drivers/xen/privcmd.c

   1 /******************************************************************************
   2  * privcmd.c
   3  *
   4  * Interface to privileged domain-0 commands.
   5  *
   6  * Copyright (c) 2002-2004, K A Fraser, B Dragovic
   7  */
   8
   9 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/sched.h>
  14 #include <linux/slab.h>
  15 #include <linux/string.h>
  16 #include <linux/errno.h>
  17 #include <linux/mm.h>
  18 #include <linux/mman.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/swap.h>
  21 #include <linux/highmem.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/seq_file.h>
  24 #include <linux/miscdevice.h>
  25
  26 #include <asm/pgalloc.h>
  27 #include <asm/pgtable.h>
  28 #include <asm/tlb.h>
  29 #include <asm/xen/hypervisor.h>
  30 #include <asm/xen/hypercall.h>
  31
  32 #include <xen/xen.h>
  33 #include <xen/privcmd.h>
  34 #include <xen/interface/xen.h>
  35 #include <xen/features.h>
  36 #include <xen/page.h>
  37 #include <xen/xen-ops.h>
  38 #include <xen/balloon.h>
  39
  40 #include "privcmd.h"
  41
  42 MODULE_LICENSE("GPL");
  43
  44 #define PRIV_VMA_LOCKED ((void *)1)
  45
  46 static int privcmd_vma_range_is_mapped(
  47                struct vm_area_struct *vma,
  48                unsigned long addr,
  49                unsigned long nr_pages);
  50
  51 static long privcmd_ioctl_hypercall(void __user *udata)
  52 {
  53         struct privcmd_hypercall hypercall;
  54         long ret;
  55
  56         if (copy_from_user(&hypercall, udata, sizeof(hypercall)))
  57                 return -EFAULT;
  58
  59         xen_preemptible_hcall_begin();
  60         ret = privcmd_call(hypercall.op,
  61                            hypercall.arg[0], hypercall.arg[1],
  62                            hypercall.arg[2], hypercall.arg[3],
  63                            hypercall.arg[4]);
  64         xen_preemptible_hcall_end();
  65
  66         return ret;
  67 }
  68
  69 static void free_page_list(struct list_head *pages)
  70 {
  71         struct page *p, *n;
  72
  73         list_for_each_entry_safe(p, n, pages, lru)
  74                 __free_page(p);
  75
  76         INIT_LIST_HEAD(pages);
  77 }
  78
  79 /*
  80  * Given an array of items in userspace, return a list of pages
  81  * containing the data.  If copying fails, either because of memory
  82  * allocation failure or a problem reading user memory, return an
  83  * error code; its up to the caller to dispose of any partial list.
  84  */
  85 static int gather_array(struct list_head *pagelist,
  86                         unsigned nelem, size_t size,
  87                         const void __user *data)
  88 {
  89         unsigned pageidx;
  90         void *pagedata;
  91         int ret;
  92
  93         if (size > PAGE_SIZE)
  94                 return 0;
  95
  96         pageidx = PAGE_SIZE;
  97         pagedata = NULL;        /* quiet, gcc */
  98         while (nelem--) {
  99                 if (pageidx > PAGE_SIZE-size) {
 100                         struct page *page = alloc_page(GFP_KERNEL);
 101
 102                         ret = -ENOMEM;
 103                         if (page == NULL)
 104                                 goto fail;
 105
 106                         pagedata = page_address(page);
 107
 108                         list_add_tail(&page->lru, pagelist);
 109                         pageidx = 0;
 110                 }
 111
 112                 ret = -EFAULT;
 113                 if (copy_from_user(pagedata + pageidx, data, size))
 114                         goto fail;
 115
 116                 data += size;
 117                 pageidx += size;
 118         }
 119
 120         ret = 0;
 121
 122 fail:
 123         return ret;
 124 }
 125
 126 /*
 127  * Call function "fn" on each element of the array fragmented
 128  * over a list of pages.
 129  */
 130 static int traverse_pages(unsigned nelem, size_t size,
 131                           struct list_head *pos,
 132                           int (*fn)(void *data, void *state),
 133                           void *state)
 134 {
 135         void *pagedata;
 136         unsigned pageidx;
 137         int ret = 0;
 138
 139         BUG_ON(size > PAGE_SIZE);
 140
 141         pageidx = PAGE_SIZE;
 142         pagedata = NULL;        /* hush, gcc */
 143
 144         while (nelem--) {
 145                 if (pageidx > PAGE_SIZE-size) {
 146                         struct page *page;
 147                         pos = pos->next;
 148                         page = list_entry(pos, struct page, lru);
 149                         pagedata = page_address(page);
 150                         pageidx = 0;
 151                 }
 152
 153                 ret = (*fn)(pagedata + pageidx, state);
 154                 if (ret)
 155                         break;
 156                 pageidx += size;
 157         }
 158
 159         return ret;
 160 }
 161
 162 /*
 163  * Similar to traverse_pages, but use each page as a "block" of
 164  * data to be processed as one unit.
 165  */
 166 static int traverse_pages_block(unsigned nelem, size_t size,
 167                                 struct list_head *pos,
 168                                 int (*fn)(void *data, int nr, void *state),
 169                                 void *state)
 170 {
 171         void *pagedata;
 172         unsigned pageidx;
 173         int ret = 0;
 174
 175         BUG_ON(size > PAGE_SIZE);
 176
 177         pageidx = PAGE_SIZE;
 178
 179         while (nelem) {
 180                 int nr = (PAGE_SIZE/size);
 181                 struct page *page;
 182                 if (nr > nelem)
 183                         nr = nelem;
 184                 pos = pos->next;
 185                 page = list_entry(pos, struct page, lru);
 186                 pagedata = page_address(page);
 187                 ret = (*fn)(pagedata, nr, state);
 188                 if (ret)
 189                         break;
 190                 nelem -= nr;
 191         }
 192
 193         return ret;
 194 }
 195
 196 struct mmap_gfn_state {
 197         unsigned long va;
 198         struct vm_area_struct *vma;
 199         domid_t domain;
 200 };
 201
 202 static int mmap_gfn_range(void *data, void *state)
 203 {
 204         struct privcmd_mmap_entry *msg = data;
 205         struct mmap_gfn_state *st = state;
 206         struct vm_area_struct *vma = st->vma;
 207         int rc;
 208
 209         /* Do not allow range to wrap the address space. */
 210         if ((msg->npages > (LONG_MAX >> PAGE_SHIFT)) ||
 211             ((unsigned long)(msg->npages << PAGE_SHIFT) >= -st->va))
 212                 return -EINVAL;
 213
 214         /* Range chunks must be contiguous in va space. */
 215         if ((msg->va != st->va) ||
 216             ((msg->va+(msg->npages<<PAGE_SHIFT)) > vma->vm_end))
 217                 return -EINVAL;
 218
 219         rc = xen_remap_domain_gfn_range(vma,
 220                                         msg->va & PAGE_MASK,
 221                                         msg->mfn, msg->npages,
 222                                         vma->vm_page_prot,
 223                                         st->domain, NULL);
 224         if (rc < 0)
 225                 return rc;
 226
 227         st->va += msg->npages << PAGE_SHIFT;
 228
 229         return 0;
 230 }
 231
 232 static long privcmd_ioctl_mmap(void __user *udata)
 233 {
 234         struct privcmd_mmap mmapcmd;
 235         struct mm_struct *mm = current->mm;
 236         struct vm_area_struct *vma;
 237         int rc;
 238         LIST_HEAD(pagelist);
 239         struct mmap_gfn_state state;
 240
 241         /* We only support privcmd_ioctl_mmap_batch for auto translated. */
 242         if (xen_feature(XENFEAT_auto_translated_physmap))
 243                 return -ENOSYS;
 244
 245         if (copy_from_user(&mmapcmd, udata, sizeof(mmapcmd)))
 246                 return -EFAULT;
 247
 248         rc = gather_array(&pagelist,
 249                           mmapcmd.num, sizeof(struct privcmd_mmap_entry),
 250                           mmapcmd.entry);
 251
 252         if (rc || list_empty(&pagelist))
 253                 goto out;
 254
 255         down_write(&mm->mmap_sem);
 256
 257         {
 258                 struct page *page = list_first_entry(&pagelist,
 259                                                      struct page, lru);
 260                 struct privcmd_mmap_entry *msg = page_address(page);
 261
 262                 vma = find_vma(mm, msg->va);
 263                 rc = -EINVAL;
 264
 265                 if (!vma || (msg->va != vma->vm_start) || vma->vm_private_data)
 266                         goto out_up;
 267                 vma->vm_private_data = PRIV_VMA_LOCKED;
 268         }
 269
 270         state.va = vma->vm_start;
 271         state.vma = vma;
 272         state.domain = mmapcmd.dom;
 273
 274         rc = traverse_pages(mmapcmd.num, sizeof(struct privcmd_mmap_entry),
 275                             &pagelist,
 276                             mmap_gfn_range, &state);
 277
 278
 279 out_up:
 280         up_write(&mm->mmap_sem);
 281
 282 out:
 283         free_page_list(&pagelist);
 284
 285         return rc;
 286 }
 287
 288 struct mmap_batch_state {
 289         domid_t domain;
 290         unsigned long va;
 291         struct vm_area_struct *vma;
 292         int index;
 293         /* A tristate:
 294          *      0 for no errors
 295          *      1 if at least one error has happened (and no
 296          *          -ENOENT errors have happened)
 297          *      -ENOENT if at least 1 -ENOENT has happened.
 298          */
 299         int global_error;
 300         int version;
 301
 302         /* User-space gfn array to store errors in the second pass for V1. */
 303         xen_pfn_t __user *user_gfn;
 304         /* User-space int array to store errors in the second pass for V2. */
 305         int __user *user_err;
 306 };
 307
 308 /* auto translated dom0 note: if domU being created is PV, then gfn is
 309  * mfn(addr on bus). If it's auto xlated, then gfn is pfn (input to HAP).
 310  */
 311 static int mmap_batch_fn(void *data, int nr, void *state)
 312 {
 313         xen_pfn_t *gfnp = data;
 314         struct mmap_batch_state *st = state;
 315         struct vm_area_struct *vma = st->vma;
 316         struct page **pages = vma->vm_private_data;
 317         struct page **cur_pages = NULL;
 318         int ret;
 319
 320         if (xen_feature(XENFEAT_auto_translated_physmap))
 321                 cur_pages = &pages[st->index];
 322
 323         BUG_ON(nr < 0);
 324         ret = xen_remap_domain_gfn_array(st->vma, st->va & PAGE_MASK, gfnp, nr,
 325                                          (int *)gfnp, st->vma->vm_page_prot,
 326                                          st->domain, cur_pages);
 327
 328         /* Adjust the global_error? */
 329         if (ret != nr) {
 330                 if (ret == -ENOENT)
 331                         st->global_error = -ENOENT;
 332                 else {
 333                         /* Record that at least one error has happened. */
 334                         if (st->global_error == 0)
 335                                 st->global_error = 1;
 336                 }
 337         }
 338         st->va += PAGE_SIZE * nr;
 339         st->index += nr;
 340
 341         return 0;
 342 }
 343
 344 static int mmap_return_error(int err, struct mmap_batch_state *st)
 345 {
 346         int ret;
 347
 348         if (st->version == 1) {
 349                 if (err) {
 350                         xen_pfn_t gfn;
 351
 352                         ret = get_user(gfn, st->user_gfn);
 353                         if (ret < 0)
 354                                 return ret;
 355                         /*
 356                          * V1 encodes the error codes in the 32bit top
 357                          * nibble of the gfn (with its known
 358                          * limitations vis-a-vis 64 bit callers).
 359                          */
 360                         gfn |= (err == -ENOENT) ?
 361                                 PRIVCMD_MMAPBATCH_PAGED_ERROR :
 362                                 PRIVCMD_MMAPBATCH_MFN_ERROR;
 363                         return __put_user(gfn, st->user_gfn++);
 364                 } else
 365                         st->user_gfn++;
 366         } else { /* st->version == 2 */
 367                 if (err)
 368                         return __put_user(err, st->user_err++);
 369                 else
 370                         st->user_err++;
 371         }
 372
 373         return 0;
 374 }
 375
 376 static int mmap_return_errors(void *data, int nr, void *state)
 377 {
 378         struct mmap_batch_state *st = state;
 379         int *errs = data;
 380         int i;
 381         int ret;
 382
 383         for (i = 0; i < nr; i++) {
 384                 ret = mmap_return_error(errs[i], st);
 385                 if (ret < 0)
 386                         return ret;
 387         }
 388         return 0;
 389 }
 390
 391 /* Allocate pfns that are then mapped with gfns from foreign domid. Update
 392  * the vma with the page info to use later.
 393  * Returns: 0 if success, otherwise -errno
 394  */
 395 static int alloc_empty_pages(struct vm_area_struct *vma, int numpgs)
 396 {
 397         int rc;
 398         struct page **pages;
 399
 400         pages = kcalloc(numpgs, sizeof(pages[0]), GFP_KERNEL);
 401         if (pages == NULL)
 402                 return -ENOMEM;
 403
 404         rc = alloc_xenballooned_pages(numpgs, pages);
 405         if (rc != 0) {
 406                 pr_warn("%s Could not alloc %d pfns rc:%d\n", __func__,
 407                         numpgs, rc);
 408                 kfree(pages);
 409                 return -ENOMEM;
 410         }
 411         BUG_ON(vma->vm_private_data != NULL);
 412         vma->vm_private_data = pages;
 413
 414         return 0;
 415 }
 416
 417 static const struct vm_operations_struct privcmd_vm_ops;
 418
 419 static long privcmd_ioctl_mmap_batch(void __user *udata, int version)
 420 {
 421         int ret;
 422         struct privcmd_mmapbatch_v2 m;
 423         struct mm_struct *mm = current->mm;
 424         struct vm_area_struct *vma;
 425         unsigned long nr_pages;
 426         LIST_HEAD(pagelist);
 427         struct mmap_batch_state state;
 428
 429         switch (version) {
 430         case 1:
 431                 if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch)))
 432                         return -EFAULT;
 433                 /* Returns per-frame error in m.arr. */
 434                 m.err = NULL;
 435                 if (!access_ok(VERIFY_WRITE, m.arr, m.num * sizeof(*m.arr)))
 436                         return -EFAULT;
 437                 break;
 438         case 2:
 439                 if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch_v2)))
 440                         return -EFAULT;
 441                 /* Returns per-frame error code in m.err. */
 442                 if (!access_ok(VERIFY_WRITE, m.err, m.num * (sizeof(*m.err))))
 443                         return -EFAULT;
 444                 break;
 445         default:
 446                 return -EINVAL;
 447         }
 448
 449         nr_pages = DIV_ROUND_UP(m.num, XEN_PFN_PER_PAGE);
 450         if ((m.num <= 0) || (nr_pages > (LONG_MAX >> PAGE_SHIFT)))
 451                 return -EINVAL;
 452
 453         ret = gather_array(&pagelist, m.num, sizeof(xen_pfn_t), m.arr);
 454
 455         if (ret)
 456                 goto out;
 457         if (list_empty(&pagelist)) {
 458                 ret = -EINVAL;
 459                 goto out;
 460         }
 461
 462         if (version == 2) {
 463                 /* Zero error array now to only copy back actual errors. */
 464                 if (clear_user(m.err, sizeof(int) * m.num)) {
 465                         ret = -EFAULT;
 466                         goto out;
 467                 }
 468         }
 469
 470         down_write(&mm->mmap_sem);
 471
 472         vma = find_vma(mm, m.addr);
 473         if (!vma ||
 474             vma->vm_ops != &privcmd_vm_ops) {
 475                 ret = -EINVAL;
 476                 goto out_unlock;
 477         }
 478
 479         /*
 480          * Caller must either:
 481          *
 482          * Map the whole VMA range, which will also allocate all the
 483          * pages required for the auto_translated_physmap case.
 484          *
 485          * Or
 486          *
 487          * Map unmapped holes left from a previous map attempt (e.g.,
 488          * because those foreign frames were previously paged out).
 489          */
 490         if (vma->vm_private_data == NULL) {
 491                 if (m.addr != vma->vm_start ||
 492                     m.addr + (nr_pages << PAGE_SHIFT) != vma->vm_end) {
 493                         ret = -EINVAL;
 494                         goto out_unlock;
 495                 }
 496                 if (xen_feature(XENFEAT_auto_translated_physmap)) {
 497                         ret = alloc_empty_pages(vma, nr_pages);
 498                         if (ret < 0)
 499                                 goto out_unlock;
 500                 } else
 501                         vma->vm_private_data = PRIV_VMA_LOCKED;
 502         } else {
 503                 if (m.addr < vma->vm_start ||
 504                     m.addr + (nr_pages << PAGE_SHIFT) > vma->vm_end) {
 505                         ret = -EINVAL;
 506                         goto out_unlock;
 507                 }
 508                 if (privcmd_vma_range_is_mapped(vma, m.addr, nr_pages)) {
 509                         ret = -EINVAL;
 510                         goto out_unlock;
 511                 }
 512         }
 513
 514         state.domain        = m.dom;
 515         state.vma           = vma;
 516         state.va            = m.addr;
 517         state.index         = 0;
 518         state.global_error  = 0;
 519         state.version       = version;
 520
 521         BUILD_BUG_ON(((PAGE_SIZE / sizeof(xen_pfn_t)) % XEN_PFN_PER_PAGE) != 0);
 522         /* mmap_batch_fn guarantees ret == 0 */
 523         BUG_ON(traverse_pages_block(m.num, sizeof(xen_pfn_t),
 524                                     &pagelist, mmap_batch_fn, &state));
 525
 526         up_write(&mm->mmap_sem);
 527
 528         if (state.global_error) {
 529                 /* Write back errors in second pass. */
 530                 state.user_gfn = (xen_pfn_t *)m.arr;
 531                 state.user_err = m.err;
 532                 ret = traverse_pages_block(m.num, sizeof(xen_pfn_t),
 533                                            &pagelist, mmap_return_errors, &state);
 534         } else
 535                 ret = 0;
 536
 537         /* If we have not had any EFAULT-like global errors then set the global
 538          * error to -ENOENT if necessary. */
 539         if ((ret == 0) && (state.global_error == -ENOENT))
 540                 ret = -ENOENT;
 541
 542 out:
 543         free_page_list(&pagelist);
 544         return ret;
 545
 546 out_unlock:
 547         up_write(&mm->mmap_sem);
 548         goto out;
 549 }
 550
 551 static long privcmd_ioctl(struct file *file,
 552                           unsigned int cmd, unsigned long data)
 553 {
 554         int ret = -ENOSYS;
 555         void __user *udata = (void __user *) data;
 556
 557         switch (cmd) {
 558         case IOCTL_PRIVCMD_HYPERCALL:
 559                 ret = privcmd_ioctl_hypercall(udata);
 560                 break;
 561
 562         case IOCTL_PRIVCMD_MMAP:
 563                 ret = privcmd_ioctl_mmap(udata);
 564                 break;
 565
 566         case IOCTL_PRIVCMD_MMAPBATCH:
 567                 ret = privcmd_ioctl_mmap_batch(udata, 1);
 568                 break;
 569
 570         case IOCTL_PRIVCMD_MMAPBATCH_V2:
 571                 ret = privcmd_ioctl_mmap_batch(udata, 2);
 572                 break;
 573
 574         default:
 575                 ret = -EINVAL;
 576                 break;
 577         }
 578
 579         return ret;
 580 }
 581
 582 static void privcmd_close(struct vm_area_struct *vma)
 583 {
 584         struct page **pages = vma->vm_private_data;
 585         int numpgs = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 586         int numgfns = (vma->vm_end - vma->vm_start) >> XEN_PAGE_SHIFT;
 587         int rc;
 588
 589         if (!xen_feature(XENFEAT_auto_translated_physmap) || !numpgs || !pages)
 590                 return;
 591
 592         rc = xen_unmap_domain_gfn_range(vma, numgfns, pages);
 593         if (rc == 0)
 594                 free_xenballooned_pages(numpgs, pages);
 595         else
 596                 pr_crit("unable to unmap MFN range: leaking %d pages. rc=%d\n",
 597                         numpgs, rc);
 598         kfree(pages);
 599 }
 600
 601 static int privcmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 602 {
 603         printk(KERN_DEBUG "privcmd_fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n",
 604                vma, vma->vm_start, vma->vm_end,
 605                vmf->pgoff, vmf->virtual_address);
 606
 607         return VM_FAULT_SIGBUS;
 608 }
 609
 610 static const struct vm_operations_struct privcmd_vm_ops = {
 611         .close = privcmd_close,
 612         .fault = privcmd_fault
 613 };
 614
 615 static int privcmd_mmap(struct file *file, struct vm_area_struct *vma)
 616 {
 617         /* DONTCOPY is essential for Xen because copy_page_range doesn't know
 618          * how to recreate these mappings */
 619         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTCOPY |
 620                          VM_DONTEXPAND | VM_DONTDUMP;
 621         vma->vm_ops = &privcmd_vm_ops;
 622         vma->vm_private_data = NULL;
 623
 624         return 0;
 625 }
 626
 627 /*
 628  * For MMAPBATCH*. This allows asserting the singleshot mapping
 629  * on a per pfn/pte basis. Mapping calls that fail with ENOENT
 630  * can be then retried until success.
 631  */
 632 static int is_mapped_fn(pte_t *pte, struct page *pmd_page,
 633                         unsigned long addr, void *data)
 634 {
 635         return pte_none(*pte) ? 0 : -EBUSY;
 636 }
 637
 638 static int privcmd_vma_range_is_mapped(
 639                    struct vm_area_struct *vma,
 640                    unsigned long addr,
 641                    unsigned long nr_pages)
 642 {
 643         return apply_to_page_range(vma->vm_mm, addr, nr_pages << PAGE_SHIFT,
 644                                    is_mapped_fn, NULL) != 0;
 645 }
 646
 647 const struct file_operations xen_privcmd_fops = {
 648         .owner = THIS_MODULE,
 649         .unlocked_ioctl = privcmd_ioctl,
 650         .mmap = privcmd_mmap,
 651 };
 652 EXPORT_SYMBOL_GPL(xen_privcmd_fops);
 653
 654 static struct miscdevice privcmd_dev = {
 655         .minor = MISC_DYNAMIC_MINOR,
 656         .name = "xen/privcmd",
 657         .fops = &xen_privcmd_fops,
 658 };
 659
 660 static int __init privcmd_init(void)
 661 {
 662         int err;
 663
 664         if (!xen_domain())
 665                 return -ENODEV;
 666
 667         err = misc_register(&privcmd_dev);
 668         if (err != 0) {
 669                 pr_err("Could not register Xen privcmd device\n");
 670                 return err;
 671         }
 672         return 0;
 673 }
 674
 675 static void __exit privcmd_exit(void)
 676 {
 677         misc_deregister(&privcmd_dev);
 678 }
 679
 680 module_init(privcmd_init);
 681 module_exit(privcmd_exit);