lib/test_hmm.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * This is a module to test the HMM (Heterogeneous Memory Management)
   4  * mirror and zone device private memory migration APIs of the kernel.
   5  * Userspace programs can register with the driver to mirror their own address
   6  * space and can use the device to read/write any valid virtual address.
   7  */
   8 #include <linux/init.h>
   9 #include <linux/fs.h>
  10 #include <linux/mm.h>
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/cdev.h>
  14 #include <linux/device.h>
  15 #include <linux/memremap.h>
  16 #include <linux/mutex.h>
  17 #include <linux/rwsem.h>
  18 #include <linux/sched.h>
  19 #include <linux/slab.h>
  20 #include <linux/highmem.h>
  21 #include <linux/delay.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/hmm.h>
  24 #include <linux/vmalloc.h>
  25 #include <linux/swap.h>
  26 #include <linux/swapops.h>
  27 #include <linux/sched/mm.h>
  28 #include <linux/platform_device.h>
  29 #include <linux/rmap.h>
  30 #include <linux/mmu_notifier.h>
  31 #include <linux/migrate.h>
  32
  33 #include "test_hmm_uapi.h"
  34
  35 #define DMIRROR_NDEVICES                4
  36 #define DMIRROR_RANGE_FAULT_TIMEOUT     1000
  37 #define DEVMEM_CHUNK_SIZE               (256 * 1024 * 1024U)
  38 #define DEVMEM_CHUNKS_RESERVE           16
  39
  40 /*
  41  * For device_private pages, dpage is just a dummy struct page
  42  * representing a piece of device memory. dmirror_devmem_alloc_page
  43  * allocates a real system memory page as backing storage to fake a
  44  * real device. zone_device_data points to that backing page. But
  45  * for device_coherent memory, the struct page represents real
  46  * physical CPU-accessible memory that we can use directly.
  47  */
  48 #define BACKING_PAGE(page) (is_device_private_page((page)) ? \
  49                            (page)->zone_device_data : (page))
  50
  51 static unsigned long spm_addr_dev0;
  52 module_param(spm_addr_dev0, long, 0644);
  53 MODULE_PARM_DESC(spm_addr_dev0,
  54                 "Specify start address for SPM (special purpose memory) used for device 0. By setting this Coherent device type will be used. Make sure spm_addr_dev1 is set too. Minimum SPM size should be DEVMEM_CHUNK_SIZE.");
  55
  56 static unsigned long spm_addr_dev1;
  57 module_param(spm_addr_dev1, long, 0644);
  58 MODULE_PARM_DESC(spm_addr_dev1,
  59                 "Specify start address for SPM (special purpose memory) used for device 1. By setting this Coherent device type will be used. Make sure spm_addr_dev0 is set too. Minimum SPM size should be DEVMEM_CHUNK_SIZE.");
  60
  61 static const struct dev_pagemap_ops dmirror_devmem_ops;
  62 static const struct mmu_interval_notifier_ops dmirror_min_ops;
  63 static dev_t dmirror_dev;
  64
  65 struct dmirror_device;
  66
  67 struct dmirror_bounce {
  68         void                    *ptr;
  69         unsigned long           size;
  70         unsigned long           addr;
  71         unsigned long           cpages;
  72 };
  73
  74 #define DPT_XA_TAG_ATOMIC 1UL
  75 #define DPT_XA_TAG_WRITE 3UL
  76
  77 /*
  78  * Data structure to track address ranges and register for mmu interval
  79  * notifier updates.
  80  */
  81 struct dmirror_interval {
  82         struct mmu_interval_notifier    notifier;
  83         struct dmirror                  *dmirror;
  84 };
  85
  86 /*
  87  * Data attached to the open device file.
  88  * Note that it might be shared after a fork().
  89  */
  90 struct dmirror {
  91         struct dmirror_device           *mdevice;
  92         struct xarray                   pt;
  93         struct mmu_interval_notifier    notifier;
  94         struct mutex                    mutex;
  95 };
  96
  97 /*
  98  * ZONE_DEVICE pages for migration and simulating device memory.
  99  */
 100 struct dmirror_chunk {
 101         struct dev_pagemap      pagemap;
 102         struct dmirror_device   *mdevice;
 103         bool remove;
 104 };
 105
 106 /*
 107  * Per device data.
 108  */
 109 struct dmirror_device {
 110         struct cdev             cdevice;
 111         unsigned int            zone_device_type;
 112         struct device           device;
 113
 114         unsigned int            devmem_capacity;
 115         unsigned int            devmem_count;
 116         struct dmirror_chunk    **devmem_chunks;
 117         struct mutex            devmem_lock;    /* protects the above */
 118
 119         unsigned long           calloc;
 120         unsigned long           cfree;
 121         struct page             *free_pages;
 122         spinlock_t              lock;           /* protects the above */
 123 };
 124
 125 static struct dmirror_device dmirror_devices[DMIRROR_NDEVICES];
 126
 127 static int dmirror_bounce_init(struct dmirror_bounce *bounce,
 128                                unsigned long addr,
 129                                unsigned long size)
 130 {
 131         bounce->addr = addr;
 132         bounce->size = size;
 133         bounce->cpages = 0;
 134         bounce->ptr = vmalloc(size);
 135         if (!bounce->ptr)
 136                 return -ENOMEM;
 137         return 0;
 138 }
 139
 140 static bool dmirror_is_private_zone(struct dmirror_device *mdevice)
 141 {
 142         return (mdevice->zone_device_type ==
 143                 HMM_DMIRROR_MEMORY_DEVICE_PRIVATE) ? true : false;
 144 }
 145
 146 static enum migrate_vma_direction
 147 dmirror_select_device(struct dmirror *dmirror)
 148 {
 149         return (dmirror->mdevice->zone_device_type ==
 150                 HMM_DMIRROR_MEMORY_DEVICE_PRIVATE) ?
 151                 MIGRATE_VMA_SELECT_DEVICE_PRIVATE :
 152                 MIGRATE_VMA_SELECT_DEVICE_COHERENT;
 153 }
 154
 155 static void dmirror_bounce_fini(struct dmirror_bounce *bounce)
 156 {
 157         vfree(bounce->ptr);
 158 }
 159
 160 static int dmirror_fops_open(struct inode *inode, struct file *filp)
 161 {
 162         struct cdev *cdev = inode->i_cdev;
 163         struct dmirror *dmirror;
 164         int ret;
 165
 166         /* Mirror this process address space */
 167         dmirror = kzalloc(sizeof(*dmirror), GFP_KERNEL);
 168         if (dmirror == NULL)
 169                 return -ENOMEM;
 170
 171         dmirror->mdevice = container_of(cdev, struct dmirror_device, cdevice);
 172         mutex_init(&dmirror->mutex);
 173         xa_init(&dmirror->pt);
 174
 175         ret = mmu_interval_notifier_insert(&dmirror->notifier, current->mm,
 176                                 0, ULONG_MAX & PAGE_MASK, &dmirror_min_ops);
 177         if (ret) {
 178                 kfree(dmirror);
 179                 return ret;
 180         }
 181
 182         filp->private_data = dmirror;
 183         return 0;
 184 }
 185
 186 static int dmirror_fops_release(struct inode *inode, struct file *filp)
 187 {
 188         struct dmirror *dmirror = filp->private_data;
 189
 190         mmu_interval_notifier_remove(&dmirror->notifier);
 191         xa_destroy(&dmirror->pt);
 192         kfree(dmirror);
 193         return 0;
 194 }
 195
 196 static struct dmirror_chunk *dmirror_page_to_chunk(struct page *page)
 197 {
 198         return container_of(page->pgmap, struct dmirror_chunk, pagemap);
 199 }
 200
 201 static struct dmirror_device *dmirror_page_to_device(struct page *page)
 202
 203 {
 204         return dmirror_page_to_chunk(page)->mdevice;
 205 }
 206
 207 static int dmirror_do_fault(struct dmirror *dmirror, struct hmm_range *range)
 208 {
 209         unsigned long *pfns = range->hmm_pfns;
 210         unsigned long pfn;
 211
 212         for (pfn = (range->start >> PAGE_SHIFT);
 213              pfn < (range->end >> PAGE_SHIFT);
 214              pfn++, pfns++) {
 215                 struct page *page;
 216                 void *entry;
 217
 218                 /*
 219                  * Since we asked for hmm_range_fault() to populate pages,
 220                  * it shouldn't return an error entry on success.
 221                  */
 222                 WARN_ON(*pfns & HMM_PFN_ERROR);
 223                 WARN_ON(!(*pfns & HMM_PFN_VALID));
 224
 225                 page = hmm_pfn_to_page(*pfns);
 226                 WARN_ON(!page);
 227
 228                 entry = page;
 229                 if (*pfns & HMM_PFN_WRITE)
 230                         entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
 231                 else if (WARN_ON(range->default_flags & HMM_PFN_WRITE))
 232                         return -EFAULT;
 233                 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
 234                 if (xa_is_err(entry))
 235                         return xa_err(entry);
 236         }
 237
 238         return 0;
 239 }
 240
 241 static void dmirror_do_update(struct dmirror *dmirror, unsigned long start,
 242                               unsigned long end)
 243 {
 244         unsigned long pfn;
 245         void *entry;
 246
 247         /*
 248          * The XArray doesn't hold references to pages since it relies on
 249          * the mmu notifier to clear page pointers when they become stale.
 250          * Therefore, it is OK to just clear the entry.
 251          */
 252         xa_for_each_range(&dmirror->pt, pfn, entry, start >> PAGE_SHIFT,
 253                           end >> PAGE_SHIFT)
 254                 xa_erase(&dmirror->pt, pfn);
 255 }
 256
 257 static bool dmirror_interval_invalidate(struct mmu_interval_notifier *mni,
 258                                 const struct mmu_notifier_range *range,
 259                                 unsigned long cur_seq)
 260 {
 261         struct dmirror *dmirror = container_of(mni, struct dmirror, notifier);
 262
 263         /*
 264          * Ignore invalidation callbacks for device private pages since
 265          * the invalidation is handled as part of the migration process.
 266          */
 267         if (range->event == MMU_NOTIFY_MIGRATE &&
 268             range->owner == dmirror->mdevice)
 269                 return true;
 270
 271         if (mmu_notifier_range_blockable(range))
 272                 mutex_lock(&dmirror->mutex);
 273         else if (!mutex_trylock(&dmirror->mutex))
 274                 return false;
 275
 276         mmu_interval_set_seq(mni, cur_seq);
 277         dmirror_do_update(dmirror, range->start, range->end);
 278
 279         mutex_unlock(&dmirror->mutex);
 280         return true;
 281 }
 282
 283 static const struct mmu_interval_notifier_ops dmirror_min_ops = {
 284         .invalidate = dmirror_interval_invalidate,
 285 };
 286
 287 static int dmirror_range_fault(struct dmirror *dmirror,
 288                                 struct hmm_range *range)
 289 {
 290         struct mm_struct *mm = dmirror->notifier.mm;
 291         unsigned long timeout =
 292                 jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
 293         int ret;
 294
 295         while (true) {
 296                 if (time_after(jiffies, timeout)) {
 297                         ret = -EBUSY;
 298                         goto out;
 299                 }
 300
 301                 range->notifier_seq = mmu_interval_read_begin(range->notifier);
 302                 mmap_read_lock(mm);
 303                 ret = hmm_range_fault(range);
 304                 mmap_read_unlock(mm);
 305                 if (ret) {
 306                         if (ret == -EBUSY)
 307                                 continue;
 308                         goto out;
 309                 }
 310
 311                 mutex_lock(&dmirror->mutex);
 312                 if (mmu_interval_read_retry(range->notifier,
 313                                             range->notifier_seq)) {
 314                         mutex_unlock(&dmirror->mutex);
 315                         continue;
 316                 }
 317                 break;
 318         }
 319
 320         ret = dmirror_do_fault(dmirror, range);
 321
 322         mutex_unlock(&dmirror->mutex);
 323 out:
 324         return ret;
 325 }
 326
 327 static int dmirror_fault(struct dmirror *dmirror, unsigned long start,
 328                          unsigned long end, bool write)
 329 {
 330         struct mm_struct *mm = dmirror->notifier.mm;
 331         unsigned long addr;
 332         unsigned long pfns[64];
 333         struct hmm_range range = {
 334                 .notifier = &dmirror->notifier,
 335                 .hmm_pfns = pfns,
 336                 .pfn_flags_mask = 0,
 337                 .default_flags =
 338                         HMM_PFN_REQ_FAULT | (write ? HMM_PFN_REQ_WRITE : 0),
 339                 .dev_private_owner = dmirror->mdevice,
 340         };
 341         int ret = 0;
 342
 343         /* Since the mm is for the mirrored process, get a reference first. */
 344         if (!mmget_not_zero(mm))
 345                 return 0;
 346
 347         for (addr = start; addr < end; addr = range.end) {
 348                 range.start = addr;
 349                 range.end = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
 350
 351                 ret = dmirror_range_fault(dmirror, &range);
 352                 if (ret)
 353                         break;
 354         }
 355
 356         mmput(mm);
 357         return ret;
 358 }
 359
 360 static int dmirror_do_read(struct dmirror *dmirror, unsigned long start,
 361                            unsigned long end, struct dmirror_bounce *bounce)
 362 {
 363         unsigned long pfn;
 364         void *ptr;
 365
 366         ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
 367
 368         for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
 369                 void *entry;
 370                 struct page *page;
 371
 372                 entry = xa_load(&dmirror->pt, pfn);
 373                 page = xa_untag_pointer(entry);
 374                 if (!page)
 375                         return -ENOENT;
 376
 377                 memcpy_from_page(ptr, page, 0, PAGE_SIZE);
 378
 379                 ptr += PAGE_SIZE;
 380                 bounce->cpages++;
 381         }
 382
 383         return 0;
 384 }
 385
 386 static int dmirror_read(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
 387 {
 388         struct dmirror_bounce bounce;
 389         unsigned long start, end;
 390         unsigned long size = cmd->npages << PAGE_SHIFT;
 391         int ret;
 392
 393         start = cmd->addr;
 394         end = start + size;
 395         if (end < start)
 396                 return -EINVAL;
 397
 398         ret = dmirror_bounce_init(&bounce, start, size);
 399         if (ret)
 400                 return ret;
 401
 402         while (1) {
 403                 mutex_lock(&dmirror->mutex);
 404                 ret = dmirror_do_read(dmirror, start, end, &bounce);
 405                 mutex_unlock(&dmirror->mutex);
 406                 if (ret != -ENOENT)
 407                         break;
 408
 409                 start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
 410                 ret = dmirror_fault(dmirror, start, end, false);
 411                 if (ret)
 412                         break;
 413                 cmd->faults++;
 414         }
 415
 416         if (ret == 0) {
 417                 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
 418                                  bounce.size))
 419                         ret = -EFAULT;
 420         }
 421         cmd->cpages = bounce.cpages;
 422         dmirror_bounce_fini(&bounce);
 423         return ret;
 424 }
 425
 426 static int dmirror_do_write(struct dmirror *dmirror, unsigned long start,
 427                             unsigned long end, struct dmirror_bounce *bounce)
 428 {
 429         unsigned long pfn;
 430         void *ptr;
 431
 432         ptr = bounce->ptr + ((start - bounce->addr) & PAGE_MASK);
 433
 434         for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
 435                 void *entry;
 436                 struct page *page;
 437
 438                 entry = xa_load(&dmirror->pt, pfn);
 439                 page = xa_untag_pointer(entry);
 440                 if (!page || xa_pointer_tag(entry) != DPT_XA_TAG_WRITE)
 441                         return -ENOENT;
 442
 443                 memcpy_to_page(page, 0, ptr, PAGE_SIZE);
 444
 445                 ptr += PAGE_SIZE;
 446                 bounce->cpages++;
 447         }
 448
 449         return 0;
 450 }
 451
 452 static int dmirror_write(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd)
 453 {
 454         struct dmirror_bounce bounce;
 455         unsigned long start, end;
 456         unsigned long size = cmd->npages << PAGE_SHIFT;
 457         int ret;
 458
 459         start = cmd->addr;
 460         end = start + size;
 461         if (end < start)
 462                 return -EINVAL;
 463
 464         ret = dmirror_bounce_init(&bounce, start, size);
 465         if (ret)
 466                 return ret;
 467         if (copy_from_user(bounce.ptr, u64_to_user_ptr(cmd->ptr),
 468                            bounce.size)) {
 469                 ret = -EFAULT;
 470                 goto fini;
 471         }
 472
 473         while (1) {
 474                 mutex_lock(&dmirror->mutex);
 475                 ret = dmirror_do_write(dmirror, start, end, &bounce);
 476                 mutex_unlock(&dmirror->mutex);
 477                 if (ret != -ENOENT)
 478                         break;
 479
 480                 start = cmd->addr + (bounce.cpages << PAGE_SHIFT);
 481                 ret = dmirror_fault(dmirror, start, end, true);
 482                 if (ret)
 483                         break;
 484                 cmd->faults++;
 485         }
 486
 487 fini:
 488         cmd->cpages = bounce.cpages;
 489         dmirror_bounce_fini(&bounce);
 490         return ret;
 491 }
 492
 493 static int dmirror_allocate_chunk(struct dmirror_device *mdevice,
 494                                    struct page **ppage)
 495 {
 496         struct dmirror_chunk *devmem;
 497         struct resource *res = NULL;
 498         unsigned long pfn;
 499         unsigned long pfn_first;
 500         unsigned long pfn_last;
 501         void *ptr;
 502         int ret = -ENOMEM;
 503
 504         devmem = kzalloc(sizeof(*devmem), GFP_KERNEL);
 505         if (!devmem)
 506                 return ret;
 507
 508         switch (mdevice->zone_device_type) {
 509         case HMM_DMIRROR_MEMORY_DEVICE_PRIVATE:
 510                 res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
 511                                               "hmm_dmirror");
 512                 if (IS_ERR_OR_NULL(res))
 513                         goto err_devmem;
 514                 devmem->pagemap.range.start = res->start;
 515                 devmem->pagemap.range.end = res->end;
 516                 devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
 517                 break;
 518         case HMM_DMIRROR_MEMORY_DEVICE_COHERENT:
 519                 devmem->pagemap.range.start = (MINOR(mdevice->cdevice.dev) - 2) ?
 520                                                         spm_addr_dev0 :
 521                                                         spm_addr_dev1;
 522                 devmem->pagemap.range.end = devmem->pagemap.range.start +
 523                                             DEVMEM_CHUNK_SIZE - 1;
 524                 devmem->pagemap.type = MEMORY_DEVICE_COHERENT;
 525                 break;
 526         default:
 527                 ret = -EINVAL;
 528                 goto err_devmem;
 529         }
 530
 531         devmem->pagemap.nr_range = 1;
 532         devmem->pagemap.ops = &dmirror_devmem_ops;
 533         devmem->pagemap.owner = mdevice;
 534
 535         mutex_lock(&mdevice->devmem_lock);
 536
 537         if (mdevice->devmem_count == mdevice->devmem_capacity) {
 538                 struct dmirror_chunk **new_chunks;
 539                 unsigned int new_capacity;
 540
 541                 new_capacity = mdevice->devmem_capacity +
 542                                 DEVMEM_CHUNKS_RESERVE;
 543                 new_chunks = krealloc(mdevice->devmem_chunks,
 544                                 sizeof(new_chunks[0]) * new_capacity,
 545                                 GFP_KERNEL);
 546                 if (!new_chunks)
 547                         goto err_release;
 548                 mdevice->devmem_capacity = new_capacity;
 549                 mdevice->devmem_chunks = new_chunks;
 550         }
 551         ptr = memremap_pages(&devmem->pagemap, numa_node_id());
 552         if (IS_ERR_OR_NULL(ptr)) {
 553                 if (ptr)
 554                         ret = PTR_ERR(ptr);
 555                 else
 556                         ret = -EFAULT;
 557                 goto err_release;
 558         }
 559
 560         devmem->mdevice = mdevice;
 561         pfn_first = devmem->pagemap.range.start >> PAGE_SHIFT;
 562         pfn_last = pfn_first + (range_len(&devmem->pagemap.range) >> PAGE_SHIFT);
 563         mdevice->devmem_chunks[mdevice->devmem_count++] = devmem;
 564
 565         mutex_unlock(&mdevice->devmem_lock);
 566
 567         pr_info("added new %u MB chunk (total %u chunks, %u MB) PFNs [0x%lx 0x%lx)\n",
 568                 DEVMEM_CHUNK_SIZE / (1024 * 1024),
 569                 mdevice->devmem_count,
 570                 mdevice->devmem_count * (DEVMEM_CHUNK_SIZE / (1024 * 1024)),
 571                 pfn_first, pfn_last);
 572
 573         spin_lock(&mdevice->lock);
 574         for (pfn = pfn_first; pfn < pfn_last; pfn++) {
 575                 struct page *page = pfn_to_page(pfn);
 576
 577                 page->zone_device_data = mdevice->free_pages;
 578                 mdevice->free_pages = page;
 579         }
 580         if (ppage) {
 581                 *ppage = mdevice->free_pages;
 582                 mdevice->free_pages = (*ppage)->zone_device_data;
 583                 mdevice->calloc++;
 584         }
 585         spin_unlock(&mdevice->lock);
 586
 587         return 0;
 588
 589 err_release:
 590         mutex_unlock(&mdevice->devmem_lock);
 591         if (res && devmem->pagemap.type == MEMORY_DEVICE_PRIVATE)
 592                 release_mem_region(devmem->pagemap.range.start,
 593                                    range_len(&devmem->pagemap.range));
 594 err_devmem:
 595         kfree(devmem);
 596
 597         return ret;
 598 }
 599
 600 static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)
 601 {
 602         struct page *dpage = NULL;
 603         struct page *rpage = NULL;
 604
 605         /*
 606          * For ZONE_DEVICE private type, this is a fake device so we allocate
 607          * real system memory to store our device memory.
 608          * For ZONE_DEVICE coherent type we use the actual dpage to store the
 609          * data and ignore rpage.
 610          */
 611         if (dmirror_is_private_zone(mdevice)) {
 612                 rpage = alloc_page(GFP_HIGHUSER);
 613                 if (!rpage)
 614                         return NULL;
 615         }
 616         spin_lock(&mdevice->lock);
 617
 618         if (mdevice->free_pages) {
 619                 dpage = mdevice->free_pages;
 620                 mdevice->free_pages = dpage->zone_device_data;
 621                 mdevice->calloc++;
 622                 spin_unlock(&mdevice->lock);
 623         } else {
 624                 spin_unlock(&mdevice->lock);
 625                 if (dmirror_allocate_chunk(mdevice, &dpage))
 626                         goto error;
 627         }
 628
 629         zone_device_page_init(dpage);
 630         dpage->zone_device_data = rpage;
 631         return dpage;
 632
 633 error:
 634         if (rpage)
 635                 __free_page(rpage);
 636         return NULL;
 637 }
 638
 639 static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args,
 640                                            struct dmirror *dmirror)
 641 {
 642         struct dmirror_device *mdevice = dmirror->mdevice;
 643         const unsigned long *src = args->src;
 644         unsigned long *dst = args->dst;
 645         unsigned long addr;
 646
 647         for (addr = args->start; addr < args->end; addr += PAGE_SIZE,
 648                                                    src++, dst++) {
 649                 struct page *spage;
 650                 struct page *dpage;
 651                 struct page *rpage;
 652
 653                 if (!(*src & MIGRATE_PFN_MIGRATE))
 654                         continue;
 655
 656                 /*
 657                  * Note that spage might be NULL which is OK since it is an
 658                  * unallocated pte_none() or read-only zero page.
 659                  */
 660                 spage = migrate_pfn_to_page(*src);
 661                 if (WARN(spage && is_zone_device_page(spage),
 662                      "page already in device spage pfn: 0x%lx\n",
 663                      page_to_pfn(spage)))
 664                         continue;
 665
 666                 dpage = dmirror_devmem_alloc_page(mdevice);
 667                 if (!dpage)
 668                         continue;
 669
 670                 rpage = BACKING_PAGE(dpage);
 671                 if (spage)
 672                         copy_highpage(rpage, spage);
 673                 else
 674                         clear_highpage(rpage);
 675
 676                 /*
 677                  * Normally, a device would use the page->zone_device_data to
 678                  * point to the mirror but here we use it to hold the page for
 679                  * the simulated device memory and that page holds the pointer
 680                  * to the mirror.
 681                  */
 682                 rpage->zone_device_data = dmirror;
 683
 684                 pr_debug("migrating from sys to dev pfn src: 0x%lx pfn dst: 0x%lx\n",
 685                          page_to_pfn(spage), page_to_pfn(dpage));
 686                 *dst = migrate_pfn(page_to_pfn(dpage));
 687                 if ((*src & MIGRATE_PFN_WRITE) ||
 688                     (!spage && args->vma->vm_flags & VM_WRITE))
 689                         *dst |= MIGRATE_PFN_WRITE;
 690         }
 691 }
 692
 693 static int dmirror_check_atomic(struct dmirror *dmirror, unsigned long start,
 694                              unsigned long end)
 695 {
 696         unsigned long pfn;
 697
 698         for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
 699                 void *entry;
 700
 701                 entry = xa_load(&dmirror->pt, pfn);
 702                 if (xa_pointer_tag(entry) == DPT_XA_TAG_ATOMIC)
 703                         return -EPERM;
 704         }
 705
 706         return 0;
 707 }
 708
 709 static int dmirror_atomic_map(unsigned long start, unsigned long end,
 710                               struct page **pages, struct dmirror *dmirror)
 711 {
 712         unsigned long pfn, mapped = 0;
 713         int i;
 714
 715         /* Map the migrated pages into the device's page tables. */
 716         mutex_lock(&dmirror->mutex);
 717
 718         for (i = 0, pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++, i++) {
 719                 void *entry;
 720
 721                 if (!pages[i])
 722                         continue;
 723
 724                 entry = pages[i];
 725                 entry = xa_tag_pointer(entry, DPT_XA_TAG_ATOMIC);
 726                 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
 727                 if (xa_is_err(entry)) {
 728                         mutex_unlock(&dmirror->mutex);
 729                         return xa_err(entry);
 730                 }
 731
 732                 mapped++;
 733         }
 734
 735         mutex_unlock(&dmirror->mutex);
 736         return mapped;
 737 }
 738
 739 static int dmirror_migrate_finalize_and_map(struct migrate_vma *args,
 740                                             struct dmirror *dmirror)
 741 {
 742         unsigned long start = args->start;
 743         unsigned long end = args->end;
 744         const unsigned long *src = args->src;
 745         const unsigned long *dst = args->dst;
 746         unsigned long pfn;
 747
 748         /* Map the migrated pages into the device's page tables. */
 749         mutex_lock(&dmirror->mutex);
 750
 751         for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++,
 752                                                                 src++, dst++) {
 753                 struct page *dpage;
 754                 void *entry;
 755
 756                 if (!(*src & MIGRATE_PFN_MIGRATE))
 757                         continue;
 758
 759                 dpage = migrate_pfn_to_page(*dst);
 760                 if (!dpage)
 761                         continue;
 762
 763                 entry = BACKING_PAGE(dpage);
 764                 if (*dst & MIGRATE_PFN_WRITE)
 765                         entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE);
 766                 entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC);
 767                 if (xa_is_err(entry)) {
 768                         mutex_unlock(&dmirror->mutex);
 769                         return xa_err(entry);
 770                 }
 771         }
 772
 773         mutex_unlock(&dmirror->mutex);
 774         return 0;
 775 }
 776
 777 static int dmirror_exclusive(struct dmirror *dmirror,
 778                              struct hmm_dmirror_cmd *cmd)
 779 {
 780         unsigned long start, end, addr;
 781         unsigned long size = cmd->npages << PAGE_SHIFT;
 782         struct mm_struct *mm = dmirror->notifier.mm;
 783         struct page *pages[64];
 784         struct dmirror_bounce bounce;
 785         unsigned long next;
 786         int ret;
 787
 788         start = cmd->addr;
 789         end = start + size;
 790         if (end < start)
 791                 return -EINVAL;
 792
 793         /* Since the mm is for the mirrored process, get a reference first. */
 794         if (!mmget_not_zero(mm))
 795                 return -EINVAL;
 796
 797         mmap_read_lock(mm);
 798         for (addr = start; addr < end; addr = next) {
 799                 unsigned long mapped = 0;
 800                 int i;
 801
 802                 if (end < addr + (ARRAY_SIZE(pages) << PAGE_SHIFT))
 803                         next = end;
 804                 else
 805                         next = addr + (ARRAY_SIZE(pages) << PAGE_SHIFT);
 806
 807                 ret = make_device_exclusive_range(mm, addr, next, pages, NULL);
 808                 /*
 809                  * Do dmirror_atomic_map() iff all pages are marked for
 810                  * exclusive access to avoid accessing uninitialized
 811                  * fields of pages.
 812                  */
 813                 if (ret == (next - addr) >> PAGE_SHIFT)
 814                         mapped = dmirror_atomic_map(addr, next, pages, dmirror);
 815                 for (i = 0; i < ret; i++) {
 816                         if (pages[i]) {
 817                                 unlock_page(pages[i]);
 818                                 put_page(pages[i]);
 819                         }
 820                 }
 821
 822                 if (addr + (mapped << PAGE_SHIFT) < next) {
 823                         mmap_read_unlock(mm);
 824                         mmput(mm);
 825                         return -EBUSY;
 826                 }
 827         }
 828         mmap_read_unlock(mm);
 829         mmput(mm);
 830
 831         /* Return the migrated data for verification. */
 832         ret = dmirror_bounce_init(&bounce, start, size);
 833         if (ret)
 834                 return ret;
 835         mutex_lock(&dmirror->mutex);
 836         ret = dmirror_do_read(dmirror, start, end, &bounce);
 837         mutex_unlock(&dmirror->mutex);
 838         if (ret == 0) {
 839                 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
 840                                  bounce.size))
 841                         ret = -EFAULT;
 842         }
 843
 844         cmd->cpages = bounce.cpages;
 845         dmirror_bounce_fini(&bounce);
 846         return ret;
 847 }
 848
 849 static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
 850                                                       struct dmirror *dmirror)
 851 {
 852         const unsigned long *src = args->src;
 853         unsigned long *dst = args->dst;
 854         unsigned long start = args->start;
 855         unsigned long end = args->end;
 856         unsigned long addr;
 857
 858         for (addr = start; addr < end; addr += PAGE_SIZE,
 859                                        src++, dst++) {
 860                 struct page *dpage, *spage;
 861
 862                 spage = migrate_pfn_to_page(*src);
 863                 if (!spage || !(*src & MIGRATE_PFN_MIGRATE))
 864                         continue;
 865
 866                 if (WARN_ON(!is_device_private_page(spage) &&
 867                             !is_device_coherent_page(spage)))
 868                         continue;
 869                 spage = BACKING_PAGE(spage);
 870                 dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
 871                 if (!dpage)
 872                         continue;
 873                 pr_debug("migrating from dev to sys pfn src: 0x%lx pfn dst: 0x%lx\n",
 874                          page_to_pfn(spage), page_to_pfn(dpage));
 875
 876                 lock_page(dpage);
 877                 xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
 878                 copy_highpage(dpage, spage);
 879                 *dst = migrate_pfn(page_to_pfn(dpage));
 880                 if (*src & MIGRATE_PFN_WRITE)
 881                         *dst |= MIGRATE_PFN_WRITE;
 882         }
 883         return 0;
 884 }
 885
 886 static unsigned long
 887 dmirror_successful_migrated_pages(struct migrate_vma *migrate)
 888 {
 889         unsigned long cpages = 0;
 890         unsigned long i;
 891
 892         for (i = 0; i < migrate->npages; i++) {
 893                 if (migrate->src[i] & MIGRATE_PFN_VALID &&
 894                     migrate->src[i] & MIGRATE_PFN_MIGRATE)
 895                         cpages++;
 896         }
 897         return cpages;
 898 }
 899
 900 static int dmirror_migrate_to_system(struct dmirror *dmirror,
 901                                      struct hmm_dmirror_cmd *cmd)
 902 {
 903         unsigned long start, end, addr;
 904         unsigned long size = cmd->npages << PAGE_SHIFT;
 905         struct mm_struct *mm = dmirror->notifier.mm;
 906         struct vm_area_struct *vma;
 907         unsigned long src_pfns[64] = { 0 };
 908         unsigned long dst_pfns[64] = { 0 };
 909         struct migrate_vma args = { 0 };
 910         unsigned long next;
 911         int ret;
 912
 913         start = cmd->addr;
 914         end = start + size;
 915         if (end < start)
 916                 return -EINVAL;
 917
 918         /* Since the mm is for the mirrored process, get a reference first. */
 919         if (!mmget_not_zero(mm))
 920                 return -EINVAL;
 921
 922         cmd->cpages = 0;
 923         mmap_read_lock(mm);
 924         for (addr = start; addr < end; addr = next) {
 925                 vma = vma_lookup(mm, addr);
 926                 if (!vma || !(vma->vm_flags & VM_READ)) {
 927                         ret = -EINVAL;
 928                         goto out;
 929                 }
 930                 next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
 931                 if (next > vma->vm_end)
 932                         next = vma->vm_end;
 933
 934                 args.vma = vma;
 935                 args.src = src_pfns;
 936                 args.dst = dst_pfns;
 937                 args.start = addr;
 938                 args.end = next;
 939                 args.pgmap_owner = dmirror->mdevice;
 940                 args.flags = dmirror_select_device(dmirror);
 941
 942                 ret = migrate_vma_setup(&args);
 943                 if (ret)
 944                         goto out;
 945
 946                 pr_debug("Migrating from device mem to sys mem\n");
 947                 dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
 948
 949                 migrate_vma_pages(&args);
 950                 cmd->cpages += dmirror_successful_migrated_pages(&args);
 951                 migrate_vma_finalize(&args);
 952         }
 953 out:
 954         mmap_read_unlock(mm);
 955         mmput(mm);
 956
 957         return ret;
 958 }
 959
 960 static int dmirror_migrate_to_device(struct dmirror *dmirror,
 961                                 struct hmm_dmirror_cmd *cmd)
 962 {
 963         unsigned long start, end, addr;
 964         unsigned long size = cmd->npages << PAGE_SHIFT;
 965         struct mm_struct *mm = dmirror->notifier.mm;
 966         struct vm_area_struct *vma;
 967         unsigned long src_pfns[64] = { 0 };
 968         unsigned long dst_pfns[64] = { 0 };
 969         struct dmirror_bounce bounce;
 970         struct migrate_vma args = { 0 };
 971         unsigned long next;
 972         int ret;
 973
 974         start = cmd->addr;
 975         end = start + size;
 976         if (end < start)
 977                 return -EINVAL;
 978
 979         /* Since the mm is for the mirrored process, get a reference first. */
 980         if (!mmget_not_zero(mm))
 981                 return -EINVAL;
 982
 983         mmap_read_lock(mm);
 984         for (addr = start; addr < end; addr = next) {
 985                 vma = vma_lookup(mm, addr);
 986                 if (!vma || !(vma->vm_flags & VM_READ)) {
 987                         ret = -EINVAL;
 988                         goto out;
 989                 }
 990                 next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
 991                 if (next > vma->vm_end)
 992                         next = vma->vm_end;
 993
 994                 args.vma = vma;
 995                 args.src = src_pfns;
 996                 args.dst = dst_pfns;
 997                 args.start = addr;
 998                 args.end = next;
 999                 args.pgmap_owner = dmirror->mdevice;
1000                 args.flags = MIGRATE_VMA_SELECT_SYSTEM;
1001                 ret = migrate_vma_setup(&args);
1002                 if (ret)
1003                         goto out;
1004
1005                 pr_debug("Migrating from sys mem to device mem\n");
1006                 dmirror_migrate_alloc_and_copy(&args, dmirror);
1007                 migrate_vma_pages(&args);
1008                 dmirror_migrate_finalize_and_map(&args, dmirror);
1009                 migrate_vma_finalize(&args);
1010         }
1011         mmap_read_unlock(mm);
1012         mmput(mm);
1013
1014         /*
1015          * Return the migrated data for verification.
1016          * Only for pages in device zone
1017          */
1018         ret = dmirror_bounce_init(&bounce, start, size);
1019         if (ret)
1020                 return ret;
1021         mutex_lock(&dmirror->mutex);
1022         ret = dmirror_do_read(dmirror, start, end, &bounce);
1023         mutex_unlock(&dmirror->mutex);
1024         if (ret == 0) {
1025                 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
1026                                  bounce.size))
1027                         ret = -EFAULT;
1028         }
1029         cmd->cpages = bounce.cpages;
1030         dmirror_bounce_fini(&bounce);
1031         return ret;
1032
1033 out:
1034         mmap_read_unlock(mm);
1035         mmput(mm);
1036         return ret;
1037 }
1038
1039 static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
1040                             unsigned char *perm, unsigned long entry)
1041 {
1042         struct page *page;
1043
1044         if (entry & HMM_PFN_ERROR) {
1045                 *perm = HMM_DMIRROR_PROT_ERROR;
1046                 return;
1047         }
1048         if (!(entry & HMM_PFN_VALID)) {
1049                 *perm = HMM_DMIRROR_PROT_NONE;
1050                 return;
1051         }
1052
1053         page = hmm_pfn_to_page(entry);
1054         if (is_device_private_page(page)) {
1055                 /* Is the page migrated to this device or some other? */
1056                 if (dmirror->mdevice == dmirror_page_to_device(page))
1057                         *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL;
1058                 else
1059                         *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE;
1060         } else if (is_device_coherent_page(page)) {
1061                 /* Is the page migrated to this device or some other? */
1062                 if (dmirror->mdevice == dmirror_page_to_device(page))
1063                         *perm = HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL;
1064                 else
1065                         *perm = HMM_DMIRROR_PROT_DEV_COHERENT_REMOTE;
1066         } else if (is_zero_pfn(page_to_pfn(page)))
1067                 *perm = HMM_DMIRROR_PROT_ZERO;
1068         else
1069                 *perm = HMM_DMIRROR_PROT_NONE;
1070         if (entry & HMM_PFN_WRITE)
1071                 *perm |= HMM_DMIRROR_PROT_WRITE;
1072         else
1073                 *perm |= HMM_DMIRROR_PROT_READ;
1074         if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PMD_SHIFT)
1075                 *perm |= HMM_DMIRROR_PROT_PMD;
1076         else if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PUD_SHIFT)
1077                 *perm |= HMM_DMIRROR_PROT_PUD;
1078 }
1079
1080 static bool dmirror_snapshot_invalidate(struct mmu_interval_notifier *mni,
1081                                 const struct mmu_notifier_range *range,
1082                                 unsigned long cur_seq)
1083 {
1084         struct dmirror_interval *dmi =
1085                 container_of(mni, struct dmirror_interval, notifier);
1086         struct dmirror *dmirror = dmi->dmirror;
1087
1088         if (mmu_notifier_range_blockable(range))
1089                 mutex_lock(&dmirror->mutex);
1090         else if (!mutex_trylock(&dmirror->mutex))
1091                 return false;
1092
1093         /*
1094          * Snapshots only need to set the sequence number since any
1095          * invalidation in the interval invalidates the whole snapshot.
1096          */
1097         mmu_interval_set_seq(mni, cur_seq);
1098
1099         mutex_unlock(&dmirror->mutex);
1100         return true;
1101 }
1102
1103 static const struct mmu_interval_notifier_ops dmirror_mrn_ops = {
1104         .invalidate = dmirror_snapshot_invalidate,
1105 };
1106
1107 static int dmirror_range_snapshot(struct dmirror *dmirror,
1108                                   struct hmm_range *range,
1109                                   unsigned char *perm)
1110 {
1111         struct mm_struct *mm = dmirror->notifier.mm;
1112         struct dmirror_interval notifier;
1113         unsigned long timeout =
1114                 jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
1115         unsigned long i;
1116         unsigned long n;
1117         int ret = 0;
1118
1119         notifier.dmirror = dmirror;
1120         range->notifier = &notifier.notifier;
1121
1122         ret = mmu_interval_notifier_insert(range->notifier, mm,
1123                         range->start, range->end - range->start,
1124                         &dmirror_mrn_ops);
1125         if (ret)
1126                 return ret;
1127
1128         while (true) {
1129                 if (time_after(jiffies, timeout)) {
1130                         ret = -EBUSY;
1131                         goto out;
1132                 }
1133
1134                 range->notifier_seq = mmu_interval_read_begin(range->notifier);
1135
1136                 mmap_read_lock(mm);
1137                 ret = hmm_range_fault(range);
1138                 mmap_read_unlock(mm);
1139                 if (ret) {
1140                         if (ret == -EBUSY)
1141                                 continue;
1142                         goto out;
1143                 }
1144
1145                 mutex_lock(&dmirror->mutex);
1146                 if (mmu_interval_read_retry(range->notifier,
1147                                             range->notifier_seq)) {
1148                         mutex_unlock(&dmirror->mutex);
1149                         continue;
1150                 }
1151                 break;
1152         }
1153
1154         n = (range->end - range->start) >> PAGE_SHIFT;
1155         for (i = 0; i < n; i++)
1156                 dmirror_mkentry(dmirror, range, perm + i, range->hmm_pfns[i]);
1157
1158         mutex_unlock(&dmirror->mutex);
1159 out:
1160         mmu_interval_notifier_remove(range->notifier);
1161         return ret;
1162 }
1163
1164 static int dmirror_snapshot(struct dmirror *dmirror,
1165                             struct hmm_dmirror_cmd *cmd)
1166 {
1167         struct mm_struct *mm = dmirror->notifier.mm;
1168         unsigned long start, end;
1169         unsigned long size = cmd->npages << PAGE_SHIFT;
1170         unsigned long addr;
1171         unsigned long next;
1172         unsigned long pfns[64];
1173         unsigned char perm[64];
1174         char __user *uptr;
1175         struct hmm_range range = {
1176                 .hmm_pfns = pfns,
1177                 .dev_private_owner = dmirror->mdevice,
1178         };
1179         int ret = 0;
1180
1181         start = cmd->addr;
1182         end = start + size;
1183         if (end < start)
1184                 return -EINVAL;
1185
1186         /* Since the mm is for the mirrored process, get a reference first. */
1187         if (!mmget_not_zero(mm))
1188                 return -EINVAL;
1189
1190         /*
1191          * Register a temporary notifier to detect invalidations even if it
1192          * overlaps with other mmu_interval_notifiers.
1193          */
1194         uptr = u64_to_user_ptr(cmd->ptr);
1195         for (addr = start; addr < end; addr = next) {
1196                 unsigned long n;
1197
1198                 next = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
1199                 range.start = addr;
1200                 range.end = next;
1201
1202                 ret = dmirror_range_snapshot(dmirror, &range, perm);
1203                 if (ret)
1204                         break;
1205
1206                 n = (range.end - range.start) >> PAGE_SHIFT;
1207                 if (copy_to_user(uptr, perm, n)) {
1208                         ret = -EFAULT;
1209                         break;
1210                 }
1211
1212                 cmd->cpages += n;
1213                 uptr += n;
1214         }
1215         mmput(mm);
1216
1217         return ret;
1218 }
1219
1220 static void dmirror_device_evict_chunk(struct dmirror_chunk *chunk)
1221 {
1222         unsigned long start_pfn = chunk->pagemap.range.start >> PAGE_SHIFT;
1223         unsigned long end_pfn = chunk->pagemap.range.end >> PAGE_SHIFT;
1224         unsigned long npages = end_pfn - start_pfn + 1;
1225         unsigned long i;
1226         unsigned long *src_pfns;
1227         unsigned long *dst_pfns;
1228
1229         src_pfns = kcalloc(npages, sizeof(*src_pfns), GFP_KERNEL);
1230         dst_pfns = kcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL);
1231
1232         migrate_device_range(src_pfns, start_pfn, npages);
1233         for (i = 0; i < npages; i++) {
1234                 struct page *dpage, *spage;
1235
1236                 spage = migrate_pfn_to_page(src_pfns[i]);
1237                 if (!spage || !(src_pfns[i] & MIGRATE_PFN_MIGRATE))
1238                         continue;
1239
1240                 if (WARN_ON(!is_device_private_page(spage) &&
1241                             !is_device_coherent_page(spage)))
1242                         continue;
1243                 spage = BACKING_PAGE(spage);
1244                 dpage = alloc_page(GFP_HIGHUSER_MOVABLE | __GFP_NOFAIL);
1245                 lock_page(dpage);
1246                 copy_highpage(dpage, spage);
1247                 dst_pfns[i] = migrate_pfn(page_to_pfn(dpage));
1248                 if (src_pfns[i] & MIGRATE_PFN_WRITE)
1249                         dst_pfns[i] |= MIGRATE_PFN_WRITE;
1250         }
1251         migrate_device_pages(src_pfns, dst_pfns, npages);
1252         migrate_device_finalize(src_pfns, dst_pfns, npages);
1253         kfree(src_pfns);
1254         kfree(dst_pfns);
1255 }
1256
1257 /* Removes free pages from the free list so they can't be re-allocated */
1258 static void dmirror_remove_free_pages(struct dmirror_chunk *devmem)
1259 {
1260         struct dmirror_device *mdevice = devmem->mdevice;
1261         struct page *page;
1262
1263         for (page = mdevice->free_pages; page; page = page->zone_device_data)
1264                 if (dmirror_page_to_chunk(page) == devmem)
1265                         mdevice->free_pages = page->zone_device_data;
1266 }
1267
1268 static void dmirror_device_remove_chunks(struct dmirror_device *mdevice)
1269 {
1270         unsigned int i;
1271
1272         mutex_lock(&mdevice->devmem_lock);
1273         if (mdevice->devmem_chunks) {
1274                 for (i = 0; i < mdevice->devmem_count; i++) {
1275                         struct dmirror_chunk *devmem =
1276                                 mdevice->devmem_chunks[i];
1277
1278                         spin_lock(&mdevice->lock);
1279                         devmem->remove = true;
1280                         dmirror_remove_free_pages(devmem);
1281                         spin_unlock(&mdevice->lock);
1282
1283                         dmirror_device_evict_chunk(devmem);
1284                         memunmap_pages(&devmem->pagemap);
1285                         if (devmem->pagemap.type == MEMORY_DEVICE_PRIVATE)
1286                                 release_mem_region(devmem->pagemap.range.start,
1287                                                    range_len(&devmem->pagemap.range));
1288                         kfree(devmem);
1289                 }
1290                 mdevice->devmem_count = 0;
1291                 mdevice->devmem_capacity = 0;
1292                 mdevice->free_pages = NULL;
1293                 kfree(mdevice->devmem_chunks);
1294                 mdevice->devmem_chunks = NULL;
1295         }
1296         mutex_unlock(&mdevice->devmem_lock);
1297 }
1298
1299 static long dmirror_fops_unlocked_ioctl(struct file *filp,
1300                                         unsigned int command,
1301                                         unsigned long arg)
1302 {
1303         void __user *uarg = (void __user *)arg;
1304         struct hmm_dmirror_cmd cmd;
1305         struct dmirror *dmirror;
1306         int ret;
1307
1308         dmirror = filp->private_data;
1309         if (!dmirror)
1310                 return -EINVAL;
1311
1312         if (copy_from_user(&cmd, uarg, sizeof(cmd)))
1313                 return -EFAULT;
1314
1315         if (cmd.addr & ~PAGE_MASK)
1316                 return -EINVAL;
1317         if (cmd.addr >= (cmd.addr + (cmd.npages << PAGE_SHIFT)))
1318                 return -EINVAL;
1319
1320         cmd.cpages = 0;
1321         cmd.faults = 0;
1322
1323         switch (command) {
1324         case HMM_DMIRROR_READ:
1325                 ret = dmirror_read(dmirror, &cmd);
1326                 break;
1327
1328         case HMM_DMIRROR_WRITE:
1329                 ret = dmirror_write(dmirror, &cmd);
1330                 break;
1331
1332         case HMM_DMIRROR_MIGRATE_TO_DEV:
1333                 ret = dmirror_migrate_to_device(dmirror, &cmd);
1334                 break;
1335
1336         case HMM_DMIRROR_MIGRATE_TO_SYS:
1337                 ret = dmirror_migrate_to_system(dmirror, &cmd);
1338                 break;
1339
1340         case HMM_DMIRROR_EXCLUSIVE:
1341                 ret = dmirror_exclusive(dmirror, &cmd);
1342                 break;
1343
1344         case HMM_DMIRROR_CHECK_EXCLUSIVE:
1345                 ret = dmirror_check_atomic(dmirror, cmd.addr,
1346                                         cmd.addr + (cmd.npages << PAGE_SHIFT));
1347                 break;
1348
1349         case HMM_DMIRROR_SNAPSHOT:
1350                 ret = dmirror_snapshot(dmirror, &cmd);
1351                 break;
1352
1353         case HMM_DMIRROR_RELEASE:
1354                 dmirror_device_remove_chunks(dmirror->mdevice);
1355                 ret = 0;
1356                 break;
1357
1358         default:
1359                 return -EINVAL;
1360         }
1361         if (ret)
1362                 return ret;
1363
1364         if (copy_to_user(uarg, &cmd, sizeof(cmd)))
1365                 return -EFAULT;
1366
1367         return 0;
1368 }
1369
1370 static int dmirror_fops_mmap(struct file *file, struct vm_area_struct *vma)
1371 {
1372         unsigned long addr;
1373
1374         for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) {
1375                 struct page *page;
1376                 int ret;
1377
1378                 page = alloc_page(GFP_KERNEL | __GFP_ZERO);
1379                 if (!page)
1380                         return -ENOMEM;
1381
1382                 ret = vm_insert_page(vma, addr, page);
1383                 if (ret) {
1384                         __free_page(page);
1385                         return ret;
1386                 }
1387                 put_page(page);
1388         }
1389
1390         return 0;
1391 }
1392
1393 static const struct file_operations dmirror_fops = {
1394         .open           = dmirror_fops_open,
1395         .release        = dmirror_fops_release,
1396         .mmap           = dmirror_fops_mmap,
1397         .unlocked_ioctl = dmirror_fops_unlocked_ioctl,
1398         .llseek         = default_llseek,
1399         .owner          = THIS_MODULE,
1400 };
1401
1402 static void dmirror_devmem_free(struct page *page)
1403 {
1404         struct page *rpage = BACKING_PAGE(page);
1405         struct dmirror_device *mdevice;
1406
1407         if (rpage != page)
1408                 __free_page(rpage);
1409
1410         mdevice = dmirror_page_to_device(page);
1411         spin_lock(&mdevice->lock);
1412
1413         /* Return page to our allocator if not freeing the chunk */
1414         if (!dmirror_page_to_chunk(page)->remove) {
1415                 mdevice->cfree++;
1416                 page->zone_device_data = mdevice->free_pages;
1417                 mdevice->free_pages = page;
1418         }
1419         spin_unlock(&mdevice->lock);
1420 }
1421
1422 static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
1423 {
1424         struct migrate_vma args = { 0 };
1425         unsigned long src_pfns = 0;
1426         unsigned long dst_pfns = 0;
1427         struct page *rpage;
1428         struct dmirror *dmirror;
1429         vm_fault_t ret;
1430
1431         /*
1432          * Normally, a device would use the page->zone_device_data to point to
1433          * the mirror but here we use it to hold the page for the simulated
1434          * device memory and that page holds the pointer to the mirror.
1435          */
1436         rpage = vmf->page->zone_device_data;
1437         dmirror = rpage->zone_device_data;
1438
1439         /* FIXME demonstrate how we can adjust migrate range */
1440         args.vma = vmf->vma;
1441         args.start = vmf->address;
1442         args.end = args.start + PAGE_SIZE;
1443         args.src = &src_pfns;
1444         args.dst = &dst_pfns;
1445         args.pgmap_owner = dmirror->mdevice;
1446         args.flags = dmirror_select_device(dmirror);
1447         args.fault_page = vmf->page;
1448
1449         if (migrate_vma_setup(&args))
1450                 return VM_FAULT_SIGBUS;
1451
1452         ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
1453         if (ret)
1454                 return ret;
1455         migrate_vma_pages(&args);
1456         /*
1457          * No device finalize step is needed since
1458          * dmirror_devmem_fault_alloc_and_copy() will have already
1459          * invalidated the device page table.
1460          */
1461         migrate_vma_finalize(&args);
1462         return 0;
1463 }
1464
1465 static const struct dev_pagemap_ops dmirror_devmem_ops = {
1466         .page_free      = dmirror_devmem_free,
1467         .migrate_to_ram = dmirror_devmem_fault,
1468 };
1469
1470 static int dmirror_device_init(struct dmirror_device *mdevice, int id)
1471 {
1472         dev_t dev;
1473         int ret;
1474
1475         dev = MKDEV(MAJOR(dmirror_dev), id);
1476         mutex_init(&mdevice->devmem_lock);
1477         spin_lock_init(&mdevice->lock);
1478
1479         cdev_init(&mdevice->cdevice, &dmirror_fops);
1480         mdevice->cdevice.owner = THIS_MODULE;
1481         device_initialize(&mdevice->device);
1482         mdevice->device.devt = dev;
1483
1484         ret = dev_set_name(&mdevice->device, "hmm_dmirror%u", id);
1485         if (ret)
1486                 return ret;
1487
1488         ret = cdev_device_add(&mdevice->cdevice, &mdevice->device);
1489         if (ret)
1490                 return ret;
1491
1492         /* Build a list of free ZONE_DEVICE struct pages */
1493         return dmirror_allocate_chunk(mdevice, NULL);
1494 }
1495
1496 static void dmirror_device_remove(struct dmirror_device *mdevice)
1497 {
1498         dmirror_device_remove_chunks(mdevice);
1499         cdev_device_del(&mdevice->cdevice, &mdevice->device);
1500 }
1501
1502 static int __init hmm_dmirror_init(void)
1503 {
1504         int ret;
1505         int id = 0;
1506         int ndevices = 0;
1507
1508         ret = alloc_chrdev_region(&dmirror_dev, 0, DMIRROR_NDEVICES,
1509                                   "HMM_DMIRROR");
1510         if (ret)
1511                 goto err_unreg;
1512
1513         memset(dmirror_devices, 0, DMIRROR_NDEVICES * sizeof(dmirror_devices[0]));
1514         dmirror_devices[ndevices++].zone_device_type =
1515                                 HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
1516         dmirror_devices[ndevices++].zone_device_type =
1517                                 HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
1518         if (spm_addr_dev0 && spm_addr_dev1) {
1519                 dmirror_devices[ndevices++].zone_device_type =
1520                                         HMM_DMIRROR_MEMORY_DEVICE_COHERENT;
1521                 dmirror_devices[ndevices++].zone_device_type =
1522                                         HMM_DMIRROR_MEMORY_DEVICE_COHERENT;
1523         }
1524         for (id = 0; id < ndevices; id++) {
1525                 ret = dmirror_device_init(dmirror_devices + id, id);
1526                 if (ret)
1527                         goto err_chrdev;
1528         }
1529
1530         pr_info("HMM test module loaded. This is only for testing HMM.\n");
1531         return 0;
1532
1533 err_chrdev:
1534         while (--id >= 0)
1535                 dmirror_device_remove(dmirror_devices + id);
1536         unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
1537 err_unreg:
1538         return ret;
1539 }
1540
1541 static void __exit hmm_dmirror_exit(void)
1542 {
1543         int id;
1544
1545         for (id = 0; id < DMIRROR_NDEVICES; id++)
1546                 if (dmirror_devices[id].zone_device_type)
1547                         dmirror_device_remove(dmirror_devices + id);
1548         unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
1549 }
1550
1551 module_init(hmm_dmirror_init);
1552 module_exit(hmm_dmirror_exit);
1553 MODULE_LICENSE("GPL");