drivers/xen/gntdev.c

   1 /******************************************************************************
   2  * gntdev.c
   3  *
   4  * Device for accessing (in user-space) pages that have been granted by other
   5  * domains.
   6  *
   7  * Copyright (c) 2006-2007, D G Murray.
   8  *           (c) 2009 Gerd Hoffmann <kraxel@redhat.com>
   9  *           (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #undef DEBUG
  22
  23 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  24
  25 #include <linux/module.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/fs.h>
  30 #include <linux/uaccess.h>
  31 #include <linux/sched.h>
  32 #include <linux/sched/mm.h>
  33 #include <linux/spinlock.h>
  34 #include <linux/slab.h>
  35 #include <linux/highmem.h>
  36 #include <linux/refcount.h>
  37 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
  38 #include <linux/of_device.h>
  39 #endif
  40
  41 #include <xen/xen.h>
  42 #include <xen/grant_table.h>
  43 #include <xen/balloon.h>
  44 #include <xen/gntdev.h>
  45 #include <xen/events.h>
  46 #include <xen/page.h>
  47 #include <asm/xen/hypervisor.h>
  48 #include <asm/xen/hypercall.h>
  49
  50 #include "gntdev-common.h"
  51 #ifdef CONFIG_XEN_GNTDEV_DMABUF
  52 #include "gntdev-dmabuf.h"
  53 #endif
  54
  55 MODULE_LICENSE("GPL");
  56 MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
  57               "Gerd Hoffmann <kraxel@redhat.com>");
  58 MODULE_DESCRIPTION("User-space granted page access driver");
  59
  60 static int limit = 1024*1024;
  61 module_param(limit, int, 0644);
  62 MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by "
  63                 "the gntdev device");
  64
  65 static atomic_t pages_mapped = ATOMIC_INIT(0);
  66
  67 static int use_ptemod;
  68 #define populate_freeable_maps use_ptemod
  69
  70 static int unmap_grant_pages(struct gntdev_grant_map *map,
  71                              int offset, int pages);
  72
  73 static struct miscdevice gntdev_miscdev;
  74
  75 /* ------------------------------------------------------------------ */
  76
  77 bool gntdev_account_mapped_pages(int count)
  78 {
  79         return atomic_add_return(count, &pages_mapped) > limit;
  80 }
  81
  82 static void gntdev_print_maps(struct gntdev_priv *priv,
  83                               char *text, int text_index)
  84 {
  85 #ifdef DEBUG
  86         struct gntdev_grant_map *map;
  87
  88         pr_debug("%s: maps list (priv %p)\n", __func__, priv);
  89         list_for_each_entry(map, &priv->maps, next)
  90                 pr_debug("  index %2d, count %2d %s\n",
  91                        map->index, map->count,
  92                        map->index == text_index && text ? text : "");
  93 #endif
  94 }
  95
  96 static void gntdev_free_map(struct gntdev_grant_map *map)
  97 {
  98         if (map == NULL)
  99                 return;
 100
 101 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
 102         if (map->dma_vaddr) {
 103                 struct gnttab_dma_alloc_args args;
 104
 105                 args.dev = map->dma_dev;
 106                 args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT);
 107                 args.nr_pages = map->count;
 108                 args.pages = map->pages;
 109                 args.frames = map->frames;
 110                 args.vaddr = map->dma_vaddr;
 111                 args.dev_bus_addr = map->dma_bus_addr;
 112
 113                 gnttab_dma_free_pages(&args);
 114         } else
 115 #endif
 116         if (map->pages)
 117                 gnttab_free_pages(map->count, map->pages);
 118
 119 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
 120         kfree(map->frames);
 121 #endif
 122         kfree(map->pages);
 123         kfree(map->grants);
 124         kfree(map->map_ops);
 125         kfree(map->unmap_ops);
 126         kfree(map->kmap_ops);
 127         kfree(map->kunmap_ops);
 128         kfree(map);
 129 }
 130
 131 struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
 132                                           int dma_flags)
 133 {
 134         struct gntdev_grant_map *add;
 135         int i;
 136
 137         add = kzalloc(sizeof(*add), GFP_KERNEL);
 138         if (NULL == add)
 139                 return NULL;
 140
 141         add->grants    = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL);
 142         add->map_ops   = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL);
 143         add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL);
 144         add->kmap_ops  = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL);
 145         add->kunmap_ops = kcalloc(count, sizeof(add->kunmap_ops[0]), GFP_KERNEL);
 146         add->pages     = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
 147         if (NULL == add->grants    ||
 148             NULL == add->map_ops   ||
 149             NULL == add->unmap_ops ||
 150             NULL == add->kmap_ops  ||
 151             NULL == add->kunmap_ops ||
 152             NULL == add->pages)
 153                 goto err;
 154
 155 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
 156         add->dma_flags = dma_flags;
 157
 158         /*
 159          * Check if this mapping is requested to be backed
 160          * by a DMA buffer.
 161          */
 162         if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) {
 163                 struct gnttab_dma_alloc_args args;
 164
 165                 add->frames = kcalloc(count, sizeof(add->frames[0]),
 166                                       GFP_KERNEL);
 167                 if (!add->frames)
 168                         goto err;
 169
 170                 /* Remember the device, so we can free DMA memory. */
 171                 add->dma_dev = priv->dma_dev;
 172
 173                 args.dev = priv->dma_dev;
 174                 args.coherent = !!(dma_flags & GNTDEV_DMA_FLAG_COHERENT);
 175                 args.nr_pages = count;
 176                 args.pages = add->pages;
 177                 args.frames = add->frames;
 178
 179                 if (gnttab_dma_alloc_pages(&args))
 180                         goto err;
 181
 182                 add->dma_vaddr = args.vaddr;
 183                 add->dma_bus_addr = args.dev_bus_addr;
 184         } else
 185 #endif
 186         if (gnttab_alloc_pages(count, add->pages))
 187                 goto err;
 188
 189         for (i = 0; i < count; i++) {
 190                 add->map_ops[i].handle = -1;
 191                 add->unmap_ops[i].handle = -1;
 192                 add->kmap_ops[i].handle = -1;
 193                 add->kunmap_ops[i].handle = -1;
 194         }
 195
 196         add->index = 0;
 197         add->count = count;
 198         refcount_set(&add->users, 1);
 199
 200         return add;
 201
 202 err:
 203         gntdev_free_map(add);
 204         return NULL;
 205 }
 206
 207 void gntdev_add_map(struct gntdev_priv *priv, struct gntdev_grant_map *add)
 208 {
 209         struct gntdev_grant_map *map;
 210
 211         list_for_each_entry(map, &priv->maps, next) {
 212                 if (add->index + add->count < map->index) {
 213                         list_add_tail(&add->next, &map->next);
 214                         goto done;
 215                 }
 216                 add->index = map->index + map->count;
 217         }
 218         list_add_tail(&add->next, &priv->maps);
 219
 220 done:
 221         gntdev_print_maps(priv, "[new]", add->index);
 222 }
 223
 224 static struct gntdev_grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
 225                                                       int index, int count)
 226 {
 227         struct gntdev_grant_map *map;
 228
 229         list_for_each_entry(map, &priv->maps, next) {
 230                 if (map->index != index)
 231                         continue;
 232                 if (count && map->count != count)
 233                         continue;
 234                 return map;
 235         }
 236         return NULL;
 237 }
 238
 239 void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map)
 240 {
 241         if (!map)
 242                 return;
 243
 244         if (!refcount_dec_and_test(&map->users))
 245                 return;
 246
 247         atomic_sub(map->count, &pages_mapped);
 248
 249         if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
 250                 notify_remote_via_evtchn(map->notify.event);
 251                 evtchn_put(map->notify.event);
 252         }
 253
 254         if (populate_freeable_maps && priv) {
 255                 mutex_lock(&priv->lock);
 256                 list_del(&map->next);
 257                 mutex_unlock(&priv->lock);
 258         }
 259
 260         if (map->pages && !use_ptemod)
 261                 unmap_grant_pages(map, 0, map->count);
 262         gntdev_free_map(map);
 263 }
 264
 265 /* ------------------------------------------------------------------ */
 266
 267 static int find_grant_ptes(pte_t *pte, pgtable_t token,
 268                 unsigned long addr, void *data)
 269 {
 270         struct gntdev_grant_map *map = data;
 271         unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
 272         int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
 273         u64 pte_maddr;
 274
 275         BUG_ON(pgnr >= map->count);
 276         pte_maddr = arbitrary_virt_to_machine(pte).maddr;
 277
 278         /*
 279          * Set the PTE as special to force get_user_pages_fast() fall
 280          * back to the slow path.  If this is not supported as part of
 281          * the grant map, it will be done afterwards.
 282          */
 283         if (xen_feature(XENFEAT_gnttab_map_avail_bits))
 284                 flags |= (1 << _GNTMAP_guest_avail0);
 285
 286         gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
 287                           map->grants[pgnr].ref,
 288                           map->grants[pgnr].domid);
 289         gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
 290                             -1 /* handle */);
 291         return 0;
 292 }
 293
 294 #ifdef CONFIG_X86
 295 static int set_grant_ptes_as_special(pte_t *pte, pgtable_t token,
 296                                      unsigned long addr, void *data)
 297 {
 298         set_pte_at(current->mm, addr, pte, pte_mkspecial(*pte));
 299         return 0;
 300 }
 301 #endif
 302
 303 int gntdev_map_grant_pages(struct gntdev_grant_map *map)
 304 {
 305         int i, err = 0;
 306
 307         if (!use_ptemod) {
 308                 /* Note: it could already be mapped */
 309                 if (map->map_ops[0].handle != -1)
 310                         return 0;
 311                 for (i = 0; i < map->count; i++) {
 312                         unsigned long addr = (unsigned long)
 313                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 314                         gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
 315                                 map->grants[i].ref,
 316                                 map->grants[i].domid);
 317                         gnttab_set_unmap_op(&map->unmap_ops[i], addr,
 318                                 map->flags, -1 /* handle */);
 319                 }
 320         } else {
 321                 /*
 322                  * Setup the map_ops corresponding to the pte entries pointing
 323                  * to the kernel linear addresses of the struct pages.
 324                  * These ptes are completely different from the user ptes dealt
 325                  * with find_grant_ptes.
 326                  */
 327                 for (i = 0; i < map->count; i++) {
 328                         unsigned long address = (unsigned long)
 329                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 330                         BUG_ON(PageHighMem(map->pages[i]));
 331
 332                         gnttab_set_map_op(&map->kmap_ops[i], address,
 333                                 map->flags | GNTMAP_host_map,
 334                                 map->grants[i].ref,
 335                                 map->grants[i].domid);
 336                         gnttab_set_unmap_op(&map->kunmap_ops[i], address,
 337                                 map->flags | GNTMAP_host_map, -1);
 338                 }
 339         }
 340
 341         pr_debug("map %d+%d\n", map->index, map->count);
 342         err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
 343                         map->pages, map->count);
 344         if (err)
 345                 return err;
 346
 347         for (i = 0; i < map->count; i++) {
 348                 if (map->map_ops[i].status) {
 349                         err = -EINVAL;
 350                         continue;
 351                 }
 352
 353                 map->unmap_ops[i].handle = map->map_ops[i].handle;
 354                 if (use_ptemod)
 355                         map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
 356 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
 357                 else if (map->dma_vaddr) {
 358                         unsigned long bfn;
 359
 360                         bfn = pfn_to_bfn(page_to_pfn(map->pages[i]));
 361                         map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(bfn);
 362                 }
 363 #endif
 364         }
 365         return err;
 366 }
 367
 368 static int __unmap_grant_pages(struct gntdev_grant_map *map, int offset,
 369                                int pages)
 370 {
 371         int i, err = 0;
 372         struct gntab_unmap_queue_data unmap_data;
 373
 374         if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
 375                 int pgno = (map->notify.addr >> PAGE_SHIFT);
 376                 if (pgno >= offset && pgno < offset + pages) {
 377                         /* No need for kmap, pages are in lowmem */
 378                         uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno]));
 379                         tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
 380                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 381                 }
 382         }
 383
 384         unmap_data.unmap_ops = map->unmap_ops + offset;
 385         unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL;
 386         unmap_data.pages = map->pages + offset;
 387         unmap_data.count = pages;
 388
 389         err = gnttab_unmap_refs_sync(&unmap_data);
 390         if (err)
 391                 return err;
 392
 393         for (i = 0; i < pages; i++) {
 394                 if (map->unmap_ops[offset+i].status)
 395                         err = -EINVAL;
 396                 pr_debug("unmap handle=%d st=%d\n",
 397                         map->unmap_ops[offset+i].handle,
 398                         map->unmap_ops[offset+i].status);
 399                 map->unmap_ops[offset+i].handle = -1;
 400         }
 401         return err;
 402 }
 403
 404 static int unmap_grant_pages(struct gntdev_grant_map *map, int offset,
 405                              int pages)
 406 {
 407         int range, err = 0;
 408
 409         pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
 410
 411         /* It is possible the requested range will have a "hole" where we
 412          * already unmapped some of the grants. Only unmap valid ranges.
 413          */
 414         while (pages && !err) {
 415                 while (pages && map->unmap_ops[offset].handle == -1) {
 416                         offset++;
 417                         pages--;
 418                 }
 419                 range = 0;
 420                 while (range < pages) {
 421                         if (map->unmap_ops[offset+range].handle == -1)
 422                                 break;
 423                         range++;
 424                 }
 425                 err = __unmap_grant_pages(map, offset, range);
 426                 offset += range;
 427                 pages -= range;
 428         }
 429
 430         return err;
 431 }
 432
 433 /* ------------------------------------------------------------------ */
 434
 435 static void gntdev_vma_open(struct vm_area_struct *vma)
 436 {
 437         struct gntdev_grant_map *map = vma->vm_private_data;
 438
 439         pr_debug("gntdev_vma_open %p\n", vma);
 440         refcount_inc(&map->users);
 441 }
 442
 443 static void gntdev_vma_close(struct vm_area_struct *vma)
 444 {
 445         struct gntdev_grant_map *map = vma->vm_private_data;
 446         struct file *file = vma->vm_file;
 447         struct gntdev_priv *priv = file->private_data;
 448
 449         pr_debug("gntdev_vma_close %p\n", vma);
 450         if (use_ptemod) {
 451                 /* It is possible that an mmu notifier could be running
 452                  * concurrently, so take priv->lock to ensure that the vma won't
 453                  * vanishing during the unmap_grant_pages call, since we will
 454                  * spin here until that completes. Such a concurrent call will
 455                  * not do any unmapping, since that has been done prior to
 456                  * closing the vma, but it may still iterate the unmap_ops list.
 457                  */
 458                 mutex_lock(&priv->lock);
 459                 map->vma = NULL;
 460                 mutex_unlock(&priv->lock);
 461         }
 462         vma->vm_private_data = NULL;
 463         gntdev_put_map(priv, map);
 464 }
 465
 466 static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma,
 467                                                  unsigned long addr)
 468 {
 469         struct gntdev_grant_map *map = vma->vm_private_data;
 470
 471         return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT];
 472 }
 473
 474 static const struct vm_operations_struct gntdev_vmops = {
 475         .open = gntdev_vma_open,
 476         .close = gntdev_vma_close,
 477         .find_special_page = gntdev_vma_find_special_page,
 478 };
 479
 480 /* ------------------------------------------------------------------ */
 481
 482 static bool in_range(struct gntdev_grant_map *map,
 483                               unsigned long start, unsigned long end)
 484 {
 485         if (!map->vma)
 486                 return false;
 487         if (map->vma->vm_start >= end)
 488                 return false;
 489         if (map->vma->vm_end <= start)
 490                 return false;
 491
 492         return true;
 493 }
 494
 495 static int unmap_if_in_range(struct gntdev_grant_map *map,
 496                               unsigned long start, unsigned long end,
 497                               bool blockable)
 498 {
 499         unsigned long mstart, mend;
 500         int err;
 501
 502         if (!in_range(map, start, end))
 503                 return 0;
 504
 505         if (!blockable)
 506                 return -EAGAIN;
 507
 508         mstart = max(start, map->vma->vm_start);
 509         mend   = min(end,   map->vma->vm_end);
 510         pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
 511                         map->index, map->count,
 512                         map->vma->vm_start, map->vma->vm_end,
 513                         start, end, mstart, mend);
 514         err = unmap_grant_pages(map,
 515                                 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
 516                                 (mend - mstart) >> PAGE_SHIFT);
 517         WARN_ON(err);
 518
 519         return 0;
 520 }
 521
 522 static int mn_invl_range_start(struct mmu_notifier *mn,
 523                                 struct mm_struct *mm,
 524                                 unsigned long start, unsigned long end,
 525                                 bool blockable)
 526 {
 527         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 528         struct gntdev_grant_map *map;
 529         int ret = 0;
 530
 531         if (blockable)
 532                 mutex_lock(&priv->lock);
 533         else if (!mutex_trylock(&priv->lock))
 534                 return -EAGAIN;
 535
 536         list_for_each_entry(map, &priv->maps, next) {
 537                 ret = unmap_if_in_range(map, start, end, blockable);
 538                 if (ret)
 539                         goto out_unlock;
 540         }
 541         list_for_each_entry(map, &priv->freeable_maps, next) {
 542                 ret = unmap_if_in_range(map, start, end, blockable);
 543                 if (ret)
 544                         goto out_unlock;
 545         }
 546
 547 out_unlock:
 548         mutex_unlock(&priv->lock);
 549
 550         return ret;
 551 }
 552
 553 static void mn_release(struct mmu_notifier *mn,
 554                        struct mm_struct *mm)
 555 {
 556         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 557         struct gntdev_grant_map *map;
 558         int err;
 559
 560         mutex_lock(&priv->lock);
 561         list_for_each_entry(map, &priv->maps, next) {
 562                 if (!map->vma)
 563                         continue;
 564                 pr_debug("map %d+%d (%lx %lx)\n",
 565                                 map->index, map->count,
 566                                 map->vma->vm_start, map->vma->vm_end);
 567                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 568                 WARN_ON(err);
 569         }
 570         list_for_each_entry(map, &priv->freeable_maps, next) {
 571                 if (!map->vma)
 572                         continue;
 573                 pr_debug("map %d+%d (%lx %lx)\n",
 574                                 map->index, map->count,
 575                                 map->vma->vm_start, map->vma->vm_end);
 576                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 577                 WARN_ON(err);
 578         }
 579         mutex_unlock(&priv->lock);
 580 }
 581
 582 static const struct mmu_notifier_ops gntdev_mmu_ops = {
 583         .release                = mn_release,
 584         .invalidate_range_start = mn_invl_range_start,
 585 };
 586
 587 /* ------------------------------------------------------------------ */
 588
 589 static int gntdev_open(struct inode *inode, struct file *flip)
 590 {
 591         struct gntdev_priv *priv;
 592         int ret = 0;
 593
 594         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 595         if (!priv)
 596                 return -ENOMEM;
 597
 598         INIT_LIST_HEAD(&priv->maps);
 599         INIT_LIST_HEAD(&priv->freeable_maps);
 600         mutex_init(&priv->lock);
 601
 602 #ifdef CONFIG_XEN_GNTDEV_DMABUF
 603         priv->dmabuf_priv = gntdev_dmabuf_init();
 604         if (IS_ERR(priv->dmabuf_priv)) {
 605                 ret = PTR_ERR(priv->dmabuf_priv);
 606                 kfree(priv);
 607                 return ret;
 608         }
 609 #endif
 610
 611         if (use_ptemod) {
 612                 priv->mm = get_task_mm(current);
 613                 if (!priv->mm) {
 614                         kfree(priv);
 615                         return -ENOMEM;
 616                 }
 617                 priv->mn.ops = &gntdev_mmu_ops;
 618                 ret = mmu_notifier_register(&priv->mn, priv->mm);
 619                 mmput(priv->mm);
 620         }
 621
 622         if (ret) {
 623                 kfree(priv);
 624                 return ret;
 625         }
 626
 627         flip->private_data = priv;
 628 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
 629         priv->dma_dev = gntdev_miscdev.this_device;
 630
 631         /*
 632          * The device is not spawn from a device tree, so arch_setup_dma_ops
 633          * is not called, thus leaving the device with dummy DMA ops.
 634          * Fix this by calling of_dma_configure() with a NULL node to set
 635          * default DMA ops.
 636          */
 637         of_dma_configure(priv->dma_dev, NULL, true);
 638 #endif
 639         pr_debug("priv %p\n", priv);
 640
 641         return 0;
 642 }
 643
 644 static int gntdev_release(struct inode *inode, struct file *flip)
 645 {
 646         struct gntdev_priv *priv = flip->private_data;
 647         struct gntdev_grant_map *map;
 648
 649         pr_debug("priv %p\n", priv);
 650
 651         mutex_lock(&priv->lock);
 652         while (!list_empty(&priv->maps)) {
 653                 map = list_entry(priv->maps.next,
 654                                  struct gntdev_grant_map, next);
 655                 list_del(&map->next);
 656                 gntdev_put_map(NULL /* already removed */, map);
 657         }
 658         WARN_ON(!list_empty(&priv->freeable_maps));
 659         mutex_unlock(&priv->lock);
 660
 661 #ifdef CONFIG_XEN_GNTDEV_DMABUF
 662         gntdev_dmabuf_fini(priv->dmabuf_priv);
 663 #endif
 664
 665         if (use_ptemod)
 666                 mmu_notifier_unregister(&priv->mn, priv->mm);
 667
 668         kfree(priv);
 669         return 0;
 670 }
 671
 672 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 673                                        struct ioctl_gntdev_map_grant_ref __user *u)
 674 {
 675         struct ioctl_gntdev_map_grant_ref op;
 676         struct gntdev_grant_map *map;
 677         int err;
 678
 679         if (copy_from_user(&op, u, sizeof(op)) != 0)
 680                 return -EFAULT;
 681         pr_debug("priv %p, add %d\n", priv, op.count);
 682         if (unlikely(op.count <= 0))
 683                 return -EINVAL;
 684
 685         err = -ENOMEM;
 686         map = gntdev_alloc_map(priv, op.count, 0 /* This is not a dma-buf. */);
 687         if (!map)
 688                 return err;
 689
 690         if (unlikely(gntdev_account_mapped_pages(op.count))) {
 691                 pr_debug("can't map: over limit\n");
 692                 gntdev_put_map(NULL, map);
 693                 return err;
 694         }
 695
 696         if (copy_from_user(map->grants, &u->refs,
 697                            sizeof(map->grants[0]) * op.count) != 0) {
 698                 gntdev_put_map(NULL, map);
 699                 return -EFAULT;
 700         }
 701
 702         mutex_lock(&priv->lock);
 703         gntdev_add_map(priv, map);
 704         op.index = map->index << PAGE_SHIFT;
 705         mutex_unlock(&priv->lock);
 706
 707         if (copy_to_user(u, &op, sizeof(op)) != 0)
 708                 return -EFAULT;
 709
 710         return 0;
 711 }
 712
 713 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
 714                                          struct ioctl_gntdev_unmap_grant_ref __user *u)
 715 {
 716         struct ioctl_gntdev_unmap_grant_ref op;
 717         struct gntdev_grant_map *map;
 718         int err = -ENOENT;
 719
 720         if (copy_from_user(&op, u, sizeof(op)) != 0)
 721                 return -EFAULT;
 722         pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
 723
 724         mutex_lock(&priv->lock);
 725         map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
 726         if (map) {
 727                 list_del(&map->next);
 728                 if (populate_freeable_maps)
 729                         list_add_tail(&map->next, &priv->freeable_maps);
 730                 err = 0;
 731         }
 732         mutex_unlock(&priv->lock);
 733         if (map)
 734                 gntdev_put_map(priv, map);
 735         return err;
 736 }
 737
 738 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 739                                               struct ioctl_gntdev_get_offset_for_vaddr __user *u)
 740 {
 741         struct ioctl_gntdev_get_offset_for_vaddr op;
 742         struct vm_area_struct *vma;
 743         struct gntdev_grant_map *map;
 744         int rv = -EINVAL;
 745
 746         if (copy_from_user(&op, u, sizeof(op)) != 0)
 747                 return -EFAULT;
 748         pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
 749
 750         down_read(&current->mm->mmap_sem);
 751         vma = find_vma(current->mm, op.vaddr);
 752         if (!vma || vma->vm_ops != &gntdev_vmops)
 753                 goto out_unlock;
 754
 755         map = vma->vm_private_data;
 756         if (!map)
 757                 goto out_unlock;
 758
 759         op.offset = map->index << PAGE_SHIFT;
 760         op.count = map->count;
 761         rv = 0;
 762
 763  out_unlock:
 764         up_read(&current->mm->mmap_sem);
 765
 766         if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0)
 767                 return -EFAULT;
 768         return rv;
 769 }
 770
 771 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 772 {
 773         struct ioctl_gntdev_unmap_notify op;
 774         struct gntdev_grant_map *map;
 775         int rc;
 776         int out_flags;
 777         unsigned int out_event;
 778
 779         if (copy_from_user(&op, u, sizeof(op)))
 780                 return -EFAULT;
 781
 782         if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
 783                 return -EINVAL;
 784
 785         /* We need to grab a reference to the event channel we are going to use
 786          * to send the notify before releasing the reference we may already have
 787          * (if someone has called this ioctl twice). This is required so that
 788          * it is possible to change the clear_byte part of the notification
 789          * without disturbing the event channel part, which may now be the last
 790          * reference to that event channel.
 791          */
 792         if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
 793                 if (evtchn_get(op.event_channel_port))
 794                         return -EINVAL;
 795         }
 796
 797         out_flags = op.action;
 798         out_event = op.event_channel_port;
 799
 800         mutex_lock(&priv->lock);
 801
 802         list_for_each_entry(map, &priv->maps, next) {
 803                 uint64_t begin = map->index << PAGE_SHIFT;
 804                 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
 805                 if (op.index >= begin && op.index < end)
 806                         goto found;
 807         }
 808         rc = -ENOENT;
 809         goto unlock_out;
 810
 811  found:
 812         if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
 813                         (map->flags & GNTMAP_readonly)) {
 814                 rc = -EINVAL;
 815                 goto unlock_out;
 816         }
 817
 818         out_flags = map->notify.flags;
 819         out_event = map->notify.event;
 820
 821         map->notify.flags = op.action;
 822         map->notify.addr = op.index - (map->index << PAGE_SHIFT);
 823         map->notify.event = op.event_channel_port;
 824
 825         rc = 0;
 826
 827  unlock_out:
 828         mutex_unlock(&priv->lock);
 829
 830         /* Drop the reference to the event channel we did not save in the map */
 831         if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
 832                 evtchn_put(out_event);
 833
 834         return rc;
 835 }
 836
 837 #define GNTDEV_COPY_BATCH 16
 838
 839 struct gntdev_copy_batch {
 840         struct gnttab_copy ops[GNTDEV_COPY_BATCH];
 841         struct page *pages[GNTDEV_COPY_BATCH];
 842         s16 __user *status[GNTDEV_COPY_BATCH];
 843         unsigned int nr_ops;
 844         unsigned int nr_pages;
 845 };
 846
 847 static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt,
 848                            bool writeable, unsigned long *gfn)
 849 {
 850         unsigned long addr = (unsigned long)virt;
 851         struct page *page;
 852         unsigned long xen_pfn;
 853         int ret;
 854
 855         ret = get_user_pages_fast(addr, 1, writeable, &page);
 856         if (ret < 0)
 857                 return ret;
 858
 859         batch->pages[batch->nr_pages++] = page;
 860
 861         xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK);
 862         *gfn = pfn_to_gfn(xen_pfn);
 863
 864         return 0;
 865 }
 866
 867 static void gntdev_put_pages(struct gntdev_copy_batch *batch)
 868 {
 869         unsigned int i;
 870
 871         for (i = 0; i < batch->nr_pages; i++)
 872                 put_page(batch->pages[i]);
 873         batch->nr_pages = 0;
 874 }
 875
 876 static int gntdev_copy(struct gntdev_copy_batch *batch)
 877 {
 878         unsigned int i;
 879
 880         gnttab_batch_copy(batch->ops, batch->nr_ops);
 881         gntdev_put_pages(batch);
 882
 883         /*
 884          * For each completed op, update the status if the op failed
 885          * and all previous ops for the segment were successful.
 886          */
 887         for (i = 0; i < batch->nr_ops; i++) {
 888                 s16 status = batch->ops[i].status;
 889                 s16 old_status;
 890
 891                 if (status == GNTST_okay)
 892                         continue;
 893
 894                 if (__get_user(old_status, batch->status[i]))
 895                         return -EFAULT;
 896
 897                 if (old_status != GNTST_okay)
 898                         continue;
 899
 900                 if (__put_user(status, batch->status[i]))
 901                         return -EFAULT;
 902         }
 903
 904         batch->nr_ops = 0;
 905         return 0;
 906 }
 907
 908 static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch,
 909                                  struct gntdev_grant_copy_segment *seg,
 910                                  s16 __user *status)
 911 {
 912         uint16_t copied = 0;
 913
 914         /*
 915          * Disallow local -> local copies since there is only space in
 916          * batch->pages for one page per-op and this would be a very
 917          * expensive memcpy().
 918          */
 919         if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref)))
 920                 return -EINVAL;
 921
 922         /* Can't cross page if source/dest is a grant ref. */
 923         if (seg->flags & GNTCOPY_source_gref) {
 924                 if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE)
 925                         return -EINVAL;
 926         }
 927         if (seg->flags & GNTCOPY_dest_gref) {
 928                 if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE)
 929                         return -EINVAL;
 930         }
 931
 932         if (put_user(GNTST_okay, status))
 933                 return -EFAULT;
 934
 935         while (copied < seg->len) {
 936                 struct gnttab_copy *op;
 937                 void __user *virt;
 938                 size_t len, off;
 939                 unsigned long gfn;
 940                 int ret;
 941
 942                 if (batch->nr_ops >= GNTDEV_COPY_BATCH) {
 943                         ret = gntdev_copy(batch);
 944                         if (ret < 0)
 945                                 return ret;
 946                 }
 947
 948                 len = seg->len - copied;
 949
 950                 op = &batch->ops[batch->nr_ops];
 951                 op->flags = 0;
 952
 953                 if (seg->flags & GNTCOPY_source_gref) {
 954                         op->source.u.ref = seg->source.foreign.ref;
 955                         op->source.domid = seg->source.foreign.domid;
 956                         op->source.offset = seg->source.foreign.offset + copied;
 957                         op->flags |= GNTCOPY_source_gref;
 958                 } else {
 959                         virt = seg->source.virt + copied;
 960                         off = (unsigned long)virt & ~XEN_PAGE_MASK;
 961                         len = min(len, (size_t)XEN_PAGE_SIZE - off);
 962
 963                         ret = gntdev_get_page(batch, virt, false, &gfn);
 964                         if (ret < 0)
 965                                 return ret;
 966
 967                         op->source.u.gmfn = gfn;
 968                         op->source.domid = DOMID_SELF;
 969                         op->source.offset = off;
 970                 }
 971
 972                 if (seg->flags & GNTCOPY_dest_gref) {
 973                         op->dest.u.ref = seg->dest.foreign.ref;
 974                         op->dest.domid = seg->dest.foreign.domid;
 975                         op->dest.offset = seg->dest.foreign.offset + copied;
 976                         op->flags |= GNTCOPY_dest_gref;
 977                 } else {
 978                         virt = seg->dest.virt + copied;
 979                         off = (unsigned long)virt & ~XEN_PAGE_MASK;
 980                         len = min(len, (size_t)XEN_PAGE_SIZE - off);
 981
 982                         ret = gntdev_get_page(batch, virt, true, &gfn);
 983                         if (ret < 0)
 984                                 return ret;
 985
 986                         op->dest.u.gmfn = gfn;
 987                         op->dest.domid = DOMID_SELF;
 988                         op->dest.offset = off;
 989                 }
 990
 991                 op->len = len;
 992                 copied += len;
 993
 994                 batch->status[batch->nr_ops] = status;
 995                 batch->nr_ops++;
 996         }
 997
 998         return 0;
 999 }
1000
1001 static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
1002 {
1003         struct ioctl_gntdev_grant_copy copy;
1004         struct gntdev_copy_batch batch;
1005         unsigned int i;
1006         int ret = 0;
1007
1008         if (copy_from_user(&copy, u, sizeof(copy)))
1009                 return -EFAULT;
1010
1011         batch.nr_ops = 0;
1012         batch.nr_pages = 0;
1013
1014         for (i = 0; i < copy.count; i++) {
1015                 struct gntdev_grant_copy_segment seg;
1016
1017                 if (copy_from_user(&seg, &copy.segments[i], sizeof(seg))) {
1018                         ret = -EFAULT;
1019                         goto out;
1020                 }
1021
1022                 ret = gntdev_grant_copy_seg(&batch, &seg, &copy.segments[i].status);
1023                 if (ret < 0)
1024                         goto out;
1025
1026                 cond_resched();
1027         }
1028         if (batch.nr_ops)
1029                 ret = gntdev_copy(&batch);
1030         return ret;
1031
1032   out:
1033         gntdev_put_pages(&batch);
1034         return ret;
1035 }
1036
1037 static long gntdev_ioctl(struct file *flip,
1038                          unsigned int cmd, unsigned long arg)
1039 {
1040         struct gntdev_priv *priv = flip->private_data;
1041         void __user *ptr = (void __user *)arg;
1042
1043         switch (cmd) {
1044         case IOCTL_GNTDEV_MAP_GRANT_REF:
1045                 return gntdev_ioctl_map_grant_ref(priv, ptr);
1046
1047         case IOCTL_GNTDEV_UNMAP_GRANT_REF:
1048                 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
1049
1050         case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
1051                 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
1052
1053         case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
1054                 return gntdev_ioctl_notify(priv, ptr);
1055
1056         case IOCTL_GNTDEV_GRANT_COPY:
1057                 return gntdev_ioctl_grant_copy(priv, ptr);
1058
1059 #ifdef CONFIG_XEN_GNTDEV_DMABUF
1060         case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS:
1061                 return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr);
1062
1063         case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED:
1064                 return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr);
1065
1066         case IOCTL_GNTDEV_DMABUF_IMP_TO_REFS:
1067                 return gntdev_ioctl_dmabuf_imp_to_refs(priv, ptr);
1068
1069         case IOCTL_GNTDEV_DMABUF_IMP_RELEASE:
1070                 return gntdev_ioctl_dmabuf_imp_release(priv, ptr);
1071 #endif
1072
1073         default:
1074                 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
1075                 return -ENOIOCTLCMD;
1076         }
1077
1078         return 0;
1079 }
1080
1081 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
1082 {
1083         struct gntdev_priv *priv = flip->private_data;
1084         int index = vma->vm_pgoff;
1085         int count = vma_pages(vma);
1086         struct gntdev_grant_map *map;
1087         int i, err = -EINVAL;
1088
1089         if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
1090                 return -EINVAL;
1091
1092         pr_debug("map %d+%d at %lx (pgoff %lx)\n",
1093                         index, count, vma->vm_start, vma->vm_pgoff);
1094
1095         mutex_lock(&priv->lock);
1096         map = gntdev_find_map_index(priv, index, count);
1097         if (!map)
1098                 goto unlock_out;
1099         if (use_ptemod && map->vma)
1100                 goto unlock_out;
1101         if (use_ptemod && priv->mm != vma->vm_mm) {
1102                 pr_warn("Huh? Other mm?\n");
1103                 goto unlock_out;
1104         }
1105
1106         refcount_inc(&map->users);
1107
1108         vma->vm_ops = &gntdev_vmops;
1109
1110         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP;
1111
1112         if (use_ptemod)
1113                 vma->vm_flags |= VM_DONTCOPY;
1114
1115         vma->vm_private_data = map;
1116
1117         if (use_ptemod)
1118                 map->vma = vma;
1119
1120         if (map->flags) {
1121                 if ((vma->vm_flags & VM_WRITE) &&
1122                                 (map->flags & GNTMAP_readonly))
1123                         goto out_unlock_put;
1124         } else {
1125                 map->flags = GNTMAP_host_map;
1126                 if (!(vma->vm_flags & VM_WRITE))
1127                         map->flags |= GNTMAP_readonly;
1128         }
1129
1130         mutex_unlock(&priv->lock);
1131
1132         if (use_ptemod) {
1133                 map->pages_vm_start = vma->vm_start;
1134                 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
1135                                           vma->vm_end - vma->vm_start,
1136                                           find_grant_ptes, map);
1137                 if (err) {
1138                         pr_warn("find_grant_ptes() failure.\n");
1139                         goto out_put_map;
1140                 }
1141         }
1142
1143         err = gntdev_map_grant_pages(map);
1144         if (err)
1145                 goto out_put_map;
1146
1147         if (!use_ptemod) {
1148                 for (i = 0; i < count; i++) {
1149                         err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
1150                                 map->pages[i]);
1151                         if (err)
1152                                 goto out_put_map;
1153                 }
1154         } else {
1155 #ifdef CONFIG_X86
1156                 /*
1157                  * If the PTEs were not made special by the grant map
1158                  * hypercall, do so here.
1159                  *
1160                  * This is racy since the mapping is already visible
1161                  * to userspace but userspace should be well-behaved
1162                  * enough to not touch it until the mmap() call
1163                  * returns.
1164                  */
1165                 if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) {
1166                         apply_to_page_range(vma->vm_mm, vma->vm_start,
1167                                             vma->vm_end - vma->vm_start,
1168                                             set_grant_ptes_as_special, NULL);
1169                 }
1170 #endif
1171         }
1172
1173         return 0;
1174
1175 unlock_out:
1176         mutex_unlock(&priv->lock);
1177         return err;
1178
1179 out_unlock_put:
1180         mutex_unlock(&priv->lock);
1181 out_put_map:
1182         if (use_ptemod) {
1183                 map->vma = NULL;
1184                 unmap_grant_pages(map, 0, map->count);
1185         }
1186         gntdev_put_map(priv, map);
1187         return err;
1188 }
1189
1190 static const struct file_operations gntdev_fops = {
1191         .owner = THIS_MODULE,
1192         .open = gntdev_open,
1193         .release = gntdev_release,
1194         .mmap = gntdev_mmap,
1195         .unlocked_ioctl = gntdev_ioctl
1196 };
1197
1198 static struct miscdevice gntdev_miscdev = {
1199         .minor        = MISC_DYNAMIC_MINOR,
1200         .name         = "xen/gntdev",
1201         .fops         = &gntdev_fops,
1202 };
1203
1204 /* ------------------------------------------------------------------ */
1205
1206 static int __init gntdev_init(void)
1207 {
1208         int err;
1209
1210         if (!xen_domain())
1211                 return -ENODEV;
1212
1213         use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);
1214
1215         err = misc_register(&gntdev_miscdev);
1216         if (err != 0) {
1217                 pr_err("Could not register gntdev device\n");
1218                 return err;
1219         }
1220         return 0;
1221 }
1222
1223 static void __exit gntdev_exit(void)
1224 {
1225         misc_deregister(&gntdev_miscdev);
1226 }
1227
1228 module_init(gntdev_init);
1229 module_exit(gntdev_exit);
1230
1231 /* ------------------------------------------------------------------ */