drivers/xen/gntdev.c

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

DEFINITIONS
