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