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 #ifndef GRANT_INVALID_REF
  28 /*
  29  * Note on usage of grant reference 0 as invalid grant reference:
  30  * grant reference 0 is valid, but never exposed to a driver,
  31  * because of the fact it is already in use/reserved by the PV console.
  32  */
  33 #define GRANT_INVALID_REF       0
  34 #endif
  35
  36 struct gntdev_dmabuf {
  37         struct gntdev_dmabuf_priv *priv;
  38         struct dma_buf *dmabuf;
  39         struct list_head next;
  40         int fd;
  41
  42         union {
  43                 struct {
  44                         /* Exported buffers are reference counted. */
  45                         struct kref refcount;
  46
  47                         struct gntdev_priv *priv;
  48                         struct gntdev_grant_map *map;
  49                 } exp;
  50                 struct {
  51                         /* Granted references of the imported buffer. */
  52                         grant_ref_t *refs;
  53                         /* Scatter-gather table of the imported buffer. */
  54                         struct sg_table *sgt;
  55                         /* dma-buf attachment of the imported buffer. */
  56                         struct dma_buf_attachment *attach;
  57                 } imp;
  58         } u;
  59
  60         /* Number of pages this buffer has. */
  61         int nr_pages;
  62         /* Pages of this buffer. */
  63         struct page **pages;
  64 };
  65
  66 struct gntdev_dmabuf_wait_obj {
  67         struct list_head next;
  68         struct gntdev_dmabuf *gntdev_dmabuf;
  69         struct completion completion;
  70 };
  71
  72 struct gntdev_dmabuf_attachment {
  73         struct sg_table *sgt;
  74         enum dma_data_direction dir;
  75 };
  76
  77 struct gntdev_dmabuf_priv {
  78         /* List of exported DMA buffers. */
  79         struct list_head exp_list;
  80         /* List of wait objects. */
  81         struct list_head exp_wait_list;
  82         /* List of imported DMA buffers. */
  83         struct list_head imp_list;
  84         /* This is the lock which protects dma_buf_xxx lists. */
  85         struct mutex lock;
  86         /*
  87          * We reference this file while exporting dma-bufs, so
  88          * the grant device context is not destroyed while there are
  89          * external users alive.
  90          */
  91         struct file *filp;
  92 };
  93
  94 /* DMA buffer export support. */
  95
  96 /* Implementation of wait for exported DMA buffer to be released. */
  97
  98 static void dmabuf_exp_release(struct kref *kref);
  99
 100 static struct gntdev_dmabuf_wait_obj *
 101 dmabuf_exp_wait_obj_new(struct gntdev_dmabuf_priv *priv,
 102                         struct gntdev_dmabuf *gntdev_dmabuf)
 103 {
 104         struct gntdev_dmabuf_wait_obj *obj;
 105
 106         obj = kzalloc(sizeof(*obj), GFP_KERNEL);
 107         if (!obj)
 108                 return ERR_PTR(-ENOMEM);
 109
 110         init_completion(&obj->completion);
 111         obj->gntdev_dmabuf = gntdev_dmabuf;
 112
 113         mutex_lock(&priv->lock);
 114         list_add(&obj->next, &priv->exp_wait_list);
 115         /* Put our reference and wait for gntdev_dmabuf's release to fire. */
 116         kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
 117         mutex_unlock(&priv->lock);
 118         return obj;
 119 }
 120
 121 static void dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv *priv,
 122                                      struct gntdev_dmabuf_wait_obj *obj)
 123 {
 124         mutex_lock(&priv->lock);
 125         list_del(&obj->next);
 126         mutex_unlock(&priv->lock);
 127         kfree(obj);
 128 }
 129
 130 static int dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj *obj,
 131                                     u32 wait_to_ms)
 132 {
 133         if (wait_for_completion_timeout(&obj->completion,
 134                         msecs_to_jiffies(wait_to_ms)) <= 0)
 135                 return -ETIMEDOUT;
 136
 137         return 0;
 138 }
 139
 140 static void dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv *priv,
 141                                        struct gntdev_dmabuf *gntdev_dmabuf)
 142 {
 143         struct gntdev_dmabuf_wait_obj *obj;
 144
 145         list_for_each_entry(obj, &priv->exp_wait_list, next)
 146                 if (obj->gntdev_dmabuf == gntdev_dmabuf) {
 147                         pr_debug("Found gntdev_dmabuf in the wait list, wake\n");
 148                         complete_all(&obj->completion);
 149                         break;
 150                 }
 151 }
 152
 153 static struct gntdev_dmabuf *
 154 dmabuf_exp_wait_obj_get_dmabuf(struct gntdev_dmabuf_priv *priv, int fd)
 155 {
 156         struct gntdev_dmabuf *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
 157
 158         mutex_lock(&priv->lock);
 159         list_for_each_entry(gntdev_dmabuf, &priv->exp_list, next)
 160                 if (gntdev_dmabuf->fd == fd) {
 161                         pr_debug("Found gntdev_dmabuf in the wait list\n");
 162                         kref_get(&gntdev_dmabuf->u.exp.refcount);
 163                         ret = gntdev_dmabuf;
 164                         break;
 165                 }
 166         mutex_unlock(&priv->lock);
 167         return ret;
 168 }
 169
 170 static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
 171                                     int wait_to_ms)
 172 {
 173         struct gntdev_dmabuf *gntdev_dmabuf;
 174         struct gntdev_dmabuf_wait_obj *obj;
 175         int ret;
 176
 177         pr_debug("Will wait for dma-buf with fd %d\n", fd);
 178         /*
 179          * Try to find the DMA buffer: if not found means that
 180          * either the buffer has already been released or file descriptor
 181          * provided is wrong.
 182          */
 183         gntdev_dmabuf = dmabuf_exp_wait_obj_get_dmabuf(priv, fd);
 184         if (IS_ERR(gntdev_dmabuf))
 185                 return PTR_ERR(gntdev_dmabuf);
 186
 187         /*
 188          * gntdev_dmabuf still exists and is reference count locked by us now,
 189          * so prepare to wait: allocate wait object and add it to the wait list,
 190          * so we can find it on release.
 191          */
 192         obj = dmabuf_exp_wait_obj_new(priv, gntdev_dmabuf);
 193         if (IS_ERR(obj))
 194                 return PTR_ERR(obj);
 195
 196         ret = dmabuf_exp_wait_obj_wait(obj, wait_to_ms);
 197         dmabuf_exp_wait_obj_free(priv, obj);
 198         return ret;
 199 }
 200
 201 /* DMA buffer export support. */
 202
 203 static struct sg_table *
 204 dmabuf_pages_to_sgt(struct page **pages, unsigned int nr_pages)
 205 {
 206         struct sg_table *sgt;
 207         int ret;
 208
 209         sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
 210         if (!sgt) {
 211                 ret = -ENOMEM;
 212                 goto out;
 213         }
 214
 215         ret = sg_alloc_table_from_pages(sgt, pages, nr_pages, 0,
 216                                         nr_pages << PAGE_SHIFT,
 217                                         GFP_KERNEL);
 218         if (ret)
 219                 goto out;
 220
 221         return sgt;
 222
 223 out:
 224         kfree(sgt);
 225         return ERR_PTR(ret);
 226 }
 227
 228 static int dmabuf_exp_ops_attach(struct dma_buf *dma_buf,
 229                                  struct dma_buf_attachment *attach)
 230 {
 231         struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach;
 232
 233         gntdev_dmabuf_attach = kzalloc(sizeof(*gntdev_dmabuf_attach),
 234                                        GFP_KERNEL);
 235         if (!gntdev_dmabuf_attach)
 236                 return -ENOMEM;
 237
 238         gntdev_dmabuf_attach->dir = DMA_NONE;
 239         attach->priv = gntdev_dmabuf_attach;
 240         return 0;
 241 }
 242
 243 static void dmabuf_exp_ops_detach(struct dma_buf *dma_buf,
 244                                   struct dma_buf_attachment *attach)
 245 {
 246         struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
 247
 248         if (gntdev_dmabuf_attach) {
 249                 struct sg_table *sgt = gntdev_dmabuf_attach->sgt;
 250
 251                 if (sgt) {
 252                         if (gntdev_dmabuf_attach->dir != DMA_NONE)
 253                                 dma_unmap_sgtable(attach->dev, sgt,
 254                                                   gntdev_dmabuf_attach->dir,
 255                                                   DMA_ATTR_SKIP_CPU_SYNC);
 256                         sg_free_table(sgt);
 257                 }
 258
 259                 kfree(sgt);
 260                 kfree(gntdev_dmabuf_attach);
 261                 attach->priv = NULL;
 262         }
 263 }
 264
 265 static struct sg_table *
 266 dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach,
 267                            enum dma_data_direction dir)
 268 {
 269         struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
 270         struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv;
 271         struct sg_table *sgt;
 272
 273         pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages,
 274                  attach->dev);
 275
 276         if (dir == DMA_NONE || !gntdev_dmabuf_attach)
 277                 return ERR_PTR(-EINVAL);
 278
 279         /* Return the cached mapping when possible. */
 280         if (gntdev_dmabuf_attach->dir == dir)
 281                 return gntdev_dmabuf_attach->sgt;
 282
 283         /*
 284          * Two mappings with different directions for the same attachment are
 285          * not allowed.
 286          */
 287         if (gntdev_dmabuf_attach->dir != DMA_NONE)
 288                 return ERR_PTR(-EBUSY);
 289
 290         sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages,
 291                                   gntdev_dmabuf->nr_pages);
 292         if (!IS_ERR(sgt)) {
 293                 if (dma_map_sgtable(attach->dev, sgt, dir,
 294                                     DMA_ATTR_SKIP_CPU_SYNC)) {
 295                         sg_free_table(sgt);
 296                         kfree(sgt);
 297                         sgt = ERR_PTR(-ENOMEM);
 298                 } else {
 299                         gntdev_dmabuf_attach->sgt = sgt;
 300                         gntdev_dmabuf_attach->dir = dir;
 301                 }
 302         }
 303         if (IS_ERR(sgt))
 304                 pr_debug("Failed to map sg table for dev %p\n", attach->dev);
 305         return sgt;
 306 }
 307
 308 static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach,
 309                                          struct sg_table *sgt,
 310                                          enum dma_data_direction dir)
 311 {
 312         /* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */
 313 }
 314
 315 static void dmabuf_exp_release(struct kref *kref)
 316 {
 317         struct gntdev_dmabuf *gntdev_dmabuf =
 318                 container_of(kref, struct gntdev_dmabuf, u.exp.refcount);
 319
 320         dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
 321         list_del(&gntdev_dmabuf->next);
 322         fput(gntdev_dmabuf->priv->filp);
 323         kfree(gntdev_dmabuf);
 324 }
 325
 326 static void dmabuf_exp_remove_map(struct gntdev_priv *priv,
 327                                   struct gntdev_grant_map *map)
 328 {
 329         mutex_lock(&priv->lock);
 330         list_del(&map->next);
 331         gntdev_put_map(NULL /* already removed */, map);
 332         mutex_unlock(&priv->lock);
 333 }
 334
 335 static void dmabuf_exp_ops_release(struct dma_buf *dma_buf)
 336 {
 337         struct gntdev_dmabuf *gntdev_dmabuf = dma_buf->priv;
 338         struct gntdev_dmabuf_priv *priv = gntdev_dmabuf->priv;
 339
 340         dmabuf_exp_remove_map(gntdev_dmabuf->u.exp.priv,
 341                               gntdev_dmabuf->u.exp.map);
 342         mutex_lock(&priv->lock);
 343         kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
 344         mutex_unlock(&priv->lock);
 345 }
 346
 347 static const struct dma_buf_ops dmabuf_exp_ops =  {
 348         .attach = dmabuf_exp_ops_attach,
 349         .detach = dmabuf_exp_ops_detach,
 350         .map_dma_buf = dmabuf_exp_ops_map_dma_buf,
 351         .unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
 352         .release = dmabuf_exp_ops_release,
 353 };
 354
 355 struct gntdev_dmabuf_export_args {
 356         struct gntdev_priv *priv;
 357         struct gntdev_grant_map *map;
 358         struct gntdev_dmabuf_priv *dmabuf_priv;
 359         struct device *dev;
 360         int count;
 361         struct page **pages;
 362         u32 fd;
 363 };
 364
 365 static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
 366 {
 367         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 368         struct gntdev_dmabuf *gntdev_dmabuf;
 369         int ret;
 370
 371         gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
 372         if (!gntdev_dmabuf)
 373                 return -ENOMEM;
 374
 375         kref_init(&gntdev_dmabuf->u.exp.refcount);
 376
 377         gntdev_dmabuf->priv = args->dmabuf_priv;
 378         gntdev_dmabuf->nr_pages = args->count;
 379         gntdev_dmabuf->pages = args->pages;
 380         gntdev_dmabuf->u.exp.priv = args->priv;
 381         gntdev_dmabuf->u.exp.map = args->map;
 382
 383         exp_info.exp_name = KBUILD_MODNAME;
 384         if (args->dev->driver && args->dev->driver->owner)
 385                 exp_info.owner = args->dev->driver->owner;
 386         else
 387                 exp_info.owner = THIS_MODULE;
 388         exp_info.ops = &dmabuf_exp_ops;
 389         exp_info.size = args->count << PAGE_SHIFT;
 390         exp_info.flags = O_RDWR;
 391         exp_info.priv = gntdev_dmabuf;
 392
 393         gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
 394         if (IS_ERR(gntdev_dmabuf->dmabuf)) {
 395                 ret = PTR_ERR(gntdev_dmabuf->dmabuf);
 396                 gntdev_dmabuf->dmabuf = NULL;
 397                 goto fail;
 398         }
 399
 400         ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC);
 401         if (ret < 0)
 402                 goto fail;
 403
 404         gntdev_dmabuf->fd = ret;
 405         args->fd = ret;
 406
 407         pr_debug("Exporting DMA buffer with fd %d\n", ret);
 408
 409         mutex_lock(&args->dmabuf_priv->lock);
 410         list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
 411         mutex_unlock(&args->dmabuf_priv->lock);
 412         get_file(gntdev_dmabuf->priv->filp);
 413         return 0;
 414
 415 fail:
 416         if (gntdev_dmabuf->dmabuf)
 417                 dma_buf_put(gntdev_dmabuf->dmabuf);
 418         kfree(gntdev_dmabuf);
 419         return ret;
 420 }
 421
 422 static struct gntdev_grant_map *
 423 dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
 424                                  int count)
 425 {
 426         struct gntdev_grant_map *map;
 427
 428         if (unlikely(gntdev_test_page_count(count)))
 429                 return ERR_PTR(-EINVAL);
 430
 431         if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
 432             (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
 433                 pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
 434                 return ERR_PTR(-EINVAL);
 435         }
 436
 437         map = gntdev_alloc_map(priv, count, dmabuf_flags);
 438         if (!map)
 439                 return ERR_PTR(-ENOMEM);
 440
 441         return map;
 442 }
 443
 444 static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
 445                                 int count, u32 domid, u32 *refs, u32 *fd)
 446 {
 447         struct gntdev_grant_map *map;
 448         struct gntdev_dmabuf_export_args args;
 449         int i, ret;
 450
 451         map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
 452         if (IS_ERR(map))
 453                 return PTR_ERR(map);
 454
 455         for (i = 0; i < count; i++) {
 456                 map->grants[i].domid = domid;
 457                 map->grants[i].ref = refs[i];
 458         }
 459
 460         mutex_lock(&priv->lock);
 461         gntdev_add_map(priv, map);
 462         mutex_unlock(&priv->lock);
 463
 464         map->flags |= GNTMAP_host_map;
 465 #if defined(CONFIG_X86)
 466         map->flags |= GNTMAP_device_map;
 467 #endif
 468
 469         ret = gntdev_map_grant_pages(map);
 470         if (ret < 0)
 471                 goto out;
 472
 473         args.priv = priv;
 474         args.map = map;
 475         args.dev = priv->dma_dev;
 476         args.dmabuf_priv = priv->dmabuf_priv;
 477         args.count = map->count;
 478         args.pages = map->pages;
 479         args.fd = -1; /* Shut up unnecessary gcc warning for i386 */
 480
 481         ret = dmabuf_exp_from_pages(&args);
 482         if (ret < 0)
 483                 goto out;
 484
 485         *fd = args.fd;
 486         return 0;
 487
 488 out:
 489         dmabuf_exp_remove_map(priv, map);
 490         return ret;
 491 }
 492
 493 /* DMA buffer import support. */
 494
 495 static int
 496 dmabuf_imp_grant_foreign_access(struct page **pages, u32 *refs,
 497                                 int count, int domid)
 498 {
 499         grant_ref_t priv_gref_head;
 500         int i, ret;
 501
 502         ret = gnttab_alloc_grant_references(count, &priv_gref_head);
 503         if (ret < 0) {
 504                 pr_debug("Cannot allocate grant references, ret %d\n", ret);
 505                 return ret;
 506         }
 507
 508         for (i = 0; i < count; i++) {
 509                 int cur_ref;
 510
 511                 cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
 512                 if (cur_ref < 0) {
 513                         ret = cur_ref;
 514                         pr_debug("Cannot claim grant reference, ret %d\n", ret);
 515                         goto out;
 516                 }
 517
 518                 gnttab_grant_foreign_access_ref(cur_ref, domid,
 519                                                 xen_page_to_gfn(pages[i]), 0);
 520                 refs[i] = cur_ref;
 521         }
 522
 523         return 0;
 524
 525 out:
 526         gnttab_free_grant_references(priv_gref_head);
 527         return ret;
 528 }
 529
 530 static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
 531 {
 532         int i;
 533
 534         for (i = 0; i < count; i++)
 535                 if (refs[i] != GRANT_INVALID_REF)
 536                         gnttab_end_foreign_access(refs[i], 0, 0UL);
 537 }
 538
 539 static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
 540 {
 541         kfree(gntdev_dmabuf->pages);
 542         kfree(gntdev_dmabuf->u.imp.refs);
 543         kfree(gntdev_dmabuf);
 544 }
 545
 546 static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
 547 {
 548         struct gntdev_dmabuf *gntdev_dmabuf;
 549         int i;
 550
 551         gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
 552         if (!gntdev_dmabuf)
 553                 goto fail_no_free;
 554
 555         gntdev_dmabuf->u.imp.refs = kcalloc(count,
 556                                             sizeof(gntdev_dmabuf->u.imp.refs[0]),
 557                                             GFP_KERNEL);
 558         if (!gntdev_dmabuf->u.imp.refs)
 559                 goto fail;
 560
 561         gntdev_dmabuf->pages = kcalloc(count,
 562                                        sizeof(gntdev_dmabuf->pages[0]),
 563                                        GFP_KERNEL);
 564         if (!gntdev_dmabuf->pages)
 565                 goto fail;
 566
 567         gntdev_dmabuf->nr_pages = count;
 568
 569         for (i = 0; i < count; i++)
 570                 gntdev_dmabuf->u.imp.refs[i] = GRANT_INVALID_REF;
 571
 572         return gntdev_dmabuf;
 573
 574 fail:
 575         dmabuf_imp_free_storage(gntdev_dmabuf);
 576 fail_no_free:
 577         return ERR_PTR(-ENOMEM);
 578 }
 579
 580 static struct gntdev_dmabuf *
 581 dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
 582                    int fd, int count, int domid)
 583 {
 584         struct gntdev_dmabuf *gntdev_dmabuf, *ret;
 585         struct dma_buf *dma_buf;
 586         struct dma_buf_attachment *attach;
 587         struct sg_table *sgt;
 588         struct sg_page_iter sg_iter;
 589         int i;
 590
 591         dma_buf = dma_buf_get(fd);
 592         if (IS_ERR(dma_buf))
 593                 return ERR_CAST(dma_buf);
 594
 595         gntdev_dmabuf = dmabuf_imp_alloc_storage(count);
 596         if (IS_ERR(gntdev_dmabuf)) {
 597                 ret = gntdev_dmabuf;
 598                 goto fail_put;
 599         }
 600
 601         gntdev_dmabuf->priv = priv;
 602         gntdev_dmabuf->fd = fd;
 603
 604         attach = dma_buf_attach(dma_buf, dev);
 605         if (IS_ERR(attach)) {
 606                 ret = ERR_CAST(attach);
 607                 goto fail_free_obj;
 608         }
 609
 610         gntdev_dmabuf->u.imp.attach = attach;
 611
 612         sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
 613         if (IS_ERR(sgt)) {
 614                 ret = ERR_CAST(sgt);
 615                 goto fail_detach;
 616         }
 617
 618         /* Check that we have zero offset. */
 619         if (sgt->sgl->offset) {
 620                 ret = ERR_PTR(-EINVAL);
 621                 pr_debug("DMA buffer has %d bytes offset, user-space expects 0\n",
 622                          sgt->sgl->offset);
 623                 goto fail_unmap;
 624         }
 625
 626         /* Check number of pages that imported buffer has. */
 627         if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
 628                 ret = ERR_PTR(-EINVAL);
 629                 pr_debug("DMA buffer has %zu pages, user-space expects %d\n",
 630                          attach->dmabuf->size, gntdev_dmabuf->nr_pages);
 631                 goto fail_unmap;
 632         }
 633
 634         gntdev_dmabuf->u.imp.sgt = sgt;
 635
 636         /* Now convert sgt to array of pages and check for page validity. */
 637         i = 0;
 638         for_each_sgtable_page(sgt, &sg_iter, 0) {
 639                 struct page *page = sg_page_iter_page(&sg_iter);
 640                 /*
 641                  * Check if page is valid: this can happen if we are given
 642                  * a page from VRAM or other resources which are not backed
 643                  * by a struct page.
 644                  */
 645                 if (!pfn_valid(page_to_pfn(page))) {
 646                         ret = ERR_PTR(-EINVAL);
 647                         goto fail_unmap;
 648                 }
 649
 650                 gntdev_dmabuf->pages[i++] = page;
 651         }
 652
 653         ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gntdev_dmabuf->pages,
 654                                                       gntdev_dmabuf->u.imp.refs,
 655                                                       count, domid));
 656         if (IS_ERR(ret))
 657                 goto fail_end_access;
 658
 659         pr_debug("Imported DMA buffer with fd %d\n", fd);
 660
 661         mutex_lock(&priv->lock);
 662         list_add(&gntdev_dmabuf->next, &priv->imp_list);
 663         mutex_unlock(&priv->lock);
 664
 665         return gntdev_dmabuf;
 666
 667 fail_end_access:
 668         dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
 669 fail_unmap:
 670         dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
 671 fail_detach:
 672         dma_buf_detach(dma_buf, attach);
 673 fail_free_obj:
 674         dmabuf_imp_free_storage(gntdev_dmabuf);
 675 fail_put:
 676         dma_buf_put(dma_buf);
 677         return ret;
 678 }
 679
 680 /*
 681  * Find the hyper dma-buf by its file descriptor and remove
 682  * it from the buffer's list.
 683  */
 684 static struct gntdev_dmabuf *
 685 dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv *priv, int fd)
 686 {
 687         struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
 688
 689         mutex_lock(&priv->lock);
 690         list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next) {
 691                 if (gntdev_dmabuf->fd == fd) {
 692                         pr_debug("Found gntdev_dmabuf in the import list\n");
 693                         ret = gntdev_dmabuf;
 694                         list_del(&gntdev_dmabuf->next);
 695                         break;
 696                 }
 697         }
 698         mutex_unlock(&priv->lock);
 699         return ret;
 700 }
 701
 702 static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
 703 {
 704         struct gntdev_dmabuf *gntdev_dmabuf;
 705         struct dma_buf_attachment *attach;
 706         struct dma_buf *dma_buf;
 707
 708         gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
 709         if (IS_ERR(gntdev_dmabuf))
 710                 return PTR_ERR(gntdev_dmabuf);
 711
 712         pr_debug("Releasing DMA buffer with fd %d\n", fd);
 713
 714         dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
 715                                       gntdev_dmabuf->nr_pages);
 716
 717         attach = gntdev_dmabuf->u.imp.attach;
 718
 719         if (gntdev_dmabuf->u.imp.sgt)
 720                 dma_buf_unmap_attachment(attach, gntdev_dmabuf->u.imp.sgt,
 721                                          DMA_BIDIRECTIONAL);
 722         dma_buf = attach->dmabuf;
 723         dma_buf_detach(attach->dmabuf, attach);
 724         dma_buf_put(dma_buf);
 725
 726         dmabuf_imp_free_storage(gntdev_dmabuf);
 727         return 0;
 728 }
 729
 730 static void dmabuf_imp_release_all(struct gntdev_dmabuf_priv *priv)
 731 {
 732         struct gntdev_dmabuf *q, *gntdev_dmabuf;
 733
 734         list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next)
 735                 dmabuf_imp_release(priv, gntdev_dmabuf->fd);
 736 }
 737
 738 /* DMA buffer IOCTL support. */
 739
 740 long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
 741                                        struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
 742 {
 743         struct ioctl_gntdev_dmabuf_exp_from_refs op;
 744         u32 *refs;
 745         long ret;
 746
 747         if (use_ptemod) {
 748                 pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
 749                          use_ptemod);
 750                 return -EINVAL;
 751         }
 752
 753         if (copy_from_user(&op, u, sizeof(op)) != 0)
 754                 return -EFAULT;
 755
 756         if (unlikely(gntdev_test_page_count(op.count)))
 757                 return -EINVAL;
 758
 759         refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
 760         if (!refs)
 761                 return -ENOMEM;
 762
 763         if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
 764                 ret = -EFAULT;
 765                 goto out;
 766         }
 767
 768         ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
 769                                    op.domid, refs, &op.fd);
 770         if (ret)
 771                 goto out;
 772
 773         if (copy_to_user(u, &op, sizeof(op)) != 0)
 774                 ret = -EFAULT;
 775
 776 out:
 777         kfree(refs);
 778         return ret;
 779 }
 780
 781 long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
 782                                            struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
 783 {
 784         struct ioctl_gntdev_dmabuf_exp_wait_released op;
 785
 786         if (copy_from_user(&op, u, sizeof(op)) != 0)
 787                 return -EFAULT;
 788
 789         return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
 790                                         op.wait_to_ms);
 791 }
 792
 793 long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
 794                                      struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
 795 {
 796         struct ioctl_gntdev_dmabuf_imp_to_refs op;
 797         struct gntdev_dmabuf *gntdev_dmabuf;
 798         long ret;
 799
 800         if (copy_from_user(&op, u, sizeof(op)) != 0)
 801                 return -EFAULT;
 802
 803         if (unlikely(gntdev_test_page_count(op.count)))
 804                 return -EINVAL;
 805
 806         gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
 807                                            priv->dma_dev, op.fd,
 808                                            op.count, op.domid);
 809         if (IS_ERR(gntdev_dmabuf))
 810                 return PTR_ERR(gntdev_dmabuf);
 811
 812         if (copy_to_user(u->refs, gntdev_dmabuf->u.imp.refs,
 813                          sizeof(*u->refs) * op.count) != 0) {
 814                 ret = -EFAULT;
 815                 goto out_release;
 816         }
 817         return 0;
 818
 819 out_release:
 820         dmabuf_imp_release(priv->dmabuf_priv, op.fd);
 821         return ret;
 822 }
 823
 824 long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
 825                                      struct ioctl_gntdev_dmabuf_imp_release __user *u)
 826 {
 827         struct ioctl_gntdev_dmabuf_imp_release op;
 828
 829         if (copy_from_user(&op, u, sizeof(op)) != 0)
 830                 return -EFAULT;
 831
 832         return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
 833 }
 834
 835 struct gntdev_dmabuf_priv *gntdev_dmabuf_init(struct file *filp)
 836 {
 837         struct gntdev_dmabuf_priv *priv;
 838
 839         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 840         if (!priv)
 841                 return ERR_PTR(-ENOMEM);
 842
 843         mutex_init(&priv->lock);
 844         INIT_LIST_HEAD(&priv->exp_list);
 845         INIT_LIST_HEAD(&priv->exp_wait_list);
 846         INIT_LIST_HEAD(&priv->imp_list);
 847
 848         priv->filp = filp;
 849
 850         return priv;
 851 }
 852
 853 void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
 854 {
 855         dmabuf_imp_release_all(priv);
 856         kfree(priv);
 857 }