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_sgtable(attach->dev, sgt,
 251                                                   gntdev_dmabuf_attach->dir,
 252                                                   DMA_ATTR_SKIP_CPU_SYNC);
 253                         sg_free_table(sgt);
 254                 }
 255
 256                 kfree(sgt);
 257                 kfree(gntdev_dmabuf_attach);
 258                 attach->priv = NULL;
 259         }
 260 }
 261
 262 static struct sg_table *
 263 dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach,
 264                            enum dma_data_direction dir)
 265 {
 266         struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
 267         struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv;
 268         struct sg_table *sgt;
 269
 270         pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages,
 271                  attach->dev);
 272
 273         if (dir == DMA_NONE || !gntdev_dmabuf_attach)
 274                 return ERR_PTR(-EINVAL);
 275
 276         /* Return the cached mapping when possible. */
 277         if (gntdev_dmabuf_attach->dir == dir)
 278                 return gntdev_dmabuf_attach->sgt;
 279
 280         /*
 281          * Two mappings with different directions for the same attachment are
 282          * not allowed.
 283          */
 284         if (gntdev_dmabuf_attach->dir != DMA_NONE)
 285                 return ERR_PTR(-EBUSY);
 286
 287         sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages,
 288                                   gntdev_dmabuf->nr_pages);
 289         if (!IS_ERR(sgt)) {
 290                 if (dma_map_sgtable(attach->dev, sgt, dir,
 291                                     DMA_ATTR_SKIP_CPU_SYNC)) {
 292                         sg_free_table(sgt);
 293                         kfree(sgt);
 294                         sgt = ERR_PTR(-ENOMEM);
 295                 } else {
 296                         gntdev_dmabuf_attach->sgt = sgt;
 297                         gntdev_dmabuf_attach->dir = dir;
 298                 }
 299         }
 300         if (IS_ERR(sgt))
 301                 pr_debug("Failed to map sg table for dev %p\n", attach->dev);
 302         return sgt;
 303 }
 304
 305 static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach,
 306                                          struct sg_table *sgt,
 307                                          enum dma_data_direction dir)
 308 {
 309         /* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */
 310 }
 311
 312 static void dmabuf_exp_release(struct kref *kref)
 313 {
 314         struct gntdev_dmabuf *gntdev_dmabuf =
 315                 container_of(kref, struct gntdev_dmabuf, u.exp.refcount);
 316
 317         dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
 318         list_del(&gntdev_dmabuf->next);
 319         fput(gntdev_dmabuf->priv->filp);
 320         kfree(gntdev_dmabuf);
 321 }
 322
 323 static void dmabuf_exp_remove_map(struct gntdev_priv *priv,
 324                                   struct gntdev_grant_map *map)
 325 {
 326         mutex_lock(&priv->lock);
 327         list_del(&map->next);
 328         gntdev_put_map(NULL /* already removed */, map);
 329         mutex_unlock(&priv->lock);
 330 }
 331
 332 static void dmabuf_exp_ops_release(struct dma_buf *dma_buf)
 333 {
 334         struct gntdev_dmabuf *gntdev_dmabuf = dma_buf->priv;
 335         struct gntdev_dmabuf_priv *priv = gntdev_dmabuf->priv;
 336
 337         dmabuf_exp_remove_map(gntdev_dmabuf->u.exp.priv,
 338                               gntdev_dmabuf->u.exp.map);
 339         mutex_lock(&priv->lock);
 340         kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
 341         mutex_unlock(&priv->lock);
 342 }
 343
 344 static const struct dma_buf_ops dmabuf_exp_ops =  {
 345         .attach = dmabuf_exp_ops_attach,
 346         .detach = dmabuf_exp_ops_detach,
 347         .map_dma_buf = dmabuf_exp_ops_map_dma_buf,
 348         .unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
 349         .release = dmabuf_exp_ops_release,
 350 };
 351
 352 struct gntdev_dmabuf_export_args {
 353         struct gntdev_priv *priv;
 354         struct gntdev_grant_map *map;
 355         struct gntdev_dmabuf_priv *dmabuf_priv;
 356         struct device *dev;
 357         int count;
 358         struct page **pages;
 359         u32 fd;
 360 };
 361
 362 static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
 363 {
 364         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 365         struct gntdev_dmabuf *gntdev_dmabuf;
 366         int ret;
 367
 368         gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
 369         if (!gntdev_dmabuf)
 370                 return -ENOMEM;
 371
 372         kref_init(&gntdev_dmabuf->u.exp.refcount);
 373
 374         gntdev_dmabuf->priv = args->dmabuf_priv;
 375         gntdev_dmabuf->nr_pages = args->count;
 376         gntdev_dmabuf->pages = args->pages;
 377         gntdev_dmabuf->u.exp.priv = args->priv;
 378         gntdev_dmabuf->u.exp.map = args->map;
 379
 380         exp_info.exp_name = KBUILD_MODNAME;
 381         if (args->dev->driver && args->dev->driver->owner)
 382                 exp_info.owner = args->dev->driver->owner;
 383         else
 384                 exp_info.owner = THIS_MODULE;
 385         exp_info.ops = &dmabuf_exp_ops;
 386         exp_info.size = args->count << PAGE_SHIFT;
 387         exp_info.flags = O_RDWR;
 388         exp_info.priv = gntdev_dmabuf;
 389
 390         gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
 391         if (IS_ERR(gntdev_dmabuf->dmabuf)) {
 392                 ret = PTR_ERR(gntdev_dmabuf->dmabuf);
 393                 gntdev_dmabuf->dmabuf = NULL;
 394                 goto fail;
 395         }
 396
 397         ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC);
 398         if (ret < 0)
 399                 goto fail;
 400
 401         gntdev_dmabuf->fd = ret;
 402         args->fd = ret;
 403
 404         pr_debug("Exporting DMA buffer with fd %d\n", ret);
 405
 406         mutex_lock(&args->dmabuf_priv->lock);
 407         list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
 408         mutex_unlock(&args->dmabuf_priv->lock);
 409         get_file(gntdev_dmabuf->priv->filp);
 410         return 0;
 411
 412 fail:
 413         if (gntdev_dmabuf->dmabuf)
 414                 dma_buf_put(gntdev_dmabuf->dmabuf);
 415         kfree(gntdev_dmabuf);
 416         return ret;
 417 }
 418
 419 static struct gntdev_grant_map *
 420 dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
 421                                  int count)
 422 {
 423         struct gntdev_grant_map *map;
 424
 425         if (unlikely(gntdev_test_page_count(count)))
 426                 return ERR_PTR(-EINVAL);
 427
 428         if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
 429             (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
 430                 pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
 431                 return ERR_PTR(-EINVAL);
 432         }
 433
 434         map = gntdev_alloc_map(priv, count, dmabuf_flags);
 435         if (!map)
 436                 return ERR_PTR(-ENOMEM);
 437
 438         return map;
 439 }
 440
 441 static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
 442                                 int count, u32 domid, u32 *refs, u32 *fd)
 443 {
 444         struct gntdev_grant_map *map;
 445         struct gntdev_dmabuf_export_args args;
 446         int i, ret;
 447
 448         map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
 449         if (IS_ERR(map))
 450                 return PTR_ERR(map);
 451
 452         for (i = 0; i < count; i++) {
 453                 map->grants[i].domid = domid;
 454                 map->grants[i].ref = refs[i];
 455         }
 456
 457         mutex_lock(&priv->lock);
 458         gntdev_add_map(priv, map);
 459         mutex_unlock(&priv->lock);
 460
 461         map->flags |= GNTMAP_host_map;
 462 #if defined(CONFIG_X86)
 463         map->flags |= GNTMAP_device_map;
 464 #endif
 465
 466         ret = gntdev_map_grant_pages(map);
 467         if (ret < 0)
 468                 goto out;
 469
 470         args.priv = priv;
 471         args.map = map;
 472         args.dev = priv->dma_dev;
 473         args.dmabuf_priv = priv->dmabuf_priv;
 474         args.count = map->count;
 475         args.pages = map->pages;
 476         args.fd = -1; /* Shut up unnecessary gcc warning for i386 */
 477
 478         ret = dmabuf_exp_from_pages(&args);
 479         if (ret < 0)
 480                 goto out;
 481
 482         *fd = args.fd;
 483         return 0;
 484
 485 out:
 486         dmabuf_exp_remove_map(priv, map);
 487         return ret;
 488 }
 489
 490 /* DMA buffer import support. */
 491
 492 static int
 493 dmabuf_imp_grant_foreign_access(struct page **pages, u32 *refs,
 494                                 int count, int domid)
 495 {
 496         grant_ref_t priv_gref_head;
 497         int i, ret;
 498
 499         ret = gnttab_alloc_grant_references(count, &priv_gref_head);
 500         if (ret < 0) {
 501                 pr_debug("Cannot allocate grant references, ret %d\n", ret);
 502                 return ret;
 503         }
 504
 505         for (i = 0; i < count; i++) {
 506                 int cur_ref;
 507
 508                 cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
 509                 if (cur_ref < 0) {
 510                         ret = cur_ref;
 511                         pr_debug("Cannot claim grant reference, ret %d\n", ret);
 512                         goto out;
 513                 }
 514
 515                 gnttab_grant_foreign_access_ref(cur_ref, domid,
 516                                                 xen_page_to_gfn(pages[i]), 0);
 517                 refs[i] = cur_ref;
 518         }
 519
 520         return 0;
 521
 522 out:
 523         gnttab_free_grant_references(priv_gref_head);
 524         return ret;
 525 }
 526
 527 static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
 528 {
 529         int i;
 530
 531         for (i = 0; i < count; i++)
 532                 if (refs[i] != GRANT_INVALID_REF)
 533                         gnttab_end_foreign_access(refs[i], 0, 0UL);
 534 }
 535
 536 static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
 537 {
 538         kfree(gntdev_dmabuf->pages);
 539         kfree(gntdev_dmabuf->u.imp.refs);
 540         kfree(gntdev_dmabuf);
 541 }
 542
 543 static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
 544 {
 545         struct gntdev_dmabuf *gntdev_dmabuf;
 546         int i;
 547
 548         gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
 549         if (!gntdev_dmabuf)
 550                 goto fail_no_free;
 551
 552         gntdev_dmabuf->u.imp.refs = kcalloc(count,
 553                                             sizeof(gntdev_dmabuf->u.imp.refs[0]),
 554                                             GFP_KERNEL);
 555         if (!gntdev_dmabuf->u.imp.refs)
 556                 goto fail;
 557
 558         gntdev_dmabuf->pages = kcalloc(count,
 559                                        sizeof(gntdev_dmabuf->pages[0]),
 560                                        GFP_KERNEL);
 561         if (!gntdev_dmabuf->pages)
 562                 goto fail;
 563
 564         gntdev_dmabuf->nr_pages = count;
 565
 566         for (i = 0; i < count; i++)
 567                 gntdev_dmabuf->u.imp.refs[i] = GRANT_INVALID_REF;
 568
 569         return gntdev_dmabuf;
 570
 571 fail:
 572         dmabuf_imp_free_storage(gntdev_dmabuf);
 573 fail_no_free:
 574         return ERR_PTR(-ENOMEM);
 575 }
 576
 577 static struct gntdev_dmabuf *
 578 dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
 579                    int fd, int count, int domid)
 580 {
 581         struct gntdev_dmabuf *gntdev_dmabuf, *ret;
 582         struct dma_buf *dma_buf;
 583         struct dma_buf_attachment *attach;
 584         struct sg_table *sgt;
 585         struct sg_page_iter sg_iter;
 586         int i;
 587
 588         dma_buf = dma_buf_get(fd);
 589         if (IS_ERR(dma_buf))
 590                 return ERR_CAST(dma_buf);
 591
 592         gntdev_dmabuf = dmabuf_imp_alloc_storage(count);
 593         if (IS_ERR(gntdev_dmabuf)) {
 594                 ret = gntdev_dmabuf;
 595                 goto fail_put;
 596         }
 597
 598         gntdev_dmabuf->priv = priv;
 599         gntdev_dmabuf->fd = fd;
 600
 601         attach = dma_buf_attach(dma_buf, dev);
 602         if (IS_ERR(attach)) {
 603                 ret = ERR_CAST(attach);
 604                 goto fail_free_obj;
 605         }
 606
 607         gntdev_dmabuf->u.imp.attach = attach;
 608
 609         sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
 610         if (IS_ERR(sgt)) {
 611                 ret = ERR_CAST(sgt);
 612                 goto fail_detach;
 613         }
 614
 615         /* Check that we have zero offset. */
 616         if (sgt->sgl->offset) {
 617                 ret = ERR_PTR(-EINVAL);
 618                 pr_debug("DMA buffer has %d bytes offset, user-space expects 0\n",
 619                          sgt->sgl->offset);
 620                 goto fail_unmap;
 621         }
 622
 623         /* Check number of pages that imported buffer has. */
 624         if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
 625                 ret = ERR_PTR(-EINVAL);
 626                 pr_debug("DMA buffer has %zu pages, user-space expects %d\n",
 627                          attach->dmabuf->size, gntdev_dmabuf->nr_pages);
 628                 goto fail_unmap;
 629         }
 630
 631         gntdev_dmabuf->u.imp.sgt = sgt;
 632
 633         /* Now convert sgt to array of pages and check for page validity. */
 634         i = 0;
 635         for_each_sgtable_page(sgt, &sg_iter, 0) {
 636                 struct page *page = sg_page_iter_page(&sg_iter);
 637                 /*
 638                  * Check if page is valid: this can happen if we are given
 639                  * a page from VRAM or other resources which are not backed
 640                  * by a struct page.
 641                  */
 642                 if (!pfn_valid(page_to_pfn(page))) {
 643                         ret = ERR_PTR(-EINVAL);
 644                         goto fail_unmap;
 645                 }
 646
 647                 gntdev_dmabuf->pages[i++] = page;
 648         }
 649
 650         ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gntdev_dmabuf->pages,
 651                                                       gntdev_dmabuf->u.imp.refs,
 652                                                       count, domid));
 653         if (IS_ERR(ret))
 654                 goto fail_end_access;
 655
 656         pr_debug("Imported DMA buffer with fd %d\n", fd);
 657
 658         mutex_lock(&priv->lock);
 659         list_add(&gntdev_dmabuf->next, &priv->imp_list);
 660         mutex_unlock(&priv->lock);
 661
 662         return gntdev_dmabuf;
 663
 664 fail_end_access:
 665         dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
 666 fail_unmap:
 667         dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
 668 fail_detach:
 669         dma_buf_detach(dma_buf, attach);
 670 fail_free_obj:
 671         dmabuf_imp_free_storage(gntdev_dmabuf);
 672 fail_put:
 673         dma_buf_put(dma_buf);
 674         return ret;
 675 }
 676
 677 /*
 678  * Find the hyper dma-buf by its file descriptor and remove
 679  * it from the buffer's list.
 680  */
 681 static struct gntdev_dmabuf *
 682 dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv *priv, int fd)
 683 {
 684         struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
 685
 686         mutex_lock(&priv->lock);
 687         list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next) {
 688                 if (gntdev_dmabuf->fd == fd) {
 689                         pr_debug("Found gntdev_dmabuf in the import list\n");
 690                         ret = gntdev_dmabuf;
 691                         list_del(&gntdev_dmabuf->next);
 692                         break;
 693                 }
 694         }
 695         mutex_unlock(&priv->lock);
 696         return ret;
 697 }
 698
 699 static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
 700 {
 701         struct gntdev_dmabuf *gntdev_dmabuf;
 702         struct dma_buf_attachment *attach;
 703         struct dma_buf *dma_buf;
 704
 705         gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
 706         if (IS_ERR(gntdev_dmabuf))
 707                 return PTR_ERR(gntdev_dmabuf);
 708
 709         pr_debug("Releasing DMA buffer with fd %d\n", fd);
 710
 711         dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
 712                                       gntdev_dmabuf->nr_pages);
 713
 714         attach = gntdev_dmabuf->u.imp.attach;
 715
 716         if (gntdev_dmabuf->u.imp.sgt)
 717                 dma_buf_unmap_attachment(attach, gntdev_dmabuf->u.imp.sgt,
 718                                          DMA_BIDIRECTIONAL);
 719         dma_buf = attach->dmabuf;
 720         dma_buf_detach(attach->dmabuf, attach);
 721         dma_buf_put(dma_buf);
 722
 723         dmabuf_imp_free_storage(gntdev_dmabuf);
 724         return 0;
 725 }
 726
 727 static void dmabuf_imp_release_all(struct gntdev_dmabuf_priv *priv)
 728 {
 729         struct gntdev_dmabuf *q, *gntdev_dmabuf;
 730
 731         list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next)
 732                 dmabuf_imp_release(priv, gntdev_dmabuf->fd);
 733 }
 734
 735 /* DMA buffer IOCTL support. */
 736
 737 long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
 738                                        struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
 739 {
 740         struct ioctl_gntdev_dmabuf_exp_from_refs op;
 741         u32 *refs;
 742         long ret;
 743
 744         if (use_ptemod) {
 745                 pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
 746                          use_ptemod);
 747                 return -EINVAL;
 748         }
 749
 750         if (copy_from_user(&op, u, sizeof(op)) != 0)
 751                 return -EFAULT;
 752
 753         if (unlikely(gntdev_test_page_count(op.count)))
 754                 return -EINVAL;
 755
 756         refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
 757         if (!refs)
 758                 return -ENOMEM;
 759
 760         if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
 761                 ret = -EFAULT;
 762                 goto out;
 763         }
 764
 765         ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
 766                                    op.domid, refs, &op.fd);
 767         if (ret)
 768                 goto out;
 769
 770         if (copy_to_user(u, &op, sizeof(op)) != 0)
 771                 ret = -EFAULT;
 772
 773 out:
 774         kfree(refs);
 775         return ret;
 776 }
 777
 778 long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
 779                                            struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
 780 {
 781         struct ioctl_gntdev_dmabuf_exp_wait_released op;
 782
 783         if (copy_from_user(&op, u, sizeof(op)) != 0)
 784                 return -EFAULT;
 785
 786         return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
 787                                         op.wait_to_ms);
 788 }
 789
 790 long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
 791                                      struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
 792 {
 793         struct ioctl_gntdev_dmabuf_imp_to_refs op;
 794         struct gntdev_dmabuf *gntdev_dmabuf;
 795         long ret;
 796
 797         if (copy_from_user(&op, u, sizeof(op)) != 0)
 798                 return -EFAULT;
 799
 800         if (unlikely(gntdev_test_page_count(op.count)))
 801                 return -EINVAL;
 802
 803         gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
 804                                            priv->dma_dev, op.fd,
 805                                            op.count, op.domid);
 806         if (IS_ERR(gntdev_dmabuf))
 807                 return PTR_ERR(gntdev_dmabuf);
 808
 809         if (copy_to_user(u->refs, gntdev_dmabuf->u.imp.refs,
 810                          sizeof(*u->refs) * op.count) != 0) {
 811                 ret = -EFAULT;
 812                 goto out_release;
 813         }
 814         return 0;
 815
 816 out_release:
 817         dmabuf_imp_release(priv->dmabuf_priv, op.fd);
 818         return ret;
 819 }
 820
 821 long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
 822                                      struct ioctl_gntdev_dmabuf_imp_release __user *u)
 823 {
 824         struct ioctl_gntdev_dmabuf_imp_release op;
 825
 826         if (copy_from_user(&op, u, sizeof(op)) != 0)
 827                 return -EFAULT;
 828
 829         return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
 830 }
 831
 832 struct gntdev_dmabuf_priv *gntdev_dmabuf_init(struct file *filp)
 833 {
 834         struct gntdev_dmabuf_priv *priv;
 835
 836         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 837         if (!priv)
 838                 return ERR_PTR(-ENOMEM);
 839
 840         mutex_init(&priv->lock);
 841         INIT_LIST_HEAD(&priv->exp_list);
 842         INIT_LIST_HEAD(&priv->exp_wait_list);
 843         INIT_LIST_HEAD(&priv->imp_list);
 844
 845         priv->filp = filp;
 846
 847         return priv;
 848 }
 849
 850 void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
 851 {
 852         dmabuf_imp_release_all(priv);
 853         kfree(priv);
 854 }