drivers/vfio/vfio_iommu_spapr_tce.c

   1 /*
   2  * VFIO: IOMMU DMA mapping support for TCE on POWER
   3  *
   4  * Copyright (C) 2013 IBM Corp.  All rights reserved.
   5  *     Author: Alexey Kardashevskiy <aik@ozlabs.ru>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * Derived from original vfio_iommu_type1.c:
  12  * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
  13  *     Author: Alex Williamson <alex.williamson@redhat.com>
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/pci.h>
  18 #include <linux/slab.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/err.h>
  21 #include <linux/vfio.h>
  22 #include <asm/iommu.h>
  23 #include <asm/tce.h>
  24
  25 #define DRIVER_VERSION  "0.1"
  26 #define DRIVER_AUTHOR   "aik@ozlabs.ru"
  27 #define DRIVER_DESC     "VFIO IOMMU SPAPR TCE"
  28
  29 static void tce_iommu_detach_group(void *iommu_data,
  30                 struct iommu_group *iommu_group);
  31
  32 static long try_increment_locked_vm(long npages)
  33 {
  34         long ret = 0, locked, lock_limit;
  35
  36         if (!current || !current->mm)
  37                 return -ESRCH; /* process exited */
  38
  39         if (!npages)
  40                 return 0;
  41
  42         down_write(&current->mm->mmap_sem);
  43         locked = current->mm->locked_vm + npages;
  44         lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
  45         if (locked > lock_limit && !capable(CAP_IPC_LOCK))
  46                 ret = -ENOMEM;
  47         else
  48                 current->mm->locked_vm += npages;
  49
  50         pr_debug("[%d] RLIMIT_MEMLOCK +%ld %ld/%ld%s\n", current->pid,
  51                         npages << PAGE_SHIFT,
  52                         current->mm->locked_vm << PAGE_SHIFT,
  53                         rlimit(RLIMIT_MEMLOCK),
  54                         ret ? " - exceeded" : "");
  55
  56         up_write(&current->mm->mmap_sem);
  57
  58         return ret;
  59 }
  60
  61 static void decrement_locked_vm(long npages)
  62 {
  63         if (!current || !current->mm || !npages)
  64                 return; /* process exited */
  65
  66         down_write(&current->mm->mmap_sem);
  67         if (WARN_ON_ONCE(npages > current->mm->locked_vm))
  68                 npages = current->mm->locked_vm;
  69         current->mm->locked_vm -= npages;
  70         pr_debug("[%d] RLIMIT_MEMLOCK -%ld %ld/%ld\n", current->pid,
  71                         npages << PAGE_SHIFT,
  72                         current->mm->locked_vm << PAGE_SHIFT,
  73                         rlimit(RLIMIT_MEMLOCK));
  74         up_write(&current->mm->mmap_sem);
  75 }
  76
  77 /*
  78  * VFIO IOMMU fd for SPAPR_TCE IOMMU implementation
  79  *
  80  * This code handles mapping and unmapping of user data buffers
  81  * into DMA'ble space using the IOMMU
  82  */
  83
  84 /*
  85  * The container descriptor supports only a single group per container.
  86  * Required by the API as the container is not supplied with the IOMMU group
  87  * at the moment of initialization.
  88  */
  89 struct tce_container {
  90         struct mutex lock;
  91         struct iommu_group *grp;
  92         bool enabled;
  93         unsigned long locked_pages;
  94 };
  95
  96 static bool tce_page_is_contained(struct page *page, unsigned page_shift)
  97 {
  98         /*
  99          * Check that the TCE table granularity is not bigger than the size of
 100          * a page we just found. Otherwise the hardware can get access to
 101          * a bigger memory chunk that it should.
 102          */
 103         return (PAGE_SHIFT + compound_order(compound_head(page))) >= page_shift;
 104 }
 105
 106 static long tce_iommu_find_table(struct tce_container *container,
 107                 phys_addr_t ioba, struct iommu_table **ptbl)
 108 {
 109         long i;
 110         struct iommu_table_group *table_group;
 111
 112         table_group = iommu_group_get_iommudata(container->grp);
 113         if (!table_group)
 114                 return -1;
 115
 116         for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
 117                 struct iommu_table *tbl = table_group->tables[i];
 118
 119                 if (tbl) {
 120                         unsigned long entry = ioba >> tbl->it_page_shift;
 121                         unsigned long start = tbl->it_offset;
 122                         unsigned long end = start + tbl->it_size;
 123
 124                         if ((start <= entry) && (entry < end)) {
 125                                 *ptbl = tbl;
 126                                 return i;
 127                         }
 128                 }
 129         }
 130
 131         return -1;
 132 }
 133
 134 static int tce_iommu_enable(struct tce_container *container)
 135 {
 136         int ret = 0;
 137         unsigned long locked;
 138         struct iommu_table *tbl;
 139         struct iommu_table_group *table_group;
 140
 141         if (!container->grp)
 142                 return -ENXIO;
 143
 144         if (!current->mm)
 145                 return -ESRCH; /* process exited */
 146
 147         if (container->enabled)
 148                 return -EBUSY;
 149
 150         /*
 151          * When userspace pages are mapped into the IOMMU, they are effectively
 152          * locked memory, so, theoretically, we need to update the accounting
 153          * of locked pages on each map and unmap.  For powerpc, the map unmap
 154          * paths can be very hot, though, and the accounting would kill
 155          * performance, especially since it would be difficult to impossible
 156          * to handle the accounting in real mode only.
 157          *
 158          * To address that, rather than precisely accounting every page, we
 159          * instead account for a worst case on locked memory when the iommu is
 160          * enabled and disabled.  The worst case upper bound on locked memory
 161          * is the size of the whole iommu window, which is usually relatively
 162          * small (compared to total memory sizes) on POWER hardware.
 163          *
 164          * Also we don't have a nice way to fail on H_PUT_TCE due to ulimits,
 165          * that would effectively kill the guest at random points, much better
 166          * enforcing the limit based on the max that the guest can map.
 167          *
 168          * Unfortunately at the moment it counts whole tables, no matter how
 169          * much memory the guest has. I.e. for 4GB guest and 4 IOMMU groups
 170          * each with 2GB DMA window, 8GB will be counted here. The reason for
 171          * this is that we cannot tell here the amount of RAM used by the guest
 172          * as this information is only available from KVM and VFIO is
 173          * KVM agnostic.
 174          */
 175         table_group = iommu_group_get_iommudata(container->grp);
 176         if (!table_group)
 177                 return -ENODEV;
 178
 179         tbl = table_group->tables[0];
 180         locked = (tbl->it_size << tbl->it_page_shift) >> PAGE_SHIFT;
 181         ret = try_increment_locked_vm(locked);
 182         if (ret)
 183                 return ret;
 184
 185         container->locked_pages = locked;
 186
 187         container->enabled = true;
 188
 189         return ret;
 190 }
 191
 192 static void tce_iommu_disable(struct tce_container *container)
 193 {
 194         if (!container->enabled)
 195                 return;
 196
 197         container->enabled = false;
 198
 199         if (!current->mm)
 200                 return;
 201
 202         decrement_locked_vm(container->locked_pages);
 203 }
 204
 205 static void *tce_iommu_open(unsigned long arg)
 206 {
 207         struct tce_container *container;
 208
 209         if (arg != VFIO_SPAPR_TCE_IOMMU) {
 210                 pr_err("tce_vfio: Wrong IOMMU type\n");
 211                 return ERR_PTR(-EINVAL);
 212         }
 213
 214         container = kzalloc(sizeof(*container), GFP_KERNEL);
 215         if (!container)
 216                 return ERR_PTR(-ENOMEM);
 217
 218         mutex_init(&container->lock);
 219
 220         return container;
 221 }
 222
 223 static void tce_iommu_release(void *iommu_data)
 224 {
 225         struct tce_container *container = iommu_data;
 226
 227         WARN_ON(container->grp);
 228
 229         if (container->grp)
 230                 tce_iommu_detach_group(iommu_data, container->grp);
 231
 232         tce_iommu_disable(container);
 233         mutex_destroy(&container->lock);
 234
 235         kfree(container);
 236 }
 237
 238 static void tce_iommu_unuse_page(struct tce_container *container,
 239                 unsigned long oldtce)
 240 {
 241         struct page *page;
 242
 243         if (!(oldtce & (TCE_PCI_READ | TCE_PCI_WRITE)))
 244                 return;
 245
 246         page = pfn_to_page(oldtce >> PAGE_SHIFT);
 247
 248         if (oldtce & TCE_PCI_WRITE)
 249                 SetPageDirty(page);
 250
 251         put_page(page);
 252 }
 253
 254 static int tce_iommu_clear(struct tce_container *container,
 255                 struct iommu_table *tbl,
 256                 unsigned long entry, unsigned long pages)
 257 {
 258         unsigned long oldtce;
 259
 260         for ( ; pages; --pages, ++entry) {
 261                 oldtce = iommu_clear_tce(tbl, entry);
 262                 if (!oldtce)
 263                         continue;
 264
 265                 tce_iommu_unuse_page(container, oldtce);
 266         }
 267
 268         return 0;
 269 }
 270
 271 static int tce_iommu_use_page(unsigned long tce, unsigned long *hpa)
 272 {
 273         struct page *page = NULL;
 274         enum dma_data_direction direction = iommu_tce_direction(tce);
 275
 276         if (get_user_pages_fast(tce & PAGE_MASK, 1,
 277                         direction != DMA_TO_DEVICE, &page) != 1)
 278                 return -EFAULT;
 279
 280         *hpa = __pa((unsigned long) page_address(page));
 281
 282         return 0;
 283 }
 284
 285 static long tce_iommu_build(struct tce_container *container,
 286                 struct iommu_table *tbl,
 287                 unsigned long entry, unsigned long tce, unsigned long pages)
 288 {
 289         long i, ret = 0;
 290         struct page *page;
 291         unsigned long hpa;
 292         enum dma_data_direction direction = iommu_tce_direction(tce);
 293
 294         for (i = 0; i < pages; ++i) {
 295                 unsigned long offset = tce & IOMMU_PAGE_MASK(tbl) & ~PAGE_MASK;
 296
 297                 ret = tce_iommu_use_page(tce, &hpa);
 298                 if (ret)
 299                         break;
 300
 301                 page = pfn_to_page(hpa >> PAGE_SHIFT);
 302                 if (!tce_page_is_contained(page, tbl->it_page_shift)) {
 303                         ret = -EPERM;
 304                         break;
 305                 }
 306
 307                 hpa |= offset;
 308                 ret = iommu_tce_build(tbl, entry + i, (unsigned long) __va(hpa),
 309                                 direction);
 310                 if (ret) {
 311                         tce_iommu_unuse_page(container, hpa);
 312                         pr_err("iommu_tce: %s failed ioba=%lx, tce=%lx, ret=%ld\n",
 313                                         __func__, entry << tbl->it_page_shift,
 314                                         tce, ret);
 315                         break;
 316                 }
 317                 tce += IOMMU_PAGE_SIZE(tbl);
 318         }
 319
 320         if (ret)
 321                 tce_iommu_clear(container, tbl, entry, i);
 322
 323         return ret;
 324 }
 325
 326 static long tce_iommu_ioctl(void *iommu_data,
 327                                  unsigned int cmd, unsigned long arg)
 328 {
 329         struct tce_container *container = iommu_data;
 330         unsigned long minsz;
 331         long ret;
 332
 333         switch (cmd) {
 334         case VFIO_CHECK_EXTENSION:
 335                 switch (arg) {
 336                 case VFIO_SPAPR_TCE_IOMMU:
 337                         ret = 1;
 338                         break;
 339                 default:
 340                         ret = vfio_spapr_iommu_eeh_ioctl(NULL, cmd, arg);
 341                         break;
 342                 }
 343
 344                 return (ret < 0) ? 0 : ret;
 345
 346         case VFIO_IOMMU_SPAPR_TCE_GET_INFO: {
 347                 struct vfio_iommu_spapr_tce_info info;
 348                 struct iommu_table *tbl;
 349                 struct iommu_table_group *table_group;
 350
 351                 if (WARN_ON(!container->grp))
 352                         return -ENXIO;
 353
 354                 table_group = iommu_group_get_iommudata(container->grp);
 355
 356                 tbl = table_group->tables[0];
 357                 if (WARN_ON_ONCE(!tbl))
 358                         return -ENXIO;
 359
 360                 minsz = offsetofend(struct vfio_iommu_spapr_tce_info,
 361                                 dma32_window_size);
 362
 363                 if (copy_from_user(&info, (void __user *)arg, minsz))
 364                         return -EFAULT;
 365
 366                 if (info.argsz < minsz)
 367                         return -EINVAL;
 368
 369                 info.dma32_window_start = tbl->it_offset << tbl->it_page_shift;
 370                 info.dma32_window_size = tbl->it_size << tbl->it_page_shift;
 371                 info.flags = 0;
 372
 373                 if (copy_to_user((void __user *)arg, &info, minsz))
 374                         return -EFAULT;
 375
 376                 return 0;
 377         }
 378         case VFIO_IOMMU_MAP_DMA: {
 379                 struct vfio_iommu_type1_dma_map param;
 380                 struct iommu_table *tbl = NULL;
 381                 unsigned long tce;
 382                 long num;
 383
 384                 if (!container->enabled)
 385                         return -EPERM;
 386
 387                 minsz = offsetofend(struct vfio_iommu_type1_dma_map, size);
 388
 389                 if (copy_from_user(&param, (void __user *)arg, minsz))
 390                         return -EFAULT;
 391
 392                 if (param.argsz < minsz)
 393                         return -EINVAL;
 394
 395                 if (param.flags & ~(VFIO_DMA_MAP_FLAG_READ |
 396                                 VFIO_DMA_MAP_FLAG_WRITE))
 397                         return -EINVAL;
 398
 399                 num = tce_iommu_find_table(container, param.iova, &tbl);
 400                 if (num < 0)
 401                         return -ENXIO;
 402
 403                 if ((param.size & ~IOMMU_PAGE_MASK(tbl)) ||
 404                                 (param.vaddr & ~IOMMU_PAGE_MASK(tbl)))
 405                         return -EINVAL;
 406
 407                 /* iova is checked by the IOMMU API */
 408                 tce = param.vaddr;
 409                 if (param.flags & VFIO_DMA_MAP_FLAG_READ)
 410                         tce |= TCE_PCI_READ;
 411                 if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
 412                         tce |= TCE_PCI_WRITE;
 413
 414                 ret = iommu_tce_put_param_check(tbl, param.iova, tce);
 415                 if (ret)
 416                         return ret;
 417
 418                 ret = tce_iommu_build(container, tbl,
 419                                 param.iova >> tbl->it_page_shift,
 420                                 tce, param.size >> tbl->it_page_shift);
 421
 422                 iommu_flush_tce(tbl);
 423
 424                 return ret;
 425         }
 426         case VFIO_IOMMU_UNMAP_DMA: {
 427                 struct vfio_iommu_type1_dma_unmap param;
 428                 struct iommu_table *tbl = NULL;
 429                 long num;
 430
 431                 if (!container->enabled)
 432                         return -EPERM;
 433
 434                 minsz = offsetofend(struct vfio_iommu_type1_dma_unmap,
 435                                 size);
 436
 437                 if (copy_from_user(&param, (void __user *)arg, minsz))
 438                         return -EFAULT;
 439
 440                 if (param.argsz < minsz)
 441                         return -EINVAL;
 442
 443                 /* No flag is supported now */
 444                 if (param.flags)
 445                         return -EINVAL;
 446
 447                 num = tce_iommu_find_table(container, param.iova, &tbl);
 448                 if (num < 0)
 449                         return -ENXIO;
 450
 451                 if (param.size & ~IOMMU_PAGE_MASK(tbl))
 452                         return -EINVAL;
 453
 454                 ret = iommu_tce_clear_param_check(tbl, param.iova, 0,
 455                                 param.size >> tbl->it_page_shift);
 456                 if (ret)
 457                         return ret;
 458
 459                 ret = tce_iommu_clear(container, tbl,
 460                                 param.iova >> tbl->it_page_shift,
 461                                 param.size >> tbl->it_page_shift);
 462                 iommu_flush_tce(tbl);
 463
 464                 return ret;
 465         }
 466         case VFIO_IOMMU_ENABLE:
 467                 mutex_lock(&container->lock);
 468                 ret = tce_iommu_enable(container);
 469                 mutex_unlock(&container->lock);
 470                 return ret;
 471
 472
 473         case VFIO_IOMMU_DISABLE:
 474                 mutex_lock(&container->lock);
 475                 tce_iommu_disable(container);
 476                 mutex_unlock(&container->lock);
 477                 return 0;
 478         case VFIO_EEH_PE_OP:
 479                 if (!container->grp)
 480                         return -ENODEV;
 481
 482                 return vfio_spapr_iommu_eeh_ioctl(container->grp,
 483                                                   cmd, arg);
 484         }
 485
 486         return -ENOTTY;
 487 }
 488
 489 static int tce_iommu_attach_group(void *iommu_data,
 490                 struct iommu_group *iommu_group)
 491 {
 492         int ret;
 493         struct tce_container *container = iommu_data;
 494         struct iommu_table_group *table_group;
 495
 496         mutex_lock(&container->lock);
 497
 498         /* pr_debug("tce_vfio: Attaching group #%u to iommu %p\n",
 499                         iommu_group_id(iommu_group), iommu_group); */
 500         if (container->grp) {
 501                 pr_warn("tce_vfio: Only one group per IOMMU container is allowed, existing id=%d, attaching id=%d\n",
 502                                 iommu_group_id(container->grp),
 503                                 iommu_group_id(iommu_group));
 504                 ret = -EBUSY;
 505                 goto unlock_exit;
 506         }
 507
 508         if (container->enabled) {
 509                 pr_err("tce_vfio: attaching group #%u to enabled container\n",
 510                                 iommu_group_id(iommu_group));
 511                 ret = -EBUSY;
 512                 goto unlock_exit;
 513         }
 514
 515         table_group = iommu_group_get_iommudata(iommu_group);
 516         if (!table_group) {
 517                 ret = -ENXIO;
 518                 goto unlock_exit;
 519         }
 520
 521         ret = iommu_take_ownership(table_group->tables[0]);
 522         if (!ret)
 523                 container->grp = iommu_group;
 524
 525 unlock_exit:
 526         mutex_unlock(&container->lock);
 527
 528         return ret;
 529 }
 530
 531 static void tce_iommu_detach_group(void *iommu_data,
 532                 struct iommu_group *iommu_group)
 533 {
 534         struct tce_container *container = iommu_data;
 535         struct iommu_table_group *table_group;
 536         struct iommu_table *tbl;
 537
 538         mutex_lock(&container->lock);
 539         if (iommu_group != container->grp) {
 540                 pr_warn("tce_vfio: detaching group #%u, expected group is #%u\n",
 541                                 iommu_group_id(iommu_group),
 542                                 iommu_group_id(container->grp));
 543                 goto unlock_exit;
 544         }
 545
 546         if (container->enabled) {
 547                 pr_warn("tce_vfio: detaching group #%u from enabled container, forcing disable\n",
 548                                 iommu_group_id(container->grp));
 549                 tce_iommu_disable(container);
 550         }
 551
 552         /* pr_debug("tce_vfio: detaching group #%u from iommu %p\n",
 553            iommu_group_id(iommu_group), iommu_group); */
 554         container->grp = NULL;
 555
 556         table_group = iommu_group_get_iommudata(iommu_group);
 557         BUG_ON(!table_group);
 558
 559         tbl = table_group->tables[0];
 560         tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
 561         iommu_release_ownership(tbl);
 562
 563 unlock_exit:
 564         mutex_unlock(&container->lock);
 565 }
 566
 567 const struct vfio_iommu_driver_ops tce_iommu_driver_ops = {
 568         .name           = "iommu-vfio-powerpc",
 569         .owner          = THIS_MODULE,
 570         .open           = tce_iommu_open,
 571         .release        = tce_iommu_release,
 572         .ioctl          = tce_iommu_ioctl,
 573         .attach_group   = tce_iommu_attach_group,
 574         .detach_group   = tce_iommu_detach_group,
 575 };
 576
 577 static int __init tce_iommu_init(void)
 578 {
 579         return vfio_register_iommu_driver(&tce_iommu_driver_ops);
 580 }
 581
 582 static void __exit tce_iommu_cleanup(void)
 583 {
 584         vfio_unregister_iommu_driver(&tce_iommu_driver_ops);
 585 }
 586
 587 module_init(tce_iommu_init);
 588 module_exit(tce_iommu_cleanup);
 589
 590 MODULE_VERSION(DRIVER_VERSION);
 591 MODULE_LICENSE("GPL v2");
 592 MODULE_AUTHOR(DRIVER_AUTHOR);
 593 MODULE_DESCRIPTION(DRIVER_DESC);
 594