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