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                 next = min(end, addr + (ARRAY_SIZE(pages) << PAGE_SHIFT));
 803
 804                 ret = make_device_exclusive_range(mm, addr, next, pages, NULL);
 805                 /*
 806                  * Do dmirror_atomic_map() iff all pages are marked for
 807                  * exclusive access to avoid accessing uninitialized
 808                  * fields of pages.
 809                  */
 810                 if (ret == (next - addr) >> PAGE_SHIFT)
 811                         mapped = dmirror_atomic_map(addr, next, pages, dmirror);
 812                 for (i = 0; i < ret; i++) {
 813                         if (pages[i]) {
 814                                 unlock_page(pages[i]);
 815                                 put_page(pages[i]);
 816                         }
 817                 }
 818
 819                 if (addr + (mapped << PAGE_SHIFT) < next) {
 820                         mmap_read_unlock(mm);
 821                         mmput(mm);
 822                         return -EBUSY;
 823                 }
 824         }
 825         mmap_read_unlock(mm);
 826         mmput(mm);
 827
 828         /* Return the migrated data for verification. */
 829         ret = dmirror_bounce_init(&bounce, start, size);
 830         if (ret)
 831                 return ret;
 832         mutex_lock(&dmirror->mutex);
 833         ret = dmirror_do_read(dmirror, start, end, &bounce);
 834         mutex_unlock(&dmirror->mutex);
 835         if (ret == 0) {
 836                 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
 837                                  bounce.size))
 838                         ret = -EFAULT;
 839         }
 840
 841         cmd->cpages = bounce.cpages;
 842         dmirror_bounce_fini(&bounce);
 843         return ret;
 844 }
 845
 846 static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args,
 847                                                       struct dmirror *dmirror)
 848 {
 849         const unsigned long *src = args->src;
 850         unsigned long *dst = args->dst;
 851         unsigned long start = args->start;
 852         unsigned long end = args->end;
 853         unsigned long addr;
 854
 855         for (addr = start; addr < end; addr += PAGE_SIZE,
 856                                        src++, dst++) {
 857                 struct page *dpage, *spage;
 858
 859                 spage = migrate_pfn_to_page(*src);
 860                 if (!spage || !(*src & MIGRATE_PFN_MIGRATE))
 861                         continue;
 862
 863                 if (WARN_ON(!is_device_private_page(spage) &&
 864                             !is_device_coherent_page(spage)))
 865                         continue;
 866                 spage = BACKING_PAGE(spage);
 867                 dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr);
 868                 if (!dpage)
 869                         continue;
 870                 pr_debug("migrating from dev to sys pfn src: 0x%lx pfn dst: 0x%lx\n",
 871                          page_to_pfn(spage), page_to_pfn(dpage));
 872
 873                 lock_page(dpage);
 874                 xa_erase(&dmirror->pt, addr >> PAGE_SHIFT);
 875                 copy_highpage(dpage, spage);
 876                 *dst = migrate_pfn(page_to_pfn(dpage));
 877                 if (*src & MIGRATE_PFN_WRITE)
 878                         *dst |= MIGRATE_PFN_WRITE;
 879         }
 880         return 0;
 881 }
 882
 883 static unsigned long
 884 dmirror_successful_migrated_pages(struct migrate_vma *migrate)
 885 {
 886         unsigned long cpages = 0;
 887         unsigned long i;
 888
 889         for (i = 0; i < migrate->npages; i++) {
 890                 if (migrate->src[i] & MIGRATE_PFN_VALID &&
 891                     migrate->src[i] & MIGRATE_PFN_MIGRATE)
 892                         cpages++;
 893         }
 894         return cpages;
 895 }
 896
 897 static int dmirror_migrate_to_system(struct dmirror *dmirror,
 898                                      struct hmm_dmirror_cmd *cmd)
 899 {
 900         unsigned long start, end, addr;
 901         unsigned long size = cmd->npages << PAGE_SHIFT;
 902         struct mm_struct *mm = dmirror->notifier.mm;
 903         struct vm_area_struct *vma;
 904         unsigned long src_pfns[64] = { 0 };
 905         unsigned long dst_pfns[64] = { 0 };
 906         struct migrate_vma args = { 0 };
 907         unsigned long next;
 908         int ret;
 909
 910         start = cmd->addr;
 911         end = start + size;
 912         if (end < start)
 913                 return -EINVAL;
 914
 915         /* Since the mm is for the mirrored process, get a reference first. */
 916         if (!mmget_not_zero(mm))
 917                 return -EINVAL;
 918
 919         cmd->cpages = 0;
 920         mmap_read_lock(mm);
 921         for (addr = start; addr < end; addr = next) {
 922                 vma = vma_lookup(mm, addr);
 923                 if (!vma || !(vma->vm_flags & VM_READ)) {
 924                         ret = -EINVAL;
 925                         goto out;
 926                 }
 927                 next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
 928                 if (next > vma->vm_end)
 929                         next = vma->vm_end;
 930
 931                 args.vma = vma;
 932                 args.src = src_pfns;
 933                 args.dst = dst_pfns;
 934                 args.start = addr;
 935                 args.end = next;
 936                 args.pgmap_owner = dmirror->mdevice;
 937                 args.flags = dmirror_select_device(dmirror);
 938
 939                 ret = migrate_vma_setup(&args);
 940                 if (ret)
 941                         goto out;
 942
 943                 pr_debug("Migrating from device mem to sys mem\n");
 944                 dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
 945
 946                 migrate_vma_pages(&args);
 947                 cmd->cpages += dmirror_successful_migrated_pages(&args);
 948                 migrate_vma_finalize(&args);
 949         }
 950 out:
 951         mmap_read_unlock(mm);
 952         mmput(mm);
 953
 954         return ret;
 955 }
 956
 957 static int dmirror_migrate_to_device(struct dmirror *dmirror,
 958                                 struct hmm_dmirror_cmd *cmd)
 959 {
 960         unsigned long start, end, addr;
 961         unsigned long size = cmd->npages << PAGE_SHIFT;
 962         struct mm_struct *mm = dmirror->notifier.mm;
 963         struct vm_area_struct *vma;
 964         unsigned long src_pfns[64] = { 0 };
 965         unsigned long dst_pfns[64] = { 0 };
 966         struct dmirror_bounce bounce;
 967         struct migrate_vma args = { 0 };
 968         unsigned long next;
 969         int ret;
 970
 971         start = cmd->addr;
 972         end = start + size;
 973         if (end < start)
 974                 return -EINVAL;
 975
 976         /* Since the mm is for the mirrored process, get a reference first. */
 977         if (!mmget_not_zero(mm))
 978                 return -EINVAL;
 979
 980         mmap_read_lock(mm);
 981         for (addr = start; addr < end; addr = next) {
 982                 vma = vma_lookup(mm, addr);
 983                 if (!vma || !(vma->vm_flags & VM_READ)) {
 984                         ret = -EINVAL;
 985                         goto out;
 986                 }
 987                 next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
 988                 if (next > vma->vm_end)
 989                         next = vma->vm_end;
 990
 991                 args.vma = vma;
 992                 args.src = src_pfns;
 993                 args.dst = dst_pfns;
 994                 args.start = addr;
 995                 args.end = next;
 996                 args.pgmap_owner = dmirror->mdevice;
 997                 args.flags = MIGRATE_VMA_SELECT_SYSTEM;
 998                 ret = migrate_vma_setup(&args);
 999                 if (ret)
1000                         goto out;
1001
1002                 pr_debug("Migrating from sys mem to device mem\n");
1003                 dmirror_migrate_alloc_and_copy(&args, dmirror);
1004                 migrate_vma_pages(&args);
1005                 dmirror_migrate_finalize_and_map(&args, dmirror);
1006                 migrate_vma_finalize(&args);
1007         }
1008         mmap_read_unlock(mm);
1009         mmput(mm);
1010
1011         /*
1012          * Return the migrated data for verification.
1013          * Only for pages in device zone
1014          */
1015         ret = dmirror_bounce_init(&bounce, start, size);
1016         if (ret)
1017                 return ret;
1018         mutex_lock(&dmirror->mutex);
1019         ret = dmirror_do_read(dmirror, start, end, &bounce);
1020         mutex_unlock(&dmirror->mutex);
1021         if (ret == 0) {
1022                 if (copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr,
1023                                  bounce.size))
1024                         ret = -EFAULT;
1025         }
1026         cmd->cpages = bounce.cpages;
1027         dmirror_bounce_fini(&bounce);
1028         return ret;
1029
1030 out:
1031         mmap_read_unlock(mm);
1032         mmput(mm);
1033         return ret;
1034 }
1035
1036 static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range,
1037                             unsigned char *perm, unsigned long entry)
1038 {
1039         struct page *page;
1040
1041         if (entry & HMM_PFN_ERROR) {
1042                 *perm = HMM_DMIRROR_PROT_ERROR;
1043                 return;
1044         }
1045         if (!(entry & HMM_PFN_VALID)) {
1046                 *perm = HMM_DMIRROR_PROT_NONE;
1047                 return;
1048         }
1049
1050         page = hmm_pfn_to_page(entry);
1051         if (is_device_private_page(page)) {
1052                 /* Is the page migrated to this device or some other? */
1053                 if (dmirror->mdevice == dmirror_page_to_device(page))
1054                         *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL;
1055                 else
1056                         *perm = HMM_DMIRROR_PROT_DEV_PRIVATE_REMOTE;
1057         } else if (is_device_coherent_page(page)) {
1058                 /* Is the page migrated to this device or some other? */
1059                 if (dmirror->mdevice == dmirror_page_to_device(page))
1060                         *perm = HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL;
1061                 else
1062                         *perm = HMM_DMIRROR_PROT_DEV_COHERENT_REMOTE;
1063         } else if (is_zero_pfn(page_to_pfn(page)))
1064                 *perm = HMM_DMIRROR_PROT_ZERO;
1065         else
1066                 *perm = HMM_DMIRROR_PROT_NONE;
1067         if (entry & HMM_PFN_WRITE)
1068                 *perm |= HMM_DMIRROR_PROT_WRITE;
1069         else
1070                 *perm |= HMM_DMIRROR_PROT_READ;
1071         if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PMD_SHIFT)
1072                 *perm |= HMM_DMIRROR_PROT_PMD;
1073         else if (hmm_pfn_to_map_order(entry) + PAGE_SHIFT == PUD_SHIFT)
1074                 *perm |= HMM_DMIRROR_PROT_PUD;
1075 }
1076
1077 static bool dmirror_snapshot_invalidate(struct mmu_interval_notifier *mni,
1078                                 const struct mmu_notifier_range *range,
1079                                 unsigned long cur_seq)
1080 {
1081         struct dmirror_interval *dmi =
1082                 container_of(mni, struct dmirror_interval, notifier);
1083         struct dmirror *dmirror = dmi->dmirror;
1084
1085         if (mmu_notifier_range_blockable(range))
1086                 mutex_lock(&dmirror->mutex);
1087         else if (!mutex_trylock(&dmirror->mutex))
1088                 return false;
1089
1090         /*
1091          * Snapshots only need to set the sequence number since any
1092          * invalidation in the interval invalidates the whole snapshot.
1093          */
1094         mmu_interval_set_seq(mni, cur_seq);
1095
1096         mutex_unlock(&dmirror->mutex);
1097         return true;
1098 }
1099
1100 static const struct mmu_interval_notifier_ops dmirror_mrn_ops = {
1101         .invalidate = dmirror_snapshot_invalidate,
1102 };
1103
1104 static int dmirror_range_snapshot(struct dmirror *dmirror,
1105                                   struct hmm_range *range,
1106                                   unsigned char *perm)
1107 {
1108         struct mm_struct *mm = dmirror->notifier.mm;
1109         struct dmirror_interval notifier;
1110         unsigned long timeout =
1111                 jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
1112         unsigned long i;
1113         unsigned long n;
1114         int ret = 0;
1115
1116         notifier.dmirror = dmirror;
1117         range->notifier = &notifier.notifier;
1118
1119         ret = mmu_interval_notifier_insert(range->notifier, mm,
1120                         range->start, range->end - range->start,
1121                         &dmirror_mrn_ops);
1122         if (ret)
1123                 return ret;
1124
1125         while (true) {
1126                 if (time_after(jiffies, timeout)) {
1127                         ret = -EBUSY;
1128                         goto out;
1129                 }
1130
1131                 range->notifier_seq = mmu_interval_read_begin(range->notifier);
1132
1133                 mmap_read_lock(mm);
1134                 ret = hmm_range_fault(range);
1135                 mmap_read_unlock(mm);
1136                 if (ret) {
1137                         if (ret == -EBUSY)
1138                                 continue;
1139                         goto out;
1140                 }
1141
1142                 mutex_lock(&dmirror->mutex);
1143                 if (mmu_interval_read_retry(range->notifier,
1144                                             range->notifier_seq)) {
1145                         mutex_unlock(&dmirror->mutex);
1146                         continue;
1147                 }
1148                 break;
1149         }
1150
1151         n = (range->end - range->start) >> PAGE_SHIFT;
1152         for (i = 0; i < n; i++)
1153                 dmirror_mkentry(dmirror, range, perm + i, range->hmm_pfns[i]);
1154
1155         mutex_unlock(&dmirror->mutex);
1156 out:
1157         mmu_interval_notifier_remove(range->notifier);
1158         return ret;
1159 }
1160
1161 static int dmirror_snapshot(struct dmirror *dmirror,
1162                             struct hmm_dmirror_cmd *cmd)
1163 {
1164         struct mm_struct *mm = dmirror->notifier.mm;
1165         unsigned long start, end;
1166         unsigned long size = cmd->npages << PAGE_SHIFT;
1167         unsigned long addr;
1168         unsigned long next;
1169         unsigned long pfns[64];
1170         unsigned char perm[64];
1171         char __user *uptr;
1172         struct hmm_range range = {
1173                 .hmm_pfns = pfns,
1174                 .dev_private_owner = dmirror->mdevice,
1175         };
1176         int ret = 0;
1177
1178         start = cmd->addr;
1179         end = start + size;
1180         if (end < start)
1181                 return -EINVAL;
1182
1183         /* Since the mm is for the mirrored process, get a reference first. */
1184         if (!mmget_not_zero(mm))
1185                 return -EINVAL;
1186
1187         /*
1188          * Register a temporary notifier to detect invalidations even if it
1189          * overlaps with other mmu_interval_notifiers.
1190          */
1191         uptr = u64_to_user_ptr(cmd->ptr);
1192         for (addr = start; addr < end; addr = next) {
1193                 unsigned long n;
1194
1195                 next = min(addr + (ARRAY_SIZE(pfns) << PAGE_SHIFT), end);
1196                 range.start = addr;
1197                 range.end = next;
1198
1199                 ret = dmirror_range_snapshot(dmirror, &range, perm);
1200                 if (ret)
1201                         break;
1202
1203                 n = (range.end - range.start) >> PAGE_SHIFT;
1204                 if (copy_to_user(uptr, perm, n)) {
1205                         ret = -EFAULT;
1206                         break;
1207                 }
1208
1209                 cmd->cpages += n;
1210                 uptr += n;
1211         }
1212         mmput(mm);
1213
1214         return ret;
1215 }
1216
1217 static void dmirror_device_evict_chunk(struct dmirror_chunk *chunk)
1218 {
1219         unsigned long start_pfn = chunk->pagemap.range.start >> PAGE_SHIFT;
1220         unsigned long end_pfn = chunk->pagemap.range.end >> PAGE_SHIFT;
1221         unsigned long npages = end_pfn - start_pfn + 1;
1222         unsigned long i;
1223         unsigned long *src_pfns;
1224         unsigned long *dst_pfns;
1225
1226         src_pfns = kvcalloc(npages, sizeof(*src_pfns), GFP_KERNEL | __GFP_NOFAIL);
1227         dst_pfns = kvcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL | __GFP_NOFAIL);
1228
1229         migrate_device_range(src_pfns, start_pfn, npages);
1230         for (i = 0; i < npages; i++) {
1231                 struct page *dpage, *spage;
1232
1233                 spage = migrate_pfn_to_page(src_pfns[i]);
1234                 if (!spage || !(src_pfns[i] & MIGRATE_PFN_MIGRATE))
1235                         continue;
1236
1237                 if (WARN_ON(!is_device_private_page(spage) &&
1238                             !is_device_coherent_page(spage)))
1239                         continue;
1240                 spage = BACKING_PAGE(spage);
1241                 dpage = alloc_page(GFP_HIGHUSER_MOVABLE | __GFP_NOFAIL);
1242                 lock_page(dpage);
1243                 copy_highpage(dpage, spage);
1244                 dst_pfns[i] = migrate_pfn(page_to_pfn(dpage));
1245                 if (src_pfns[i] & MIGRATE_PFN_WRITE)
1246                         dst_pfns[i] |= MIGRATE_PFN_WRITE;
1247         }
1248         migrate_device_pages(src_pfns, dst_pfns, npages);
1249         migrate_device_finalize(src_pfns, dst_pfns, npages);
1250         kvfree(src_pfns);
1251         kvfree(dst_pfns);
1252 }
1253
1254 /* Removes free pages from the free list so they can't be re-allocated */
1255 static void dmirror_remove_free_pages(struct dmirror_chunk *devmem)
1256 {
1257         struct dmirror_device *mdevice = devmem->mdevice;
1258         struct page *page;
1259
1260         for (page = mdevice->free_pages; page; page = page->zone_device_data)
1261                 if (dmirror_page_to_chunk(page) == devmem)
1262                         mdevice->free_pages = page->zone_device_data;
1263 }
1264
1265 static void dmirror_device_remove_chunks(struct dmirror_device *mdevice)
1266 {
1267         unsigned int i;
1268
1269         mutex_lock(&mdevice->devmem_lock);
1270         if (mdevice->devmem_chunks) {
1271                 for (i = 0; i < mdevice->devmem_count; i++) {
1272                         struct dmirror_chunk *devmem =
1273                                 mdevice->devmem_chunks[i];
1274
1275                         spin_lock(&mdevice->lock);
1276                         devmem->remove = true;
1277                         dmirror_remove_free_pages(devmem);
1278                         spin_unlock(&mdevice->lock);
1279
1280                         dmirror_device_evict_chunk(devmem);
1281                         memunmap_pages(&devmem->pagemap);
1282                         if (devmem->pagemap.type == MEMORY_DEVICE_PRIVATE)
1283                                 release_mem_region(devmem->pagemap.range.start,
1284                                                    range_len(&devmem->pagemap.range));
1285                         kfree(devmem);
1286                 }
1287                 mdevice->devmem_count = 0;
1288                 mdevice->devmem_capacity = 0;
1289                 mdevice->free_pages = NULL;
1290                 kfree(mdevice->devmem_chunks);
1291                 mdevice->devmem_chunks = NULL;
1292         }
1293         mutex_unlock(&mdevice->devmem_lock);
1294 }
1295
1296 static long dmirror_fops_unlocked_ioctl(struct file *filp,
1297                                         unsigned int command,
1298                                         unsigned long arg)
1299 {
1300         void __user *uarg = (void __user *)arg;
1301         struct hmm_dmirror_cmd cmd;
1302         struct dmirror *dmirror;
1303         int ret;
1304
1305         dmirror = filp->private_data;
1306         if (!dmirror)
1307                 return -EINVAL;
1308
1309         if (copy_from_user(&cmd, uarg, sizeof(cmd)))
1310                 return -EFAULT;
1311
1312         if (cmd.addr & ~PAGE_MASK)
1313                 return -EINVAL;
1314         if (cmd.addr >= (cmd.addr + (cmd.npages << PAGE_SHIFT)))
1315                 return -EINVAL;
1316
1317         cmd.cpages = 0;
1318         cmd.faults = 0;
1319
1320         switch (command) {
1321         case HMM_DMIRROR_READ:
1322                 ret = dmirror_read(dmirror, &cmd);
1323                 break;
1324
1325         case HMM_DMIRROR_WRITE:
1326                 ret = dmirror_write(dmirror, &cmd);
1327                 break;
1328
1329         case HMM_DMIRROR_MIGRATE_TO_DEV:
1330                 ret = dmirror_migrate_to_device(dmirror, &cmd);
1331                 break;
1332
1333         case HMM_DMIRROR_MIGRATE_TO_SYS:
1334                 ret = dmirror_migrate_to_system(dmirror, &cmd);
1335                 break;
1336
1337         case HMM_DMIRROR_EXCLUSIVE:
1338                 ret = dmirror_exclusive(dmirror, &cmd);
1339                 break;
1340
1341         case HMM_DMIRROR_CHECK_EXCLUSIVE:
1342                 ret = dmirror_check_atomic(dmirror, cmd.addr,
1343                                         cmd.addr + (cmd.npages << PAGE_SHIFT));
1344                 break;
1345
1346         case HMM_DMIRROR_SNAPSHOT:
1347                 ret = dmirror_snapshot(dmirror, &cmd);
1348                 break;
1349
1350         case HMM_DMIRROR_RELEASE:
1351                 dmirror_device_remove_chunks(dmirror->mdevice);
1352                 ret = 0;
1353                 break;
1354
1355         default:
1356                 return -EINVAL;
1357         }
1358         if (ret)
1359                 return ret;
1360
1361         if (copy_to_user(uarg, &cmd, sizeof(cmd)))
1362                 return -EFAULT;
1363
1364         return 0;
1365 }
1366
1367 static int dmirror_fops_mmap(struct file *file, struct vm_area_struct *vma)
1368 {
1369         unsigned long addr;
1370
1371         for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) {
1372                 struct page *page;
1373                 int ret;
1374
1375                 page = alloc_page(GFP_KERNEL | __GFP_ZERO);
1376                 if (!page)
1377                         return -ENOMEM;
1378
1379                 ret = vm_insert_page(vma, addr, page);
1380                 if (ret) {
1381                         __free_page(page);
1382                         return ret;
1383                 }
1384                 put_page(page);
1385         }
1386
1387         return 0;
1388 }
1389
1390 static const struct file_operations dmirror_fops = {
1391         .open           = dmirror_fops_open,
1392         .release        = dmirror_fops_release,
1393         .mmap           = dmirror_fops_mmap,
1394         .unlocked_ioctl = dmirror_fops_unlocked_ioctl,
1395         .llseek         = default_llseek,
1396         .owner          = THIS_MODULE,
1397 };
1398
1399 static void dmirror_devmem_free(struct page *page)
1400 {
1401         struct page *rpage = BACKING_PAGE(page);
1402         struct dmirror_device *mdevice;
1403
1404         if (rpage != page)
1405                 __free_page(rpage);
1406
1407         mdevice = dmirror_page_to_device(page);
1408         spin_lock(&mdevice->lock);
1409
1410         /* Return page to our allocator if not freeing the chunk */
1411         if (!dmirror_page_to_chunk(page)->remove) {
1412                 mdevice->cfree++;
1413                 page->zone_device_data = mdevice->free_pages;
1414                 mdevice->free_pages = page;
1415         }
1416         spin_unlock(&mdevice->lock);
1417 }
1418
1419 static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf)
1420 {
1421         struct migrate_vma args = { 0 };
1422         unsigned long src_pfns = 0;
1423         unsigned long dst_pfns = 0;
1424         struct page *rpage;
1425         struct dmirror *dmirror;
1426         vm_fault_t ret;
1427
1428         /*
1429          * Normally, a device would use the page->zone_device_data to point to
1430          * the mirror but here we use it to hold the page for the simulated
1431          * device memory and that page holds the pointer to the mirror.
1432          */
1433         rpage = vmf->page->zone_device_data;
1434         dmirror = rpage->zone_device_data;
1435
1436         /* FIXME demonstrate how we can adjust migrate range */
1437         args.vma = vmf->vma;
1438         args.start = vmf->address;
1439         args.end = args.start + PAGE_SIZE;
1440         args.src = &src_pfns;
1441         args.dst = &dst_pfns;
1442         args.pgmap_owner = dmirror->mdevice;
1443         args.flags = dmirror_select_device(dmirror);
1444         args.fault_page = vmf->page;
1445
1446         if (migrate_vma_setup(&args))
1447                 return VM_FAULT_SIGBUS;
1448
1449         ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
1450         if (ret)
1451                 return ret;
1452         migrate_vma_pages(&args);
1453         /*
1454          * No device finalize step is needed since
1455          * dmirror_devmem_fault_alloc_and_copy() will have already
1456          * invalidated the device page table.
1457          */
1458         migrate_vma_finalize(&args);
1459         return 0;
1460 }
1461
1462 static const struct dev_pagemap_ops dmirror_devmem_ops = {
1463         .page_free      = dmirror_devmem_free,
1464         .migrate_to_ram = dmirror_devmem_fault,
1465 };
1466
1467 static int dmirror_device_init(struct dmirror_device *mdevice, int id)
1468 {
1469         dev_t dev;
1470         int ret;
1471
1472         dev = MKDEV(MAJOR(dmirror_dev), id);
1473         mutex_init(&mdevice->devmem_lock);
1474         spin_lock_init(&mdevice->lock);
1475
1476         cdev_init(&mdevice->cdevice, &dmirror_fops);
1477         mdevice->cdevice.owner = THIS_MODULE;
1478         device_initialize(&mdevice->device);
1479         mdevice->device.devt = dev;
1480
1481         ret = dev_set_name(&mdevice->device, "hmm_dmirror%u", id);
1482         if (ret)
1483                 return ret;
1484
1485         ret = cdev_device_add(&mdevice->cdevice, &mdevice->device);
1486         if (ret)
1487                 return ret;
1488
1489         /* Build a list of free ZONE_DEVICE struct pages */
1490         return dmirror_allocate_chunk(mdevice, NULL);
1491 }
1492
1493 static void dmirror_device_remove(struct dmirror_device *mdevice)
1494 {
1495         dmirror_device_remove_chunks(mdevice);
1496         cdev_device_del(&mdevice->cdevice, &mdevice->device);
1497 }
1498
1499 static int __init hmm_dmirror_init(void)
1500 {
1501         int ret;
1502         int id = 0;
1503         int ndevices = 0;
1504
1505         ret = alloc_chrdev_region(&dmirror_dev, 0, DMIRROR_NDEVICES,
1506                                   "HMM_DMIRROR");
1507         if (ret)
1508                 goto err_unreg;
1509
1510         memset(dmirror_devices, 0, DMIRROR_NDEVICES * sizeof(dmirror_devices[0]));
1511         dmirror_devices[ndevices++].zone_device_type =
1512                                 HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
1513         dmirror_devices[ndevices++].zone_device_type =
1514                                 HMM_DMIRROR_MEMORY_DEVICE_PRIVATE;
1515         if (spm_addr_dev0 && spm_addr_dev1) {
1516                 dmirror_devices[ndevices++].zone_device_type =
1517                                         HMM_DMIRROR_MEMORY_DEVICE_COHERENT;
1518                 dmirror_devices[ndevices++].zone_device_type =
1519                                         HMM_DMIRROR_MEMORY_DEVICE_COHERENT;
1520         }
1521         for (id = 0; id < ndevices; id++) {
1522                 ret = dmirror_device_init(dmirror_devices + id, id);
1523                 if (ret)
1524                         goto err_chrdev;
1525         }
1526
1527         pr_info("HMM test module loaded. This is only for testing HMM.\n");
1528         return 0;
1529
1530 err_chrdev:
1531         while (--id >= 0)
1532                 dmirror_device_remove(dmirror_devices + id);
1533         unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
1534 err_unreg:
1535         return ret;
1536 }
1537
1538 static void __exit hmm_dmirror_exit(void)
1539 {
1540         int id;
1541
1542         for (id = 0; id < DMIRROR_NDEVICES; id++)
1543                 if (dmirror_devices[id].zone_device_type)
1544                         dmirror_device_remove(dmirror_devices + id);
1545         unregister_chrdev_region(dmirror_dev, DMIRROR_NDEVICES);
1546 }
1547
1548 module_init(hmm_dmirror_init);
1549 module_exit(hmm_dmirror_exit);
1550 MODULE_DESCRIPTION("HMM (Heterogeneous Memory Management) test module");
1551 MODULE_LICENSE("GPL");