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