drivers/xen/privcmd.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /******************************************************************************
   3  * privcmd.c
   4  *
   5  * Interface to privileged domain-0 commands.
   6  *
   7  * Copyright (c) 2002-2004, K A Fraser, B Dragovic
   8  */
   9
  10 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/sched.h>
  15 #include <linux/slab.h>
  16 #include <linux/string.h>
  17 #include <linux/errno.h>
  18 #include <linux/mm.h>
  19 #include <linux/mman.h>
  20 #include <linux/uaccess.h>
  21 #include <linux/swap.h>
  22 #include <linux/highmem.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/seq_file.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/moduleparam.h>
  27
  28 #include <asm/xen/hypervisor.h>
  29 #include <asm/xen/hypercall.h>
  30
  31 #include <xen/xen.h>
  32 #include <xen/privcmd.h>
  33 #include <xen/interface/xen.h>
  34 #include <xen/interface/memory.h>
  35 #include <xen/interface/hvm/dm_op.h>
  36 #include <xen/features.h>
  37 #include <xen/page.h>
  38 #include <xen/xen-ops.h>
  39 #include <xen/balloon.h>
  40
  41 #include "privcmd.h"
  42
  43 MODULE_LICENSE("GPL");
  44
  45 #define PRIV_VMA_LOCKED ((void *)1)
  46
  47 static unsigned int privcmd_dm_op_max_num = 16;
  48 module_param_named(dm_op_max_nr_bufs, privcmd_dm_op_max_num, uint, 0644);
  49 MODULE_PARM_DESC(dm_op_max_nr_bufs,
  50                  "Maximum number of buffers per dm_op hypercall");
  51
  52 static unsigned int privcmd_dm_op_buf_max_size = 4096;
  53 module_param_named(dm_op_buf_max_size, privcmd_dm_op_buf_max_size, uint,
  54                    0644);
  55 MODULE_PARM_DESC(dm_op_buf_max_size,
  56                  "Maximum size of a dm_op hypercall buffer");
  57
  58 struct privcmd_data {
  59         domid_t domid;
  60 };
  61
  62 static int privcmd_vma_range_is_mapped(
  63                struct vm_area_struct *vma,
  64                unsigned long addr,
  65                unsigned long nr_pages);
  66
  67 static long privcmd_ioctl_hypercall(struct file *file, void __user *udata)
  68 {
  69         struct privcmd_data *data = file->private_data;
  70         struct privcmd_hypercall hypercall;
  71         long ret;
  72
  73         /* Disallow arbitrary hypercalls if restricted */
  74         if (data->domid != DOMID_INVALID)
  75                 return -EPERM;
  76
  77         if (copy_from_user(&hypercall, udata, sizeof(hypercall)))
  78                 return -EFAULT;
  79
  80         xen_preemptible_hcall_begin();
  81         ret = privcmd_call(hypercall.op,
  82                            hypercall.arg[0], hypercall.arg[1],
  83                            hypercall.arg[2], hypercall.arg[3],
  84                            hypercall.arg[4]);
  85         xen_preemptible_hcall_end();
  86
  87         return ret;
  88 }
  89
  90 static void free_page_list(struct list_head *pages)
  91 {
  92         struct page *p, *n;
  93
  94         list_for_each_entry_safe(p, n, pages, lru)
  95                 __free_page(p);
  96
  97         INIT_LIST_HEAD(pages);
  98 }
  99
 100 /*
 101  * Given an array of items in userspace, return a list of pages
 102  * containing the data.  If copying fails, either because of memory
 103  * allocation failure or a problem reading user memory, return an
 104  * error code; its up to the caller to dispose of any partial list.
 105  */
 106 static int gather_array(struct list_head *pagelist,
 107                         unsigned nelem, size_t size,
 108                         const void __user *data)
 109 {
 110         unsigned pageidx;
 111         void *pagedata;
 112         int ret;
 113
 114         if (size > PAGE_SIZE)
 115                 return 0;
 116
 117         pageidx = PAGE_SIZE;
 118         pagedata = NULL;        /* quiet, gcc */
 119         while (nelem--) {
 120                 if (pageidx > PAGE_SIZE-size) {
 121                         struct page *page = alloc_page(GFP_KERNEL);
 122
 123                         ret = -ENOMEM;
 124                         if (page == NULL)
 125                                 goto fail;
 126
 127                         pagedata = page_address(page);
 128
 129                         list_add_tail(&page->lru, pagelist);
 130                         pageidx = 0;
 131                 }
 132
 133                 ret = -EFAULT;
 134                 if (copy_from_user(pagedata + pageidx, data, size))
 135                         goto fail;
 136
 137                 data += size;
 138                 pageidx += size;
 139         }
 140
 141         ret = 0;
 142
 143 fail:
 144         return ret;
 145 }
 146
 147 /*
 148  * Call function "fn" on each element of the array fragmented
 149  * over a list of pages.
 150  */
 151 static int traverse_pages(unsigned nelem, size_t size,
 152                           struct list_head *pos,
 153                           int (*fn)(void *data, void *state),
 154                           void *state)
 155 {
 156         void *pagedata;
 157         unsigned pageidx;
 158         int ret = 0;
 159
 160         BUG_ON(size > PAGE_SIZE);
 161
 162         pageidx = PAGE_SIZE;
 163         pagedata = NULL;        /* hush, gcc */
 164
 165         while (nelem--) {
 166                 if (pageidx > PAGE_SIZE-size) {
 167                         struct page *page;
 168                         pos = pos->next;
 169                         page = list_entry(pos, struct page, lru);
 170                         pagedata = page_address(page);
 171                         pageidx = 0;
 172                 }
 173
 174                 ret = (*fn)(pagedata + pageidx, state);
 175                 if (ret)
 176                         break;
 177                 pageidx += size;
 178         }
 179
 180         return ret;
 181 }
 182
 183 /*
 184  * Similar to traverse_pages, but use each page as a "block" of
 185  * data to be processed as one unit.
 186  */
 187 static int traverse_pages_block(unsigned nelem, size_t size,
 188                                 struct list_head *pos,
 189                                 int (*fn)(void *data, int nr, void *state),
 190                                 void *state)
 191 {
 192         void *pagedata;
 193         int ret = 0;
 194
 195         BUG_ON(size > PAGE_SIZE);
 196
 197         while (nelem) {
 198                 int nr = (PAGE_SIZE/size);
 199                 struct page *page;
 200                 if (nr > nelem)
 201                         nr = nelem;
 202                 pos = pos->next;
 203                 page = list_entry(pos, struct page, lru);
 204                 pagedata = page_address(page);
 205                 ret = (*fn)(pagedata, nr, state);
 206                 if (ret)
 207                         break;
 208                 nelem -= nr;
 209         }
 210
 211         return ret;
 212 }
 213
 214 struct mmap_gfn_state {
 215         unsigned long va;
 216         struct vm_area_struct *vma;
 217         domid_t domain;
 218 };
 219
 220 static int mmap_gfn_range(void *data, void *state)
 221 {
 222         struct privcmd_mmap_entry *msg = data;
 223         struct mmap_gfn_state *st = state;
 224         struct vm_area_struct *vma = st->vma;
 225         int rc;
 226
 227         /* Do not allow range to wrap the address space. */
 228         if ((msg->npages > (LONG_MAX >> PAGE_SHIFT)) ||
 229             ((unsigned long)(msg->npages << PAGE_SHIFT) >= -st->va))
 230                 return -EINVAL;
 231
 232         /* Range chunks must be contiguous in va space. */
 233         if ((msg->va != st->va) ||
 234             ((msg->va+(msg->npages<<PAGE_SHIFT)) > vma->vm_end))
 235                 return -EINVAL;
 236
 237         rc = xen_remap_domain_gfn_range(vma,
 238                                         msg->va & PAGE_MASK,
 239                                         msg->mfn, msg->npages,
 240                                         vma->vm_page_prot,
 241                                         st->domain, NULL);
 242         if (rc < 0)
 243                 return rc;
 244
 245         st->va += msg->npages << PAGE_SHIFT;
 246
 247         return 0;
 248 }
 249
 250 static long privcmd_ioctl_mmap(struct file *file, void __user *udata)
 251 {
 252         struct privcmd_data *data = file->private_data;
 253         struct privcmd_mmap mmapcmd;
 254         struct mm_struct *mm = current->mm;
 255         struct vm_area_struct *vma;
 256         int rc;
 257         LIST_HEAD(pagelist);
 258         struct mmap_gfn_state state;
 259
 260         /* We only support privcmd_ioctl_mmap_batch for non-auto-translated. */
 261         if (xen_feature(XENFEAT_auto_translated_physmap))
 262                 return -ENOSYS;
 263
 264         if (copy_from_user(&mmapcmd, udata, sizeof(mmapcmd)))
 265                 return -EFAULT;
 266
 267         /* If restriction is in place, check the domid matches */
 268         if (data->domid != DOMID_INVALID && data->domid != mmapcmd.dom)
 269                 return -EPERM;
 270
 271         rc = gather_array(&pagelist,
 272                           mmapcmd.num, sizeof(struct privcmd_mmap_entry),
 273                           mmapcmd.entry);
 274
 275         if (rc || list_empty(&pagelist))
 276                 goto out;
 277
 278         mmap_write_lock(mm);
 279
 280         {
 281                 struct page *page = list_first_entry(&pagelist,
 282                                                      struct page, lru);
 283                 struct privcmd_mmap_entry *msg = page_address(page);
 284
 285                 vma = vma_lookup(mm, msg->va);
 286                 rc = -EINVAL;
 287
 288                 if (!vma || (msg->va != vma->vm_start) || vma->vm_private_data)
 289                         goto out_up;
 290                 vma->vm_private_data = PRIV_VMA_LOCKED;
 291         }
 292
 293         state.va = vma->vm_start;
 294         state.vma = vma;
 295         state.domain = mmapcmd.dom;
 296
 297         rc = traverse_pages(mmapcmd.num, sizeof(struct privcmd_mmap_entry),
 298                             &pagelist,
 299                             mmap_gfn_range, &state);
 300
 301
 302 out_up:
 303         mmap_write_unlock(mm);
 304
 305 out:
 306         free_page_list(&pagelist);
 307
 308         return rc;
 309 }
 310
 311 struct mmap_batch_state {
 312         domid_t domain;
 313         unsigned long va;
 314         struct vm_area_struct *vma;
 315         int index;
 316         /* A tristate:
 317          *      0 for no errors
 318          *      1 if at least one error has happened (and no
 319          *          -ENOENT errors have happened)
 320          *      -ENOENT if at least 1 -ENOENT has happened.
 321          */
 322         int global_error;
 323         int version;
 324
 325         /* User-space gfn array to store errors in the second pass for V1. */
 326         xen_pfn_t __user *user_gfn;
 327         /* User-space int array to store errors in the second pass for V2. */
 328         int __user *user_err;
 329 };
 330
 331 /* auto translated dom0 note: if domU being created is PV, then gfn is
 332  * mfn(addr on bus). If it's auto xlated, then gfn is pfn (input to HAP).
 333  */
 334 static int mmap_batch_fn(void *data, int nr, void *state)
 335 {
 336         xen_pfn_t *gfnp = data;
 337         struct mmap_batch_state *st = state;
 338         struct vm_area_struct *vma = st->vma;
 339         struct page **pages = vma->vm_private_data;
 340         struct page **cur_pages = NULL;
 341         int ret;
 342
 343         if (xen_feature(XENFEAT_auto_translated_physmap))
 344                 cur_pages = &pages[st->index];
 345
 346         BUG_ON(nr < 0);
 347         ret = xen_remap_domain_gfn_array(st->vma, st->va & PAGE_MASK, gfnp, nr,
 348                                          (int *)gfnp, st->vma->vm_page_prot,
 349                                          st->domain, cur_pages);
 350
 351         /* Adjust the global_error? */
 352         if (ret != nr) {
 353                 if (ret == -ENOENT)
 354                         st->global_error = -ENOENT;
 355                 else {
 356                         /* Record that at least one error has happened. */
 357                         if (st->global_error == 0)
 358                                 st->global_error = 1;
 359                 }
 360         }
 361         st->va += XEN_PAGE_SIZE * nr;
 362         st->index += nr / XEN_PFN_PER_PAGE;
 363
 364         return 0;
 365 }
 366
 367 static int mmap_return_error(int err, struct mmap_batch_state *st)
 368 {
 369         int ret;
 370
 371         if (st->version == 1) {
 372                 if (err) {
 373                         xen_pfn_t gfn;
 374
 375                         ret = get_user(gfn, st->user_gfn);
 376                         if (ret < 0)
 377                                 return ret;
 378                         /*
 379                          * V1 encodes the error codes in the 32bit top
 380                          * nibble of the gfn (with its known
 381                          * limitations vis-a-vis 64 bit callers).
 382                          */
 383                         gfn |= (err == -ENOENT) ?
 384                                 PRIVCMD_MMAPBATCH_PAGED_ERROR :
 385                                 PRIVCMD_MMAPBATCH_MFN_ERROR;
 386                         return __put_user(gfn, st->user_gfn++);
 387                 } else
 388                         st->user_gfn++;
 389         } else { /* st->version == 2 */
 390                 if (err)
 391                         return __put_user(err, st->user_err++);
 392                 else
 393                         st->user_err++;
 394         }
 395
 396         return 0;
 397 }
 398
 399 static int mmap_return_errors(void *data, int nr, void *state)
 400 {
 401         struct mmap_batch_state *st = state;
 402         int *errs = data;
 403         int i;
 404         int ret;
 405
 406         for (i = 0; i < nr; i++) {
 407                 ret = mmap_return_error(errs[i], st);
 408                 if (ret < 0)
 409                         return ret;
 410         }
 411         return 0;
 412 }
 413
 414 /* Allocate pfns that are then mapped with gfns from foreign domid. Update
 415  * the vma with the page info to use later.
 416  * Returns: 0 if success, otherwise -errno
 417  */
 418 static int alloc_empty_pages(struct vm_area_struct *vma, int numpgs)
 419 {
 420         int rc;
 421         struct page **pages;
 422
 423         pages = kvcalloc(numpgs, sizeof(pages[0]), GFP_KERNEL);
 424         if (pages == NULL)
 425                 return -ENOMEM;
 426
 427         rc = xen_alloc_unpopulated_pages(numpgs, pages);
 428         if (rc != 0) {
 429                 pr_warn("%s Could not alloc %d pfns rc:%d\n", __func__,
 430                         numpgs, rc);
 431                 kvfree(pages);
 432                 return -ENOMEM;
 433         }
 434         BUG_ON(vma->vm_private_data != NULL);
 435         vma->vm_private_data = pages;
 436
 437         return 0;
 438 }
 439
 440 static const struct vm_operations_struct privcmd_vm_ops;
 441
 442 static long privcmd_ioctl_mmap_batch(
 443         struct file *file, void __user *udata, int version)
 444 {
 445         struct privcmd_data *data = file->private_data;
 446         int ret;
 447         struct privcmd_mmapbatch_v2 m;
 448         struct mm_struct *mm = current->mm;
 449         struct vm_area_struct *vma;
 450         unsigned long nr_pages;
 451         LIST_HEAD(pagelist);
 452         struct mmap_batch_state state;
 453
 454         switch (version) {
 455         case 1:
 456                 if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch)))
 457                         return -EFAULT;
 458                 /* Returns per-frame error in m.arr. */
 459                 m.err = NULL;
 460                 if (!access_ok(m.arr, m.num * sizeof(*m.arr)))
 461                         return -EFAULT;
 462                 break;
 463         case 2:
 464                 if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch_v2)))
 465                         return -EFAULT;
 466                 /* Returns per-frame error code in m.err. */
 467                 if (!access_ok(m.err, m.num * (sizeof(*m.err))))
 468                         return -EFAULT;
 469                 break;
 470         default:
 471                 return -EINVAL;
 472         }
 473
 474         /* If restriction is in place, check the domid matches */
 475         if (data->domid != DOMID_INVALID && data->domid != m.dom)
 476                 return -EPERM;
 477
 478         nr_pages = DIV_ROUND_UP(m.num, XEN_PFN_PER_PAGE);
 479         if ((m.num <= 0) || (nr_pages > (LONG_MAX >> PAGE_SHIFT)))
 480                 return -EINVAL;
 481
 482         ret = gather_array(&pagelist, m.num, sizeof(xen_pfn_t), m.arr);
 483
 484         if (ret)
 485                 goto out;
 486         if (list_empty(&pagelist)) {
 487                 ret = -EINVAL;
 488                 goto out;
 489         }
 490
 491         if (version == 2) {
 492                 /* Zero error array now to only copy back actual errors. */
 493                 if (clear_user(m.err, sizeof(int) * m.num)) {
 494                         ret = -EFAULT;
 495                         goto out;
 496                 }
 497         }
 498
 499         mmap_write_lock(mm);
 500
 501         vma = find_vma(mm, m.addr);
 502         if (!vma ||
 503             vma->vm_ops != &privcmd_vm_ops) {
 504                 ret = -EINVAL;
 505                 goto out_unlock;
 506         }
 507
 508         /*
 509          * Caller must either:
 510          *
 511          * Map the whole VMA range, which will also allocate all the
 512          * pages required for the auto_translated_physmap case.
 513          *
 514          * Or
 515          *
 516          * Map unmapped holes left from a previous map attempt (e.g.,
 517          * because those foreign frames were previously paged out).
 518          */
 519         if (vma->vm_private_data == NULL) {
 520                 if (m.addr != vma->vm_start ||
 521                     m.addr + (nr_pages << PAGE_SHIFT) != vma->vm_end) {
 522                         ret = -EINVAL;
 523                         goto out_unlock;
 524                 }
 525                 if (xen_feature(XENFEAT_auto_translated_physmap)) {
 526                         ret = alloc_empty_pages(vma, nr_pages);
 527                         if (ret < 0)
 528                                 goto out_unlock;
 529                 } else
 530                         vma->vm_private_data = PRIV_VMA_LOCKED;
 531         } else {
 532                 if (m.addr < vma->vm_start ||
 533                     m.addr + (nr_pages << PAGE_SHIFT) > vma->vm_end) {
 534                         ret = -EINVAL;
 535                         goto out_unlock;
 536                 }
 537                 if (privcmd_vma_range_is_mapped(vma, m.addr, nr_pages)) {
 538                         ret = -EINVAL;
 539                         goto out_unlock;
 540                 }
 541         }
 542
 543         state.domain        = m.dom;
 544         state.vma           = vma;
 545         state.va            = m.addr;
 546         state.index         = 0;
 547         state.global_error  = 0;
 548         state.version       = version;
 549
 550         BUILD_BUG_ON(((PAGE_SIZE / sizeof(xen_pfn_t)) % XEN_PFN_PER_PAGE) != 0);
 551         /* mmap_batch_fn guarantees ret == 0 */
 552         BUG_ON(traverse_pages_block(m.num, sizeof(xen_pfn_t),
 553                                     &pagelist, mmap_batch_fn, &state));
 554
 555         mmap_write_unlock(mm);
 556
 557         if (state.global_error) {
 558                 /* Write back errors in second pass. */
 559                 state.user_gfn = (xen_pfn_t *)m.arr;
 560                 state.user_err = m.err;
 561                 ret = traverse_pages_block(m.num, sizeof(xen_pfn_t),
 562                                            &pagelist, mmap_return_errors, &state);
 563         } else
 564                 ret = 0;
 565
 566         /* If we have not had any EFAULT-like global errors then set the global
 567          * error to -ENOENT if necessary. */
 568         if ((ret == 0) && (state.global_error == -ENOENT))
 569                 ret = -ENOENT;
 570
 571 out:
 572         free_page_list(&pagelist);
 573         return ret;
 574
 575 out_unlock:
 576         mmap_write_unlock(mm);
 577         goto out;
 578 }
 579
 580 static int lock_pages(
 581         struct privcmd_dm_op_buf kbufs[], unsigned int num,
 582         struct page *pages[], unsigned int nr_pages, unsigned int *pinned)
 583 {
 584         unsigned int i, off = 0;
 585
 586         for (i = 0; i < num; ) {
 587                 unsigned int requested;
 588                 int page_count;
 589
 590                 requested = DIV_ROUND_UP(
 591                         offset_in_page(kbufs[i].uptr) + kbufs[i].size,
 592                         PAGE_SIZE) - off;
 593                 if (requested > nr_pages)
 594                         return -ENOSPC;
 595
 596                 page_count = pin_user_pages_fast(
 597                         (unsigned long)kbufs[i].uptr + off * PAGE_SIZE,
 598                         requested, FOLL_WRITE, pages);
 599                 if (page_count <= 0)
 600                         return page_count ? : -EFAULT;
 601
 602                 *pinned += page_count;
 603                 nr_pages -= page_count;
 604                 pages += page_count;
 605
 606                 off = (requested == page_count) ? 0 : off + page_count;
 607                 i += !off;
 608         }
 609
 610         return 0;
 611 }
 612
 613 static void unlock_pages(struct page *pages[], unsigned int nr_pages)
 614 {
 615         unpin_user_pages_dirty_lock(pages, nr_pages, true);
 616 }
 617
 618 static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
 619 {
 620         struct privcmd_data *data = file->private_data;
 621         struct privcmd_dm_op kdata;
 622         struct privcmd_dm_op_buf *kbufs;
 623         unsigned int nr_pages = 0;
 624         struct page **pages = NULL;
 625         struct xen_dm_op_buf *xbufs = NULL;
 626         unsigned int i;
 627         long rc;
 628         unsigned int pinned = 0;
 629
 630         if (copy_from_user(&kdata, udata, sizeof(kdata)))
 631                 return -EFAULT;
 632
 633         /* If restriction is in place, check the domid matches */
 634         if (data->domid != DOMID_INVALID && data->domid != kdata.dom)
 635                 return -EPERM;
 636
 637         if (kdata.num == 0)
 638                 return 0;
 639
 640         if (kdata.num > privcmd_dm_op_max_num)
 641                 return -E2BIG;
 642
 643         kbufs = kcalloc(kdata.num, sizeof(*kbufs), GFP_KERNEL);
 644         if (!kbufs)
 645                 return -ENOMEM;
 646
 647         if (copy_from_user(kbufs, kdata.ubufs,
 648                            sizeof(*kbufs) * kdata.num)) {
 649                 rc = -EFAULT;
 650                 goto out;
 651         }
 652
 653         for (i = 0; i < kdata.num; i++) {
 654                 if (kbufs[i].size > privcmd_dm_op_buf_max_size) {
 655                         rc = -E2BIG;
 656                         goto out;
 657                 }
 658
 659                 if (!access_ok(kbufs[i].uptr,
 660                                kbufs[i].size)) {
 661                         rc = -EFAULT;
 662                         goto out;
 663                 }
 664
 665                 nr_pages += DIV_ROUND_UP(
 666                         offset_in_page(kbufs[i].uptr) + kbufs[i].size,
 667                         PAGE_SIZE);
 668         }
 669
 670         pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
 671         if (!pages) {
 672                 rc = -ENOMEM;
 673                 goto out;
 674         }
 675
 676         xbufs = kcalloc(kdata.num, sizeof(*xbufs), GFP_KERNEL);
 677         if (!xbufs) {
 678                 rc = -ENOMEM;
 679                 goto out;
 680         }
 681
 682         rc = lock_pages(kbufs, kdata.num, pages, nr_pages, &pinned);
 683         if (rc < 0)
 684                 goto out;
 685
 686         for (i = 0; i < kdata.num; i++) {
 687                 set_xen_guest_handle(xbufs[i].h, kbufs[i].uptr);
 688                 xbufs[i].size = kbufs[i].size;
 689         }
 690
 691         xen_preemptible_hcall_begin();
 692         rc = HYPERVISOR_dm_op(kdata.dom, kdata.num, xbufs);
 693         xen_preemptible_hcall_end();
 694
 695 out:
 696         unlock_pages(pages, pinned);
 697         kfree(xbufs);
 698         kfree(pages);
 699         kfree(kbufs);
 700
 701         return rc;
 702 }
 703
 704 static long privcmd_ioctl_restrict(struct file *file, void __user *udata)
 705 {
 706         struct privcmd_data *data = file->private_data;
 707         domid_t dom;
 708
 709         if (copy_from_user(&dom, udata, sizeof(dom)))
 710                 return -EFAULT;
 711
 712         /* Set restriction to the specified domain, or check it matches */
 713         if (data->domid == DOMID_INVALID)
 714                 data->domid = dom;
 715         else if (data->domid != dom)
 716                 return -EINVAL;
 717
 718         return 0;
 719 }
 720
 721 static long privcmd_ioctl_mmap_resource(struct file *file,
 722                                 struct privcmd_mmap_resource __user *udata)
 723 {
 724         struct privcmd_data *data = file->private_data;
 725         struct mm_struct *mm = current->mm;
 726         struct vm_area_struct *vma;
 727         struct privcmd_mmap_resource kdata;
 728         xen_pfn_t *pfns = NULL;
 729         struct xen_mem_acquire_resource xdata = { };
 730         int rc;
 731
 732         if (copy_from_user(&kdata, udata, sizeof(kdata)))
 733                 return -EFAULT;
 734
 735         /* If restriction is in place, check the domid matches */
 736         if (data->domid != DOMID_INVALID && data->domid != kdata.dom)
 737                 return -EPERM;
 738
 739         /* Both fields must be set or unset */
 740         if (!!kdata.addr != !!kdata.num)
 741                 return -EINVAL;
 742
 743         xdata.domid = kdata.dom;
 744         xdata.type = kdata.type;
 745         xdata.id = kdata.id;
 746
 747         if (!kdata.addr && !kdata.num) {
 748                 /* Query the size of the resource. */
 749                 rc = HYPERVISOR_memory_op(XENMEM_acquire_resource, &xdata);
 750                 if (rc)
 751                         return rc;
 752                 return __put_user(xdata.nr_frames, &udata->num);
 753         }
 754
 755         mmap_write_lock(mm);
 756
 757         vma = find_vma(mm, kdata.addr);
 758         if (!vma || vma->vm_ops != &privcmd_vm_ops) {
 759                 rc = -EINVAL;
 760                 goto out;
 761         }
 762
 763         pfns = kcalloc(kdata.num, sizeof(*pfns), GFP_KERNEL | __GFP_NOWARN);
 764         if (!pfns) {
 765                 rc = -ENOMEM;
 766                 goto out;
 767         }
 768
 769         if (IS_ENABLED(CONFIG_XEN_AUTO_XLATE) &&
 770             xen_feature(XENFEAT_auto_translated_physmap)) {
 771                 unsigned int nr = DIV_ROUND_UP(kdata.num, XEN_PFN_PER_PAGE);
 772                 struct page **pages;
 773                 unsigned int i;
 774
 775                 rc = alloc_empty_pages(vma, nr);
 776                 if (rc < 0)
 777                         goto out;
 778
 779                 pages = vma->vm_private_data;
 780                 for (i = 0; i < kdata.num; i++) {
 781                         xen_pfn_t pfn =
 782                                 page_to_xen_pfn(pages[i / XEN_PFN_PER_PAGE]);
 783
 784                         pfns[i] = pfn + (i % XEN_PFN_PER_PAGE);
 785                 }
 786         } else
 787                 vma->vm_private_data = PRIV_VMA_LOCKED;
 788
 789         xdata.frame = kdata.idx;
 790         xdata.nr_frames = kdata.num;
 791         set_xen_guest_handle(xdata.frame_list, pfns);
 792
 793         xen_preemptible_hcall_begin();
 794         rc = HYPERVISOR_memory_op(XENMEM_acquire_resource, &xdata);
 795         xen_preemptible_hcall_end();
 796
 797         if (rc)
 798                 goto out;
 799
 800         if (IS_ENABLED(CONFIG_XEN_AUTO_XLATE) &&
 801             xen_feature(XENFEAT_auto_translated_physmap)) {
 802                 rc = xen_remap_vma_range(vma, kdata.addr, kdata.num << PAGE_SHIFT);
 803         } else {
 804                 unsigned int domid =
 805                         (xdata.flags & XENMEM_rsrc_acq_caller_owned) ?
 806                         DOMID_SELF : kdata.dom;
 807                 int num, *errs = (int *)pfns;
 808
 809                 BUILD_BUG_ON(sizeof(*errs) > sizeof(*pfns));
 810                 num = xen_remap_domain_mfn_array(vma,
 811                                                  kdata.addr & PAGE_MASK,
 812                                                  pfns, kdata.num, errs,
 813                                                  vma->vm_page_prot,
 814                                                  domid);
 815                 if (num < 0)
 816                         rc = num;
 817                 else if (num != kdata.num) {
 818                         unsigned int i;
 819
 820                         for (i = 0; i < num; i++) {
 821                                 rc = errs[i];
 822                                 if (rc < 0)
 823                                         break;
 824                         }
 825                 } else
 826                         rc = 0;
 827         }
 828
 829 out:
 830         mmap_write_unlock(mm);
 831         kfree(pfns);
 832
 833         return rc;
 834 }
 835
 836 static long privcmd_ioctl(struct file *file,
 837                           unsigned int cmd, unsigned long data)
 838 {
 839         int ret = -ENOTTY;
 840         void __user *udata = (void __user *) data;
 841
 842         switch (cmd) {
 843         case IOCTL_PRIVCMD_HYPERCALL:
 844                 ret = privcmd_ioctl_hypercall(file, udata);
 845                 break;
 846
 847         case IOCTL_PRIVCMD_MMAP:
 848                 ret = privcmd_ioctl_mmap(file, udata);
 849                 break;
 850
 851         case IOCTL_PRIVCMD_MMAPBATCH:
 852                 ret = privcmd_ioctl_mmap_batch(file, udata, 1);
 853                 break;
 854
 855         case IOCTL_PRIVCMD_MMAPBATCH_V2:
 856                 ret = privcmd_ioctl_mmap_batch(file, udata, 2);
 857                 break;
 858
 859         case IOCTL_PRIVCMD_DM_OP:
 860                 ret = privcmd_ioctl_dm_op(file, udata);
 861                 break;
 862
 863         case IOCTL_PRIVCMD_RESTRICT:
 864                 ret = privcmd_ioctl_restrict(file, udata);
 865                 break;
 866
 867         case IOCTL_PRIVCMD_MMAP_RESOURCE:
 868                 ret = privcmd_ioctl_mmap_resource(file, udata);
 869                 break;
 870
 871         default:
 872                 break;
 873         }
 874
 875         return ret;
 876 }
 877
 878 static int privcmd_open(struct inode *ino, struct file *file)
 879 {
 880         struct privcmd_data *data = kzalloc(sizeof(*data), GFP_KERNEL);
 881
 882         if (!data)
 883                 return -ENOMEM;
 884
 885         /* DOMID_INVALID implies no restriction */
 886         data->domid = DOMID_INVALID;
 887
 888         file->private_data = data;
 889         return 0;
 890 }
 891
 892 static int privcmd_release(struct inode *ino, struct file *file)
 893 {
 894         struct privcmd_data *data = file->private_data;
 895
 896         kfree(data);
 897         return 0;
 898 }
 899
 900 static void privcmd_close(struct vm_area_struct *vma)
 901 {
 902         struct page **pages = vma->vm_private_data;
 903         int numpgs = vma_pages(vma);
 904         int numgfns = (vma->vm_end - vma->vm_start) >> XEN_PAGE_SHIFT;
 905         int rc;
 906
 907         if (!xen_feature(XENFEAT_auto_translated_physmap) || !numpgs || !pages)
 908                 return;
 909
 910         rc = xen_unmap_domain_gfn_range(vma, numgfns, pages);
 911         if (rc == 0)
 912                 xen_free_unpopulated_pages(numpgs, pages);
 913         else
 914                 pr_crit("unable to unmap MFN range: leaking %d pages. rc=%d\n",
 915                         numpgs, rc);
 916         kvfree(pages);
 917 }
 918
 919 static vm_fault_t privcmd_fault(struct vm_fault *vmf)
 920 {
 921         printk(KERN_DEBUG "privcmd_fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n",
 922                vmf->vma, vmf->vma->vm_start, vmf->vma->vm_end,
 923                vmf->pgoff, (void *)vmf->address);
 924
 925         return VM_FAULT_SIGBUS;
 926 }
 927
 928 static const struct vm_operations_struct privcmd_vm_ops = {
 929         .close = privcmd_close,
 930         .fault = privcmd_fault
 931 };
 932
 933 static int privcmd_mmap(struct file *file, struct vm_area_struct *vma)
 934 {
 935         /* DONTCOPY is essential for Xen because copy_page_range doesn't know
 936          * how to recreate these mappings */
 937         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTCOPY |
 938                          VM_DONTEXPAND | VM_DONTDUMP;
 939         vma->vm_ops = &privcmd_vm_ops;
 940         vma->vm_private_data = NULL;
 941
 942         return 0;
 943 }
 944
 945 /*
 946  * For MMAPBATCH*. This allows asserting the singleshot mapping
 947  * on a per pfn/pte basis. Mapping calls that fail with ENOENT
 948  * can be then retried until success.
 949  */
 950 static int is_mapped_fn(pte_t *pte, unsigned long addr, void *data)
 951 {
 952         return pte_none(*pte) ? 0 : -EBUSY;
 953 }
 954
 955 static int privcmd_vma_range_is_mapped(
 956                    struct vm_area_struct *vma,
 957                    unsigned long addr,
 958                    unsigned long nr_pages)
 959 {
 960         return apply_to_page_range(vma->vm_mm, addr, nr_pages << PAGE_SHIFT,
 961                                    is_mapped_fn, NULL) != 0;
 962 }
 963
 964 const struct file_operations xen_privcmd_fops = {
 965         .owner = THIS_MODULE,
 966         .unlocked_ioctl = privcmd_ioctl,
 967         .open = privcmd_open,
 968         .release = privcmd_release,
 969         .mmap = privcmd_mmap,
 970 };
 971 EXPORT_SYMBOL_GPL(xen_privcmd_fops);
 972
 973 static struct miscdevice privcmd_dev = {
 974         .minor = MISC_DYNAMIC_MINOR,
 975         .name = "xen/privcmd",
 976         .fops = &xen_privcmd_fops,
 977 };
 978
 979 static int __init privcmd_init(void)
 980 {
 981         int err;
 982
 983         if (!xen_domain())
 984                 return -ENODEV;
 985
 986         err = misc_register(&privcmd_dev);
 987         if (err != 0) {
 988                 pr_err("Could not register Xen privcmd device\n");
 989                 return err;
 990         }
 991
 992         err = misc_register(&xen_privcmdbuf_dev);
 993         if (err != 0) {
 994                 pr_err("Could not register Xen hypercall-buf device\n");
 995                 misc_deregister(&privcmd_dev);
 996                 return err;
 997         }
 998
 999         return 0;
1000 }
1001
1002 static void __exit privcmd_exit(void)
1003 {
1004         misc_deregister(&privcmd_dev);
1005         misc_deregister(&xen_privcmdbuf_dev);
1006 }
1007
1008 module_init(privcmd_init);
1009 module_exit(privcmd_exit);