP | VM_IO | VM_DONTEXPAND | VM_DONTDUMP);
482 	return 0;
483 }
484 EXPORT_SYMBOL(ttm_bo_mmap_obj);
485