drivers/dax/device.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright(c) 2016-2018 Intel Corporation. All rights reserved. */
   3 #include <linux/memremap.h>
   4 #include <linux/pagemap.h>
   5 #include <linux/module.h>
   6 #include <linux/device.h>
   7 #include <linux/pfn_t.h>
   8 #include <linux/cdev.h>
   9 #include <linux/slab.h>
  10 #include <linux/dax.h>
  11 #include <linux/fs.h>
  12 #include <linux/mm.h>
  13 #include <linux/mman.h>
  14 #include "dax-private.h"
  15 #include "bus.h"
  16
  17 static struct dev_dax *ref_to_dev_dax(struct percpu_ref *ref)
  18 {
  19         return container_of(ref, struct dev_dax, ref);
  20 }
  21
  22 static void dev_dax_percpu_release(struct percpu_ref *ref)
  23 {
  24         struct dev_dax *dev_dax = ref_to_dev_dax(ref);
  25
  26         dev_dbg(&dev_dax->dev, "%s\n", __func__);
  27         complete(&dev_dax->cmp);
  28 }
  29
  30 static void dev_dax_percpu_exit(struct percpu_ref *ref)
  31 {
  32         struct dev_dax *dev_dax = ref_to_dev_dax(ref);
  33
  34         dev_dbg(&dev_dax->dev, "%s\n", __func__);
  35         wait_for_completion(&dev_dax->cmp);
  36         percpu_ref_exit(ref);
  37 }
  38
  39 static void dev_dax_percpu_kill(struct percpu_ref *data)
  40 {
  41         struct percpu_ref *ref = data;
  42         struct dev_dax *dev_dax = ref_to_dev_dax(ref);
  43
  44         dev_dbg(&dev_dax->dev, "%s\n", __func__);
  45         percpu_ref_kill(ref);
  46 }
  47
  48 static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
  49                 const char *func)
  50 {
  51         struct dax_region *dax_region = dev_dax->region;
  52         struct device *dev = &dev_dax->dev;
  53         unsigned long mask;
  54
  55         if (!dax_alive(dev_dax->dax_dev))
  56                 return -ENXIO;
  57
  58         /* prevent private mappings from being established */
  59         if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
  60                 dev_info_ratelimited(dev,
  61                                 "%s: %s: fail, attempted private mapping\n",
  62                                 current->comm, func);
  63                 return -EINVAL;
  64         }
  65
  66         mask = dax_region->align - 1;
  67         if (vma->vm_start & mask || vma->vm_end & mask) {
  68                 dev_info_ratelimited(dev,
  69                                 "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
  70                                 current->comm, func, vma->vm_start, vma->vm_end,
  71                                 mask);
  72                 return -EINVAL;
  73         }
  74
  75         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
  76                         && (vma->vm_flags & VM_DONTCOPY) == 0) {
  77                 dev_info_ratelimited(dev,
  78                                 "%s: %s: fail, dax range requires MADV_DONTFORK\n",
  79                                 current->comm, func);
  80                 return -EINVAL;
  81         }
  82
  83         if (!vma_is_dax(vma)) {
  84                 dev_info_ratelimited(dev,
  85                                 "%s: %s: fail, vma is not DAX capable\n",
  86                                 current->comm, func);
  87                 return -EINVAL;
  88         }
  89
  90         return 0;
  91 }
  92
  93 /* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
  94 __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
  95                 unsigned long size)
  96 {
  97         struct resource *res = &dev_dax->region->res;
  98         phys_addr_t phys;
  99
 100         phys = pgoff * PAGE_SIZE + res->start;
 101         if (phys >= res->start && phys <= res->end) {
 102                 if (phys + size - 1 <= res->end)
 103                         return phys;
 104         }
 105
 106         return -1;
 107 }
 108
 109 static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
 110                                 struct vm_fault *vmf, pfn_t *pfn)
 111 {
 112         struct device *dev = &dev_dax->dev;
 113         struct dax_region *dax_region;
 114         phys_addr_t phys;
 115         unsigned int fault_size = PAGE_SIZE;
 116
 117         if (check_vma(dev_dax, vmf->vma, __func__))
 118                 return VM_FAULT_SIGBUS;
 119
 120         dax_region = dev_dax->region;
 121         if (dax_region->align > PAGE_SIZE) {
 122                 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 123                         dax_region->align, fault_size);
 124                 return VM_FAULT_SIGBUS;
 125         }
 126
 127         if (fault_size != dax_region->align)
 128                 return VM_FAULT_SIGBUS;
 129
 130         phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
 131         if (phys == -1) {
 132                 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", vmf->pgoff);
 133                 return VM_FAULT_SIGBUS;
 134         }
 135
 136         *pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 137
 138         return vmf_insert_mixed(vmf->vma, vmf->address, *pfn);
 139 }
 140
 141 static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
 142                                 struct vm_fault *vmf, pfn_t *pfn)
 143 {
 144         unsigned long pmd_addr = vmf->address & PMD_MASK;
 145         struct device *dev = &dev_dax->dev;
 146         struct dax_region *dax_region;
 147         phys_addr_t phys;
 148         pgoff_t pgoff;
 149         unsigned int fault_size = PMD_SIZE;
 150
 151         if (check_vma(dev_dax, vmf->vma, __func__))
 152                 return VM_FAULT_SIGBUS;
 153
 154         dax_region = dev_dax->region;
 155         if (dax_region->align > PMD_SIZE) {
 156                 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 157                         dax_region->align, fault_size);
 158                 return VM_FAULT_SIGBUS;
 159         }
 160
 161         /* dax pmd mappings require pfn_t_devmap() */
 162         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 163                 dev_dbg(dev, "region lacks devmap flags\n");
 164                 return VM_FAULT_SIGBUS;
 165         }
 166
 167         if (fault_size < dax_region->align)
 168                 return VM_FAULT_SIGBUS;
 169         else if (fault_size > dax_region->align)
 170                 return VM_FAULT_FALLBACK;
 171
 172         /* if we are outside of the VMA */
 173         if (pmd_addr < vmf->vma->vm_start ||
 174                         (pmd_addr + PMD_SIZE) > vmf->vma->vm_end)
 175                 return VM_FAULT_SIGBUS;
 176
 177         pgoff = linear_page_index(vmf->vma, pmd_addr);
 178         phys = dax_pgoff_to_phys(dev_dax, pgoff, PMD_SIZE);
 179         if (phys == -1) {
 180                 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
 181                 return VM_FAULT_SIGBUS;
 182         }
 183
 184         *pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 185
 186         return vmf_insert_pfn_pmd(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
 187 }
 188
 189 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 190 static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
 191                                 struct vm_fault *vmf, pfn_t *pfn)
 192 {
 193         unsigned long pud_addr = vmf->address & PUD_MASK;
 194         struct device *dev = &dev_dax->dev;
 195         struct dax_region *dax_region;
 196         phys_addr_t phys;
 197         pgoff_t pgoff;
 198         unsigned int fault_size = PUD_SIZE;
 199
 200
 201         if (check_vma(dev_dax, vmf->vma, __func__))
 202                 return VM_FAULT_SIGBUS;
 203
 204         dax_region = dev_dax->region;
 205         if (dax_region->align > PUD_SIZE) {
 206                 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 207                         dax_region->align, fault_size);
 208                 return VM_FAULT_SIGBUS;
 209         }
 210
 211         /* dax pud mappings require pfn_t_devmap() */
 212         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 213                 dev_dbg(dev, "region lacks devmap flags\n");
 214                 return VM_FAULT_SIGBUS;
 215         }
 216
 217         if (fault_size < dax_region->align)
 218                 return VM_FAULT_SIGBUS;
 219         else if (fault_size > dax_region->align)
 220                 return VM_FAULT_FALLBACK;
 221
 222         /* if we are outside of the VMA */
 223         if (pud_addr < vmf->vma->vm_start ||
 224                         (pud_addr + PUD_SIZE) > vmf->vma->vm_end)
 225                 return VM_FAULT_SIGBUS;
 226
 227         pgoff = linear_page_index(vmf->vma, pud_addr);
 228         phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
 229         if (phys == -1) {
 230                 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
 231                 return VM_FAULT_SIGBUS;
 232         }
 233
 234         *pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 235
 236         return vmf_insert_pfn_pud(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
 237 }
 238 #else
 239 static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
 240                                 struct vm_fault *vmf, pfn_t *pfn)
 241 {
 242         return VM_FAULT_FALLBACK;
 243 }
 244 #endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 245
 246 static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
 247                 enum page_entry_size pe_size)
 248 {
 249         struct file *filp = vmf->vma->vm_file;
 250         unsigned long fault_size;
 251         vm_fault_t rc = VM_FAULT_SIGBUS;
 252         int id;
 253         pfn_t pfn;
 254         struct dev_dax *dev_dax = filp->private_data;
 255
 256         dev_dbg(&dev_dax->dev, "%s: %s (%#lx - %#lx) size = %d\n", current->comm,
 257                         (vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read",
 258                         vmf->vma->vm_start, vmf->vma->vm_end, pe_size);
 259
 260         id = dax_read_lock();
 261         switch (pe_size) {
 262         case PE_SIZE_PTE:
 263                 fault_size = PAGE_SIZE;
 264                 rc = __dev_dax_pte_fault(dev_dax, vmf, &pfn);
 265                 break;
 266         case PE_SIZE_PMD:
 267                 fault_size = PMD_SIZE;
 268                 rc = __dev_dax_pmd_fault(dev_dax, vmf, &pfn);
 269                 break;
 270         case PE_SIZE_PUD:
 271                 fault_size = PUD_SIZE;
 272                 rc = __dev_dax_pud_fault(dev_dax, vmf, &pfn);
 273                 break;
 274         default:
 275                 rc = VM_FAULT_SIGBUS;
 276         }
 277
 278         if (rc == VM_FAULT_NOPAGE) {
 279                 unsigned long i;
 280                 pgoff_t pgoff;
 281
 282                 /*
 283                  * In the device-dax case the only possibility for a
 284                  * VM_FAULT_NOPAGE result is when device-dax capacity is
 285                  * mapped. No need to consider the zero page, or racing
 286                  * conflicting mappings.
 287                  */
 288                 pgoff = linear_page_index(vmf->vma, vmf->address
 289                                 & ~(fault_size - 1));
 290                 for (i = 0; i < fault_size / PAGE_SIZE; i++) {
 291                         struct page *page;
 292
 293                         page = pfn_to_page(pfn_t_to_pfn(pfn) + i);
 294                         if (page->mapping)
 295                                 continue;
 296                         page->mapping = filp->f_mapping;
 297                         page->index = pgoff + i;
 298                 }
 299         }
 300         dax_read_unlock(id);
 301
 302         return rc;
 303 }
 304
 305 static vm_fault_t dev_dax_fault(struct vm_fault *vmf)
 306 {
 307         return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
 308 }
 309
 310 static int dev_dax_split(struct vm_area_struct *vma, unsigned long addr)
 311 {
 312         struct file *filp = vma->vm_file;
 313         struct dev_dax *dev_dax = filp->private_data;
 314         struct dax_region *dax_region = dev_dax->region;
 315
 316         if (!IS_ALIGNED(addr, dax_region->align))
 317                 return -EINVAL;
 318         return 0;
 319 }
 320
 321 static unsigned long dev_dax_pagesize(struct vm_area_struct *vma)
 322 {
 323         struct file *filp = vma->vm_file;
 324         struct dev_dax *dev_dax = filp->private_data;
 325         struct dax_region *dax_region = dev_dax->region;
 326
 327         return dax_region->align;
 328 }
 329
 330 static const struct vm_operations_struct dax_vm_ops = {
 331         .fault = dev_dax_fault,
 332         .huge_fault = dev_dax_huge_fault,
 333         .split = dev_dax_split,
 334         .pagesize = dev_dax_pagesize,
 335 };
 336
 337 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 338 {
 339         struct dev_dax *dev_dax = filp->private_data;
 340         int rc, id;
 341
 342         dev_dbg(&dev_dax->dev, "trace\n");
 343
 344         /*
 345          * We lock to check dax_dev liveness and will re-check at
 346          * fault time.
 347          */
 348         id = dax_read_lock();
 349         rc = check_vma(dev_dax, vma, __func__);
 350         dax_read_unlock(id);
 351         if (rc)
 352                 return rc;
 353
 354         vma->vm_ops = &dax_vm_ops;
 355         vma->vm_flags |= VM_HUGEPAGE;
 356         return 0;
 357 }
 358
 359 /* return an unmapped area aligned to the dax region specified alignment */
 360 static unsigned long dax_get_unmapped_area(struct file *filp,
 361                 unsigned long addr, unsigned long len, unsigned long pgoff,
 362                 unsigned long flags)
 363 {
 364         unsigned long off, off_end, off_align, len_align, addr_align, align;
 365         struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
 366         struct dax_region *dax_region;
 367
 368         if (!dev_dax || addr)
 369                 goto out;
 370
 371         dax_region = dev_dax->region;
 372         align = dax_region->align;
 373         off = pgoff << PAGE_SHIFT;
 374         off_end = off + len;
 375         off_align = round_up(off, align);
 376
 377         if ((off_end <= off_align) || ((off_end - off_align) < align))
 378                 goto out;
 379
 380         len_align = len + align;
 381         if ((off + len_align) < off)
 382                 goto out;
 383
 384         addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 385                         pgoff, flags);
 386         if (!IS_ERR_VALUE(addr_align)) {
 387                 addr_align += (off - addr_align) & (align - 1);
 388                 return addr_align;
 389         }
 390  out:
 391         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 392 }
 393
 394 static const struct address_space_operations dev_dax_aops = {
 395         .set_page_dirty         = noop_set_page_dirty,
 396         .invalidatepage         = noop_invalidatepage,
 397 };
 398
 399 static int dax_open(struct inode *inode, struct file *filp)
 400 {
 401         struct dax_device *dax_dev = inode_dax(inode);
 402         struct inode *__dax_inode = dax_inode(dax_dev);
 403         struct dev_dax *dev_dax = dax_get_private(dax_dev);
 404
 405         dev_dbg(&dev_dax->dev, "trace\n");
 406         inode->i_mapping = __dax_inode->i_mapping;
 407         inode->i_mapping->host = __dax_inode;
 408         inode->i_mapping->a_ops = &dev_dax_aops;
 409         filp->f_mapping = inode->i_mapping;
 410         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 411         filp->private_data = dev_dax;
 412         inode->i_flags = S_DAX;
 413
 414         return 0;
 415 }
 416
 417 static int dax_release(struct inode *inode, struct file *filp)
 418 {
 419         struct dev_dax *dev_dax = filp->private_data;
 420
 421         dev_dbg(&dev_dax->dev, "trace\n");
 422         return 0;
 423 }
 424
 425 static const struct file_operations dax_fops = {
 426         .llseek = noop_llseek,
 427         .owner = THIS_MODULE,
 428         .open = dax_open,
 429         .release = dax_release,
 430         .get_unmapped_area = dax_get_unmapped_area,
 431         .mmap = dax_mmap,
 432         .mmap_supported_flags = MAP_SYNC,
 433 };
 434
 435 static void dev_dax_cdev_del(void *cdev)
 436 {
 437         cdev_del(cdev);
 438 }
 439
 440 static void dev_dax_kill(void *dev_dax)
 441 {
 442         kill_dev_dax(dev_dax);
 443 }
 444
 445 int dev_dax_probe(struct device *dev)
 446 {
 447         struct dev_dax *dev_dax = to_dev_dax(dev);
 448         struct dax_device *dax_dev = dev_dax->dax_dev;
 449         struct resource *res = &dev_dax->region->res;
 450         struct inode *inode;
 451         struct cdev *cdev;
 452         void *addr;
 453         int rc;
 454
 455         /* 1:1 map region resource range to device-dax instance range */
 456         if (!devm_request_mem_region(dev, res->start, resource_size(res),
 457                                 dev_name(dev))) {
 458                 dev_warn(dev, "could not reserve region %pR\n", res);
 459                 return -EBUSY;
 460         }
 461
 462         init_completion(&dev_dax->cmp);
 463         rc = percpu_ref_init(&dev_dax->ref, dev_dax_percpu_release, 0,
 464                         GFP_KERNEL);
 465         if (rc)
 466                 return rc;
 467
 468         dev_dax->pgmap.ref = &dev_dax->ref;
 469         dev_dax->pgmap.kill = dev_dax_percpu_kill;
 470         dev_dax->pgmap.cleanup = dev_dax_percpu_exit;
 471         addr = devm_memremap_pages(dev, &dev_dax->pgmap);
 472         if (IS_ERR(addr))
 473                 return PTR_ERR(addr);
 474
 475         inode = dax_inode(dax_dev);
 476         cdev = inode->i_cdev;
 477         cdev_init(cdev, &dax_fops);
 478         if (dev->class) {
 479                 /* for the CONFIG_DEV_DAX_PMEM_COMPAT case */
 480                 cdev->owner = dev->parent->driver->owner;
 481         } else
 482                 cdev->owner = dev->driver->owner;
 483         cdev_set_parent(cdev, &dev->kobj);
 484         rc = cdev_add(cdev, dev->devt, 1);
 485         if (rc)
 486                 return rc;
 487
 488         rc = devm_add_action_or_reset(dev, dev_dax_cdev_del, cdev);
 489         if (rc)
 490                 return rc;
 491
 492         run_dax(dax_dev);
 493         return devm_add_action_or_reset(dev, dev_dax_kill, dev_dax);
 494 }
 495 EXPORT_SYMBOL_GPL(dev_dax_probe);
 496
 497 static int dev_dax_remove(struct device *dev)
 498 {
 499         /* all probe actions are unwound by devm */
 500         return 0;
 501 }
 502
 503 static struct dax_device_driver device_dax_driver = {
 504         .drv = {
 505                 .probe = dev_dax_probe,
 506                 .remove = dev_dax_remove,
 507         },
 508         .match_always = 1,
 509 };
 510
 511 static int __init dax_init(void)
 512 {
 513         return dax_driver_register(&device_dax_driver);
 514 }
 515
 516 static void __exit dax_exit(void)
 517 {
 518         dax_driver_unregister(&device_dax_driver);
 519 }
 520
 521 MODULE_AUTHOR("Intel Corporation");
 522 MODULE_LICENSE("GPL v2");
 523 module_init(dax_init);
 524 module_exit(dax_exit);
 525 MODULE_ALIAS_DAX_DEVICE(0);