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