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