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 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/sched.h>
  12 #include <linux/slab.h>
  13 #include <linux/string.h>
  14 #include <linux/errno.h>
  15 #include <linux/mm.h>
  16 #include <linux/mman.h>
  17 #include <linux/uaccess.h>
  18 #include <linux/swap.h>
  19 #include <linux/highmem.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/seq_file.h>
  22 #include <linux/miscdevice.h>
  23
  24 #include <asm/pgalloc.h>
  25 #include <asm/pgtable.h>
  26 #include <asm/tlb.h>
  27 #include <asm/xen/hypervisor.h>
  28 #include <asm/xen/hypercall.h>
  29
  30 #include <xen/xen.h>
  31 #include <xen/privcmd.h>
  32 #include <xen/interface/xen.h>
  33 #include <xen/features.h>
  34 #include <xen/page.h>
  35 #include <xen/xen-ops.h>
  36
  37 #include "privcmd.h"
  38
  39 MODULE_LICENSE("GPL");
  40
  41 #ifndef HAVE_ARCH_PRIVCMD_MMAP
  42 static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma);
  43 #endif
  44
  45 static long privcmd_ioctl_hypercall(void __user *udata)
  46 {
  47         struct privcmd_hypercall hypercall;
  48         long ret;
  49
  50         if (copy_from_user(&hypercall, udata, sizeof(hypercall)))
  51                 return -EFAULT;
  52
  53         ret = privcmd_call(hypercall.op,
  54                            hypercall.arg[0], hypercall.arg[1],
  55                            hypercall.arg[2], hypercall.arg[3],
  56                            hypercall.arg[4]);
  57
  58         return ret;
  59 }
  60
  61 static void free_page_list(struct list_head *pages)
  62 {
  63         struct page *p, *n;
  64
  65         list_for_each_entry_safe(p, n, pages, lru)
  66                 __free_page(p);
  67
  68         INIT_LIST_HEAD(pages);
  69 }
  70
  71 /*
  72  * Given an array of items in userspace, return a list of pages
  73  * containing the data.  If copying fails, either because of memory
  74  * allocation failure or a problem reading user memory, return an
  75  * error code; its up to the caller to dispose of any partial list.
  76  */
  77 static int gather_array(struct list_head *pagelist,
  78                         unsigned nelem, size_t size,
  79                         void __user *data)
  80 {
  81         unsigned pageidx;
  82         void *pagedata;
  83         int ret;
  84
  85         if (size > PAGE_SIZE)
  86                 return 0;
  87
  88         pageidx = PAGE_SIZE;
  89         pagedata = NULL;        /* quiet, gcc */
  90         while (nelem--) {
  91                 if (pageidx > PAGE_SIZE-size) {
  92                         struct page *page = alloc_page(GFP_KERNEL);
  93
  94                         ret = -ENOMEM;
  95                         if (page == NULL)
  96                                 goto fail;
  97
  98                         pagedata = page_address(page);
  99
 100                         list_add_tail(&page->lru, pagelist);
 101                         pageidx = 0;
 102                 }
 103
 104                 ret = -EFAULT;
 105                 if (copy_from_user(pagedata + pageidx, data, size))
 106                         goto fail;
 107
 108                 data += size;
 109                 pageidx += size;
 110         }
 111
 112         ret = 0;
 113
 114 fail:
 115         return ret;
 116 }
 117
 118 /*
 119  * Call function "fn" on each element of the array fragmented
 120  * over a list of pages.
 121  */
 122 static int traverse_pages(unsigned nelem, size_t size,
 123                           struct list_head *pos,
 124                           int (*fn)(void *data, void *state),
 125                           void *state)
 126 {
 127         void *pagedata;
 128         unsigned pageidx;
 129         int ret = 0;
 130
 131         BUG_ON(size > PAGE_SIZE);
 132
 133         pageidx = PAGE_SIZE;
 134         pagedata = NULL;        /* hush, gcc */
 135
 136         while (nelem--) {
 137                 if (pageidx > PAGE_SIZE-size) {
 138                         struct page *page;
 139                         pos = pos->next;
 140                         page = list_entry(pos, struct page, lru);
 141                         pagedata = page_address(page);
 142                         pageidx = 0;
 143                 }
 144
 145                 ret = (*fn)(pagedata + pageidx, state);
 146                 if (ret)
 147                         break;
 148                 pageidx += size;
 149         }
 150
 151         return ret;
 152 }
 153
 154 struct mmap_mfn_state {
 155         unsigned long va;
 156         struct vm_area_struct *vma;
 157         domid_t domain;
 158 };
 159
 160 static int mmap_mfn_range(void *data, void *state)
 161 {
 162         struct privcmd_mmap_entry *msg = data;
 163         struct mmap_mfn_state *st = state;
 164         struct vm_area_struct *vma = st->vma;
 165         int rc;
 166
 167         /* Do not allow range to wrap the address space. */
 168         if ((msg->npages > (LONG_MAX >> PAGE_SHIFT)) ||
 169             ((unsigned long)(msg->npages << PAGE_SHIFT) >= -st->va))
 170                 return -EINVAL;
 171
 172         /* Range chunks must be contiguous in va space. */
 173         if ((msg->va != st->va) ||
 174             ((msg->va+(msg->npages<<PAGE_SHIFT)) > vma->vm_end))
 175                 return -EINVAL;
 176
 177         rc = xen_remap_domain_mfn_range(vma,
 178                                         msg->va & PAGE_MASK,
 179                                         msg->mfn, msg->npages,
 180                                         vma->vm_page_prot,
 181                                         st->domain);
 182         if (rc < 0)
 183                 return rc;
 184
 185         st->va += msg->npages << PAGE_SHIFT;
 186
 187         return 0;
 188 }
 189
 190 static long privcmd_ioctl_mmap(void __user *udata)
 191 {
 192         struct privcmd_mmap mmapcmd;
 193         struct mm_struct *mm = current->mm;
 194         struct vm_area_struct *vma;
 195         int rc;
 196         LIST_HEAD(pagelist);
 197         struct mmap_mfn_state state;
 198
 199         if (!xen_initial_domain())
 200                 return -EPERM;
 201
 202         if (copy_from_user(&mmapcmd, udata, sizeof(mmapcmd)))
 203                 return -EFAULT;
 204
 205         rc = gather_array(&pagelist,
 206                           mmapcmd.num, sizeof(struct privcmd_mmap_entry),
 207                           mmapcmd.entry);
 208
 209         if (rc || list_empty(&pagelist))
 210                 goto out;
 211
 212         down_write(&mm->mmap_sem);
 213
 214         {
 215                 struct page *page = list_first_entry(&pagelist,
 216                                                      struct page, lru);
 217                 struct privcmd_mmap_entry *msg = page_address(page);
 218
 219                 vma = find_vma(mm, msg->va);
 220                 rc = -EINVAL;
 221
 222                 if (!vma || (msg->va != vma->vm_start) ||
 223                     !privcmd_enforce_singleshot_mapping(vma))
 224                         goto out_up;
 225         }
 226
 227         state.va = vma->vm_start;
 228         state.vma = vma;
 229         state.domain = mmapcmd.dom;
 230
 231         rc = traverse_pages(mmapcmd.num, sizeof(struct privcmd_mmap_entry),
 232                             &pagelist,
 233                             mmap_mfn_range, &state);
 234
 235
 236 out_up:
 237         up_write(&mm->mmap_sem);
 238
 239 out:
 240         free_page_list(&pagelist);
 241
 242         return rc;
 243 }
 244
 245 struct mmap_batch_state {
 246         domid_t domain;
 247         unsigned long va;
 248         struct vm_area_struct *vma;
 249         int err;
 250
 251         xen_pfn_t __user *user;
 252 };
 253
 254 static int mmap_batch_fn(void *data, void *state)
 255 {
 256         xen_pfn_t *mfnp = data;
 257         struct mmap_batch_state *st = state;
 258
 259         if (xen_remap_domain_mfn_range(st->vma, st->va & PAGE_MASK, *mfnp, 1,
 260                                        st->vma->vm_page_prot, st->domain) < 0) {
 261                 *mfnp |= 0xf0000000U;
 262                 st->err++;
 263         }
 264         st->va += PAGE_SIZE;
 265
 266         return 0;
 267 }
 268
 269 static int mmap_return_errors(void *data, void *state)
 270 {
 271         xen_pfn_t *mfnp = data;
 272         struct mmap_batch_state *st = state;
 273
 274         return put_user(*mfnp, st->user++);
 275 }
 276
 277 static struct vm_operations_struct privcmd_vm_ops;
 278
 279 static long privcmd_ioctl_mmap_batch(void __user *udata)
 280 {
 281         int ret;
 282         struct privcmd_mmapbatch m;
 283         struct mm_struct *mm = current->mm;
 284         struct vm_area_struct *vma;
 285         unsigned long nr_pages;
 286         LIST_HEAD(pagelist);
 287         struct mmap_batch_state state;
 288
 289         if (!xen_initial_domain())
 290                 return -EPERM;
 291
 292         if (copy_from_user(&m, udata, sizeof(m)))
 293                 return -EFAULT;
 294
 295         nr_pages = m.num;
 296         if ((m.num <= 0) || (nr_pages > (LONG_MAX >> PAGE_SHIFT)))
 297                 return -EINVAL;
 298
 299         ret = gather_array(&pagelist, m.num, sizeof(xen_pfn_t),
 300                            m.arr);
 301
 302         if (ret || list_empty(&pagelist))
 303                 goto out;
 304
 305         down_write(&mm->mmap_sem);
 306
 307         vma = find_vma(mm, m.addr);
 308         ret = -EINVAL;
 309         if (!vma ||
 310             vma->vm_ops != &privcmd_vm_ops ||
 311             (m.addr != vma->vm_start) ||
 312             ((m.addr + (nr_pages << PAGE_SHIFT)) != vma->vm_end) ||
 313             !privcmd_enforce_singleshot_mapping(vma)) {
 314                 up_write(&mm->mmap_sem);
 315                 goto out;
 316         }
 317
 318         state.domain = m.dom;
 319         state.vma = vma;
 320         state.va = m.addr;
 321         state.err = 0;
 322
 323         ret = traverse_pages(m.num, sizeof(xen_pfn_t),
 324                              &pagelist, mmap_batch_fn, &state);
 325
 326         up_write(&mm->mmap_sem);
 327
 328         if (state.err > 0) {
 329                 state.user = m.arr;
 330                 ret = traverse_pages(m.num, sizeof(xen_pfn_t),
 331                                &pagelist,
 332                                mmap_return_errors, &state);
 333         }
 334
 335 out:
 336         free_page_list(&pagelist);
 337
 338         return ret;
 339 }
 340
 341 static long privcmd_ioctl(struct file *file,
 342                           unsigned int cmd, unsigned long data)
 343 {
 344         int ret = -ENOSYS;
 345         void __user *udata = (void __user *) data;
 346
 347         switch (cmd) {
 348         case IOCTL_PRIVCMD_HYPERCALL:
 349                 ret = privcmd_ioctl_hypercall(udata);
 350                 break;
 351
 352         case IOCTL_PRIVCMD_MMAP:
 353                 ret = privcmd_ioctl_mmap(udata);
 354                 break;
 355
 356         case IOCTL_PRIVCMD_MMAPBATCH:
 357                 ret = privcmd_ioctl_mmap_batch(udata);
 358                 break;
 359
 360         default:
 361                 ret = -EINVAL;
 362                 break;
 363         }
 364
 365         return ret;
 366 }
 367
 368 static int privcmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 369 {
 370         printk(KERN_DEBUG "privcmd_fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n",
 371                vma, vma->vm_start, vma->vm_end,
 372                vmf->pgoff, vmf->virtual_address);
 373
 374         return VM_FAULT_SIGBUS;
 375 }
 376
 377 static struct vm_operations_struct privcmd_vm_ops = {
 378         .fault = privcmd_fault
 379 };
 380
 381 static int privcmd_mmap(struct file *file, struct vm_area_struct *vma)
 382 {
 383         /* Unsupported for auto-translate guests. */
 384         if (xen_feature(XENFEAT_auto_translated_physmap))
 385                 return -ENOSYS;
 386
 387         /* DONTCOPY is essential for Xen because copy_page_range doesn't know
 388          * how to recreate these mappings */
 389         vma->vm_flags |= VM_RESERVED | VM_IO | VM_DONTCOPY | VM_PFNMAP;
 390         vma->vm_ops = &privcmd_vm_ops;
 391         vma->vm_private_data = NULL;
 392
 393         return 0;
 394 }
 395
 396 static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma)
 397 {
 398         return (xchg(&vma->vm_private_data, (void *)1) == NULL);
 399 }
 400
 401 const struct file_operations xen_privcmd_fops = {
 402         .owner = THIS_MODULE,
 403         .unlocked_ioctl = privcmd_ioctl,
 404         .mmap = privcmd_mmap,
 405 };
 406 EXPORT_SYMBOL_GPL(xen_privcmd_fops);
 407
 408 static struct miscdevice privcmd_dev = {
 409         .minor = MISC_DYNAMIC_MINOR,
 410         .name = "xen/privcmd",
 411         .fops = &xen_privcmd_fops,
 412 };
 413
 414 static int __init privcmd_init(void)
 415 {
 416         int err;
 417
 418         if (!xen_domain())
 419                 return -ENODEV;
 420
 421         err = misc_register(&privcmd_dev);
 422         if (err != 0) {
 423                 printk(KERN_ERR "Could not register Xen privcmd device\n");
 424                 return err;
 425         }
 426         return 0;
 427 }
 428
 429 static void __exit privcmd_exit(void)
 430 {
 431         misc_deregister(&privcmd_dev);
 432 }
 433
 434 module_init(privcmd_init);
 435 module_exit(privcmd_exit);