drivers/block/virtio_blk.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 //#define DEBUG
   3 #include <linux/spinlock.h>
   4 #include <linux/slab.h>
   5 #include <linux/blkdev.h>
   6 #include <linux/hdreg.h>
   7 #include <linux/module.h>
   8 #include <linux/mutex.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/virtio.h>
  11 #include <linux/virtio_blk.h>
  12 #include <linux/scatterlist.h>
  13 #include <linux/string_helpers.h>
  14 #include <linux/idr.h>
  15 #include <linux/blk-mq.h>
  16 #include <linux/blk-mq-virtio.h>
  17 #include <linux/numa.h>
  18 #include <uapi/linux/virtio_ring.h>
  19
  20 #define PART_BITS 4
  21 #define VQ_NAME_LEN 16
  22 #define MAX_DISCARD_SEGMENTS 256u
  23
  24 /* The maximum number of sg elements that fit into a virtqueue */
  25 #define VIRTIO_BLK_MAX_SG_ELEMS 32768
  26
  27 #ifdef CONFIG_ARCH_NO_SG_CHAIN
  28 #define VIRTIO_BLK_INLINE_SG_CNT        0
  29 #else
  30 #define VIRTIO_BLK_INLINE_SG_CNT        2
  31 #endif
  32
  33 static unsigned int num_request_queues;
  34 module_param(num_request_queues, uint, 0644);
  35 MODULE_PARM_DESC(num_request_queues,
  36                  "Limit the number of request queues to use for blk device. "
  37                  "0 for no limit. "
  38                  "Values > nr_cpu_ids truncated to nr_cpu_ids.");
  39
  40 static int major;
  41 static DEFINE_IDA(vd_index_ida);
  42
  43 static struct workqueue_struct *virtblk_wq;
  44
  45 struct virtio_blk_vq {
  46         struct virtqueue *vq;
  47         spinlock_t lock;
  48         char name[VQ_NAME_LEN];
  49 } ____cacheline_aligned_in_smp;
  50
  51 struct virtio_blk {
  52         /*
  53          * This mutex must be held by anything that may run after
  54          * virtblk_remove() sets vblk->vdev to NULL.
  55          *
  56          * blk-mq, virtqueue processing, and sysfs attribute code paths are
  57          * shut down before vblk->vdev is set to NULL and therefore do not need
  58          * to hold this mutex.
  59          */
  60         struct mutex vdev_mutex;
  61         struct virtio_device *vdev;
  62
  63         /* The disk structure for the kernel. */
  64         struct gendisk *disk;
  65
  66         /* Block layer tags. */
  67         struct blk_mq_tag_set tag_set;
  68
  69         /* Process context for config space updates */
  70         struct work_struct config_work;
  71
  72         /* Ida index - used to track minor number allocations. */
  73         int index;
  74
  75         /* num of vqs */
  76         int num_vqs;
  77         struct virtio_blk_vq *vqs;
  78 };
  79
  80 struct virtblk_req {
  81         struct virtio_blk_outhdr out_hdr;
  82         u8 status;
  83         struct sg_table sg_table;
  84         struct scatterlist sg[];
  85 };
  86
  87 static inline blk_status_t virtblk_result(struct virtblk_req *vbr)
  88 {
  89         switch (vbr->status) {
  90         case VIRTIO_BLK_S_OK:
  91                 return BLK_STS_OK;
  92         case VIRTIO_BLK_S_UNSUPP:
  93                 return BLK_STS_NOTSUPP;
  94         default:
  95                 return BLK_STS_IOERR;
  96         }
  97 }
  98
  99 static int virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr,
 100                 struct scatterlist *data_sg, bool have_data)
 101 {
 102         struct scatterlist hdr, status, *sgs[3];
 103         unsigned int num_out = 0, num_in = 0;
 104
 105         sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
 106         sgs[num_out++] = &hdr;
 107
 108         if (have_data) {
 109                 if (vbr->out_hdr.type & cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT))
 110                         sgs[num_out++] = data_sg;
 111                 else
 112                         sgs[num_out + num_in++] = data_sg;
 113         }
 114
 115         sg_init_one(&status, &vbr->status, sizeof(vbr->status));
 116         sgs[num_out + num_in++] = &status;
 117
 118         return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
 119 }
 120
 121 static int virtblk_setup_discard_write_zeroes(struct request *req, bool unmap)
 122 {
 123         unsigned short segments = blk_rq_nr_discard_segments(req);
 124         unsigned short n = 0;
 125         struct virtio_blk_discard_write_zeroes *range;
 126         struct bio *bio;
 127         u32 flags = 0;
 128
 129         if (unmap)
 130                 flags |= VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP;
 131
 132         range = kmalloc_array(segments, sizeof(*range), GFP_ATOMIC);
 133         if (!range)
 134                 return -ENOMEM;
 135
 136         /*
 137          * Single max discard segment means multi-range discard isn't
 138          * supported, and block layer only runs contiguity merge like
 139          * normal RW request. So we can't reply on bio for retrieving
 140          * each range info.
 141          */
 142         if (queue_max_discard_segments(req->q) == 1) {
 143                 range[0].flags = cpu_to_le32(flags);
 144                 range[0].num_sectors = cpu_to_le32(blk_rq_sectors(req));
 145                 range[0].sector = cpu_to_le64(blk_rq_pos(req));
 146                 n = 1;
 147         } else {
 148                 __rq_for_each_bio(bio, req) {
 149                         u64 sector = bio->bi_iter.bi_sector;
 150                         u32 num_sectors = bio->bi_iter.bi_size >> SECTOR_SHIFT;
 151
 152                         range[n].flags = cpu_to_le32(flags);
 153                         range[n].num_sectors = cpu_to_le32(num_sectors);
 154                         range[n].sector = cpu_to_le64(sector);
 155                         n++;
 156                 }
 157         }
 158
 159         WARN_ON_ONCE(n != segments);
 160
 161         req->special_vec.bv_page = virt_to_page(range);
 162         req->special_vec.bv_offset = offset_in_page(range);
 163         req->special_vec.bv_len = sizeof(*range) * segments;
 164         req->rq_flags |= RQF_SPECIAL_PAYLOAD;
 165
 166         return 0;
 167 }
 168
 169 static void virtblk_unmap_data(struct request *req, struct virtblk_req *vbr)
 170 {
 171         if (blk_rq_nr_phys_segments(req))
 172                 sg_free_table_chained(&vbr->sg_table,
 173                                       VIRTIO_BLK_INLINE_SG_CNT);
 174 }
 175
 176 static int virtblk_map_data(struct blk_mq_hw_ctx *hctx, struct request *req,
 177                 struct virtblk_req *vbr)
 178 {
 179         int err;
 180
 181         if (!blk_rq_nr_phys_segments(req))
 182                 return 0;
 183
 184         vbr->sg_table.sgl = vbr->sg;
 185         err = sg_alloc_table_chained(&vbr->sg_table,
 186                                      blk_rq_nr_phys_segments(req),
 187                                      vbr->sg_table.sgl,
 188                                      VIRTIO_BLK_INLINE_SG_CNT);
 189         if (unlikely(err))
 190                 return -ENOMEM;
 191
 192         return blk_rq_map_sg(hctx->queue, req, vbr->sg_table.sgl);
 193 }
 194
 195 static void virtblk_cleanup_cmd(struct request *req)
 196 {
 197         if (req->rq_flags & RQF_SPECIAL_PAYLOAD)
 198                 kfree(bvec_virt(&req->special_vec));
 199 }
 200
 201 static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev,
 202                                       struct request *req,
 203                                       struct virtblk_req *vbr)
 204 {
 205         bool unmap = false;
 206         u32 type;
 207
 208         vbr->out_hdr.sector = 0;
 209
 210         switch (req_op(req)) {
 211         case REQ_OP_READ:
 212                 type = VIRTIO_BLK_T_IN;
 213                 vbr->out_hdr.sector = cpu_to_virtio64(vdev,
 214                                                       blk_rq_pos(req));
 215                 break;
 216         case REQ_OP_WRITE:
 217                 type = VIRTIO_BLK_T_OUT;
 218                 vbr->out_hdr.sector = cpu_to_virtio64(vdev,
 219                                                       blk_rq_pos(req));
 220                 break;
 221         case REQ_OP_FLUSH:
 222                 type = VIRTIO_BLK_T_FLUSH;
 223                 break;
 224         case REQ_OP_DISCARD:
 225                 type = VIRTIO_BLK_T_DISCARD;
 226                 break;
 227         case REQ_OP_WRITE_ZEROES:
 228                 type = VIRTIO_BLK_T_WRITE_ZEROES;
 229                 unmap = !(req->cmd_flags & REQ_NOUNMAP);
 230                 break;
 231         case REQ_OP_DRV_IN:
 232                 type = VIRTIO_BLK_T_GET_ID;
 233                 break;
 234         default:
 235                 WARN_ON_ONCE(1);
 236                 return BLK_STS_IOERR;
 237         }
 238
 239         vbr->out_hdr.type = cpu_to_virtio32(vdev, type);
 240         vbr->out_hdr.ioprio = cpu_to_virtio32(vdev, req_get_ioprio(req));
 241
 242         if (type == VIRTIO_BLK_T_DISCARD || type == VIRTIO_BLK_T_WRITE_ZEROES) {
 243                 if (virtblk_setup_discard_write_zeroes(req, unmap))
 244                         return BLK_STS_RESOURCE;
 245         }
 246
 247         return 0;
 248 }
 249
 250 static inline void virtblk_request_done(struct request *req)
 251 {
 252         struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
 253
 254         virtblk_unmap_data(req, vbr);
 255         virtblk_cleanup_cmd(req);
 256         blk_mq_end_request(req, virtblk_result(vbr));
 257 }
 258
 259 static void virtblk_done(struct virtqueue *vq)
 260 {
 261         struct virtio_blk *vblk = vq->vdev->priv;
 262         bool req_done = false;
 263         int qid = vq->index;
 264         struct virtblk_req *vbr;
 265         unsigned long flags;
 266         unsigned int len;
 267
 268         spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
 269         do {
 270                 virtqueue_disable_cb(vq);
 271                 while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
 272                         struct request *req = blk_mq_rq_from_pdu(vbr);
 273
 274                         if (likely(!blk_should_fake_timeout(req->q)))
 275                                 blk_mq_complete_request(req);
 276                         req_done = true;
 277                 }
 278                 if (unlikely(virtqueue_is_broken(vq)))
 279                         break;
 280         } while (!virtqueue_enable_cb(vq));
 281
 282         /* In case queue is stopped waiting for more buffers. */
 283         if (req_done)
 284                 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
 285         spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
 286 }
 287
 288 static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx)
 289 {
 290         struct virtio_blk *vblk = hctx->queue->queuedata;
 291         struct virtio_blk_vq *vq = &vblk->vqs[hctx->queue_num];
 292         bool kick;
 293
 294         spin_lock_irq(&vq->lock);
 295         kick = virtqueue_kick_prepare(vq->vq);
 296         spin_unlock_irq(&vq->lock);
 297
 298         if (kick)
 299                 virtqueue_notify(vq->vq);
 300 }
 301
 302 static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
 303                            const struct blk_mq_queue_data *bd)
 304 {
 305         struct virtio_blk *vblk = hctx->queue->queuedata;
 306         struct request *req = bd->rq;
 307         struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
 308         unsigned long flags;
 309         int num;
 310         int qid = hctx->queue_num;
 311         bool notify = false;
 312         blk_status_t status;
 313         int err;
 314
 315         status = virtblk_setup_cmd(vblk->vdev, req, vbr);
 316         if (unlikely(status))
 317                 return status;
 318
 319         blk_mq_start_request(req);
 320
 321         num = virtblk_map_data(hctx, req, vbr);
 322         if (unlikely(num < 0)) {
 323                 virtblk_cleanup_cmd(req);
 324                 return BLK_STS_RESOURCE;
 325         }
 326
 327         spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
 328         err = virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg_table.sgl, num);
 329         if (err) {
 330                 virtqueue_kick(vblk->vqs[qid].vq);
 331                 /* Don't stop the queue if -ENOMEM: we may have failed to
 332                  * bounce the buffer due to global resource outage.
 333                  */
 334                 if (err == -ENOSPC)
 335                         blk_mq_stop_hw_queue(hctx);
 336                 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
 337                 virtblk_unmap_data(req, vbr);
 338                 virtblk_cleanup_cmd(req);
 339                 switch (err) {
 340                 case -ENOSPC:
 341                         return BLK_STS_DEV_RESOURCE;
 342                 case -ENOMEM:
 343                         return BLK_STS_RESOURCE;
 344                 default:
 345                         return BLK_STS_IOERR;
 346                 }
 347         }
 348
 349         if (bd->last && virtqueue_kick_prepare(vblk->vqs[qid].vq))
 350                 notify = true;
 351         spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
 352
 353         if (notify)
 354                 virtqueue_notify(vblk->vqs[qid].vq);
 355         return BLK_STS_OK;
 356 }
 357
 358 /* return id (s/n) string for *disk to *id_str
 359  */
 360 static int virtblk_get_id(struct gendisk *disk, char *id_str)
 361 {
 362         struct virtio_blk *vblk = disk->private_data;
 363         struct request_queue *q = vblk->disk->queue;
 364         struct request *req;
 365         int err;
 366
 367         req = blk_mq_alloc_request(q, REQ_OP_DRV_IN, 0);
 368         if (IS_ERR(req))
 369                 return PTR_ERR(req);
 370
 371         err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
 372         if (err)
 373                 goto out;
 374
 375         blk_execute_rq(req, false);
 376         err = blk_status_to_errno(virtblk_result(blk_mq_rq_to_pdu(req)));
 377 out:
 378         blk_mq_free_request(req);
 379         return err;
 380 }
 381
 382 /* We provide getgeo only to please some old bootloader/partitioning tools */
 383 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
 384 {
 385         struct virtio_blk *vblk = bd->bd_disk->private_data;
 386         int ret = 0;
 387
 388         mutex_lock(&vblk->vdev_mutex);
 389
 390         if (!vblk->vdev) {
 391                 ret = -ENXIO;
 392                 goto out;
 393         }
 394
 395         /* see if the host passed in geometry config */
 396         if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) {
 397                 virtio_cread(vblk->vdev, struct virtio_blk_config,
 398                              geometry.cylinders, &geo->cylinders);
 399                 virtio_cread(vblk->vdev, struct virtio_blk_config,
 400                              geometry.heads, &geo->heads);
 401                 virtio_cread(vblk->vdev, struct virtio_blk_config,
 402                              geometry.sectors, &geo->sectors);
 403         } else {
 404                 /* some standard values, similar to sd */
 405                 geo->heads = 1 << 6;
 406                 geo->sectors = 1 << 5;
 407                 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
 408         }
 409 out:
 410         mutex_unlock(&vblk->vdev_mutex);
 411         return ret;
 412 }
 413
 414 static void virtblk_free_disk(struct gendisk *disk)
 415 {
 416         struct virtio_blk *vblk = disk->private_data;
 417
 418         ida_simple_remove(&vd_index_ida, vblk->index);
 419         mutex_destroy(&vblk->vdev_mutex);
 420         kfree(vblk);
 421 }
 422
 423 static const struct block_device_operations virtblk_fops = {
 424         .owner          = THIS_MODULE,
 425         .getgeo         = virtblk_getgeo,
 426         .free_disk      = virtblk_free_disk,
 427 };
 428
 429 static int index_to_minor(int index)
 430 {
 431         return index << PART_BITS;
 432 }
 433
 434 static int minor_to_index(int minor)
 435 {
 436         return minor >> PART_BITS;
 437 }
 438
 439 static ssize_t serial_show(struct device *dev,
 440                            struct device_attribute *attr, char *buf)
 441 {
 442         struct gendisk *disk = dev_to_disk(dev);
 443         int err;
 444
 445         /* sysfs gives us a PAGE_SIZE buffer */
 446         BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
 447
 448         buf[VIRTIO_BLK_ID_BYTES] = '\0';
 449         err = virtblk_get_id(disk, buf);
 450         if (!err)
 451                 return strlen(buf);
 452
 453         if (err == -EIO) /* Unsupported? Make it empty. */
 454                 return 0;
 455
 456         return err;
 457 }
 458
 459 static DEVICE_ATTR_RO(serial);
 460
 461 /* The queue's logical block size must be set before calling this */
 462 static void virtblk_update_capacity(struct virtio_blk *vblk, bool resize)
 463 {
 464         struct virtio_device *vdev = vblk->vdev;
 465         struct request_queue *q = vblk->disk->queue;
 466         char cap_str_2[10], cap_str_10[10];
 467         unsigned long long nblocks;
 468         u64 capacity;
 469
 470         /* Host must always specify the capacity. */
 471         virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
 472
 473         nblocks = DIV_ROUND_UP_ULL(capacity, queue_logical_block_size(q) >> 9);
 474
 475         string_get_size(nblocks, queue_logical_block_size(q),
 476                         STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
 477         string_get_size(nblocks, queue_logical_block_size(q),
 478                         STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
 479
 480         dev_notice(&vdev->dev,
 481                    "[%s] %s%llu %d-byte logical blocks (%s/%s)\n",
 482                    vblk->disk->disk_name,
 483                    resize ? "new size: " : "",
 484                    nblocks,
 485                    queue_logical_block_size(q),
 486                    cap_str_10,
 487                    cap_str_2);
 488
 489         set_capacity_and_notify(vblk->disk, capacity);
 490 }
 491
 492 static void virtblk_config_changed_work(struct work_struct *work)
 493 {
 494         struct virtio_blk *vblk =
 495                 container_of(work, struct virtio_blk, config_work);
 496
 497         virtblk_update_capacity(vblk, true);
 498 }
 499
 500 static void virtblk_config_changed(struct virtio_device *vdev)
 501 {
 502         struct virtio_blk *vblk = vdev->priv;
 503
 504         queue_work(virtblk_wq, &vblk->config_work);
 505 }
 506
 507 static int init_vq(struct virtio_blk *vblk)
 508 {
 509         int err;
 510         int i;
 511         vq_callback_t **callbacks;
 512         const char **names;
 513         struct virtqueue **vqs;
 514         unsigned short num_vqs;
 515         struct virtio_device *vdev = vblk->vdev;
 516         struct irq_affinity desc = { 0, };
 517
 518         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
 519                                    struct virtio_blk_config, num_queues,
 520                                    &num_vqs);
 521         if (err)
 522                 num_vqs = 1;
 523         if (!err && !num_vqs) {
 524                 dev_err(&vdev->dev, "MQ advertised but zero queues reported\n");
 525                 return -EINVAL;
 526         }
 527
 528         num_vqs = min_t(unsigned int,
 529                         min_not_zero(num_request_queues, nr_cpu_ids),
 530                         num_vqs);
 531
 532         vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL);
 533         if (!vblk->vqs)
 534                 return -ENOMEM;
 535
 536         names = kmalloc_array(num_vqs, sizeof(*names), GFP_KERNEL);
 537         callbacks = kmalloc_array(num_vqs, sizeof(*callbacks), GFP_KERNEL);
 538         vqs = kmalloc_array(num_vqs, sizeof(*vqs), GFP_KERNEL);
 539         if (!names || !callbacks || !vqs) {
 540                 err = -ENOMEM;
 541                 goto out;
 542         }
 543
 544         for (i = 0; i < num_vqs; i++) {
 545                 callbacks[i] = virtblk_done;
 546                 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
 547                 names[i] = vblk->vqs[i].name;
 548         }
 549
 550         /* Discover virtqueues and write information to configuration.  */
 551         err = virtio_find_vqs(vdev, num_vqs, vqs, callbacks, names, &desc);
 552         if (err)
 553                 goto out;
 554
 555         for (i = 0; i < num_vqs; i++) {
 556                 spin_lock_init(&vblk->vqs[i].lock);
 557                 vblk->vqs[i].vq = vqs[i];
 558         }
 559         vblk->num_vqs = num_vqs;
 560
 561 out:
 562         kfree(vqs);
 563         kfree(callbacks);
 564         kfree(names);
 565         if (err)
 566                 kfree(vblk->vqs);
 567         return err;
 568 }
 569
 570 /*
 571  * Legacy naming scheme used for virtio devices.  We are stuck with it for
 572  * virtio blk but don't ever use it for any new driver.
 573  */
 574 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
 575 {
 576         const int base = 'z' - 'a' + 1;
 577         char *begin = buf + strlen(prefix);
 578         char *end = buf + buflen;
 579         char *p;
 580         int unit;
 581
 582         p = end - 1;
 583         *p = '\0';
 584         unit = base;
 585         do {
 586                 if (p == begin)
 587                         return -EINVAL;
 588                 *--p = 'a' + (index % unit);
 589                 index = (index / unit) - 1;
 590         } while (index >= 0);
 591
 592         memmove(begin, p, end - p);
 593         memcpy(buf, prefix, strlen(prefix));
 594
 595         return 0;
 596 }
 597
 598 static int virtblk_get_cache_mode(struct virtio_device *vdev)
 599 {
 600         u8 writeback;
 601         int err;
 602
 603         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
 604                                    struct virtio_blk_config, wce,
 605                                    &writeback);
 606
 607         /*
 608          * If WCE is not configurable and flush is not available,
 609          * assume no writeback cache is in use.
 610          */
 611         if (err)
 612                 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH);
 613
 614         return writeback;
 615 }
 616
 617 static void virtblk_update_cache_mode(struct virtio_device *vdev)
 618 {
 619         u8 writeback = virtblk_get_cache_mode(vdev);
 620         struct virtio_blk *vblk = vdev->priv;
 621
 622         blk_queue_write_cache(vblk->disk->queue, writeback, false);
 623 }
 624
 625 static const char *const virtblk_cache_types[] = {
 626         "write through", "write back"
 627 };
 628
 629 static ssize_t
 630 cache_type_store(struct device *dev, struct device_attribute *attr,
 631                  const char *buf, size_t count)
 632 {
 633         struct gendisk *disk = dev_to_disk(dev);
 634         struct virtio_blk *vblk = disk->private_data;
 635         struct virtio_device *vdev = vblk->vdev;
 636         int i;
 637
 638         BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
 639         i = sysfs_match_string(virtblk_cache_types, buf);
 640         if (i < 0)
 641                 return i;
 642
 643         virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
 644         virtblk_update_cache_mode(vdev);
 645         return count;
 646 }
 647
 648 static ssize_t
 649 cache_type_show(struct device *dev, struct device_attribute *attr, char *buf)
 650 {
 651         struct gendisk *disk = dev_to_disk(dev);
 652         struct virtio_blk *vblk = disk->private_data;
 653         u8 writeback = virtblk_get_cache_mode(vblk->vdev);
 654
 655         BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
 656         return sysfs_emit(buf, "%s\n", virtblk_cache_types[writeback]);
 657 }
 658
 659 static DEVICE_ATTR_RW(cache_type);
 660
 661 static struct attribute *virtblk_attrs[] = {
 662         &dev_attr_serial.attr,
 663         &dev_attr_cache_type.attr,
 664         NULL,
 665 };
 666
 667 static umode_t virtblk_attrs_are_visible(struct kobject *kobj,
 668                 struct attribute *a, int n)
 669 {
 670         struct device *dev = kobj_to_dev(kobj);
 671         struct gendisk *disk = dev_to_disk(dev);
 672         struct virtio_blk *vblk = disk->private_data;
 673         struct virtio_device *vdev = vblk->vdev;
 674
 675         if (a == &dev_attr_cache_type.attr &&
 676             !virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
 677                 return S_IRUGO;
 678
 679         return a->mode;
 680 }
 681
 682 static const struct attribute_group virtblk_attr_group = {
 683         .attrs = virtblk_attrs,
 684         .is_visible = virtblk_attrs_are_visible,
 685 };
 686
 687 static const struct attribute_group *virtblk_attr_groups[] = {
 688         &virtblk_attr_group,
 689         NULL,
 690 };
 691
 692 static int virtblk_map_queues(struct blk_mq_tag_set *set)
 693 {
 694         struct virtio_blk *vblk = set->driver_data;
 695
 696         return blk_mq_virtio_map_queues(&set->map[HCTX_TYPE_DEFAULT],
 697                                         vblk->vdev, 0);
 698 }
 699
 700 static const struct blk_mq_ops virtio_mq_ops = {
 701         .queue_rq       = virtio_queue_rq,
 702         .commit_rqs     = virtio_commit_rqs,
 703         .complete       = virtblk_request_done,
 704         .map_queues     = virtblk_map_queues,
 705 };
 706
 707 static unsigned int virtblk_queue_depth;
 708 module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
 709
 710 static int virtblk_probe(struct virtio_device *vdev)
 711 {
 712         struct virtio_blk *vblk;
 713         struct request_queue *q;
 714         int err, index;
 715
 716         u32 v, blk_size, max_size, sg_elems, opt_io_size;
 717         u16 min_io_size;
 718         u8 physical_block_exp, alignment_offset;
 719         unsigned int queue_depth;
 720
 721         if (!vdev->config->get) {
 722                 dev_err(&vdev->dev, "%s failure: config access disabled\n",
 723                         __func__);
 724                 return -EINVAL;
 725         }
 726
 727         err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
 728                              GFP_KERNEL);
 729         if (err < 0)
 730                 goto out;
 731         index = err;
 732
 733         /* We need to know how many segments before we allocate. */
 734         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
 735                                    struct virtio_blk_config, seg_max,
 736                                    &sg_elems);
 737
 738         /* We need at least one SG element, whatever they say. */
 739         if (err || !sg_elems)
 740                 sg_elems = 1;
 741
 742         /* Prevent integer overflows and honor max vq size */
 743         sg_elems = min_t(u32, sg_elems, VIRTIO_BLK_MAX_SG_ELEMS - 2);
 744
 745         vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
 746         if (!vblk) {
 747                 err = -ENOMEM;
 748                 goto out_free_index;
 749         }
 750
 751         mutex_init(&vblk->vdev_mutex);
 752
 753         vblk->vdev = vdev;
 754
 755         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
 756
 757         err = init_vq(vblk);
 758         if (err)
 759                 goto out_free_vblk;
 760
 761         /* Default queue sizing is to fill the ring. */
 762         if (!virtblk_queue_depth) {
 763                 queue_depth = vblk->vqs[0].vq->num_free;
 764                 /* ... but without indirect descs, we use 2 descs per req */
 765                 if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
 766                         queue_depth /= 2;
 767         } else {
 768                 queue_depth = virtblk_queue_depth;
 769         }
 770
 771         memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
 772         vblk->tag_set.ops = &virtio_mq_ops;
 773         vblk->tag_set.queue_depth = queue_depth;
 774         vblk->tag_set.numa_node = NUMA_NO_NODE;
 775         vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
 776         vblk->tag_set.cmd_size =
 777                 sizeof(struct virtblk_req) +
 778                 sizeof(struct scatterlist) * VIRTIO_BLK_INLINE_SG_CNT;
 779         vblk->tag_set.driver_data = vblk;
 780         vblk->tag_set.nr_hw_queues = vblk->num_vqs;
 781
 782         err = blk_mq_alloc_tag_set(&vblk->tag_set);
 783         if (err)
 784                 goto out_free_vq;
 785
 786         vblk->disk = blk_mq_alloc_disk(&vblk->tag_set, vblk);
 787         if (IS_ERR(vblk->disk)) {
 788                 err = PTR_ERR(vblk->disk);
 789                 goto out_free_tags;
 790         }
 791         q = vblk->disk->queue;
 792
 793         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
 794
 795         vblk->disk->major = major;
 796         vblk->disk->first_minor = index_to_minor(index);
 797         vblk->disk->minors = 1 << PART_BITS;
 798         vblk->disk->private_data = vblk;
 799         vblk->disk->fops = &virtblk_fops;
 800         vblk->index = index;
 801
 802         /* configure queue flush support */
 803         virtblk_update_cache_mode(vdev);
 804
 805         /* If disk is read-only in the host, the guest should obey */
 806         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
 807                 set_disk_ro(vblk->disk, 1);
 808
 809         /* We can handle whatever the host told us to handle. */
 810         blk_queue_max_segments(q, sg_elems);
 811
 812         /* No real sector limit. */
 813         blk_queue_max_hw_sectors(q, -1U);
 814
 815         max_size = virtio_max_dma_size(vdev);
 816
 817         /* Host can optionally specify maximum segment size and number of
 818          * segments. */
 819         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
 820                                    struct virtio_blk_config, size_max, &v);
 821         if (!err)
 822                 max_size = min(max_size, v);
 823
 824         blk_queue_max_segment_size(q, max_size);
 825
 826         /* Host can optionally specify the block size of the device */
 827         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
 828                                    struct virtio_blk_config, blk_size,
 829                                    &blk_size);
 830         if (!err) {
 831                 err = blk_validate_block_size(blk_size);
 832                 if (err) {
 833                         dev_err(&vdev->dev,
 834                                 "virtio_blk: invalid block size: 0x%x\n",
 835                                 blk_size);
 836                         goto out_cleanup_disk;
 837                 }
 838
 839                 blk_queue_logical_block_size(q, blk_size);
 840         } else
 841                 blk_size = queue_logical_block_size(q);
 842
 843         /* Use topology information if available */
 844         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
 845                                    struct virtio_blk_config, physical_block_exp,
 846                                    &physical_block_exp);
 847         if (!err && physical_block_exp)
 848                 blk_queue_physical_block_size(q,
 849                                 blk_size * (1 << physical_block_exp));
 850
 851         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
 852                                    struct virtio_blk_config, alignment_offset,
 853                                    &alignment_offset);
 854         if (!err && alignment_offset)
 855                 blk_queue_alignment_offset(q, blk_size * alignment_offset);
 856
 857         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
 858                                    struct virtio_blk_config, min_io_size,
 859                                    &min_io_size);
 860         if (!err && min_io_size)
 861                 blk_queue_io_min(q, blk_size * min_io_size);
 862
 863         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
 864                                    struct virtio_blk_config, opt_io_size,
 865                                    &opt_io_size);
 866         if (!err && opt_io_size)
 867                 blk_queue_io_opt(q, blk_size * opt_io_size);
 868
 869         if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) {
 870                 virtio_cread(vdev, struct virtio_blk_config,
 871                              discard_sector_alignment, &v);
 872                 if (v)
 873                         q->limits.discard_granularity = v << SECTOR_SHIFT;
 874                 else
 875                         q->limits.discard_granularity = blk_size;
 876
 877                 virtio_cread(vdev, struct virtio_blk_config,
 878                              max_discard_sectors, &v);
 879                 blk_queue_max_discard_sectors(q, v ? v : UINT_MAX);
 880
 881                 virtio_cread(vdev, struct virtio_blk_config, max_discard_seg,
 882                              &v);
 883
 884                 /*
 885                  * max_discard_seg == 0 is out of spec but we always
 886                  * handled it.
 887                  */
 888                 if (!v)
 889                         v = sg_elems;
 890                 blk_queue_max_discard_segments(q,
 891                                                min(v, MAX_DISCARD_SEGMENTS));
 892         }
 893
 894         if (virtio_has_feature(vdev, VIRTIO_BLK_F_WRITE_ZEROES)) {
 895                 virtio_cread(vdev, struct virtio_blk_config,
 896                              max_write_zeroes_sectors, &v);
 897                 blk_queue_max_write_zeroes_sectors(q, v ? v : UINT_MAX);
 898         }
 899
 900         virtblk_update_capacity(vblk, false);
 901         virtio_device_ready(vdev);
 902
 903         err = device_add_disk(&vdev->dev, vblk->disk, virtblk_attr_groups);
 904         if (err)
 905                 goto out_cleanup_disk;
 906
 907         return 0;
 908
 909 out_cleanup_disk:
 910         blk_cleanup_disk(vblk->disk);
 911 out_free_tags:
 912         blk_mq_free_tag_set(&vblk->tag_set);
 913 out_free_vq:
 914         vdev->config->del_vqs(vdev);
 915         kfree(vblk->vqs);
 916 out_free_vblk:
 917         kfree(vblk);
 918 out_free_index:
 919         ida_simple_remove(&vd_index_ida, index);
 920 out:
 921         return err;
 922 }
 923
 924 static void virtblk_remove(struct virtio_device *vdev)
 925 {
 926         struct virtio_blk *vblk = vdev->priv;
 927
 928         /* Make sure no work handler is accessing the device. */
 929         flush_work(&vblk->config_work);
 930
 931         del_gendisk(vblk->disk);
 932         blk_cleanup_queue(vblk->disk->queue);
 933         blk_mq_free_tag_set(&vblk->tag_set);
 934
 935         mutex_lock(&vblk->vdev_mutex);
 936
 937         /* Stop all the virtqueues. */
 938         virtio_reset_device(vdev);
 939
 940         /* Virtqueues are stopped, nothing can use vblk->vdev anymore. */
 941         vblk->vdev = NULL;
 942
 943         vdev->config->del_vqs(vdev);
 944         kfree(vblk->vqs);
 945
 946         mutex_unlock(&vblk->vdev_mutex);
 947
 948         put_disk(vblk->disk);
 949 }
 950
 951 #ifdef CONFIG_PM_SLEEP
 952 static int virtblk_freeze(struct virtio_device *vdev)
 953 {
 954         struct virtio_blk *vblk = vdev->priv;
 955
 956         /* Ensure we don't receive any more interrupts */
 957         virtio_reset_device(vdev);
 958
 959         /* Make sure no work handler is accessing the device. */
 960         flush_work(&vblk->config_work);
 961
 962         blk_mq_quiesce_queue(vblk->disk->queue);
 963
 964         vdev->config->del_vqs(vdev);
 965         kfree(vblk->vqs);
 966
 967         return 0;
 968 }
 969
 970 static int virtblk_restore(struct virtio_device *vdev)
 971 {
 972         struct virtio_blk *vblk = vdev->priv;
 973         int ret;
 974
 975         ret = init_vq(vdev->priv);
 976         if (ret)
 977                 return ret;
 978
 979         virtio_device_ready(vdev);
 980
 981         blk_mq_unquiesce_queue(vblk->disk->queue);
 982         return 0;
 983 }
 984 #endif
 985
 986 static const struct virtio_device_id id_table[] = {
 987         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
 988         { 0 },
 989 };
 990
 991 static unsigned int features_legacy[] = {
 992         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
 993         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
 994         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
 995         VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
 996 }
 997 ;
 998 static unsigned int features[] = {
 999         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
1000         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
1001         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
1002         VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
1003 };
1004
1005 static struct virtio_driver virtio_blk = {
1006         .feature_table                  = features,
1007         .feature_table_size             = ARRAY_SIZE(features),
1008         .feature_table_legacy           = features_legacy,
1009         .feature_table_size_legacy      = ARRAY_SIZE(features_legacy),
1010         .driver.name                    = KBUILD_MODNAME,
1011         .driver.owner                   = THIS_MODULE,
1012         .id_table                       = id_table,
1013         .probe                          = virtblk_probe,
1014         .remove                         = virtblk_remove,
1015         .config_changed                 = virtblk_config_changed,
1016 #ifdef CONFIG_PM_SLEEP
1017         .freeze                         = virtblk_freeze,
1018         .restore                        = virtblk_restore,
1019 #endif
1020 };
1021
1022 static int __init virtio_blk_init(void)
1023 {
1024         int error;
1025
1026         virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
1027         if (!virtblk_wq)
1028                 return -ENOMEM;
1029
1030         major = register_blkdev(0, "virtblk");
1031         if (major < 0) {
1032                 error = major;
1033                 goto out_destroy_workqueue;
1034         }
1035
1036         error = register_virtio_driver(&virtio_blk);
1037         if (error)
1038                 goto out_unregister_blkdev;
1039         return 0;
1040
1041 out_unregister_blkdev:
1042         unregister_blkdev(major, "virtblk");
1043 out_destroy_workqueue:
1044         destroy_workqueue(virtblk_wq);
1045         return error;
1046 }
1047
1048 static void __exit virtio_blk_fini(void)
1049 {
1050         unregister_virtio_driver(&virtio_blk);
1051         unregister_blkdev(major, "virtblk");
1052         destroy_workqueue(virtblk_wq);
1053 }
1054 module_init(virtio_blk_init);
1055 module_exit(virtio_blk_fini);
1056
1057 MODULE_DEVICE_TABLE(virtio, id_table);
1058 MODULE_DESCRIPTION("Virtio block driver");
1059 MODULE_LICENSE("GPL");