drivers/vdpa/vdpa_sim/vdpa_sim_blk.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * VDPA simulator for block device.
   4  *
   5  * Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
   6  * Copyright (c) 2021, Red Hat Inc. All rights reserved.
   7  *
   8  */
   9
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/device.h>
  13 #include <linux/kernel.h>
  14 #include <linux/blkdev.h>
  15 #include <linux/vringh.h>
  16 #include <linux/vdpa.h>
  17 #include <uapi/linux/virtio_blk.h>
  18
  19 #include "vdpa_sim.h"
  20
  21 #define DRV_VERSION  "0.1"
  22 #define DRV_AUTHOR   "Max Gurtovoy <mgurtovoy@nvidia.com>"
  23 #define DRV_DESC     "vDPA Device Simulator for block device"
  24 #define DRV_LICENSE  "GPL v2"
  25
  26 #define VDPASIM_BLK_FEATURES    (VDPASIM_FEATURES | \
  27                                  (1ULL << VIRTIO_BLK_F_FLUSH)    | \
  28                                  (1ULL << VIRTIO_BLK_F_SIZE_MAX) | \
  29                                  (1ULL << VIRTIO_BLK_F_SEG_MAX)  | \
  30                                  (1ULL << VIRTIO_BLK_F_BLK_SIZE) | \
  31                                  (1ULL << VIRTIO_BLK_F_TOPOLOGY) | \
  32                                  (1ULL << VIRTIO_BLK_F_MQ)       | \
  33                                  (1ULL << VIRTIO_BLK_F_DISCARD)  | \
  34                                  (1ULL << VIRTIO_BLK_F_WRITE_ZEROES))
  35
  36 #define VDPASIM_BLK_CAPACITY    0x40000
  37 #define VDPASIM_BLK_SIZE_MAX    0x1000
  38 #define VDPASIM_BLK_SEG_MAX     32
  39 #define VDPASIM_BLK_DWZ_MAX_SECTORS UINT_MAX
  40
  41 /* 1 virtqueue, 1 address space, 1 virtqueue group */
  42 #define VDPASIM_BLK_VQ_NUM      1
  43 #define VDPASIM_BLK_AS_NUM      1
  44 #define VDPASIM_BLK_GROUP_NUM   1
  45
  46 struct vdpasim_blk {
  47         struct vdpasim vdpasim;
  48         void *buffer;
  49         bool shared_backend;
  50 };
  51
  52 static struct vdpasim_blk *sim_to_blk(struct vdpasim *vdpasim)
  53 {
  54         return container_of(vdpasim, struct vdpasim_blk, vdpasim);
  55 }
  56
  57 static char vdpasim_blk_id[VIRTIO_BLK_ID_BYTES] = "vdpa_blk_sim";
  58
  59 static bool shared_backend;
  60 module_param(shared_backend, bool, 0444);
  61 MODULE_PARM_DESC(shared_backend, "Enable the shared backend between virtio-blk devices");
  62
  63 static void *shared_buffer;
  64 /* mutex to synchronize shared_buffer access */
  65 static DEFINE_MUTEX(shared_buffer_mutex);
  66
  67 static void vdpasim_blk_buffer_lock(struct vdpasim_blk *blk)
  68 {
  69         if (blk->shared_backend)
  70                 mutex_lock(&shared_buffer_mutex);
  71 }
  72
  73 static void vdpasim_blk_buffer_unlock(struct vdpasim_blk *blk)
  74 {
  75         if (blk->shared_backend)
  76                 mutex_unlock(&shared_buffer_mutex);
  77 }
  78
  79 static bool vdpasim_blk_check_range(struct vdpasim *vdpasim, u64 start_sector,
  80                                     u64 num_sectors, u64 max_sectors)
  81 {
  82         if (start_sector > VDPASIM_BLK_CAPACITY) {
  83                 dev_dbg(&vdpasim->vdpa.dev,
  84                         "starting sector exceeds the capacity - start: 0x%llx capacity: 0x%x\n",
  85                         start_sector, VDPASIM_BLK_CAPACITY);
  86         }
  87
  88         if (num_sectors > max_sectors) {
  89                 dev_dbg(&vdpasim->vdpa.dev,
  90                         "number of sectors exceeds the max allowed in a request - num: 0x%llx max: 0x%llx\n",
  91                         num_sectors, max_sectors);
  92                 return false;
  93         }
  94
  95         if (num_sectors > VDPASIM_BLK_CAPACITY - start_sector) {
  96                 dev_dbg(&vdpasim->vdpa.dev,
  97                         "request exceeds the capacity - start: 0x%llx num: 0x%llx capacity: 0x%x\n",
  98                         start_sector, num_sectors, VDPASIM_BLK_CAPACITY);
  99                 return false;
 100         }
 101
 102         return true;
 103 }
 104
 105 /* Returns 'true' if the request is handled (with or without an I/O error)
 106  * and the status is correctly written in the last byte of the 'in iov',
 107  * 'false' otherwise.
 108  */
 109 static bool vdpasim_blk_handle_req(struct vdpasim *vdpasim,
 110                                    struct vdpasim_virtqueue *vq)
 111 {
 112         struct vdpasim_blk *blk = sim_to_blk(vdpasim);
 113         size_t pushed = 0, to_pull, to_push;
 114         struct virtio_blk_outhdr hdr;
 115         bool handled = false;
 116         ssize_t bytes;
 117         loff_t offset;
 118         u64 sector;
 119         u8 status;
 120         u32 type;
 121         int ret;
 122
 123         ret = vringh_getdesc_iotlb(&vq->vring, &vq->out_iov, &vq->in_iov,
 124                                    &vq->head, GFP_ATOMIC);
 125         if (ret != 1)
 126                 return false;
 127
 128         if (vq->out_iov.used < 1 || vq->in_iov.used < 1) {
 129                 dev_dbg(&vdpasim->vdpa.dev, "missing headers - out_iov: %u in_iov %u\n",
 130                         vq->out_iov.used, vq->in_iov.used);
 131                 goto err;
 132         }
 133
 134         if (vq->in_iov.iov[vq->in_iov.used - 1].iov_len < 1) {
 135                 dev_dbg(&vdpasim->vdpa.dev, "request in header too short\n");
 136                 goto err;
 137         }
 138
 139         /* The last byte is the status and we checked if the last iov has
 140          * enough room for it.
 141          */
 142         to_push = vringh_kiov_length(&vq->in_iov) - 1;
 143
 144         to_pull = vringh_kiov_length(&vq->out_iov);
 145
 146         bytes = vringh_iov_pull_iotlb(&vq->vring, &vq->out_iov, &hdr,
 147                                       sizeof(hdr));
 148         if (bytes != sizeof(hdr)) {
 149                 dev_dbg(&vdpasim->vdpa.dev, "request out header too short\n");
 150                 goto err;
 151         }
 152
 153         to_pull -= bytes;
 154
 155         type = vdpasim32_to_cpu(vdpasim, hdr.type);
 156         sector = vdpasim64_to_cpu(vdpasim, hdr.sector);
 157         offset = sector << SECTOR_SHIFT;
 158         status = VIRTIO_BLK_S_OK;
 159
 160         if (type != VIRTIO_BLK_T_IN && type != VIRTIO_BLK_T_OUT &&
 161             sector != 0) {
 162                 dev_dbg(&vdpasim->vdpa.dev,
 163                         "sector must be 0 for %u request - sector: 0x%llx\n",
 164                         type, sector);
 165                 status = VIRTIO_BLK_S_IOERR;
 166                 goto err_status;
 167         }
 168
 169         switch (type) {
 170         case VIRTIO_BLK_T_IN:
 171                 if (!vdpasim_blk_check_range(vdpasim, sector,
 172                                              to_push >> SECTOR_SHIFT,
 173                                              VDPASIM_BLK_SIZE_MAX * VDPASIM_BLK_SEG_MAX)) {
 174                         status = VIRTIO_BLK_S_IOERR;
 175                         break;
 176                 }
 177
 178                 vdpasim_blk_buffer_lock(blk);
 179                 bytes = vringh_iov_push_iotlb(&vq->vring, &vq->in_iov,
 180                                               blk->buffer + offset, to_push);
 181                 vdpasim_blk_buffer_unlock(blk);
 182                 if (bytes < 0) {
 183                         dev_dbg(&vdpasim->vdpa.dev,
 184                                 "vringh_iov_push_iotlb() error: %zd offset: 0x%llx len: 0x%zx\n",
 185                                 bytes, offset, to_push);
 186                         status = VIRTIO_BLK_S_IOERR;
 187                         break;
 188                 }
 189
 190                 pushed += bytes;
 191                 break;
 192
 193         case VIRTIO_BLK_T_OUT:
 194                 if (!vdpasim_blk_check_range(vdpasim, sector,
 195                                              to_pull >> SECTOR_SHIFT,
 196                                              VDPASIM_BLK_SIZE_MAX * VDPASIM_BLK_SEG_MAX)) {
 197                         status = VIRTIO_BLK_S_IOERR;
 198                         break;
 199                 }
 200
 201                 vdpasim_blk_buffer_lock(blk);
 202                 bytes = vringh_iov_pull_iotlb(&vq->vring, &vq->out_iov,
 203                                               blk->buffer + offset, to_pull);
 204                 vdpasim_blk_buffer_unlock(blk);
 205                 if (bytes < 0) {
 206                         dev_dbg(&vdpasim->vdpa.dev,
 207                                 "vringh_iov_pull_iotlb() error: %zd offset: 0x%llx len: 0x%zx\n",
 208                                 bytes, offset, to_pull);
 209                         status = VIRTIO_BLK_S_IOERR;
 210                         break;
 211                 }
 212                 break;
 213
 214         case VIRTIO_BLK_T_GET_ID:
 215                 bytes = vringh_iov_push_iotlb(&vq->vring, &vq->in_iov,
 216                                               vdpasim_blk_id,
 217                                               VIRTIO_BLK_ID_BYTES);
 218                 if (bytes < 0) {
 219                         dev_dbg(&vdpasim->vdpa.dev,
 220                                 "vringh_iov_push_iotlb() error: %zd\n", bytes);
 221                         status = VIRTIO_BLK_S_IOERR;
 222                         break;
 223                 }
 224
 225                 pushed += bytes;
 226                 break;
 227
 228         case VIRTIO_BLK_T_FLUSH:
 229                 /* nothing to do */
 230                 break;
 231
 232         case VIRTIO_BLK_T_DISCARD:
 233         case VIRTIO_BLK_T_WRITE_ZEROES: {
 234                 struct virtio_blk_discard_write_zeroes range;
 235                 u32 num_sectors, flags;
 236
 237                 if (to_pull != sizeof(range)) {
 238                         dev_dbg(&vdpasim->vdpa.dev,
 239                                 "discard/write_zeroes header len: 0x%zx [expected: 0x%zx]\n",
 240                                 to_pull, sizeof(range));
 241                         status = VIRTIO_BLK_S_IOERR;
 242                         break;
 243                 }
 244
 245                 bytes = vringh_iov_pull_iotlb(&vq->vring, &vq->out_iov, &range,
 246                                               to_pull);
 247                 if (bytes < 0) {
 248                         dev_dbg(&vdpasim->vdpa.dev,
 249                                 "vringh_iov_pull_iotlb() error: %zd offset: 0x%llx len: 0x%zx\n",
 250                                 bytes, offset, to_pull);
 251                         status = VIRTIO_BLK_S_IOERR;
 252                         break;
 253                 }
 254
 255                 sector = le64_to_cpu(range.sector);
 256                 offset = sector << SECTOR_SHIFT;
 257                 num_sectors = le32_to_cpu(range.num_sectors);
 258                 flags = le32_to_cpu(range.flags);
 259
 260                 if (type == VIRTIO_BLK_T_DISCARD && flags != 0) {
 261                         dev_dbg(&vdpasim->vdpa.dev,
 262                                 "discard unexpected flags set - flags: 0x%x\n",
 263                                 flags);
 264                         status = VIRTIO_BLK_S_UNSUPP;
 265                         break;
 266                 }
 267
 268                 if (type == VIRTIO_BLK_T_WRITE_ZEROES &&
 269                     flags & ~VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP) {
 270                         dev_dbg(&vdpasim->vdpa.dev,
 271                                 "write_zeroes unexpected flags set - flags: 0x%x\n",
 272                                 flags);
 273                         status = VIRTIO_BLK_S_UNSUPP;
 274                         break;
 275                 }
 276
 277                 if (!vdpasim_blk_check_range(vdpasim, sector, num_sectors,
 278                                              VDPASIM_BLK_DWZ_MAX_SECTORS)) {
 279                         status = VIRTIO_BLK_S_IOERR;
 280                         break;
 281                 }
 282
 283                 if (type == VIRTIO_BLK_T_WRITE_ZEROES) {
 284                         vdpasim_blk_buffer_lock(blk);
 285                         memset(blk->buffer + offset, 0,
 286                                num_sectors << SECTOR_SHIFT);
 287                         vdpasim_blk_buffer_unlock(blk);
 288                 }
 289
 290                 break;
 291         }
 292         default:
 293                 dev_dbg(&vdpasim->vdpa.dev,
 294                         "Unsupported request type %d\n", type);
 295                 status = VIRTIO_BLK_S_IOERR;
 296                 break;
 297         }
 298
 299 err_status:
 300         /* If some operations fail, we need to skip the remaining bytes
 301          * to put the status in the last byte
 302          */
 303         if (to_push - pushed > 0)
 304                 vringh_kiov_advance(&vq->in_iov, to_push - pushed);
 305
 306         /* Last byte is the status */
 307         bytes = vringh_iov_push_iotlb(&vq->vring, &vq->in_iov, &status, 1);
 308         if (bytes != 1)
 309                 goto err;
 310
 311         pushed += bytes;
 312
 313         /* Make sure data is wrote before advancing index */
 314         smp_wmb();
 315
 316         handled = true;
 317
 318 err:
 319         vringh_complete_iotlb(&vq->vring, vq->head, pushed);
 320
 321         return handled;
 322 }
 323
 324 static void vdpasim_blk_work(struct vdpasim *vdpasim)
 325 {
 326         bool reschedule = false;
 327         int i;
 328
 329         mutex_lock(&vdpasim->mutex);
 330
 331         if (!(vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK))
 332                 goto out;
 333
 334         if (!vdpasim->running)
 335                 goto out;
 336
 337         for (i = 0; i < VDPASIM_BLK_VQ_NUM; i++) {
 338                 struct vdpasim_virtqueue *vq = &vdpasim->vqs[i];
 339                 int reqs = 0;
 340
 341                 if (!vq->ready)
 342                         continue;
 343
 344                 while (vdpasim_blk_handle_req(vdpasim, vq)) {
 345                         /* Make sure used is visible before rasing the interrupt. */
 346                         smp_wmb();
 347
 348                         local_bh_disable();
 349                         if (vringh_need_notify_iotlb(&vq->vring) > 0)
 350                                 vringh_notify(&vq->vring);
 351                         local_bh_enable();
 352
 353                         if (++reqs > 4) {
 354                                 reschedule = true;
 355                                 break;
 356                         }
 357                 }
 358         }
 359 out:
 360         mutex_unlock(&vdpasim->mutex);
 361
 362         if (reschedule)
 363                 vdpasim_schedule_work(vdpasim);
 364 }
 365
 366 static void vdpasim_blk_get_config(struct vdpasim *vdpasim, void *config)
 367 {
 368         struct virtio_blk_config *blk_config = config;
 369
 370         memset(config, 0, sizeof(struct virtio_blk_config));
 371
 372         blk_config->capacity = cpu_to_vdpasim64(vdpasim, VDPASIM_BLK_CAPACITY);
 373         blk_config->size_max = cpu_to_vdpasim32(vdpasim, VDPASIM_BLK_SIZE_MAX);
 374         blk_config->seg_max = cpu_to_vdpasim32(vdpasim, VDPASIM_BLK_SEG_MAX);
 375         blk_config->num_queues = cpu_to_vdpasim16(vdpasim, VDPASIM_BLK_VQ_NUM);
 376         blk_config->min_io_size = cpu_to_vdpasim16(vdpasim, 1);
 377         blk_config->opt_io_size = cpu_to_vdpasim32(vdpasim, 1);
 378         blk_config->blk_size = cpu_to_vdpasim32(vdpasim, SECTOR_SIZE);
 379         /* VIRTIO_BLK_F_DISCARD */
 380         blk_config->discard_sector_alignment =
 381                 cpu_to_vdpasim32(vdpasim, SECTOR_SIZE);
 382         blk_config->max_discard_sectors =
 383                 cpu_to_vdpasim32(vdpasim, VDPASIM_BLK_DWZ_MAX_SECTORS);
 384         blk_config->max_discard_seg = cpu_to_vdpasim32(vdpasim, 1);
 385         /* VIRTIO_BLK_F_WRITE_ZEROES */
 386         blk_config->max_write_zeroes_sectors =
 387                 cpu_to_vdpasim32(vdpasim, VDPASIM_BLK_DWZ_MAX_SECTORS);
 388         blk_config->max_write_zeroes_seg = cpu_to_vdpasim32(vdpasim, 1);
 389
 390 }
 391
 392 static void vdpasim_blk_free(struct vdpasim *vdpasim)
 393 {
 394         struct vdpasim_blk *blk = sim_to_blk(vdpasim);
 395
 396         if (!blk->shared_backend)
 397                 kvfree(blk->buffer);
 398 }
 399
 400 static void vdpasim_blk_mgmtdev_release(struct device *dev)
 401 {
 402 }
 403
 404 static struct device vdpasim_blk_mgmtdev = {
 405         .init_name = "vdpasim_blk",
 406         .release = vdpasim_blk_mgmtdev_release,
 407 };
 408
 409 static int vdpasim_blk_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
 410                                const struct vdpa_dev_set_config *config)
 411 {
 412         struct vdpasim_dev_attr dev_attr = {};
 413         struct vdpasim_blk *blk;
 414         struct vdpasim *simdev;
 415         int ret;
 416
 417         dev_attr.mgmt_dev = mdev;
 418         dev_attr.name = name;
 419         dev_attr.id = VIRTIO_ID_BLOCK;
 420         dev_attr.supported_features = VDPASIM_BLK_FEATURES;
 421         dev_attr.nvqs = VDPASIM_BLK_VQ_NUM;
 422         dev_attr.ngroups = VDPASIM_BLK_GROUP_NUM;
 423         dev_attr.nas = VDPASIM_BLK_AS_NUM;
 424         dev_attr.alloc_size = sizeof(struct vdpasim_blk);
 425         dev_attr.config_size = sizeof(struct virtio_blk_config);
 426         dev_attr.get_config = vdpasim_blk_get_config;
 427         dev_attr.work_fn = vdpasim_blk_work;
 428         dev_attr.free = vdpasim_blk_free;
 429
 430         simdev = vdpasim_create(&dev_attr, config);
 431         if (IS_ERR(simdev))
 432                 return PTR_ERR(simdev);
 433
 434         blk = sim_to_blk(simdev);
 435         blk->shared_backend = shared_backend;
 436
 437         if (blk->shared_backend) {
 438                 blk->buffer = shared_buffer;
 439         } else {
 440                 blk->buffer = kvmalloc(VDPASIM_BLK_CAPACITY << SECTOR_SHIFT,
 441                                        GFP_KERNEL);
 442                 if (!blk->buffer) {
 443                         ret = -ENOMEM;
 444                         goto put_dev;
 445                 }
 446         }
 447
 448         ret = _vdpa_register_device(&simdev->vdpa, VDPASIM_BLK_VQ_NUM);
 449         if (ret)
 450                 goto put_dev;
 451
 452         return 0;
 453
 454 put_dev:
 455         put_device(&simdev->vdpa.dev);
 456         return ret;
 457 }
 458
 459 static void vdpasim_blk_dev_del(struct vdpa_mgmt_dev *mdev,
 460                                 struct vdpa_device *dev)
 461 {
 462         struct vdpasim *simdev = container_of(dev, struct vdpasim, vdpa);
 463
 464         _vdpa_unregister_device(&simdev->vdpa);
 465 }
 466
 467 static const struct vdpa_mgmtdev_ops vdpasim_blk_mgmtdev_ops = {
 468         .dev_add = vdpasim_blk_dev_add,
 469         .dev_del = vdpasim_blk_dev_del
 470 };
 471
 472 static struct virtio_device_id id_table[] = {
 473         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
 474         { 0 },
 475 };
 476
 477 static struct vdpa_mgmt_dev mgmt_dev = {
 478         .device = &vdpasim_blk_mgmtdev,
 479         .id_table = id_table,
 480         .ops = &vdpasim_blk_mgmtdev_ops,
 481 };
 482
 483 static int __init vdpasim_blk_init(void)
 484 {
 485         int ret;
 486
 487         ret = device_register(&vdpasim_blk_mgmtdev);
 488         if (ret) {
 489                 put_device(&vdpasim_blk_mgmtdev);
 490                 return ret;
 491         }
 492
 493         ret = vdpa_mgmtdev_register(&mgmt_dev);
 494         if (ret)
 495                 goto parent_err;
 496
 497         if (shared_backend) {
 498                 shared_buffer = kvmalloc(VDPASIM_BLK_CAPACITY << SECTOR_SHIFT,
 499                                          GFP_KERNEL);
 500                 if (!shared_buffer) {
 501                         ret = -ENOMEM;
 502                         goto parent_err;
 503                 }
 504         }
 505
 506         return 0;
 507
 508 parent_err:
 509         device_unregister(&vdpasim_blk_mgmtdev);
 510         return ret;
 511 }
 512
 513 static void __exit vdpasim_blk_exit(void)
 514 {
 515         kvfree(shared_buffer);
 516         vdpa_mgmtdev_unregister(&mgmt_dev);
 517         device_unregister(&vdpasim_blk_mgmtdev);
 518 }
 519
 520 module_init(vdpasim_blk_init)
 521 module_exit(vdpasim_blk_exit)
 522
 523 MODULE_VERSION(DRV_VERSION);
 524 MODULE_LICENSE(DRV_LICENSE);
 525 MODULE_AUTHOR(DRV_AUTHOR);
 526 MODULE_DESCRIPTION(DRV_DESC);