drivers/xen/gntdev-dmabuf.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /*
   4  * Xen dma-buf functionality for gntdev.
   5  *
   6  * DMA buffer implementation is based on drivers/gpu/drm/drm_prime.c.
   7  *
   8  * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/errno.h>
  13 #include <linux/dma-buf.h>
  14 #include <linux/slab.h>
  15 #include <linux/types.h>
  16 #include <linux/uaccess.h>
  17
  18 #include <xen/xen.h>
  19 #include <xen/grant_table.h>
  20
  21 #include "gntdev-common.h"
  22 #include "gntdev-dmabuf.h"
  23
  24 #ifndef GRANT_INVALID_REF
  25 /*
  26  * Note on usage of grant reference 0 as invalid grant reference:
  27  * grant reference 0 is valid, but never exposed to a driver,
  28  * because of the fact it is already in use/reserved by the PV console.
  29  */
  30 #define GRANT_INVALID_REF       0
  31 #endif
  32
  33 struct gntdev_dmabuf {
  34         struct gntdev_dmabuf_priv *priv;
  35         struct dma_buf *dmabuf;
  36         struct list_head next;
  37         int fd;
  38
  39         union {
  40                 struct {
  41                         /* Exported buffers are reference counted. */
  42                         struct kref refcount;
  43
  44                         struct gntdev_priv *priv;
  45                         struct gntdev_grant_map *map;
  46                 } exp;
  47                 struct {
  48                         /* Granted references of the imported buffer. */
  49                         grant_ref_t *refs;
  50                         /* Scatter-gather table of the imported buffer. */
  51                         struct sg_table *sgt;
  52                         /* dma-buf attachment of the imported buffer. */
  53                         struct dma_buf_attachment *attach;
  54                 } imp;
  55         } u;
  56
  57         /* Number of pages this buffer has. */
  58         int nr_pages;
  59         /* Pages of this buffer. */
  60         struct page **pages;
  61 };
  62
  63 struct gntdev_dmabuf_wait_obj {
  64         struct list_head next;
  65         struct gntdev_dmabuf *gntdev_dmabuf;
  66         struct completion completion;
  67 };
  68
  69 struct gntdev_dmabuf_attachment {
  70         struct sg_table *sgt;
  71         enum dma_data_direction dir;
  72 };
  73
  74 struct gntdev_dmabuf_priv {
  75         /* List of exported DMA buffers. */
  76         struct list_head exp_list;
  77         /* List of wait objects. */
  78         struct list_head exp_wait_list;
  79         /* List of imported DMA buffers. */
  80         struct list_head imp_list;
  81         /* This is the lock which protects dma_buf_xxx lists. */
  82         struct mutex lock;
  83 };
  84
  85 /* DMA buffer export support. */
  86
  87 /* Implementation of wait for exported DMA buffer to be released. */
  88
  89 static void dmabuf_exp_release(struct kref *kref);
  90
  91 static struct gntdev_dmabuf_wait_obj *
  92 dmabuf_exp_wait_obj_new(struct gntdev_dmabuf_priv *priv,
  93                         struct gntdev_dmabuf *gntdev_dmabuf)
  94 {
  95         struct gntdev_dmabuf_wait_obj *obj;
  96
  97         obj = kzalloc(sizeof(*obj), GFP_KERNEL);
  98         if (!obj)
  99                 return ERR_PTR(-ENOMEM);
 100
 101         init_completion(&obj->completion);
 102         obj->gntdev_dmabuf = gntdev_dmabuf;
 103
 104         mutex_lock(&priv->lock);
 105         list_add(&obj->next, &priv->exp_wait_list);
 106         /* Put our reference and wait for gntdev_dmabuf's release to fire. */
 107         kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
 108         mutex_unlock(&priv->lock);
 109         return obj;
 110 }
 111
 112 static void dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv *priv,
 113                                      struct gntdev_dmabuf_wait_obj *obj)
 114 {
 115         mutex_lock(&priv->lock);
 116         list_del(&obj->next);
 117         mutex_unlock(&priv->lock);
 118         kfree(obj);
 119 }
 120
 121 static int dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj *obj,
 122                                     u32 wait_to_ms)
 123 {
 124         if (wait_for_completion_timeout(&obj->completion,
 125                         msecs_to_jiffies(wait_to_ms)) <= 0)
 126                 return -ETIMEDOUT;
 127
 128         return 0;
 129 }
 130
 131 static void dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv *priv,
 132                                        struct gntdev_dmabuf *gntdev_dmabuf)
 133 {
 134         struct gntdev_dmabuf_wait_obj *obj;
 135
 136         list_for_each_entry(obj, &priv->exp_wait_list, next)
 137                 if (obj->gntdev_dmabuf == gntdev_dmabuf) {
 138                         pr_debug("Found gntdev_dmabuf in the wait list, wake\n");
 139                         complete_all(&obj->completion);
 140                         break;
 141                 }
 142 }
 143
 144 static struct gntdev_dmabuf *
 145 dmabuf_exp_wait_obj_get_dmabuf(struct gntdev_dmabuf_priv *priv, int fd)
 146 {
 147         struct gntdev_dmabuf *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
 148
 149         mutex_lock(&priv->lock);
 150         list_for_each_entry(gntdev_dmabuf, &priv->exp_list, next)
 151                 if (gntdev_dmabuf->fd == fd) {
 152                         pr_debug("Found gntdev_dmabuf in the wait list\n");
 153                         kref_get(&gntdev_dmabuf->u.exp.refcount);
 154                         ret = gntdev_dmabuf;
 155                         break;
 156                 }
 157         mutex_unlock(&priv->lock);
 158         return ret;
 159 }
 160
 161 static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
 162                                     int wait_to_ms)
 163 {
 164         struct gntdev_dmabuf *gntdev_dmabuf;
 165         struct gntdev_dmabuf_wait_obj *obj;
 166         int ret;
 167
 168         pr_debug("Will wait for dma-buf with fd %d\n", fd);
 169         /*
 170          * Try to find the DMA buffer: if not found means that
 171          * either the buffer has already been released or file descriptor
 172          * provided is wrong.
 173          */
 174         gntdev_dmabuf = dmabuf_exp_wait_obj_get_dmabuf(priv, fd);
 175         if (IS_ERR(gntdev_dmabuf))
 176                 return PTR_ERR(gntdev_dmabuf);
 177
 178         /*
 179          * gntdev_dmabuf still exists and is reference count locked by us now,
 180          * so prepare to wait: allocate wait object and add it to the wait list,
 181          * so we can find it on release.
 182          */
 183         obj = dmabuf_exp_wait_obj_new(priv, gntdev_dmabuf);
 184         if (IS_ERR(obj))
 185                 return PTR_ERR(obj);
 186
 187         ret = dmabuf_exp_wait_obj_wait(obj, wait_to_ms);
 188         dmabuf_exp_wait_obj_free(priv, obj);
 189         return ret;
 190 }
 191
 192 /* DMA buffer export support. */
 193
 194 static struct sg_table *
 195 dmabuf_pages_to_sgt(struct page **pages, unsigned int nr_pages)
 196 {
 197         struct sg_table *sgt;
 198         int ret;
 199
 200         sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
 201         if (!sgt) {
 202                 ret = -ENOMEM;
 203                 goto out;
 204         }
 205
 206         ret = sg_alloc_table_from_pages(sgt, pages, nr_pages, 0,
 207                                         nr_pages << PAGE_SHIFT,
 208                                         GFP_KERNEL);
 209         if (ret)
 210                 goto out;
 211
 212         return sgt;
 213
 214 out:
 215         kfree(sgt);
 216         return ERR_PTR(ret);
 217 }
 218
 219 static int dmabuf_exp_ops_attach(struct dma_buf *dma_buf,
 220                                  struct dma_buf_attachment *attach)
 221 {
 222         struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach;
 223
 224         gntdev_dmabuf_attach = kzalloc(sizeof(*gntdev_dmabuf_attach),
 225                                        GFP_KERNEL);
 226         if (!gntdev_dmabuf_attach)
 227                 return -ENOMEM;
 228
 229         gntdev_dmabuf_attach->dir = DMA_NONE;
 230         attach->priv = gntdev_dmabuf_attach;
 231         return 0;
 232 }
 233
 234 static void dmabuf_exp_ops_detach(struct dma_buf *dma_buf,
 235                                   struct dma_buf_attachment *attach)
 236 {
 237         struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
 238
 239         if (gntdev_dmabuf_attach) {
 240                 struct sg_table *sgt = gntdev_dmabuf_attach->sgt;
 241
 242                 if (sgt) {
 243                         if (gntdev_dmabuf_attach->dir != DMA_NONE)
 244                                 dma_unmap_sg_attrs(attach->dev, sgt->sgl,
 245                                                    sgt->nents,
 246                                                    gntdev_dmabuf_attach->dir,
 247                                                    DMA_ATTR_SKIP_CPU_SYNC);
 248                         sg_free_table(sgt);
 249                 }
 250
 251                 kfree(sgt);
 252                 kfree(gntdev_dmabuf_attach);
 253                 attach->priv = NULL;
 254         }
 255 }
 256
 257 static struct sg_table *
 258 dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach,
 259                            enum dma_data_direction dir)
 260 {
 261         struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
 262         struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv;
 263         struct sg_table *sgt;
 264
 265         pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages,
 266                  attach->dev);
 267
 268         if (dir == DMA_NONE || !gntdev_dmabuf_attach)
 269                 return ERR_PTR(-EINVAL);
 270
 271         /* Return the cached mapping when possible. */
 272         if (gntdev_dmabuf_attach->dir == dir)
 273                 return gntdev_dmabuf_attach->sgt;
 274
 275         /*
 276          * Two mappings with different directions for the same attachment are
 277          * not allowed.
 278          */
 279         if (gntdev_dmabuf_attach->dir != DMA_NONE)
 280                 return ERR_PTR(-EBUSY);
 281
 282         sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages,
 283                                   gntdev_dmabuf->nr_pages);
 284         if (!IS_ERR(sgt)) {
 285                 if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
 286                                       DMA_ATTR_SKIP_CPU_SYNC)) {
 287                         sg_free_table(sgt);
 288                         kfree(sgt);
 289                         sgt = ERR_PTR(-ENOMEM);
 290                 } else {
 291                         gntdev_dmabuf_attach->sgt = sgt;
 292                         gntdev_dmabuf_attach->dir = dir;
 293                 }
 294         }
 295         if (IS_ERR(sgt))
 296                 pr_debug("Failed to map sg table for dev %p\n", attach->dev);
 297         return sgt;
 298 }
 299
 300 static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach,
 301                                          struct sg_table *sgt,
 302                                          enum dma_data_direction dir)
 303 {
 304         /* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */
 305 }
 306
 307 static void dmabuf_exp_release(struct kref *kref)
 308 {
 309         struct gntdev_dmabuf *gntdev_dmabuf =
 310                 container_of(kref, struct gntdev_dmabuf, u.exp.refcount);
 311
 312         dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
 313         list_del(&gntdev_dmabuf->next);
 314         kfree(gntdev_dmabuf);
 315 }
 316
 317 static void dmabuf_exp_remove_map(struct gntdev_priv *priv,
 318                                   struct gntdev_grant_map *map)
 319 {
 320         mutex_lock(&priv->lock);
 321         list_del(&map->next);
 322         gntdev_put_map(NULL /* already removed */, map);
 323         mutex_unlock(&priv->lock);
 324 }
 325
 326 static void dmabuf_exp_ops_release(struct dma_buf *dma_buf)
 327 {
 328         struct gntdev_dmabuf *gntdev_dmabuf = dma_buf->priv;
 329         struct gntdev_dmabuf_priv *priv = gntdev_dmabuf->priv;
 330
 331         dmabuf_exp_remove_map(gntdev_dmabuf->u.exp.priv,
 332                               gntdev_dmabuf->u.exp.map);
 333         mutex_lock(&priv->lock);
 334         kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
 335         mutex_unlock(&priv->lock);
 336 }
 337
 338 static void *dmabuf_exp_ops_kmap(struct dma_buf *dma_buf,
 339                                  unsigned long page_num)
 340 {
 341         /* Not implemented. */
 342         return NULL;
 343 }
 344
 345 static void dmabuf_exp_ops_kunmap(struct dma_buf *dma_buf,
 346                                   unsigned long page_num, void *addr)
 347 {
 348         /* Not implemented. */
 349 }
 350
 351 static int dmabuf_exp_ops_mmap(struct dma_buf *dma_buf,
 352                                struct vm_area_struct *vma)
 353 {
 354         /* Not implemented. */
 355         return 0;
 356 }
 357
 358 static const struct dma_buf_ops dmabuf_exp_ops =  {
 359         .attach = dmabuf_exp_ops_attach,
 360         .detach = dmabuf_exp_ops_detach,
 361         .map_dma_buf = dmabuf_exp_ops_map_dma_buf,
 362         .unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
 363         .release = dmabuf_exp_ops_release,
 364         .map = dmabuf_exp_ops_kmap,
 365         .unmap = dmabuf_exp_ops_kunmap,
 366         .mmap = dmabuf_exp_ops_mmap,
 367 };
 368
 369 struct gntdev_dmabuf_export_args {
 370         struct gntdev_priv *priv;
 371         struct gntdev_grant_map *map;
 372         struct gntdev_dmabuf_priv *dmabuf_priv;
 373         struct device *dev;
 374         int count;
 375         struct page **pages;
 376         u32 fd;
 377 };
 378
 379 static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
 380 {
 381         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 382         struct gntdev_dmabuf *gntdev_dmabuf;
 383         int ret;
 384
 385         gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
 386         if (!gntdev_dmabuf)
 387                 return -ENOMEM;
 388
 389         kref_init(&gntdev_dmabuf->u.exp.refcount);
 390
 391         gntdev_dmabuf->priv = args->dmabuf_priv;
 392         gntdev_dmabuf->nr_pages = args->count;
 393         gntdev_dmabuf->pages = args->pages;
 394         gntdev_dmabuf->u.exp.priv = args->priv;
 395         gntdev_dmabuf->u.exp.map = args->map;
 396
 397         exp_info.exp_name = KBUILD_MODNAME;
 398         if (args->dev->driver && args->dev->driver->owner)
 399                 exp_info.owner = args->dev->driver->owner;
 400         else
 401                 exp_info.owner = THIS_MODULE;
 402         exp_info.ops = &dmabuf_exp_ops;
 403         exp_info.size = args->count << PAGE_SHIFT;
 404         exp_info.flags = O_RDWR;
 405         exp_info.priv = gntdev_dmabuf;
 406
 407         gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
 408         if (IS_ERR(gntdev_dmabuf->dmabuf)) {
 409                 ret = PTR_ERR(gntdev_dmabuf->dmabuf);
 410                 gntdev_dmabuf->dmabuf = NULL;
 411                 goto fail;
 412         }
 413
 414         ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC);
 415         if (ret < 0)
 416                 goto fail;
 417
 418         gntdev_dmabuf->fd = ret;
 419         args->fd = ret;
 420
 421         pr_debug("Exporting DMA buffer with fd %d\n", ret);
 422
 423         mutex_lock(&args->dmabuf_priv->lock);
 424         list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
 425         mutex_unlock(&args->dmabuf_priv->lock);
 426         return 0;
 427
 428 fail:
 429         if (gntdev_dmabuf->dmabuf)
 430                 dma_buf_put(gntdev_dmabuf->dmabuf);
 431         kfree(gntdev_dmabuf);
 432         return ret;
 433 }
 434
 435 static struct gntdev_grant_map *
 436 dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
 437                                  int count)
 438 {
 439         struct gntdev_grant_map *map;
 440
 441         if (unlikely(count <= 0))
 442                 return ERR_PTR(-EINVAL);
 443
 444         if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
 445             (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
 446                 pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
 447                 return ERR_PTR(-EINVAL);
 448         }
 449
 450         map = gntdev_alloc_map(priv, count, dmabuf_flags);
 451         if (!map)
 452                 return ERR_PTR(-ENOMEM);
 453
 454         if (unlikely(gntdev_account_mapped_pages(count))) {
 455                 pr_debug("can't map %d pages: over limit\n", count);
 456                 gntdev_put_map(NULL, map);
 457                 return ERR_PTR(-ENOMEM);
 458         }
 459         return map;
 460 }
 461
 462 static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
 463                                 int count, u32 domid, u32 *refs, u32 *fd)
 464 {
 465         struct gntdev_grant_map *map;
 466         struct gntdev_dmabuf_export_args args;
 467         int i, ret;
 468
 469         map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
 470         if (IS_ERR(map))
 471                 return PTR_ERR(map);
 472
 473         for (i = 0; i < count; i++) {
 474                 map->grants[i].domid = domid;
 475                 map->grants[i].ref = refs[i];
 476         }
 477
 478         mutex_lock(&priv->lock);
 479         gntdev_add_map(priv, map);
 480         mutex_unlock(&priv->lock);
 481
 482         map->flags |= GNTMAP_host_map;
 483 #if defined(CONFIG_X86)
 484         map->flags |= GNTMAP_device_map;
 485 #endif
 486
 487         ret = gntdev_map_grant_pages(map);
 488         if (ret < 0)
 489                 goto out;
 490
 491         args.priv = priv;
 492         args.map = map;
 493         args.dev = priv->dma_dev;
 494         args.dmabuf_priv = priv->dmabuf_priv;
 495         args.count = map->count;
 496         args.pages = map->pages;
 497         args.fd = -1; /* Shut up unnecessary gcc warning for i386 */
 498
 499         ret = dmabuf_exp_from_pages(&args);
 500         if (ret < 0)
 501                 goto out;
 502
 503         *fd = args.fd;
 504         return 0;
 505
 506 out:
 507         dmabuf_exp_remove_map(priv, map);
 508         return ret;
 509 }
 510
 511 /* DMA buffer import support. */
 512
 513 static int
 514 dmabuf_imp_grant_foreign_access(struct page **pages, u32 *refs,
 515                                 int count, int domid)
 516 {
 517         grant_ref_t priv_gref_head;
 518         int i, ret;
 519
 520         ret = gnttab_alloc_grant_references(count, &priv_gref_head);
 521         if (ret < 0) {
 522                 pr_debug("Cannot allocate grant references, ret %d\n", ret);
 523                 return ret;
 524         }
 525
 526         for (i = 0; i < count; i++) {
 527                 int cur_ref;
 528
 529                 cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
 530                 if (cur_ref < 0) {
 531                         ret = cur_ref;
 532                         pr_debug("Cannot claim grant reference, ret %d\n", ret);
 533                         goto out;
 534                 }
 535
 536                 gnttab_grant_foreign_access_ref(cur_ref, domid,
 537                                                 xen_page_to_gfn(pages[i]), 0);
 538                 refs[i] = cur_ref;
 539         }
 540
 541         return 0;
 542
 543 out:
 544         gnttab_free_grant_references(priv_gref_head);
 545         return ret;
 546 }
 547
 548 static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
 549 {
 550         int i;
 551
 552         for (i = 0; i < count; i++)
 553                 if (refs[i] != GRANT_INVALID_REF)
 554                         gnttab_end_foreign_access(refs[i], 0, 0UL);
 555 }
 556
 557 static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
 558 {
 559         kfree(gntdev_dmabuf->pages);
 560         kfree(gntdev_dmabuf->u.imp.refs);
 561         kfree(gntdev_dmabuf);
 562 }
 563
 564 static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
 565 {
 566         struct gntdev_dmabuf *gntdev_dmabuf;
 567         int i;
 568
 569         gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
 570         if (!gntdev_dmabuf)
 571                 goto fail_no_free;
 572
 573         gntdev_dmabuf->u.imp.refs = kcalloc(count,
 574                                             sizeof(gntdev_dmabuf->u.imp.refs[0]),
 575                                             GFP_KERNEL);
 576         if (!gntdev_dmabuf->u.imp.refs)
 577                 goto fail;
 578
 579         gntdev_dmabuf->pages = kcalloc(count,
 580                                        sizeof(gntdev_dmabuf->pages[0]),
 581                                        GFP_KERNEL);
 582         if (!gntdev_dmabuf->pages)
 583                 goto fail;
 584
 585         gntdev_dmabuf->nr_pages = count;
 586
 587         for (i = 0; i < count; i++)
 588                 gntdev_dmabuf->u.imp.refs[i] = GRANT_INVALID_REF;
 589
 590         return gntdev_dmabuf;
 591
 592 fail:
 593         dmabuf_imp_free_storage(gntdev_dmabuf);
 594 fail_no_free:
 595         return ERR_PTR(-ENOMEM);
 596 }
 597
 598 static struct gntdev_dmabuf *
 599 dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
 600                    int fd, int count, int domid)
 601 {
 602         struct gntdev_dmabuf *gntdev_dmabuf, *ret;
 603         struct dma_buf *dma_buf;
 604         struct dma_buf_attachment *attach;
 605         struct sg_table *sgt;
 606         struct sg_page_iter sg_iter;
 607         int i;
 608
 609         dma_buf = dma_buf_get(fd);
 610         if (IS_ERR(dma_buf))
 611                 return ERR_CAST(dma_buf);
 612
 613         gntdev_dmabuf = dmabuf_imp_alloc_storage(count);
 614         if (IS_ERR(gntdev_dmabuf)) {
 615                 ret = gntdev_dmabuf;
 616                 goto fail_put;
 617         }
 618
 619         gntdev_dmabuf->priv = priv;
 620         gntdev_dmabuf->fd = fd;
 621
 622         attach = dma_buf_attach(dma_buf, dev);
 623         if (IS_ERR(attach)) {
 624                 ret = ERR_CAST(attach);
 625                 goto fail_free_obj;
 626         }
 627
 628         gntdev_dmabuf->u.imp.attach = attach;
 629
 630         sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
 631         if (IS_ERR(sgt)) {
 632                 ret = ERR_CAST(sgt);
 633                 goto fail_detach;
 634         }
 635
 636         /* Check number of pages that imported buffer has. */
 637         if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
 638                 ret = ERR_PTR(-EINVAL);
 639                 pr_debug("DMA buffer has %zu pages, user-space expects %d\n",
 640                          attach->dmabuf->size, gntdev_dmabuf->nr_pages);
 641                 goto fail_unmap;
 642         }
 643
 644         gntdev_dmabuf->u.imp.sgt = sgt;
 645
 646         /* Now convert sgt to array of pages and check for page validity. */
 647         i = 0;
 648         for_each_sg_page(sgt->sgl, &sg_iter, sgt->nents, 0) {
 649                 struct page *page = sg_page_iter_page(&sg_iter);
 650                 /*
 651                  * Check if page is valid: this can happen if we are given
 652                  * a page from VRAM or other resources which are not backed
 653                  * by a struct page.
 654                  */
 655                 if (!pfn_valid(page_to_pfn(page))) {
 656                         ret = ERR_PTR(-EINVAL);
 657                         goto fail_unmap;
 658                 }
 659
 660                 gntdev_dmabuf->pages[i++] = page;
 661         }
 662
 663         ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gntdev_dmabuf->pages,
 664                                                       gntdev_dmabuf->u.imp.refs,
 665                                                       count, domid));
 666         if (IS_ERR(ret))
 667                 goto fail_end_access;
 668
 669         pr_debug("Imported DMA buffer with fd %d\n", fd);
 670
 671         mutex_lock(&priv->lock);
 672         list_add(&gntdev_dmabuf->next, &priv->imp_list);
 673         mutex_unlock(&priv->lock);
 674
 675         return gntdev_dmabuf;
 676
 677 fail_end_access:
 678         dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
 679 fail_unmap:
 680         dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
 681 fail_detach:
 682         dma_buf_detach(dma_buf, attach);
 683 fail_free_obj:
 684         dmabuf_imp_free_storage(gntdev_dmabuf);
 685 fail_put:
 686         dma_buf_put(dma_buf);
 687         return ret;
 688 }
 689
 690 /*
 691  * Find the hyper dma-buf by its file descriptor and remove
 692  * it from the buffer's list.
 693  */
 694 static struct gntdev_dmabuf *
 695 dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv *priv, int fd)
 696 {
 697         struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
 698
 699         mutex_lock(&priv->lock);
 700         list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next) {
 701                 if (gntdev_dmabuf->fd == fd) {
 702                         pr_debug("Found gntdev_dmabuf in the import list\n");
 703                         ret = gntdev_dmabuf;
 704                         list_del(&gntdev_dmabuf->next);
 705                         break;
 706                 }
 707         }
 708         mutex_unlock(&priv->lock);
 709         return ret;
 710 }
 711
 712 static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
 713 {
 714         struct gntdev_dmabuf *gntdev_dmabuf;
 715         struct dma_buf_attachment *attach;
 716         struct dma_buf *dma_buf;
 717
 718         gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
 719         if (IS_ERR(gntdev_dmabuf))
 720                 return PTR_ERR(gntdev_dmabuf);
 721
 722         pr_debug("Releasing DMA buffer with fd %d\n", fd);
 723
 724         dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
 725                                       gntdev_dmabuf->nr_pages);
 726
 727         attach = gntdev_dmabuf->u.imp.attach;
 728
 729         if (gntdev_dmabuf->u.imp.sgt)
 730                 dma_buf_unmap_attachment(attach, gntdev_dmabuf->u.imp.sgt,
 731                                          DMA_BIDIRECTIONAL);
 732         dma_buf = attach->dmabuf;
 733         dma_buf_detach(attach->dmabuf, attach);
 734         dma_buf_put(dma_buf);
 735
 736         dmabuf_imp_free_storage(gntdev_dmabuf);
 737         return 0;
 738 }
 739
 740 /* DMA buffer IOCTL support. */
 741
 742 long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
 743                                        struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
 744 {
 745         struct ioctl_gntdev_dmabuf_exp_from_refs op;
 746         u32 *refs;
 747         long ret;
 748
 749         if (use_ptemod) {
 750                 pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
 751                          use_ptemod);
 752                 return -EINVAL;
 753         }
 754
 755         if (copy_from_user(&op, u, sizeof(op)) != 0)
 756                 return -EFAULT;
 757
 758         if (unlikely(op.count <= 0))
 759                 return -EINVAL;
 760
 761         refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
 762         if (!refs)
 763                 return -ENOMEM;
 764
 765         if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
 766                 ret = -EFAULT;
 767                 goto out;
 768         }
 769
 770         ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
 771                                    op.domid, refs, &op.fd);
 772         if (ret)
 773                 goto out;
 774
 775         if (copy_to_user(u, &op, sizeof(op)) != 0)
 776                 ret = -EFAULT;
 777
 778 out:
 779         kfree(refs);
 780         return ret;
 781 }
 782
 783 long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
 784                                            struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
 785 {
 786         struct ioctl_gntdev_dmabuf_exp_wait_released op;
 787
 788         if (copy_from_user(&op, u, sizeof(op)) != 0)
 789                 return -EFAULT;
 790
 791         return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
 792                                         op.wait_to_ms);
 793 }
 794
 795 long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
 796                                      struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
 797 {
 798         struct ioctl_gntdev_dmabuf_imp_to_refs op;
 799         struct gntdev_dmabuf *gntdev_dmabuf;
 800         long ret;
 801
 802         if (copy_from_user(&op, u, sizeof(op)) != 0)
 803                 return -EFAULT;
 804
 805         if (unlikely(op.count <= 0))
 806                 return -EINVAL;
 807
 808         gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
 809                                            priv->dma_dev, op.fd,
 810                                            op.count, op.domid);
 811         if (IS_ERR(gntdev_dmabuf))
 812                 return PTR_ERR(gntdev_dmabuf);
 813
 814         if (copy_to_user(u->refs, gntdev_dmabuf->u.imp.refs,
 815                          sizeof(*u->refs) * op.count) != 0) {
 816                 ret = -EFAULT;
 817                 goto out_release;
 818         }
 819         return 0;
 820
 821 out_release:
 822         dmabuf_imp_release(priv->dmabuf_priv, op.fd);
 823         return ret;
 824 }
 825
 826 long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
 827                                      struct ioctl_gntdev_dmabuf_imp_release __user *u)
 828 {
 829         struct ioctl_gntdev_dmabuf_imp_release op;
 830
 831         if (copy_from_user(&op, u, sizeof(op)) != 0)
 832                 return -EFAULT;
 833
 834         return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
 835 }
 836
 837 struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void)
 838 {
 839         struct gntdev_dmabuf_priv *priv;
 840
 841         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 842         if (!priv)
 843                 return ERR_PTR(-ENOMEM);
 844
 845         mutex_init(&priv->lock);
 846         INIT_LIST_HEAD(&priv->exp_list);
 847         INIT_LIST_HEAD(&priv->exp_wait_list);
 848         INIT_LIST_HEAD(&priv->imp_list);
 849
 850         return priv;
 851 }
 852
 853 void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
 854 {
 855         kfree(priv);
 856 }