1/* SPDX-License-Identifier: GPL-2.0 OR MIT */
2/**************************************************************************
3 *
4 * Copyright (c) 2009-2023 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 * While no substantial code is shared, the prime code is inspired by
32 * drm_prime.c, with
33 * Authors:
34 * Dave Airlie <airlied@redhat.com>
35 * Rob Clark <rob.clark@linaro.org>
36 */
37/** @file ttm_ref_object.c
38 *
39 * Base- and reference object implementation for the various
40 * ttm objects. Implements reference counting, minimal security checks
41 * and release on file close.
42 */
43
44
45#define pr_fmt(fmt) "[TTM] " fmt
46
47#include "ttm_object.h"
48#include "vmwgfx_drv.h"
49
50#include <linux/list.h>
51#include <linux/spinlock.h>
52#include <linux/slab.h>
53#include <linux/atomic.h>
54#include <linux/module.h>
55#include <linux/hashtable.h>
56
57MODULE_IMPORT_NS("DMA_BUF");
58
59#define VMW_TTM_OBJECT_REF_HT_ORDER 10
60
61/**
62 * struct ttm_object_file
63 *
64 * @tdev: Pointer to the ttm_object_device.
65 *
66 * @lock: Lock that protects the ref_list list and the
67 * ref_hash hash tables.
68 *
69 * @ref_list: List of ttm_ref_objects to be destroyed at
70 * file release.
71 *
72 * @ref_hash: Hash tables of ref objects, one per ttm_ref_type,
73 * for fast lookup of ref objects given a base object.
74 *
75 * @refcount: reference/usage count
76 */
77struct ttm_object_file {
78 struct ttm_object_device *tdev;
79 spinlock_t lock;
80 struct list_head ref_list;
81 DECLARE_HASHTABLE(ref_hash, VMW_TTM_OBJECT_REF_HT_ORDER);
82 struct kref refcount;
83};
84
85/*
86 * struct ttm_object_device
87 *
88 * @object_lock: lock that protects idr.
89 *
90 * This is the per-device data structure needed for ttm object management.
91 */
92
93struct ttm_object_device {
94 spinlock_t object_lock;
95 struct dma_buf_ops ops;
96 void (*dmabuf_release)(struct dma_buf *dma_buf);
97 struct idr idr;
98};
99
100/*
101 * struct ttm_ref_object
102 *
103 * @hash: Hash entry for the per-file object reference hash.
104 *
105 * @head: List entry for the per-file list of ref-objects.
106 *
107 * @kref: Ref count.
108 *
109 * @obj: Base object this ref object is referencing.
110 *
111 * @ref_type: Type of ref object.
112 *
113 * This is similar to an idr object, but it also has a hash table entry
114 * that allows lookup with a pointer to the referenced object as a key. In
115 * that way, one can easily detect whether a base object is referenced by
116 * a particular ttm_object_file. It also carries a ref count to avoid creating
117 * multiple ref objects if a ttm_object_file references the same base
118 * object more than once.
119 */
120
121struct ttm_ref_object {
122 struct rcu_head rcu_head;
123 struct vmwgfx_hash_item hash;
124 struct list_head head;
125 struct kref kref;
126 struct ttm_base_object *obj;
127 struct ttm_object_file *tfile;
128};
129
130static void ttm_prime_dmabuf_release(struct dma_buf *dma_buf);
131
132static inline struct ttm_object_file *
133ttm_object_file_ref(struct ttm_object_file *tfile)
134{
135 kref_get(kref: &tfile->refcount);
136 return tfile;
137}
138
139static int ttm_tfile_find_ref_rcu(struct ttm_object_file *tfile,
140 uint64_t key,
141 struct vmwgfx_hash_item **p_hash)
142{
143 struct vmwgfx_hash_item *hash;
144
145 hash_for_each_possible_rcu(tfile->ref_hash, hash, head, key) {
146 if (hash->key == key) {
147 *p_hash = hash;
148 return 0;
149 }
150 }
151 return -EINVAL;
152}
153
154static int ttm_tfile_find_ref(struct ttm_object_file *tfile,
155 uint64_t key,
156 struct vmwgfx_hash_item **p_hash)
157{
158 struct vmwgfx_hash_item *hash;
159
160 hash_for_each_possible(tfile->ref_hash, hash, head, key) {
161 if (hash->key == key) {
162 *p_hash = hash;
163 return 0;
164 }
165 }
166 return -EINVAL;
167}
168
169static void ttm_object_file_destroy(struct kref *kref)
170{
171 struct ttm_object_file *tfile =
172 container_of(kref, struct ttm_object_file, refcount);
173
174 kfree(objp: tfile);
175}
176
177
178static inline void ttm_object_file_unref(struct ttm_object_file **p_tfile)
179{
180 struct ttm_object_file *tfile = *p_tfile;
181
182 *p_tfile = NULL;
183 kref_put(kref: &tfile->refcount, release: ttm_object_file_destroy);
184}
185
186
187int ttm_base_object_init(struct ttm_object_file *tfile,
188 struct ttm_base_object *base,
189 bool shareable,
190 enum ttm_object_type object_type,
191 void (*refcount_release) (struct ttm_base_object **))
192{
193 struct ttm_object_device *tdev = tfile->tdev;
194 int ret;
195
196 base->shareable = shareable;
197 base->tfile = ttm_object_file_ref(tfile);
198 base->refcount_release = refcount_release;
199 base->object_type = object_type;
200 kref_init(kref: &base->refcount);
201 idr_preload(GFP_KERNEL);
202 spin_lock(lock: &tdev->object_lock);
203 ret = idr_alloc(&tdev->idr, ptr: base, start: 1, end: 0, GFP_NOWAIT);
204 spin_unlock(lock: &tdev->object_lock);
205 idr_preload_end();
206 if (ret < 0)
207 return ret;
208
209 base->handle = ret;
210 ret = ttm_ref_object_add(tfile, base, NULL, require_existed: false);
211 if (unlikely(ret != 0))
212 goto out_err1;
213
214 ttm_base_object_unref(p_base: &base);
215
216 return 0;
217out_err1:
218 spin_lock(lock: &tdev->object_lock);
219 idr_remove(&tdev->idr, id: base->handle);
220 spin_unlock(lock: &tdev->object_lock);
221 return ret;
222}
223
224static void ttm_release_base(struct kref *kref)
225{
226 struct ttm_base_object *base =
227 container_of(kref, struct ttm_base_object, refcount);
228 struct ttm_object_device *tdev = base->tfile->tdev;
229
230 spin_lock(lock: &tdev->object_lock);
231 idr_remove(&tdev->idr, id: base->handle);
232 spin_unlock(lock: &tdev->object_lock);
233
234 /*
235 * Note: We don't use synchronize_rcu() here because it's far
236 * too slow. It's up to the user to free the object using
237 * call_rcu() or ttm_base_object_kfree().
238 */
239
240 ttm_object_file_unref(p_tfile: &base->tfile);
241 if (base->refcount_release)
242 base->refcount_release(&base);
243}
244
245void ttm_base_object_unref(struct ttm_base_object **p_base)
246{
247 struct ttm_base_object *base = *p_base;
248
249 *p_base = NULL;
250
251 kref_put(kref: &base->refcount, release: ttm_release_base);
252}
253
254struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile,
255 uint64_t key)
256{
257 struct ttm_base_object *base = NULL;
258 struct vmwgfx_hash_item *hash;
259 int ret;
260
261 spin_lock(lock: &tfile->lock);
262 ret = ttm_tfile_find_ref(tfile, key, p_hash: &hash);
263
264 if (likely(ret == 0)) {
265 base = hlist_entry(hash, struct ttm_ref_object, hash)->obj;
266 if (!kref_get_unless_zero(kref: &base->refcount))
267 base = NULL;
268 }
269 spin_unlock(lock: &tfile->lock);
270
271
272 return base;
273}
274
275struct ttm_base_object *
276ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint64_t key)
277{
278 struct ttm_base_object *base;
279
280 rcu_read_lock();
281 base = idr_find(&tdev->idr, id: key);
282
283 if (base && !kref_get_unless_zero(kref: &base->refcount))
284 base = NULL;
285 rcu_read_unlock();
286
287 return base;
288}
289
290int ttm_ref_object_add(struct ttm_object_file *tfile,
291 struct ttm_base_object *base,
292 bool *existed,
293 bool require_existed)
294{
295 struct ttm_ref_object *ref;
296 struct vmwgfx_hash_item *hash;
297 int ret = -EINVAL;
298
299 if (base->tfile != tfile && !base->shareable)
300 return -EPERM;
301
302 if (existed != NULL)
303 *existed = true;
304
305 while (ret == -EINVAL) {
306 rcu_read_lock();
307 ret = ttm_tfile_find_ref_rcu(tfile, key: base->handle, p_hash: &hash);
308
309 if (ret == 0) {
310 ref = hlist_entry(hash, struct ttm_ref_object, hash);
311 if (kref_get_unless_zero(kref: &ref->kref)) {
312 rcu_read_unlock();
313 break;
314 }
315 }
316
317 rcu_read_unlock();
318 if (require_existed)
319 return -EPERM;
320
321 ref = kmalloc(sizeof(*ref), GFP_KERNEL);
322 if (unlikely(ref == NULL)) {
323 return -ENOMEM;
324 }
325
326 ref->hash.key = base->handle;
327 ref->obj = base;
328 ref->tfile = tfile;
329 kref_init(kref: &ref->kref);
330
331 spin_lock(lock: &tfile->lock);
332 hash_add_rcu(tfile->ref_hash, &ref->hash.head, ref->hash.key);
333 ret = 0;
334
335 list_add_tail(new: &ref->head, head: &tfile->ref_list);
336 kref_get(kref: &base->refcount);
337 spin_unlock(lock: &tfile->lock);
338 if (existed != NULL)
339 *existed = false;
340 }
341
342 return ret;
343}
344
345static void __releases(tfile->lock) __acquires(tfile->lock)
346ttm_ref_object_release(struct kref *kref)
347{
348 struct ttm_ref_object *ref =
349 container_of(kref, struct ttm_ref_object, kref);
350 struct ttm_object_file *tfile = ref->tfile;
351
352 hash_del_rcu(node: &ref->hash.head);
353 list_del(entry: &ref->head);
354 spin_unlock(lock: &tfile->lock);
355
356 ttm_base_object_unref(p_base: &ref->obj);
357 kfree_rcu(ref, rcu_head);
358 spin_lock(lock: &tfile->lock);
359}
360
361int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
362 unsigned long key)
363{
364 struct ttm_ref_object *ref;
365 struct vmwgfx_hash_item *hash;
366 int ret;
367
368 spin_lock(lock: &tfile->lock);
369 ret = ttm_tfile_find_ref(tfile, key, p_hash: &hash);
370 if (unlikely(ret != 0)) {
371 spin_unlock(lock: &tfile->lock);
372 return -EINVAL;
373 }
374 ref = hlist_entry(hash, struct ttm_ref_object, hash);
375 kref_put(kref: &ref->kref, release: ttm_ref_object_release);
376 spin_unlock(lock: &tfile->lock);
377 return 0;
378}
379
380void ttm_object_file_release(struct ttm_object_file **p_tfile)
381{
382 struct ttm_ref_object *ref;
383 struct list_head *list;
384 struct ttm_object_file *tfile = *p_tfile;
385
386 *p_tfile = NULL;
387 spin_lock(lock: &tfile->lock);
388
389 /*
390 * Since we release the lock within the loop, we have to
391 * restart it from the beginning each time.
392 */
393
394 while (!list_empty(head: &tfile->ref_list)) {
395 list = tfile->ref_list.next;
396 ref = list_entry(list, struct ttm_ref_object, head);
397 ttm_ref_object_release(kref: &ref->kref);
398 }
399
400 spin_unlock(lock: &tfile->lock);
401
402 ttm_object_file_unref(p_tfile: &tfile);
403}
404
405struct ttm_object_file *ttm_object_file_init(struct ttm_object_device *tdev)
406{
407 struct ttm_object_file *tfile = kmalloc(sizeof(*tfile), GFP_KERNEL);
408
409 if (unlikely(tfile == NULL))
410 return NULL;
411
412 spin_lock_init(&tfile->lock);
413 tfile->tdev = tdev;
414 kref_init(kref: &tfile->refcount);
415 INIT_LIST_HEAD(list: &tfile->ref_list);
416
417 hash_init(tfile->ref_hash);
418
419 return tfile;
420}
421
422struct ttm_object_device *
423ttm_object_device_init(const struct dma_buf_ops *ops)
424{
425 struct ttm_object_device *tdev = kmalloc(sizeof(*tdev), GFP_KERNEL);
426
427 if (unlikely(tdev == NULL))
428 return NULL;
429
430 spin_lock_init(&tdev->object_lock);
431
432 /*
433 * Our base is at VMWGFX_NUM_MOB + 1 because we want to create
434 * a seperate namespace for GEM handles (which are
435 * 1..VMWGFX_NUM_MOB) and the surface handles. Some ioctl's
436 * can take either handle as an argument so we want to
437 * easily be able to tell whether the handle refers to a
438 * GEM buffer or a surface.
439 */
440 idr_init_base(idr: &tdev->idr, VMWGFX_NUM_MOB + 1);
441 tdev->ops = *ops;
442 tdev->dmabuf_release = tdev->ops.release;
443 tdev->ops.release = ttm_prime_dmabuf_release;
444 return tdev;
445}
446
447void ttm_object_device_release(struct ttm_object_device **p_tdev)
448{
449 struct ttm_object_device *tdev = *p_tdev;
450
451 *p_tdev = NULL;
452
453 WARN_ON_ONCE(!idr_is_empty(&tdev->idr));
454 idr_destroy(&tdev->idr);
455
456 kfree(objp: tdev);
457}
458
459/**
460 * get_dma_buf_unless_doomed - get a dma_buf reference if possible.
461 *
462 * @dmabuf: Non-refcounted pointer to a struct dma-buf.
463 *
464 * Obtain a file reference from a lookup structure that doesn't refcount
465 * the file, but synchronizes with its release method to make sure it has
466 * not been freed yet. See for example kref_get_unless_zero documentation.
467 * Returns true if refcounting succeeds, false otherwise.
468 *
469 * Nobody really wants this as a public API yet, so let it mature here
470 * for some time...
471 */
472static bool __must_check get_dma_buf_unless_doomed(struct dma_buf *dmabuf)
473{
474 return file_ref_get(ref: &dmabuf->file->f_ref);
475}
476
477/**
478 * ttm_prime_refcount_release - refcount release method for a prime object.
479 *
480 * @p_base: Pointer to ttm_base_object pointer.
481 *
482 * This is a wrapper that calls the refcount_release founction of the
483 * underlying object. At the same time it cleans up the prime object.
484 * This function is called when all references to the base object we
485 * derive from are gone.
486 */
487static void ttm_prime_refcount_release(struct ttm_base_object **p_base)
488{
489 struct ttm_base_object *base = *p_base;
490 struct ttm_prime_object *prime;
491
492 *p_base = NULL;
493 prime = container_of(base, struct ttm_prime_object, base);
494 BUG_ON(prime->dma_buf != NULL);
495 mutex_destroy(lock: &prime->mutex);
496 if (prime->refcount_release)
497 prime->refcount_release(&base);
498}
499
500/**
501 * ttm_prime_dmabuf_release - Release method for the dma-bufs we export
502 *
503 * @dma_buf:
504 *
505 * This function first calls the dma_buf release method the driver
506 * provides. Then it cleans up our dma_buf pointer used for lookup,
507 * and finally releases the reference the dma_buf has on our base
508 * object.
509 */
510static void ttm_prime_dmabuf_release(struct dma_buf *dma_buf)
511{
512 struct ttm_prime_object *prime =
513 (struct ttm_prime_object *) dma_buf->priv;
514 struct ttm_base_object *base = &prime->base;
515 struct ttm_object_device *tdev = base->tfile->tdev;
516
517 if (tdev->dmabuf_release)
518 tdev->dmabuf_release(dma_buf);
519 mutex_lock(&prime->mutex);
520 if (prime->dma_buf == dma_buf)
521 prime->dma_buf = NULL;
522 mutex_unlock(lock: &prime->mutex);
523 ttm_base_object_unref(p_base: &base);
524}
525
526/**
527 * ttm_prime_fd_to_handle - Get a base object handle from a prime fd
528 *
529 * @tfile: A struct ttm_object_file identifying the caller.
530 * @fd: The prime / dmabuf fd.
531 * @handle: The returned handle.
532 *
533 * This function returns a handle to an object that previously exported
534 * a dma-buf. Note that we don't handle imports yet, because we simply
535 * have no consumers of that implementation.
536 */
537int ttm_prime_fd_to_handle(struct ttm_object_file *tfile,
538 int fd, u32 *handle)
539{
540 struct ttm_object_device *tdev = tfile->tdev;
541 struct dma_buf *dma_buf;
542 struct ttm_prime_object *prime;
543 struct ttm_base_object *base;
544 int ret;
545
546 dma_buf = dma_buf_get(fd);
547 if (IS_ERR(ptr: dma_buf))
548 return PTR_ERR(ptr: dma_buf);
549
550 if (dma_buf->ops != &tdev->ops)
551 return -ENOSYS;
552
553 prime = (struct ttm_prime_object *) dma_buf->priv;
554 base = &prime->base;
555 *handle = base->handle;
556 ret = ttm_ref_object_add(tfile, base, NULL, require_existed: false);
557
558 dma_buf_put(dmabuf: dma_buf);
559
560 return ret;
561}
562
563/**
564 * ttm_prime_handle_to_fd - Return a dma_buf fd from a ttm prime object
565 *
566 * @tfile: Struct ttm_object_file identifying the caller.
567 * @handle: Handle to the object we're exporting from.
568 * @flags: flags for dma-buf creation. We just pass them on.
569 * @prime_fd: The returned file descriptor.
570 *
571 */
572int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,
573 uint32_t handle, uint32_t flags,
574 int *prime_fd)
575{
576 struct ttm_object_device *tdev = tfile->tdev;
577 struct ttm_base_object *base;
578 struct dma_buf *dma_buf;
579 struct ttm_prime_object *prime;
580 int ret;
581
582 base = ttm_base_object_lookup(tfile, key: handle);
583 if (unlikely(base == NULL ||
584 base->object_type != ttm_prime_type)) {
585 ret = -ENOENT;
586 goto out_unref;
587 }
588
589 prime = container_of(base, struct ttm_prime_object, base);
590 if (unlikely(!base->shareable)) {
591 ret = -EPERM;
592 goto out_unref;
593 }
594
595 ret = mutex_lock_interruptible(&prime->mutex);
596 if (unlikely(ret != 0)) {
597 ret = -ERESTARTSYS;
598 goto out_unref;
599 }
600
601 dma_buf = prime->dma_buf;
602 if (!dma_buf || !get_dma_buf_unless_doomed(dmabuf: dma_buf)) {
603 DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
604 exp_info.ops = &tdev->ops;
605 exp_info.size = prime->size;
606 exp_info.flags = flags;
607 exp_info.priv = prime;
608
609 /*
610 * Need to create a new dma_buf
611 */
612
613 dma_buf = dma_buf_export(exp_info: &exp_info);
614 if (IS_ERR(ptr: dma_buf)) {
615 ret = PTR_ERR(ptr: dma_buf);
616 mutex_unlock(lock: &prime->mutex);
617 goto out_unref;
618 }
619
620 /*
621 * dma_buf has taken the base object reference
622 */
623 base = NULL;
624 prime->dma_buf = dma_buf;
625 }
626 mutex_unlock(lock: &prime->mutex);
627
628 ret = dma_buf_fd(dmabuf: dma_buf, flags);
629 if (ret >= 0) {
630 *prime_fd = ret;
631 ret = 0;
632 } else
633 dma_buf_put(dmabuf: dma_buf);
634
635out_unref:
636 if (base)
637 ttm_base_object_unref(p_base: &base);
638 return ret;
639}
640
641/**
642 * ttm_prime_object_init - Initialize a ttm_prime_object
643 *
644 * @tfile: struct ttm_object_file identifying the caller
645 * @size: The size of the dma_bufs we export.
646 * @prime: The object to be initialized.
647 * @type: See ttm_base_object_init
648 * @refcount_release: See ttm_base_object_init
649 *
650 * Initializes an object which is compatible with the drm_prime model
651 * for data sharing between processes and devices.
652 */
653int ttm_prime_object_init(struct ttm_object_file *tfile, size_t size,
654 struct ttm_prime_object *prime,
655 enum ttm_object_type type,
656 void (*refcount_release) (struct ttm_base_object **))
657{
658 bool shareable = !!(type == VMW_RES_SURFACE);
659 mutex_init(&prime->mutex);
660 prime->size = PAGE_ALIGN(size);
661 prime->real_type = type;
662 prime->dma_buf = NULL;
663 prime->refcount_release = refcount_release;
664 return ttm_base_object_init(tfile, base: &prime->base, shareable,
665 object_type: ttm_prime_type,
666 refcount_release: ttm_prime_refcount_release);
667}
668

source code of linux/drivers/gpu/drm/vmwgfx/ttm_object.c