root/drivers/xen/gntdev-dmabuf.c

DEFINITIONS

1. dmabuf_exp_wait_obj_new
2. dmabuf_exp_wait_obj_free
3. dmabuf_exp_wait_obj_wait
4. dmabuf_exp_wait_obj_signal
5. dmabuf_exp_wait_obj_get_dmabuf
6. dmabuf_exp_wait_released
7. dmabuf_pages_to_sgt
8. dmabuf_exp_ops_attach
9. dmabuf_exp_ops_detach
10. dmabuf_exp_ops_map_dma_buf
11. dmabuf_exp_ops_unmap_dma_buf
12. dmabuf_exp_release
13. dmabuf_exp_remove_map
14. dmabuf_exp_ops_release
15. dmabuf_exp_ops_kmap
16. dmabuf_exp_ops_kunmap
17. dmabuf_exp_ops_mmap
18. dmabuf_exp_from_pages
19. dmabuf_exp_alloc_backing_storage
20. dmabuf_exp_from_refs
21. dmabuf_imp_grant_foreign_access
22. dmabuf_imp_end_foreign_access
23. dmabuf_imp_free_storage
24. dmabuf_imp_alloc_storage
25. dmabuf_imp_to_refs
26. dmabuf_imp_find_unlink
27. dmabuf_imp_release
28. dmabuf_imp_release_all
29. gntdev_ioctl_dmabuf_exp_from_refs
30. gntdev_ioctl_dmabuf_exp_wait_released
31. gntdev_ioctl_dmabuf_imp_to_refs
32. gntdev_ioctl_dmabuf_imp_release
33. gntdev_dmabuf_init
34. gntdev_dmabuf_fini

   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 void *dmabuf_exp_ops_kmap(struct dma_buf *dma_buf,
 346                                  unsigned long page_num)
 347 {
 348         /* Not implemented. */
 349         return NULL;
 350 }
 351 
 352 static void dmabuf_exp_ops_kunmap(struct dma_buf *dma_buf,
 353                                   unsigned long page_num, void *addr)
 354 {
 355         /* Not implemented. */
 356 }
 357 
 358 static int dmabuf_exp_ops_mmap(struct dma_buf *dma_buf,
 359                                struct vm_area_struct *vma)
 360 {
 361         /* Not implemented. */
 362         return 0;
 363 }
 364 
 365 static const struct dma_buf_ops dmabuf_exp_ops =  {
 366         .attach = dmabuf_exp_ops_attach,
 367         .detach = dmabuf_exp_ops_detach,
 368         .map_dma_buf = dmabuf_exp_ops_map_dma_buf,
 369         .unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
 370         .release = dmabuf_exp_ops_release,
 371         .map = dmabuf_exp_ops_kmap,
 372         .unmap = dmabuf_exp_ops_kunmap,
 373         .mmap = dmabuf_exp_ops_mmap,
 374 };
 375 
 376 struct gntdev_dmabuf_export_args {
 377         struct gntdev_priv *priv;
 378         struct gntdev_grant_map *map;
 379         struct gntdev_dmabuf_priv *dmabuf_priv;
 380         struct device *dev;
 381         int count;
 382         struct page **pages;
 383         u32 fd;
 384 };
 385 
 386 static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
 387 {
 388         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 389         struct gntdev_dmabuf *gntdev_dmabuf;
 390         int ret;
 391 
 392         gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
 393         if (!gntdev_dmabuf)
 394                 return -ENOMEM;
 395 
 396         kref_init(&gntdev_dmabuf->u.exp.refcount);
 397 
 398         gntdev_dmabuf->priv = args->dmabuf_priv;
 399         gntdev_dmabuf->nr_pages = args->count;
 400         gntdev_dmabuf->pages = args->pages;
 401         gntdev_dmabuf->u.exp.priv = args->priv;
 402         gntdev_dmabuf->u.exp.map = args->map;
 403 
 404         exp_info.exp_name = KBUILD_MODNAME;
 405         if (args->dev->driver && args->dev->driver->owner)
 406                 exp_info.owner = args->dev->driver->owner;
 407         else
 408                 exp_info.owner = THIS_MODULE;
 409         exp_info.ops = &dmabuf_exp_ops;
 410         exp_info.size = args->count << PAGE_SHIFT;
 411         exp_info.flags = O_RDWR;
 412         exp_info.priv = gntdev_dmabuf;
 413 
 414         gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
 415         if (IS_ERR(gntdev_dmabuf->dmabuf)) {
 416                 ret = PTR_ERR(gntdev_dmabuf->dmabuf);
 417                 gntdev_dmabuf->dmabuf = NULL;
 418                 goto fail;
 419         }
 420 
 421         ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC);
 422         if (ret < 0)
 423                 goto fail;
 424 
 425         gntdev_dmabuf->fd = ret;
 426         args->fd = ret;
 427 
 428         pr_debug("Exporting DMA buffer with fd %d\n", ret);
 429 
 430         mutex_lock(&args->dmabuf_priv->lock);
 431         list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
 432         mutex_unlock(&args->dmabuf_priv->lock);
 433         get_file(gntdev_dmabuf->priv->filp);
 434         return 0;
 435 
 436 fail:
 437         if (gntdev_dmabuf->dmabuf)
 438                 dma_buf_put(gntdev_dmabuf->dmabuf);
 439         kfree(gntdev_dmabuf);
 440         return ret;
 441 }
 442 
 443 static struct gntdev_grant_map *
 444 dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
 445                                  int count)
 446 {
 447         struct gntdev_grant_map *map;
 448 
 449         if (unlikely(count <= 0))
 450                 return ERR_PTR(-EINVAL);
 451 
 452         if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
 453             (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
 454                 pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
 455                 return ERR_PTR(-EINVAL);
 456         }
 457 
 458         map = gntdev_alloc_map(priv, count, dmabuf_flags);
 459         if (!map)
 460                 return ERR_PTR(-ENOMEM);
 461 
 462         if (unlikely(gntdev_account_mapped_pages(count))) {
 463                 pr_debug("can't map %d pages: over limit\n", count);
 464                 gntdev_put_map(NULL, map);
 465                 return ERR_PTR(-ENOMEM);
 466         }
 467         return map;
 468 }
 469 
 470 static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
 471                                 int count, u32 domid, u32 *refs, u32 *fd)
 472 {
 473         struct gntdev_grant_map *map;
 474         struct gntdev_dmabuf_export_args args;
 475         int i, ret;
 476 
 477         map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
 478         if (IS_ERR(map))
 479                 return PTR_ERR(map);
 480 
 481         for (i = 0; i < count; i++) {
 482                 map->grants[i].domid = domid;
 483                 map->grants[i].ref = refs[i];
 484         }
 485 
 486         mutex_lock(&priv->lock);
 487         gntdev_add_map(priv, map);
 488         mutex_unlock(&priv->lock);
 489 
 490         map->flags |= GNTMAP_host_map;
 491 #if defined(CONFIG_X86)
 492         map->flags |= GNTMAP_device_map;
 493 #endif
 494 
 495         ret = gntdev_map_grant_pages(map);
 496         if (ret < 0)
 497                 goto out;
 498 
 499         args.priv = priv;
 500         args.map = map;
 501         args.dev = priv->dma_dev;
 502         args.dmabuf_priv = priv->dmabuf_priv;
 503         args.count = map->count;
 504         args.pages = map->pages;
 505         args.fd = -1; /* Shut up unnecessary gcc warning for i386 */
 506 
 507         ret = dmabuf_exp_from_pages(&args);
 508         if (ret < 0)
 509                 goto out;
 510 
 511         *fd = args.fd;
 512         return 0;
 513 
 514 out:
 515         dmabuf_exp_remove_map(priv, map);
 516         return ret;
 517 }
 518 
 519 /* DMA buffer import support. */
 520 
 521 static int
 522 dmabuf_imp_grant_foreign_access(struct page **pages, u32 *refs,
 523                                 int count, int domid)
 524 {
 525         grant_ref_t priv_gref_head;
 526         int i, ret;
 527 
 528         ret = gnttab_alloc_grant_references(count, &priv_gref_head);
 529         if (ret < 0) {
 530                 pr_debug("Cannot allocate grant references, ret %d\n", ret);
 531                 return ret;
 532         }
 533 
 534         for (i = 0; i < count; i++) {
 535                 int cur_ref;
 536 
 537                 cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
 538                 if (cur_ref < 0) {
 539                         ret = cur_ref;
 540                         pr_debug("Cannot claim grant reference, ret %d\n", ret);
 541                         goto out;
 542                 }
 543 
 544                 gnttab_grant_foreign_access_ref(cur_ref, domid,
 545                                                 xen_page_to_gfn(pages[i]), 0);
 546                 refs[i] = cur_ref;
 547         }
 548 
 549         return 0;
 550 
 551 out:
 552         gnttab_free_grant_references(priv_gref_head);
 553         return ret;
 554 }
 555 
 556 static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
 557 {
 558         int i;
 559 
 560         for (i = 0; i < count; i++)
 561                 if (refs[i] != GRANT_INVALID_REF)
 562                         gnttab_end_foreign_access(refs[i], 0, 0UL);
 563 }
 564 
 565 static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
 566 {
 567         kfree(gntdev_dmabuf->pages);
 568         kfree(gntdev_dmabuf->u.imp.refs);
 569         kfree(gntdev_dmabuf);
 570 }
 571 
 572 static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
 573 {
 574         struct gntdev_dmabuf *gntdev_dmabuf;
 575         int i;
 576 
 577         gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
 578         if (!gntdev_dmabuf)
 579                 goto fail_no_free;
 580 
 581         gntdev_dmabuf->u.imp.refs = kcalloc(count,
 582                                             sizeof(gntdev_dmabuf->u.imp.refs[0]),
 583                                             GFP_KERNEL);
 584         if (!gntdev_dmabuf->u.imp.refs)
 585                 goto fail;
 586 
 587         gntdev_dmabuf->pages = kcalloc(count,
 588                                        sizeof(gntdev_dmabuf->pages[0]),
 589                                        GFP_KERNEL);
 590         if (!gntdev_dmabuf->pages)
 591                 goto fail;
 592 
 593         gntdev_dmabuf->nr_pages = count;
 594 
 595         for (i = 0; i < count; i++)
 596                 gntdev_dmabuf->u.imp.refs[i] = GRANT_INVALID_REF;
 597 
 598         return gntdev_dmabuf;
 599 
 600 fail:
 601         dmabuf_imp_free_storage(gntdev_dmabuf);
 602 fail_no_free:
 603         return ERR_PTR(-ENOMEM);
 604 }
 605 
 606 static struct gntdev_dmabuf *
 607 dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
 608                    int fd, int count, int domid)
 609 {
 610         struct gntdev_dmabuf *gntdev_dmabuf, *ret;
 611         struct dma_buf *dma_buf;
 612         struct dma_buf_attachment *attach;
 613         struct sg_table *sgt;
 614         struct sg_page_iter sg_iter;
 615         int i;
 616 
 617         dma_buf = dma_buf_get(fd);
 618         if (IS_ERR(dma_buf))
 619                 return ERR_CAST(dma_buf);
 620 
 621         gntdev_dmabuf = dmabuf_imp_alloc_storage(count);
 622         if (IS_ERR(gntdev_dmabuf)) {
 623                 ret = gntdev_dmabuf;
 624                 goto fail_put;
 625         }
 626 
 627         gntdev_dmabuf->priv = priv;
 628         gntdev_dmabuf->fd = fd;
 629 
 630         attach = dma_buf_attach(dma_buf, dev);
 631         if (IS_ERR(attach)) {
 632                 ret = ERR_CAST(attach);
 633                 goto fail_free_obj;
 634         }
 635 
 636         gntdev_dmabuf->u.imp.attach = attach;
 637 
 638         sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
 639         if (IS_ERR(sgt)) {
 640                 ret = ERR_CAST(sgt);
 641                 goto fail_detach;
 642         }
 643 
 644         /* Check number of pages that imported buffer has. */
 645         if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
 646                 ret = ERR_PTR(-EINVAL);
 647                 pr_debug("DMA buffer has %zu pages, user-space expects %d\n",
 648                          attach->dmabuf->size, gntdev_dmabuf->nr_pages);
 649                 goto fail_unmap;
 650         }
 651 
 652         gntdev_dmabuf->u.imp.sgt = sgt;
 653 
 654         /* Now convert sgt to array of pages and check for page validity. */
 655         i = 0;
 656         for_each_sg_page(sgt->sgl, &sg_iter, sgt->nents, 0) {
 657                 struct page *page = sg_page_iter_page(&sg_iter);
 658                 /*
 659                  * Check if page is valid: this can happen if we are given
 660                  * a page from VRAM or other resources which are not backed
 661                  * by a struct page.
 662                  */
 663                 if (!pfn_valid(page_to_pfn(page))) {
 664                         ret = ERR_PTR(-EINVAL);
 665                         goto fail_unmap;
 666                 }
 667 
 668                 gntdev_dmabuf->pages[i++] = page;
 669         }
 670 
 671         ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gntdev_dmabuf->pages,
 672                                                       gntdev_dmabuf->u.imp.refs,
 673                                                       count, domid));
 674         if (IS_ERR(ret))
 675                 goto fail_end_access;
 676 
 677         pr_debug("Imported DMA buffer with fd %d\n", fd);
 678 
 679         mutex_lock(&priv->lock);
 680         list_add(&gntdev_dmabuf->next, &priv->imp_list);
 681         mutex_unlock(&priv->lock);
 682 
 683         return gntdev_dmabuf;
 684 
 685 fail_end_access:
 686         dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
 687 fail_unmap:
 688         dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
 689 fail_detach:
 690         dma_buf_detach(dma_buf, attach);
 691 fail_free_obj:
 692         dmabuf_imp_free_storage(gntdev_dmabuf);
 693 fail_put:
 694         dma_buf_put(dma_buf);
 695         return ret;
 696 }
 697 
 698 /*
 699  * Find the hyper dma-buf by its file descriptor and remove
 700  * it from the buffer's list.
 701  */
 702 static struct gntdev_dmabuf *
 703 dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv *priv, int fd)
 704 {
 705         struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
 706 
 707         mutex_lock(&priv->lock);
 708         list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next) {
 709                 if (gntdev_dmabuf->fd == fd) {
 710                         pr_debug("Found gntdev_dmabuf in the import list\n");
 711                         ret = gntdev_dmabuf;
 712                         list_del(&gntdev_dmabuf->next);
 713                         break;
 714                 }
 715         }
 716         mutex_unlock(&priv->lock);
 717         return ret;
 718 }
 719 
 720 static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
 721 {
 722         struct gntdev_dmabuf *gntdev_dmabuf;
 723         struct dma_buf_attachment *attach;
 724         struct dma_buf *dma_buf;
 725 
 726         gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
 727         if (IS_ERR(gntdev_dmabuf))
 728                 return PTR_ERR(gntdev_dmabuf);
 729 
 730         pr_debug("Releasing DMA buffer with fd %d\n", fd);
 731 
 732         dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
 733                                       gntdev_dmabuf->nr_pages);
 734 
 735         attach = gntdev_dmabuf->u.imp.attach;
 736 
 737         if (gntdev_dmabuf->u.imp.sgt)
 738                 dma_buf_unmap_attachment(attach, gntdev_dmabuf->u.imp.sgt,
 739                                          DMA_BIDIRECTIONAL);
 740         dma_buf = attach->dmabuf;
 741         dma_buf_detach(attach->dmabuf, attach);
 742         dma_buf_put(dma_buf);
 743 
 744         dmabuf_imp_free_storage(gntdev_dmabuf);
 745         return 0;
 746 }
 747 
 748 static void dmabuf_imp_release_all(struct gntdev_dmabuf_priv *priv)
 749 {
 750         struct gntdev_dmabuf *q, *gntdev_dmabuf;
 751 
 752         list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next)
 753                 dmabuf_imp_release(priv, gntdev_dmabuf->fd);
 754 }
 755 
 756 /* DMA buffer IOCTL support. */
 757 
 758 long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
 759                                        struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
 760 {
 761         struct ioctl_gntdev_dmabuf_exp_from_refs op;
 762         u32 *refs;
 763         long ret;
 764 
 765         if (use_ptemod) {
 766                 pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
 767                          use_ptemod);
 768                 return -EINVAL;
 769         }
 770 
 771         if (copy_from_user(&op, u, sizeof(op)) != 0)
 772                 return -EFAULT;
 773 
 774         if (unlikely(op.count <= 0))
 775                 return -EINVAL;
 776 
 777         refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
 778         if (!refs)
 779                 return -ENOMEM;
 780 
 781         if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
 782                 ret = -EFAULT;
 783                 goto out;
 784         }
 785 
 786         ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
 787                                    op.domid, refs, &op.fd);
 788         if (ret)
 789                 goto out;
 790 
 791         if (copy_to_user(u, &op, sizeof(op)) != 0)
 792                 ret = -EFAULT;
 793 
 794 out:
 795         kfree(refs);
 796         return ret;
 797 }
 798 
 799 long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
 800                                            struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
 801 {
 802         struct ioctl_gntdev_dmabuf_exp_wait_released op;
 803 
 804         if (copy_from_user(&op, u, sizeof(op)) != 0)
 805                 return -EFAULT;
 806 
 807         return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
 808                                         op.wait_to_ms);
 809 }
 810 
 811 long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
 812                                      struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
 813 {
 814         struct ioctl_gntdev_dmabuf_imp_to_refs op;
 815         struct gntdev_dmabuf *gntdev_dmabuf;
 816         long ret;
 817 
 818         if (copy_from_user(&op, u, sizeof(op)) != 0)
 819                 return -EFAULT;
 820 
 821         if (unlikely(op.count <= 0))
 822                 return -EINVAL;
 823 
 824         gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
 825                                            priv->dma_dev, op.fd,
 826                                            op.count, op.domid);
 827         if (IS_ERR(gntdev_dmabuf))
 828                 return PTR_ERR(gntdev_dmabuf);
 829 
 830         if (copy_to_user(u->refs, gntdev_dmabuf->u.imp.refs,
 831                          sizeof(*u->refs) * op.count) != 0) {
 832                 ret = -EFAULT;
 833                 goto out_release;
 834         }
 835         return 0;
 836 
 837 out_release:
 838         dmabuf_imp_release(priv->dmabuf_priv, op.fd);
 839         return ret;
 840 }
 841 
 842 long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
 843                                      struct ioctl_gntdev_dmabuf_imp_release __user *u)
 844 {
 845         struct ioctl_gntdev_dmabuf_imp_release op;
 846 
 847         if (copy_from_user(&op, u, sizeof(op)) != 0)
 848                 return -EFAULT;
 849 
 850         return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
 851 }
 852 
 853 struct gntdev_dmabuf_priv *gntdev_dmabuf_init(struct file *filp)
 854 {
 855         struct gntdev_dmabuf_priv *priv;
 856 
 857         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 858         if (!priv)
 859                 return ERR_PTR(-ENOMEM);
 860 
 861         mutex_init(&priv->lock);
 862         INIT_LIST_HEAD(&priv->exp_list);
 863         INIT_LIST_HEAD(&priv->exp_wait_list);
 864         INIT_LIST_HEAD(&priv->imp_list);
 865 
 866         priv->filp = filp;
 867 
 868         return priv;
 869 }
 870 
 871 void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
 872 {
 873         dmabuf_imp_release_all(priv);
 874         kfree(priv);
 875 }