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 #include <linux/module.h>
  18
  19 #include <xen/xen.h>
  20 #include <xen/grant_table.h>
  21
  22 #include "gntdev-common.h"
  23 #include "gntdev-dmabuf.h"
  24
  25 MODULE_IMPORT_NS(DMA_BUF);
  26
  27 struct gntdev_dmabuf {
  28         struct gntdev_dmabuf_priv *priv;
  29         struct dma_buf *dmabuf;
  30         struct list_head next;
  31         int fd;
  32
  33         union {
  34                 struct {
  35                         /* Exported buffers are reference counted. */
  36                         struct kref refcount;
  37
  38                         struct gntdev_priv *priv;
  39                         struct gntdev_grant_map *map;
  40                 } exp;
  41                 struct {
  42                         /* Granted references of the imported buffer. */
  43                         grant_ref_t *refs;
  44                         /* Scatter-gather table of the imported buffer. */
  45                         struct sg_table *sgt;
  46                         /* dma-buf attachment of the imported buffer. */
  47                         struct dma_buf_attachment *attach;
  48                 } imp;
  49         } u;
  50
  51         /* Number of pages this buffer has. */
  52         int nr_pages;
  53         /* Pages of this buffer. */
  54         struct page **pages;
  55 };
  56
  57 struct gntdev_dmabuf_wait_obj {
  58         struct list_head next;
  59         struct gntdev_dmabuf *gntdev_dmabuf;
  60         struct completion completion;
  61 };
  62
  63 struct gntdev_dmabuf_attachment {
  64         struct sg_table *sgt;
  65         enum dma_data_direction dir;
  66 };
  67
  68 struct gntdev_dmabuf_priv {
  69         /* List of exported DMA buffers. */
  70         struct list_head exp_list;
  71         /* List of wait objects. */
  72         struct list_head exp_wait_list;
  73         /* List of imported DMA buffers. */
  74         struct list_head imp_list;
  75         /* This is the lock which protects dma_buf_xxx lists. */
  76         struct mutex lock;
  77         /*
  78          * We reference this file while exporting dma-bufs, so
  79          * the grant device context is not destroyed while there are
  80          * external users alive.
  81          */
  82         struct file *filp;
  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_sgtable(attach->dev, sgt,
 245                                                   gntdev_dmabuf_attach->dir,
 246                                                   DMA_ATTR_SKIP_CPU_SYNC);
 247                         sg_free_table(sgt);
 248                 }
 249
 250                 kfree(sgt);
 251                 kfree(gntdev_dmabuf_attach);
 252                 attach->priv = NULL;
 253         }
 254 }
 255
 256 static struct sg_table *
 257 dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach,
 258                            enum dma_data_direction dir)
 259 {
 260         struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
 261         struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv;
 262         struct sg_table *sgt;
 263
 264         pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages,
 265                  attach->dev);
 266
 267         if (dir == DMA_NONE || !gntdev_dmabuf_attach)
 268                 return ERR_PTR(-EINVAL);
 269
 270         /* Return the cached mapping when possible. */
 271         if (gntdev_dmabuf_attach->dir == dir)
 272                 return gntdev_dmabuf_attach->sgt;
 273
 274         /*
 275          * Two mappings with different directions for the same attachment are
 276          * not allowed.
 277          */
 278         if (gntdev_dmabuf_attach->dir != DMA_NONE)
 279                 return ERR_PTR(-EBUSY);
 280
 281         sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages,
 282                                   gntdev_dmabuf->nr_pages);
 283         if (!IS_ERR(sgt)) {
 284                 if (dma_map_sgtable(attach->dev, sgt, dir,
 285                                     DMA_ATTR_SKIP_CPU_SYNC)) {
 286                         sg_free_table(sgt);
 287                         kfree(sgt);
 288                         sgt = ERR_PTR(-ENOMEM);
 289                 } else {
 290                         gntdev_dmabuf_attach->sgt = sgt;
 291                         gntdev_dmabuf_attach->dir = dir;
 292                 }
 293         }
 294         if (IS_ERR(sgt))
 295                 pr_debug("Failed to map sg table for dev %p\n", attach->dev);
 296         return sgt;
 297 }
 298
 299 static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach,
 300                                          struct sg_table *sgt,
 301                                          enum dma_data_direction dir)
 302 {
 303         /* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */
 304 }
 305
 306 static void dmabuf_exp_release(struct kref *kref)
 307 {
 308         struct gntdev_dmabuf *gntdev_dmabuf =
 309                 container_of(kref, struct gntdev_dmabuf, u.exp.refcount);
 310
 311         dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
 312         list_del(&gntdev_dmabuf->next);
 313         fput(gntdev_dmabuf->priv->filp);
 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 const struct dma_buf_ops dmabuf_exp_ops =  {
 339         .attach = dmabuf_exp_ops_attach,
 340         .detach = dmabuf_exp_ops_detach,
 341         .map_dma_buf = dmabuf_exp_ops_map_dma_buf,
 342         .unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
 343         .release = dmabuf_exp_ops_release,
 344 };
 345
 346 struct gntdev_dmabuf_export_args {
 347         struct gntdev_priv *priv;
 348         struct gntdev_grant_map *map;
 349         struct gntdev_dmabuf_priv *dmabuf_priv;
 350         struct device *dev;
 351         int count;
 352         struct page **pages;
 353         u32 fd;
 354 };
 355
 356 static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
 357 {
 358         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 359         struct gntdev_dmabuf *gntdev_dmabuf;
 360         int ret;
 361
 362         gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
 363         if (!gntdev_dmabuf)
 364                 return -ENOMEM;
 365
 366         kref_init(&gntdev_dmabuf->u.exp.refcount);
 367
 368         gntdev_dmabuf->priv = args->dmabuf_priv;
 369         gntdev_dmabuf->nr_pages = args->count;
 370         gntdev_dmabuf->pages = args->pages;
 371         gntdev_dmabuf->u.exp.priv = args->priv;
 372         gntdev_dmabuf->u.exp.map = args->map;
 373
 374         exp_info.exp_name = KBUILD_MODNAME;
 375         if (args->dev->driver && args->dev->driver->owner)
 376                 exp_info.owner = args->dev->driver->owner;
 377         else
 378                 exp_info.owner = THIS_MODULE;
 379         exp_info.ops = &dmabuf_exp_ops;
 380         exp_info.size = args->count << PAGE_SHIFT;
 381         exp_info.flags = O_RDWR;
 382         exp_info.priv = gntdev_dmabuf;
 383
 384         gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
 385         if (IS_ERR(gntdev_dmabuf->dmabuf)) {
 386                 ret = PTR_ERR(gntdev_dmabuf->dmabuf);
 387                 gntdev_dmabuf->dmabuf = NULL;
 388                 goto fail;
 389         }
 390
 391         ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC);
 392         if (ret < 0)
 393                 goto fail;
 394
 395         gntdev_dmabuf->fd = ret;
 396         args->fd = ret;
 397
 398         pr_debug("Exporting DMA buffer with fd %d\n", ret);
 399
 400         mutex_lock(&args->dmabuf_priv->lock);
 401         list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
 402         mutex_unlock(&args->dmabuf_priv->lock);
 403         get_file(gntdev_dmabuf->priv->filp);
 404         return 0;
 405
 406 fail:
 407         if (gntdev_dmabuf->dmabuf)
 408                 dma_buf_put(gntdev_dmabuf->dmabuf);
 409         kfree(gntdev_dmabuf);
 410         return ret;
 411 }
 412
 413 static struct gntdev_grant_map *
 414 dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
 415                                  int count)
 416 {
 417         struct gntdev_grant_map *map;
 418
 419         if (unlikely(gntdev_test_page_count(count)))
 420                 return ERR_PTR(-EINVAL);
 421
 422         if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
 423             (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
 424                 pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
 425                 return ERR_PTR(-EINVAL);
 426         }
 427
 428         map = gntdev_alloc_map(priv, count, dmabuf_flags);
 429         if (!map)
 430                 return ERR_PTR(-ENOMEM);
 431
 432         return map;
 433 }
 434
 435 static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
 436                                 int count, u32 domid, u32 *refs, u32 *fd)
 437 {
 438         struct gntdev_grant_map *map;
 439         struct gntdev_dmabuf_export_args args;
 440         int i, ret;
 441
 442         map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
 443         if (IS_ERR(map))
 444                 return PTR_ERR(map);
 445
 446         for (i = 0; i < count; i++) {
 447                 map->grants[i].domid = domid;
 448                 map->grants[i].ref = refs[i];
 449         }
 450
 451         mutex_lock(&priv->lock);
 452         gntdev_add_map(priv, map);
 453         mutex_unlock(&priv->lock);
 454
 455         map->flags |= GNTMAP_host_map;
 456 #if defined(CONFIG_X86)
 457         map->flags |= GNTMAP_device_map;
 458 #endif
 459
 460         ret = gntdev_map_grant_pages(map);
 461         if (ret < 0)
 462                 goto out;
 463
 464         args.priv = priv;
 465         args.map = map;
 466         args.dev = priv->dma_dev;
 467         args.dmabuf_priv = priv->dmabuf_priv;
 468         args.count = map->count;
 469         args.pages = map->pages;
 470         args.fd = -1; /* Shut up unnecessary gcc warning for i386 */
 471
 472         ret = dmabuf_exp_from_pages(&args);
 473         if (ret < 0)
 474                 goto out;
 475
 476         *fd = args.fd;
 477         return 0;
 478
 479 out:
 480         dmabuf_exp_remove_map(priv, map);
 481         return ret;
 482 }
 483
 484 /* DMA buffer import support. */
 485
 486 static int
 487 dmabuf_imp_grant_foreign_access(struct page **pages, u32 *refs,
 488                                 int count, int domid)
 489 {
 490         grant_ref_t priv_gref_head;
 491         int i, ret;
 492
 493         ret = gnttab_alloc_grant_references(count, &priv_gref_head);
 494         if (ret < 0) {
 495                 pr_debug("Cannot allocate grant references, ret %d\n", ret);
 496                 return ret;
 497         }
 498
 499         for (i = 0; i < count; i++) {
 500                 int cur_ref;
 501
 502                 cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
 503                 if (cur_ref < 0) {
 504                         ret = cur_ref;
 505                         pr_debug("Cannot claim grant reference, ret %d\n", ret);
 506                         goto out;
 507                 }
 508
 509                 gnttab_grant_foreign_access_ref(cur_ref, domid,
 510                                                 xen_page_to_gfn(pages[i]), 0);
 511                 refs[i] = cur_ref;
 512         }
 513
 514         return 0;
 515
 516 out:
 517         gnttab_free_grant_references(priv_gref_head);
 518         return ret;
 519 }
 520
 521 static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
 522 {
 523         int i;
 524
 525         for (i = 0; i < count; i++)
 526                 if (refs[i] != INVALID_GRANT_REF)
 527                         gnttab_end_foreign_access(refs[i], NULL);
 528 }
 529
 530 static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
 531 {
 532         kfree(gntdev_dmabuf->pages);
 533         kfree(gntdev_dmabuf->u.imp.refs);
 534         kfree(gntdev_dmabuf);
 535 }
 536
 537 static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
 538 {
 539         struct gntdev_dmabuf *gntdev_dmabuf;
 540         int i;
 541
 542         gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
 543         if (!gntdev_dmabuf)
 544                 goto fail_no_free;
 545
 546         gntdev_dmabuf->u.imp.refs = kcalloc(count,
 547                                             sizeof(gntdev_dmabuf->u.imp.refs[0]),
 548                                             GFP_KERNEL);
 549         if (!gntdev_dmabuf->u.imp.refs)
 550                 goto fail;
 551
 552         gntdev_dmabuf->pages = kcalloc(count,
 553                                        sizeof(gntdev_dmabuf->pages[0]),
 554                                        GFP_KERNEL);
 555         if (!gntdev_dmabuf->pages)
 556                 goto fail;
 557
 558         gntdev_dmabuf->nr_pages = count;
 559
 560         for (i = 0; i < count; i++)
 561                 gntdev_dmabuf->u.imp.refs[i] = INVALID_GRANT_REF;
 562
 563         return gntdev_dmabuf;
 564
 565 fail:
 566         dmabuf_imp_free_storage(gntdev_dmabuf);
 567 fail_no_free:
 568         return ERR_PTR(-ENOMEM);
 569 }
 570
 571 static struct gntdev_dmabuf *
 572 dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
 573                    int fd, int count, int domid)
 574 {
 575         struct gntdev_dmabuf *gntdev_dmabuf, *ret;
 576         struct dma_buf *dma_buf;
 577         struct dma_buf_attachment *attach;
 578         struct sg_table *sgt;
 579         struct sg_page_iter sg_iter;
 580         int i;
 581
 582         dma_buf = dma_buf_get(fd);
 583         if (IS_ERR(dma_buf))
 584                 return ERR_CAST(dma_buf);
 585
 586         gntdev_dmabuf = dmabuf_imp_alloc_storage(count);
 587         if (IS_ERR(gntdev_dmabuf)) {
 588                 ret = gntdev_dmabuf;
 589                 goto fail_put;
 590         }
 591
 592         gntdev_dmabuf->priv = priv;
 593         gntdev_dmabuf->fd = fd;
 594
 595         attach = dma_buf_attach(dma_buf, dev);
 596         if (IS_ERR(attach)) {
 597                 ret = ERR_CAST(attach);
 598                 goto fail_free_obj;
 599         }
 600
 601         gntdev_dmabuf->u.imp.attach = attach;
 602
 603         sgt = dma_buf_map_attachment_unlocked(attach, DMA_BIDIRECTIONAL);
 604         if (IS_ERR(sgt)) {
 605                 ret = ERR_CAST(sgt);
 606                 goto fail_detach;
 607         }
 608
 609         /* Check that we have zero offset. */
 610         if (sgt->sgl->offset) {
 611                 ret = ERR_PTR(-EINVAL);
 612                 pr_debug("DMA buffer has %d bytes offset, user-space expects 0\n",
 613                          sgt->sgl->offset);
 614                 goto fail_unmap;
 615         }
 616
 617         /* Check number of pages that imported buffer has. */
 618         if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
 619                 ret = ERR_PTR(-EINVAL);
 620                 pr_debug("DMA buffer has %zu pages, user-space expects %d\n",
 621                          attach->dmabuf->size, gntdev_dmabuf->nr_pages);
 622                 goto fail_unmap;
 623         }
 624
 625         gntdev_dmabuf->u.imp.sgt = sgt;
 626
 627         /* Now convert sgt to array of pages and check for page validity. */
 628         i = 0;
 629         for_each_sgtable_page(sgt, &sg_iter, 0) {
 630                 struct page *page = sg_page_iter_page(&sg_iter);
 631                 /*
 632                  * Check if page is valid: this can happen if we are given
 633                  * a page from VRAM or other resources which are not backed
 634                  * by a struct page.
 635                  */
 636                 if (!pfn_valid(page_to_pfn(page))) {
 637                         ret = ERR_PTR(-EINVAL);
 638                         goto fail_unmap;
 639                 }
 640
 641                 gntdev_dmabuf->pages[i++] = page;
 642         }
 643
 644         ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gntdev_dmabuf->pages,
 645                                                       gntdev_dmabuf->u.imp.refs,
 646                                                       count, domid));
 647         if (IS_ERR(ret))
 648                 goto fail_end_access;
 649
 650         pr_debug("Imported DMA buffer with fd %d\n", fd);
 651
 652         mutex_lock(&priv->lock);
 653         list_add(&gntdev_dmabuf->next, &priv->imp_list);
 654         mutex_unlock(&priv->lock);
 655
 656         return gntdev_dmabuf;
 657
 658 fail_end_access:
 659         dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
 660 fail_unmap:
 661         dma_buf_unmap_attachment_unlocked(attach, sgt, DMA_BIDIRECTIONAL);
 662 fail_detach:
 663         dma_buf_detach(dma_buf, attach);
 664 fail_free_obj:
 665         dmabuf_imp_free_storage(gntdev_dmabuf);
 666 fail_put:
 667         dma_buf_put(dma_buf);
 668         return ret;
 669 }
 670
 671 /*
 672  * Find the hyper dma-buf by its file descriptor and remove
 673  * it from the buffer's list.
 674  */
 675 static struct gntdev_dmabuf *
 676 dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv *priv, int fd)
 677 {
 678         struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
 679
 680         mutex_lock(&priv->lock);
 681         list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next) {
 682                 if (gntdev_dmabuf->fd == fd) {
 683                         pr_debug("Found gntdev_dmabuf in the import list\n");
 684                         ret = gntdev_dmabuf;
 685                         list_del(&gntdev_dmabuf->next);
 686                         break;
 687                 }
 688         }
 689         mutex_unlock(&priv->lock);
 690         return ret;
 691 }
 692
 693 static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
 694 {
 695         struct gntdev_dmabuf *gntdev_dmabuf;
 696         struct dma_buf_attachment *attach;
 697         struct dma_buf *dma_buf;
 698
 699         gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
 700         if (IS_ERR(gntdev_dmabuf))
 701                 return PTR_ERR(gntdev_dmabuf);
 702
 703         pr_debug("Releasing DMA buffer with fd %d\n", fd);
 704
 705         dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
 706                                       gntdev_dmabuf->nr_pages);
 707
 708         attach = gntdev_dmabuf->u.imp.attach;
 709
 710         if (gntdev_dmabuf->u.imp.sgt)
 711                 dma_buf_unmap_attachment_unlocked(attach, gntdev_dmabuf->u.imp.sgt,
 712                                                   DMA_BIDIRECTIONAL);
 713         dma_buf = attach->dmabuf;
 714         dma_buf_detach(attach->dmabuf, attach);
 715         dma_buf_put(dma_buf);
 716
 717         dmabuf_imp_free_storage(gntdev_dmabuf);
 718         return 0;
 719 }
 720
 721 static void dmabuf_imp_release_all(struct gntdev_dmabuf_priv *priv)
 722 {
 723         struct gntdev_dmabuf *q, *gntdev_dmabuf;
 724
 725         list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next)
 726                 dmabuf_imp_release(priv, gntdev_dmabuf->fd);
 727 }
 728
 729 /* DMA buffer IOCTL support. */
 730
 731 long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
 732                                        struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
 733 {
 734         struct ioctl_gntdev_dmabuf_exp_from_refs op;
 735         u32 *refs;
 736         long ret;
 737
 738         if (use_ptemod) {
 739                 pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
 740                          use_ptemod);
 741                 return -EINVAL;
 742         }
 743
 744         if (copy_from_user(&op, u, sizeof(op)) != 0)
 745                 return -EFAULT;
 746
 747         if (unlikely(gntdev_test_page_count(op.count)))
 748                 return -EINVAL;
 749
 750         refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
 751         if (!refs)
 752                 return -ENOMEM;
 753
 754         if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
 755                 ret = -EFAULT;
 756                 goto out;
 757         }
 758
 759         ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
 760                                    op.domid, refs, &op.fd);
 761         if (ret)
 762                 goto out;
 763
 764         if (copy_to_user(u, &op, sizeof(op)) != 0)
 765                 ret = -EFAULT;
 766
 767 out:
 768         kfree(refs);
 769         return ret;
 770 }
 771
 772 long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
 773                                            struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
 774 {
 775         struct ioctl_gntdev_dmabuf_exp_wait_released op;
 776
 777         if (copy_from_user(&op, u, sizeof(op)) != 0)
 778                 return -EFAULT;
 779
 780         return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
 781                                         op.wait_to_ms);
 782 }
 783
 784 long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
 785                                      struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
 786 {
 787         struct ioctl_gntdev_dmabuf_imp_to_refs op;
 788         struct gntdev_dmabuf *gntdev_dmabuf;
 789         long ret;
 790
 791         if (copy_from_user(&op, u, sizeof(op)) != 0)
 792                 return -EFAULT;
 793
 794         if (unlikely(gntdev_test_page_count(op.count)))
 795                 return -EINVAL;
 796
 797         gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
 798                                            priv->dma_dev, op.fd,
 799                                            op.count, op.domid);
 800         if (IS_ERR(gntdev_dmabuf))
 801                 return PTR_ERR(gntdev_dmabuf);
 802
 803         if (copy_to_user(u->refs, gntdev_dmabuf->u.imp.refs,
 804                          sizeof(*u->refs) * op.count) != 0) {
 805                 ret = -EFAULT;
 806                 goto out_release;
 807         }
 808         return 0;
 809
 810 out_release:
 811         dmabuf_imp_release(priv->dmabuf_priv, op.fd);
 812         return ret;
 813 }
 814
 815 long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
 816                                      struct ioctl_gntdev_dmabuf_imp_release __user *u)
 817 {
 818         struct ioctl_gntdev_dmabuf_imp_release op;
 819
 820         if (copy_from_user(&op, u, sizeof(op)) != 0)
 821                 return -EFAULT;
 822
 823         return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
 824 }
 825
 826 struct gntdev_dmabuf_priv *gntdev_dmabuf_init(struct file *filp)
 827 {
 828         struct gntdev_dmabuf_priv *priv;
 829
 830         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 831         if (!priv)
 832                 return ERR_PTR(-ENOMEM);
 833
 834         mutex_init(&priv->lock);
 835         INIT_LIST_HEAD(&priv->exp_list);
 836         INIT_LIST_HEAD(&priv->exp_wait_list);
 837         INIT_LIST_HEAD(&priv->imp_list);
 838
 839         priv->filp = filp;
 840
 841         return priv;
 842 }
 843
 844 void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
 845 {
 846         dmabuf_imp_release_all(priv);
 847         kfree(priv);
 848 }