drivers/fpga/dfl-afu-dma-region.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Driver for FPGA Accelerated Function Unit (AFU) DMA Region Management
   4  *
   5  * Copyright (C) 2017-2018 Intel Corporation, Inc.
   6  *
   7  * Authors:
   8  *   Wu Hao <hao.wu@intel.com>
   9  *   Xiao Guangrong <guangrong.xiao@linux.intel.com>
  10  */
  11
  12 #include <linux/dma-mapping.h>
  13 #include <linux/sched/signal.h>
  14 #include <linux/uaccess.h>
  15
  16 #include "dfl-afu.h"
  17
  18 static void put_all_pages(struct page **pages, int npages)
  19 {
  20         int i;
  21
  22         for (i = 0; i < npages; i++)
  23                 if (pages[i])
  24                         put_page(pages[i]);
  25 }
  26
  27 void afu_dma_region_init(struct dfl_feature_platform_data *pdata)
  28 {
  29         struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
  30
  31         afu->dma_regions = RB_ROOT;
  32 }
  33
  34 /**
  35  * afu_dma_adjust_locked_vm - adjust locked memory
  36  * @dev: port device
  37  * @npages: number of pages
  38  * @incr: increase or decrease locked memory
  39  *
  40  * Increase or decrease the locked memory size with npages input.
  41  *
  42  * Return 0 on success.
  43  * Return -ENOMEM if locked memory size is over the limit and no CAP_IPC_LOCK.
  44  */
  45 static int afu_dma_adjust_locked_vm(struct device *dev, long npages, bool incr)
  46 {
  47         unsigned long locked, lock_limit;
  48         int ret = 0;
  49
  50         /* the task is exiting. */
  51         if (!current->mm)
  52                 return 0;
  53
  54         down_write(&current->mm->mmap_sem);
  55
  56         if (incr) {
  57                 locked = current->mm->locked_vm + npages;
  58                 lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
  59
  60                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
  61                         ret = -ENOMEM;
  62                 else
  63                         current->mm->locked_vm += npages;
  64         } else {
  65                 if (WARN_ON_ONCE(npages > current->mm->locked_vm))
  66                         npages = current->mm->locked_vm;
  67                 current->mm->locked_vm -= npages;
  68         }
  69
  70         dev_dbg(dev, "[%d] RLIMIT_MEMLOCK %c%ld %ld/%ld%s\n", current->pid,
  71                 incr ? '+' : '-', npages << PAGE_SHIFT,
  72                 current->mm->locked_vm << PAGE_SHIFT, rlimit(RLIMIT_MEMLOCK),
  73                 ret ? "- exceeded" : "");
  74
  75         up_write(&current->mm->mmap_sem);
  76
  77         return ret;
  78 }
  79
  80 /**
  81  * afu_dma_pin_pages - pin pages of given dma memory region
  82  * @pdata: feature device platform data
  83  * @region: dma memory region to be pinned
  84  *
  85  * Pin all the pages of given dfl_afu_dma_region.
  86  * Return 0 for success or negative error code.
  87  */
  88 static int afu_dma_pin_pages(struct dfl_feature_platform_data *pdata,
  89                              struct dfl_afu_dma_region *region)
  90 {
  91         int npages = region->length >> PAGE_SHIFT;
  92         struct device *dev = &pdata->dev->dev;
  93         int ret, pinned;
  94
  95         ret = afu_dma_adjust_locked_vm(dev, npages, true);
  96         if (ret)
  97                 return ret;
  98
  99         region->pages = kcalloc(npages, sizeof(struct page *), GFP_KERNEL);
 100         if (!region->pages) {
 101                 ret = -ENOMEM;
 102                 goto unlock_vm;
 103         }
 104
 105         pinned = get_user_pages_fast(region->user_addr, npages, 1,
 106                                      region->pages);
 107         if (pinned < 0) {
 108                 ret = pinned;
 109                 goto put_pages;
 110         } else if (pinned != npages) {
 111                 ret = -EFAULT;
 112                 goto free_pages;
 113         }
 114
 115         dev_dbg(dev, "%d pages pinned\n", pinned);
 116
 117         return 0;
 118
 119 put_pages:
 120         put_all_pages(region->pages, pinned);
 121 free_pages:
 122         kfree(region->pages);
 123 unlock_vm:
 124         afu_dma_adjust_locked_vm(dev, npages, false);
 125         return ret;
 126 }
 127
 128 /**
 129  * afu_dma_unpin_pages - unpin pages of given dma memory region
 130  * @pdata: feature device platform data
 131  * @region: dma memory region to be unpinned
 132  *
 133  * Unpin all the pages of given dfl_afu_dma_region.
 134  * Return 0 for success or negative error code.
 135  */
 136 static void afu_dma_unpin_pages(struct dfl_feature_platform_data *pdata,
 137                                 struct dfl_afu_dma_region *region)
 138 {
 139         long npages = region->length >> PAGE_SHIFT;
 140         struct device *dev = &pdata->dev->dev;
 141
 142         put_all_pages(region->pages, npages);
 143         kfree(region->pages);
 144         afu_dma_adjust_locked_vm(dev, npages, false);
 145
 146         dev_dbg(dev, "%ld pages unpinned\n", npages);
 147 }
 148
 149 /**
 150  * afu_dma_check_continuous_pages - check if pages are continuous
 151  * @region: dma memory region
 152  *
 153  * Return true if pages of given dma memory region have continuous physical
 154  * address, otherwise return false.
 155  */
 156 static bool afu_dma_check_continuous_pages(struct dfl_afu_dma_region *region)
 157 {
 158         int npages = region->length >> PAGE_SHIFT;
 159         int i;
 160
 161         for (i = 0; i < npages - 1; i++)
 162                 if (page_to_pfn(region->pages[i]) + 1 !=
 163                                 page_to_pfn(region->pages[i + 1]))
 164                         return false;
 165
 166         return true;
 167 }
 168
 169 /**
 170  * dma_region_check_iova - check if memory area is fully contained in the region
 171  * @region: dma memory region
 172  * @iova: address of the dma memory area
 173  * @size: size of the dma memory area
 174  *
 175  * Compare the dma memory area defined by @iova and @size with given dma region.
 176  * Return true if memory area is fully contained in the region, otherwise false.
 177  */
 178 static bool dma_region_check_iova(struct dfl_afu_dma_region *region,
 179                                   u64 iova, u64 size)
 180 {
 181         if (!size && region->iova != iova)
 182                 return false;
 183
 184         return (region->iova <= iova) &&
 185                 (region->length + region->iova >= iova + size);
 186 }
 187
 188 /**
 189  * afu_dma_region_add - add given dma region to rbtree
 190  * @pdata: feature device platform data
 191  * @region: dma region to be added
 192  *
 193  * Return 0 for success, -EEXIST if dma region has already been added.
 194  *
 195  * Needs to be called with pdata->lock heold.
 196  */
 197 static int afu_dma_region_add(struct dfl_feature_platform_data *pdata,
 198                               struct dfl_afu_dma_region *region)
 199 {
 200         struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
 201         struct rb_node **new, *parent = NULL;
 202
 203         dev_dbg(&pdata->dev->dev, "add region (iova = %llx)\n",
 204                 (unsigned long long)region->iova);
 205
 206         new = &afu->dma_regions.rb_node;
 207
 208         while (*new) {
 209                 struct dfl_afu_dma_region *this;
 210
 211                 this = container_of(*new, struct dfl_afu_dma_region, node);
 212
 213                 parent = *new;
 214
 215                 if (dma_region_check_iova(this, region->iova, region->length))
 216                         return -EEXIST;
 217
 218                 if (region->iova < this->iova)
 219                         new = &((*new)->rb_left);
 220                 else if (region->iova > this->iova)
 221                         new = &((*new)->rb_right);
 222                 else
 223                         return -EEXIST;
 224         }
 225
 226         rb_link_node(&region->node, parent, new);
 227         rb_insert_color(&region->node, &afu->dma_regions);
 228
 229         return 0;
 230 }
 231
 232 /**
 233  * afu_dma_region_remove - remove given dma region from rbtree
 234  * @pdata: feature device platform data
 235  * @region: dma region to be removed
 236  *
 237  * Needs to be called with pdata->lock heold.
 238  */
 239 static void afu_dma_region_remove(struct dfl_feature_platform_data *pdata,
 240                                   struct dfl_afu_dma_region *region)
 241 {
 242         struct dfl_afu *afu;
 243
 244         dev_dbg(&pdata->dev->dev, "del region (iova = %llx)\n",
 245                 (unsigned long long)region->iova);
 246
 247         afu = dfl_fpga_pdata_get_private(pdata);
 248         rb_erase(&region->node, &afu->dma_regions);
 249 }
 250
 251 /**
 252  * afu_dma_region_destroy - destroy all regions in rbtree
 253  * @pdata: feature device platform data
 254  *
 255  * Needs to be called with pdata->lock heold.
 256  */
 257 void afu_dma_region_destroy(struct dfl_feature_platform_data *pdata)
 258 {
 259         struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
 260         struct rb_node *node = rb_first(&afu->dma_regions);
 261         struct dfl_afu_dma_region *region;
 262
 263         while (node) {
 264                 region = container_of(node, struct dfl_afu_dma_region, node);
 265
 266                 dev_dbg(&pdata->dev->dev, "del region (iova = %llx)\n",
 267                         (unsigned long long)region->iova);
 268
 269                 rb_erase(node, &afu->dma_regions);
 270
 271                 if (region->iova)
 272                         dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
 273                                        region->iova, region->length,
 274                                        DMA_BIDIRECTIONAL);
 275
 276                 if (region->pages)
 277                         afu_dma_unpin_pages(pdata, region);
 278
 279                 node = rb_next(node);
 280                 kfree(region);
 281         }
 282 }
 283
 284 /**
 285  * afu_dma_region_find - find the dma region from rbtree based on iova and size
 286  * @pdata: feature device platform data
 287  * @iova: address of the dma memory area
 288  * @size: size of the dma memory area
 289  *
 290  * It finds the dma region from the rbtree based on @iova and @size:
 291  * - if @size == 0, it finds the dma region which starts from @iova
 292  * - otherwise, it finds the dma region which fully contains
 293  *   [@iova, @iova+size)
 294  * If nothing is matched returns NULL.
 295  *
 296  * Needs to be called with pdata->lock held.
 297  */
 298 struct dfl_afu_dma_region *
 299 afu_dma_region_find(struct dfl_feature_platform_data *pdata, u64 iova, u64 size)
 300 {
 301         struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
 302         struct rb_node *node = afu->dma_regions.rb_node;
 303         struct device *dev = &pdata->dev->dev;
 304
 305         while (node) {
 306                 struct dfl_afu_dma_region *region;
 307
 308                 region = container_of(node, struct dfl_afu_dma_region, node);
 309
 310                 if (dma_region_check_iova(region, iova, size)) {
 311                         dev_dbg(dev, "find region (iova = %llx)\n",
 312                                 (unsigned long long)region->iova);
 313                         return region;
 314                 }
 315
 316                 if (iova < region->iova)
 317                         node = node->rb_left;
 318                 else if (iova > region->iova)
 319                         node = node->rb_right;
 320                 else
 321                         /* the iova region is not fully covered. */
 322                         break;
 323         }
 324
 325         dev_dbg(dev, "region with iova %llx and size %llx is not found\n",
 326                 (unsigned long long)iova, (unsigned long long)size);
 327
 328         return NULL;
 329 }
 330
 331 /**
 332  * afu_dma_region_find_iova - find the dma region from rbtree by iova
 333  * @pdata: feature device platform data
 334  * @iova: address of the dma region
 335  *
 336  * Needs to be called with pdata->lock held.
 337  */
 338 static struct dfl_afu_dma_region *
 339 afu_dma_region_find_iova(struct dfl_feature_platform_data *pdata, u64 iova)
 340 {
 341         return afu_dma_region_find(pdata, iova, 0);
 342 }
 343
 344 /**
 345  * afu_dma_map_region - map memory region for dma
 346  * @pdata: feature device platform data
 347  * @user_addr: address of the memory region
 348  * @length: size of the memory region
 349  * @iova: pointer of iova address
 350  *
 351  * Map memory region defined by @user_addr and @length, and return dma address
 352  * of the memory region via @iova.
 353  * Return 0 for success, otherwise error code.
 354  */
 355 int afu_dma_map_region(struct dfl_feature_platform_data *pdata,
 356                        u64 user_addr, u64 length, u64 *iova)
 357 {
 358         struct dfl_afu_dma_region *region;
 359         int ret;
 360
 361         /*
 362          * Check Inputs, only accept page-aligned user memory region with
 363          * valid length.
 364          */
 365         if (!PAGE_ALIGNED(user_addr) || !PAGE_ALIGNED(length) || !length)
 366                 return -EINVAL;
 367
 368         /* Check overflow */
 369         if (user_addr + length < user_addr)
 370                 return -EINVAL;
 371
 372         if (!access_ok((void __user *)(unsigned long)user_addr,
 373                        length))
 374                 return -EINVAL;
 375
 376         region = kzalloc(sizeof(*region), GFP_KERNEL);
 377         if (!region)
 378                 return -ENOMEM;
 379
 380         region->user_addr = user_addr;
 381         region->length = length;
 382
 383         /* Pin the user memory region */
 384         ret = afu_dma_pin_pages(pdata, region);
 385         if (ret) {
 386                 dev_err(&pdata->dev->dev, "failed to pin memory region\n");
 387                 goto free_region;
 388         }
 389
 390         /* Only accept continuous pages, return error else */
 391         if (!afu_dma_check_continuous_pages(region)) {
 392                 dev_err(&pdata->dev->dev, "pages are not continuous\n");
 393                 ret = -EINVAL;
 394                 goto unpin_pages;
 395         }
 396
 397         /* As pages are continuous then start to do DMA mapping */
 398         region->iova = dma_map_page(dfl_fpga_pdata_to_parent(pdata),
 399                                     region->pages[0], 0,
 400                                     region->length,
 401                                     DMA_BIDIRECTIONAL);
 402         if (dma_mapping_error(&pdata->dev->dev, region->iova)) {
 403                 dev_err(&pdata->dev->dev, "failed to map for dma\n");
 404                 ret = -EFAULT;
 405                 goto unpin_pages;
 406         }
 407
 408         *iova = region->iova;
 409
 410         mutex_lock(&pdata->lock);
 411         ret = afu_dma_region_add(pdata, region);
 412         mutex_unlock(&pdata->lock);
 413         if (ret) {
 414                 dev_err(&pdata->dev->dev, "failed to add dma region\n");
 415                 goto unmap_dma;
 416         }
 417
 418         return 0;
 419
 420 unmap_dma:
 421         dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
 422                        region->iova, region->length, DMA_BIDIRECTIONAL);
 423 unpin_pages:
 424         afu_dma_unpin_pages(pdata, region);
 425 free_region:
 426         kfree(region);
 427         return ret;
 428 }
 429
 430 /**
 431  * afu_dma_unmap_region - unmap dma memory region
 432  * @pdata: feature device platform data
 433  * @iova: dma address of the region
 434  *
 435  * Unmap dma memory region based on @iova.
 436  * Return 0 for success, otherwise error code.
 437  */
 438 int afu_dma_unmap_region(struct dfl_feature_platform_data *pdata, u64 iova)
 439 {
 440         struct dfl_afu_dma_region *region;
 441
 442         mutex_lock(&pdata->lock);
 443         region = afu_dma_region_find_iova(pdata, iova);
 444         if (!region) {
 445                 mutex_unlock(&pdata->lock);
 446                 return -EINVAL;
 447         }
 448
 449         if (region->in_use) {
 450                 mutex_unlock(&pdata->lock);
 451                 return -EBUSY;
 452         }
 453
 454         afu_dma_region_remove(pdata, region);
 455         mutex_unlock(&pdata->lock);
 456
 457         dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
 458                        region->iova, region->length, DMA_BIDIRECTIONAL);
 459         afu_dma_unpin_pages(pdata, region);
 460         kfree(region);
 461
 462         return 0;
 463 }