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 unsigned int poll_queues;
  41 module_param(poll_queues, uint, 0644);
  42 MODULE_PARM_DESC(poll_queues, "The number of dedicated virtqueues for polling I/O");
  43
  44 static int major;
  45 static DEFINE_IDA(vd_index_ida);
  46
  47 static struct workqueue_struct *virtblk_wq;
  48
  49 struct virtio_blk_vq {
  50         struct virtqueue *vq;
  51         spinlock_t lock;
  52         char name[VQ_NAME_LEN];
  53 } ____cacheline_aligned_in_smp;
  54
  55 struct virtio_blk {
  56         /*
  57          * This mutex must be held by anything that may run after
  58          * virtblk_remove() sets vblk->vdev to NULL.
  59          *
  60          * blk-mq, virtqueue processing, and sysfs attribute code paths are
  61          * shut down before vblk->vdev is set to NULL and therefore do not need
  62          * to hold this mutex.
  63          */
  64         struct mutex vdev_mutex;
  65         struct virtio_device *vdev;
  66
  67         /* The disk structure for the kernel. */
  68         struct gendisk *disk;
  69
  70         /* Block layer tags. */
  71         struct blk_mq_tag_set tag_set;
  72
  73         /* Process context for config space updates */
  74         struct work_struct config_work;
  75
  76         /* Ida index - used to track minor number allocations. */
  77         int index;
  78
  79         /* num of vqs */
  80         int num_vqs;
  81         int io_queues[HCTX_MAX_TYPES];
  82         struct virtio_blk_vq *vqs;
  83 };
  84
  85 struct virtblk_req {
  86         struct virtio_blk_outhdr out_hdr;
  87         u8 status;
  88         struct sg_table sg_table;
  89         struct scatterlist sg[];
  90 };
  91
  92 static inline blk_status_t virtblk_result(struct virtblk_req *vbr)
  93 {
  94         switch (vbr->status) {
  95         case VIRTIO_BLK_S_OK:
  96                 return BLK_STS_OK;
  97         case VIRTIO_BLK_S_UNSUPP:
  98                 return BLK_STS_NOTSUPP;
  99         default:
 100                 return BLK_STS_IOERR;
 101         }
 102 }
 103
 104 static inline struct virtio_blk_vq *get_virtio_blk_vq(struct blk_mq_hw_ctx *hctx)
 105 {
 106         struct virtio_blk *vblk = hctx->queue->queuedata;
 107         struct virtio_blk_vq *vq = &vblk->vqs[hctx->queue_num];
 108
 109         return vq;
 110 }
 111
 112 static int virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr)
 113 {
 114         struct scatterlist hdr, status, *sgs[3];
 115         unsigned int num_out = 0, num_in = 0;
 116
 117         sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
 118         sgs[num_out++] = &hdr;
 119
 120         if (vbr->sg_table.nents) {
 121                 if (vbr->out_hdr.type & cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT))
 122                         sgs[num_out++] = vbr->sg_table.sgl;
 123                 else
 124                         sgs[num_out + num_in++] = vbr->sg_table.sgl;
 125         }
 126
 127         sg_init_one(&status, &vbr->status, sizeof(vbr->status));
 128         sgs[num_out + num_in++] = &status;
 129
 130         return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
 131 }
 132
 133 static int virtblk_setup_discard_write_zeroes(struct request *req, bool unmap)
 134 {
 135         unsigned short segments = blk_rq_nr_discard_segments(req);
 136         unsigned short n = 0;
 137         struct virtio_blk_discard_write_zeroes *range;
 138         struct bio *bio;
 139         u32 flags = 0;
 140
 141         if (unmap)
 142                 flags |= VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP;
 143
 144         range = kmalloc_array(segments, sizeof(*range), GFP_ATOMIC);
 145         if (!range)
 146                 return -ENOMEM;
 147
 148         /*
 149          * Single max discard segment means multi-range discard isn't
 150          * supported, and block layer only runs contiguity merge like
 151          * normal RW request. So we can't reply on bio for retrieving
 152          * each range info.
 153          */
 154         if (queue_max_discard_segments(req->q) == 1) {
 155                 range[0].flags = cpu_to_le32(flags);
 156                 range[0].num_sectors = cpu_to_le32(blk_rq_sectors(req));
 157                 range[0].sector = cpu_to_le64(blk_rq_pos(req));
 158                 n = 1;
 159         } else {
 160                 __rq_for_each_bio(bio, req) {
 161                         u64 sector = bio->bi_iter.bi_sector;
 162                         u32 num_sectors = bio->bi_iter.bi_size >> SECTOR_SHIFT;
 163
 164                         range[n].flags = cpu_to_le32(flags);
 165                         range[n].num_sectors = cpu_to_le32(num_sectors);
 166                         range[n].sector = cpu_to_le64(sector);
 167                         n++;
 168                 }
 169         }
 170
 171         WARN_ON_ONCE(n != segments);
 172
 173         req->special_vec.bv_page = virt_to_page(range);
 174         req->special_vec.bv_offset = offset_in_page(range);
 175         req->special_vec.bv_len = sizeof(*range) * segments;
 176         req->rq_flags |= RQF_SPECIAL_PAYLOAD;
 177
 178         return 0;
 179 }
 180
 181 static void virtblk_unmap_data(struct request *req, struct virtblk_req *vbr)
 182 {
 183         if (blk_rq_nr_phys_segments(req))
 184                 sg_free_table_chained(&vbr->sg_table,
 185                                       VIRTIO_BLK_INLINE_SG_CNT);
 186 }
 187
 188 static int virtblk_map_data(struct blk_mq_hw_ctx *hctx, struct request *req,
 189                 struct virtblk_req *vbr)
 190 {
 191         int err;
 192
 193         if (!blk_rq_nr_phys_segments(req))
 194                 return 0;
 195
 196         vbr->sg_table.sgl = vbr->sg;
 197         err = sg_alloc_table_chained(&vbr->sg_table,
 198                                      blk_rq_nr_phys_segments(req),
 199                                      vbr->sg_table.sgl,
 200                                      VIRTIO_BLK_INLINE_SG_CNT);
 201         if (unlikely(err))
 202                 return -ENOMEM;
 203
 204         return blk_rq_map_sg(hctx->queue, req, vbr->sg_table.sgl);
 205 }
 206
 207 static void virtblk_cleanup_cmd(struct request *req)
 208 {
 209         if (req->rq_flags & RQF_SPECIAL_PAYLOAD)
 210                 kfree(bvec_virt(&req->special_vec));
 211 }
 212
 213 static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev,
 214                                       struct request *req,
 215                                       struct virtblk_req *vbr)
 216 {
 217         bool unmap = false;
 218         u32 type;
 219
 220         vbr->out_hdr.sector = 0;
 221
 222         switch (req_op(req)) {
 223         case REQ_OP_READ:
 224                 type = VIRTIO_BLK_T_IN;
 225                 vbr->out_hdr.sector = cpu_to_virtio64(vdev,
 226                                                       blk_rq_pos(req));
 227                 break;
 228         case REQ_OP_WRITE:
 229                 type = VIRTIO_BLK_T_OUT;
 230                 vbr->out_hdr.sector = cpu_to_virtio64(vdev,
 231                                                       blk_rq_pos(req));
 232                 break;
 233         case REQ_OP_FLUSH:
 234                 type = VIRTIO_BLK_T_FLUSH;
 235                 break;
 236         case REQ_OP_DISCARD:
 237                 type = VIRTIO_BLK_T_DISCARD;
 238                 break;
 239         case REQ_OP_WRITE_ZEROES:
 240                 type = VIRTIO_BLK_T_WRITE_ZEROES;
 241                 unmap = !(req->cmd_flags & REQ_NOUNMAP);
 242                 break;
 243         case REQ_OP_DRV_IN:
 244                 type = VIRTIO_BLK_T_GET_ID;
 245                 break;
 246         default:
 247                 WARN_ON_ONCE(1);
 248                 return BLK_STS_IOERR;
 249         }
 250
 251         vbr->out_hdr.type = cpu_to_virtio32(vdev, type);
 252         vbr->out_hdr.ioprio = cpu_to_virtio32(vdev, req_get_ioprio(req));
 253
 254         if (type == VIRTIO_BLK_T_DISCARD || type == VIRTIO_BLK_T_WRITE_ZEROES) {
 255                 if (virtblk_setup_discard_write_zeroes(req, unmap))
 256                         return BLK_STS_RESOURCE;
 257         }
 258
 259         return 0;
 260 }
 261
 262 static inline void virtblk_request_done(struct request *req)
 263 {
 264         struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
 265
 266         virtblk_unmap_data(req, vbr);
 267         virtblk_cleanup_cmd(req);
 268         blk_mq_end_request(req, virtblk_result(vbr));
 269 }
 270
 271 static void virtblk_done(struct virtqueue *vq)
 272 {
 273         struct virtio_blk *vblk = vq->vdev->priv;
 274         bool req_done = false;
 275         int qid = vq->index;
 276         struct virtblk_req *vbr;
 277         unsigned long flags;
 278         unsigned int len;
 279
 280         spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
 281         do {
 282                 virtqueue_disable_cb(vq);
 283                 while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
 284                         struct request *req = blk_mq_rq_from_pdu(vbr);
 285
 286                         if (likely(!blk_should_fake_timeout(req->q)))
 287                                 blk_mq_complete_request(req);
 288                         req_done = true;
 289                 }
 290                 if (unlikely(virtqueue_is_broken(vq)))
 291                         break;
 292         } while (!virtqueue_enable_cb(vq));
 293
 294         /* In case queue is stopped waiting for more buffers. */
 295         if (req_done)
 296                 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
 297         spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
 298 }
 299
 300 static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx)
 301 {
 302         struct virtio_blk *vblk = hctx->queue->queuedata;
 303         struct virtio_blk_vq *vq = &vblk->vqs[hctx->queue_num];
 304         bool kick;
 305
 306         spin_lock_irq(&vq->lock);
 307         kick = virtqueue_kick_prepare(vq->vq);
 308         spin_unlock_irq(&vq->lock);
 309
 310         if (kick)
 311                 virtqueue_notify(vq->vq);
 312 }
 313
 314 static blk_status_t virtblk_prep_rq(struct blk_mq_hw_ctx *hctx,
 315                                         struct virtio_blk *vblk,
 316                                         struct request *req,
 317                                         struct virtblk_req *vbr)
 318 {
 319         blk_status_t status;
 320
 321         status = virtblk_setup_cmd(vblk->vdev, req, vbr);
 322         if (unlikely(status))
 323                 return status;
 324
 325         blk_mq_start_request(req);
 326
 327         vbr->sg_table.nents = virtblk_map_data(hctx, req, vbr);
 328         if (unlikely(vbr->sg_table.nents < 0)) {
 329                 virtblk_cleanup_cmd(req);
 330                 return BLK_STS_RESOURCE;
 331         }
 332
 333         return BLK_STS_OK;
 334 }
 335
 336 static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
 337                            const struct blk_mq_queue_data *bd)
 338 {
 339         struct virtio_blk *vblk = hctx->queue->queuedata;
 340         struct request *req = bd->rq;
 341         struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
 342         unsigned long flags;
 343         int qid = hctx->queue_num;
 344         bool notify = false;
 345         blk_status_t status;
 346         int err;
 347
 348         status = virtblk_prep_rq(hctx, vblk, req, vbr);
 349         if (unlikely(status))
 350                 return status;
 351
 352         spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
 353         err = virtblk_add_req(vblk->vqs[qid].vq, vbr);
 354         if (err) {
 355                 virtqueue_kick(vblk->vqs[qid].vq);
 356                 /* Don't stop the queue if -ENOMEM: we may have failed to
 357                  * bounce the buffer due to global resource outage.
 358                  */
 359                 if (err == -ENOSPC)
 360                         blk_mq_stop_hw_queue(hctx);
 361                 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
 362                 virtblk_unmap_data(req, vbr);
 363                 virtblk_cleanup_cmd(req);
 364                 switch (err) {
 365                 case -ENOSPC:
 366                         return BLK_STS_DEV_RESOURCE;
 367                 case -ENOMEM:
 368                         return BLK_STS_RESOURCE;
 369                 default:
 370                         return BLK_STS_IOERR;
 371                 }
 372         }
 373
 374         if (bd->last && virtqueue_kick_prepare(vblk->vqs[qid].vq))
 375                 notify = true;
 376         spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
 377
 378         if (notify)
 379                 virtqueue_notify(vblk->vqs[qid].vq);
 380         return BLK_STS_OK;
 381 }
 382
 383 static bool virtblk_prep_rq_batch(struct request *req)
 384 {
 385         struct virtio_blk *vblk = req->mq_hctx->queue->queuedata;
 386         struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
 387
 388         req->mq_hctx->tags->rqs[req->tag] = req;
 389
 390         return virtblk_prep_rq(req->mq_hctx, vblk, req, vbr) == BLK_STS_OK;
 391 }
 392
 393 static bool virtblk_add_req_batch(struct virtio_blk_vq *vq,
 394                                         struct request **rqlist,
 395                                         struct request **requeue_list)
 396 {
 397         unsigned long flags;
 398         int err;
 399         bool kick;
 400
 401         spin_lock_irqsave(&vq->lock, flags);
 402
 403         while (!rq_list_empty(*rqlist)) {
 404                 struct request *req = rq_list_pop(rqlist);
 405                 struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
 406
 407                 err = virtblk_add_req(vq->vq, vbr);
 408                 if (err) {
 409                         virtblk_unmap_data(req, vbr);
 410                         virtblk_cleanup_cmd(req);
 411                         rq_list_add(requeue_list, req);
 412                 }
 413         }
 414
 415         kick = virtqueue_kick_prepare(vq->vq);
 416         spin_unlock_irqrestore(&vq->lock, flags);
 417
 418         return kick;
 419 }
 420
 421 static void virtio_queue_rqs(struct request **rqlist)
 422 {
 423         struct request *req, *next, *prev = NULL;
 424         struct request *requeue_list = NULL;
 425
 426         rq_list_for_each_safe(rqlist, req, next) {
 427                 struct virtio_blk_vq *vq = get_virtio_blk_vq(req->mq_hctx);
 428                 bool kick;
 429
 430                 if (!virtblk_prep_rq_batch(req)) {
 431                         rq_list_move(rqlist, &requeue_list, req, prev);
 432                         req = prev;
 433                         if (!req)
 434                                 continue;
 435                 }
 436
 437                 if (!next || req->mq_hctx != next->mq_hctx) {
 438                         req->rq_next = NULL;
 439                         kick = virtblk_add_req_batch(vq, rqlist, &requeue_list);
 440                         if (kick)
 441                                 virtqueue_notify(vq->vq);
 442
 443                         *rqlist = next;
 444                         prev = NULL;
 445                 } else
 446                         prev = req;
 447         }
 448
 449         *rqlist = requeue_list;
 450 }
 451
 452 /* return id (s/n) string for *disk to *id_str
 453  */
 454 static int virtblk_get_id(struct gendisk *disk, char *id_str)
 455 {
 456         struct virtio_blk *vblk = disk->private_data;
 457         struct request_queue *q = vblk->disk->queue;
 458         struct request *req;
 459         int err;
 460
 461         req = blk_mq_alloc_request(q, REQ_OP_DRV_IN, 0);
 462         if (IS_ERR(req))
 463                 return PTR_ERR(req);
 464
 465         err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
 466         if (err)
 467                 goto out;
 468
 469         blk_execute_rq(req, false);
 470         err = blk_status_to_errno(virtblk_result(blk_mq_rq_to_pdu(req)));
 471 out:
 472         blk_mq_free_request(req);
 473         return err;
 474 }
 475
 476 /* We provide getgeo only to please some old bootloader/partitioning tools */
 477 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
 478 {
 479         struct virtio_blk *vblk = bd->bd_disk->private_data;
 480         int ret = 0;
 481
 482         mutex_lock(&vblk->vdev_mutex);
 483
 484         if (!vblk->vdev) {
 485                 ret = -ENXIO;
 486                 goto out;
 487         }
 488
 489         /* see if the host passed in geometry config */
 490         if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) {
 491                 virtio_cread(vblk->vdev, struct virtio_blk_config,
 492                              geometry.cylinders, &geo->cylinders);
 493                 virtio_cread(vblk->vdev, struct virtio_blk_config,
 494                              geometry.heads, &geo->heads);
 495                 virtio_cread(vblk->vdev, struct virtio_blk_config,
 496                              geometry.sectors, &geo->sectors);
 497         } else {
 498                 /* some standard values, similar to sd */
 499                 geo->heads = 1 << 6;
 500                 geo->sectors = 1 << 5;
 501                 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
 502         }
 503 out:
 504         mutex_unlock(&vblk->vdev_mutex);
 505         return ret;
 506 }
 507
 508 static void virtblk_free_disk(struct gendisk *disk)
 509 {
 510         struct virtio_blk *vblk = disk->private_data;
 511
 512         ida_simple_remove(&vd_index_ida, vblk->index);
 513         mutex_destroy(&vblk->vdev_mutex);
 514         kfree(vblk);
 515 }
 516
 517 static const struct block_device_operations virtblk_fops = {
 518         .owner          = THIS_MODULE,
 519         .getgeo         = virtblk_getgeo,
 520         .free_disk      = virtblk_free_disk,
 521 };
 522
 523 static int index_to_minor(int index)
 524 {
 525         return index << PART_BITS;
 526 }
 527
 528 static int minor_to_index(int minor)
 529 {
 530         return minor >> PART_BITS;
 531 }
 532
 533 static ssize_t serial_show(struct device *dev,
 534                            struct device_attribute *attr, char *buf)
 535 {
 536         struct gendisk *disk = dev_to_disk(dev);
 537         int err;
 538
 539         /* sysfs gives us a PAGE_SIZE buffer */
 540         BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
 541
 542         buf[VIRTIO_BLK_ID_BYTES] = '\0';
 543         err = virtblk_get_id(disk, buf);
 544         if (!err)
 545                 return strlen(buf);
 546
 547         if (err == -EIO) /* Unsupported? Make it empty. */
 548                 return 0;
 549
 550         return err;
 551 }
 552
 553 static DEVICE_ATTR_RO(serial);
 554
 555 /* The queue's logical block size must be set before calling this */
 556 static void virtblk_update_capacity(struct virtio_blk *vblk, bool resize)
 557 {
 558         struct virtio_device *vdev = vblk->vdev;
 559         struct request_queue *q = vblk->disk->queue;
 560         char cap_str_2[10], cap_str_10[10];
 561         unsigned long long nblocks;
 562         u64 capacity;
 563
 564         /* Host must always specify the capacity. */
 565         virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
 566
 567         nblocks = DIV_ROUND_UP_ULL(capacity, queue_logical_block_size(q) >> 9);
 568
 569         string_get_size(nblocks, queue_logical_block_size(q),
 570                         STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
 571         string_get_size(nblocks, queue_logical_block_size(q),
 572                         STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
 573
 574         dev_notice(&vdev->dev,
 575                    "[%s] %s%llu %d-byte logical blocks (%s/%s)\n",
 576                    vblk->disk->disk_name,
 577                    resize ? "new size: " : "",
 578                    nblocks,
 579                    queue_logical_block_size(q),
 580                    cap_str_10,
 581                    cap_str_2);
 582
 583         set_capacity_and_notify(vblk->disk, capacity);
 584 }
 585
 586 static void virtblk_config_changed_work(struct work_struct *work)
 587 {
 588         struct virtio_blk *vblk =
 589                 container_of(work, struct virtio_blk, config_work);
 590
 591         virtblk_update_capacity(vblk, true);
 592 }
 593
 594 static void virtblk_config_changed(struct virtio_device *vdev)
 595 {
 596         struct virtio_blk *vblk = vdev->priv;
 597
 598         queue_work(virtblk_wq, &vblk->config_work);
 599 }
 600
 601 static int init_vq(struct virtio_blk *vblk)
 602 {
 603         int err;
 604         int i;
 605         vq_callback_t **callbacks;
 606         const char **names;
 607         struct virtqueue **vqs;
 608         unsigned short num_vqs;
 609         unsigned int num_poll_vqs;
 610         struct virtio_device *vdev = vblk->vdev;
 611         struct irq_affinity desc = { 0, };
 612
 613         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
 614                                    struct virtio_blk_config, num_queues,
 615                                    &num_vqs);
 616         if (err)
 617                 num_vqs = 1;
 618
 619         if (!err && !num_vqs) {
 620                 dev_err(&vdev->dev, "MQ advertised but zero queues reported\n");
 621                 return -EINVAL;
 622         }
 623
 624         num_vqs = min_t(unsigned int,
 625                         min_not_zero(num_request_queues, nr_cpu_ids),
 626                         num_vqs);
 627
 628         num_poll_vqs = min_t(unsigned int, poll_queues, num_vqs - 1);
 629
 630         vblk->io_queues[HCTX_TYPE_DEFAULT] = num_vqs - num_poll_vqs;
 631         vblk->io_queues[HCTX_TYPE_READ] = 0;
 632         vblk->io_queues[HCTX_TYPE_POLL] = num_poll_vqs;
 633
 634         dev_info(&vdev->dev, "%d/%d/%d default/read/poll queues\n",
 635                                 vblk->io_queues[HCTX_TYPE_DEFAULT],
 636                                 vblk->io_queues[HCTX_TYPE_READ],
 637                                 vblk->io_queues[HCTX_TYPE_POLL]);
 638
 639         vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL);
 640         if (!vblk->vqs)
 641                 return -ENOMEM;
 642
 643         names = kmalloc_array(num_vqs, sizeof(*names), GFP_KERNEL);
 644         callbacks = kmalloc_array(num_vqs, sizeof(*callbacks), GFP_KERNEL);
 645         vqs = kmalloc_array(num_vqs, sizeof(*vqs), GFP_KERNEL);
 646         if (!names || !callbacks || !vqs) {
 647                 err = -ENOMEM;
 648                 goto out;
 649         }
 650
 651         for (i = 0; i < num_vqs - num_poll_vqs; i++) {
 652                 callbacks[i] = virtblk_done;
 653                 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
 654                 names[i] = vblk->vqs[i].name;
 655         }
 656
 657         for (; i < num_vqs; i++) {
 658                 callbacks[i] = NULL;
 659                 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req_poll.%d", i);
 660                 names[i] = vblk->vqs[i].name;
 661         }
 662
 663         /* Discover virtqueues and write information to configuration.  */
 664         err = virtio_find_vqs(vdev, num_vqs, vqs, callbacks, names, &desc);
 665         if (err)
 666                 goto out;
 667
 668         for (i = 0; i < num_vqs; i++) {
 669                 spin_lock_init(&vblk->vqs[i].lock);
 670                 vblk->vqs[i].vq = vqs[i];
 671         }
 672         vblk->num_vqs = num_vqs;
 673
 674 out:
 675         kfree(vqs);
 676         kfree(callbacks);
 677         kfree(names);
 678         if (err)
 679                 kfree(vblk->vqs);
 680         return err;
 681 }
 682
 683 /*
 684  * Legacy naming scheme used for virtio devices.  We are stuck with it for
 685  * virtio blk but don't ever use it for any new driver.
 686  */
 687 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
 688 {
 689         const int base = 'z' - 'a' + 1;
 690         char *begin = buf + strlen(prefix);
 691         char *end = buf + buflen;
 692         char *p;
 693         int unit;
 694
 695         p = end - 1;
 696         *p = '\0';
 697         unit = base;
 698         do {
 699                 if (p == begin)
 700                         return -EINVAL;
 701                 *--p = 'a' + (index % unit);
 702                 index = (index / unit) - 1;
 703         } while (index >= 0);
 704
 705         memmove(begin, p, end - p);
 706         memcpy(buf, prefix, strlen(prefix));
 707
 708         return 0;
 709 }
 710
 711 static int virtblk_get_cache_mode(struct virtio_device *vdev)
 712 {
 713         u8 writeback;
 714         int err;
 715
 716         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
 717                                    struct virtio_blk_config, wce,
 718                                    &writeback);
 719
 720         /*
 721          * If WCE is not configurable and flush is not available,
 722          * assume no writeback cache is in use.
 723          */
 724         if (err)
 725                 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH);
 726
 727         return writeback;
 728 }
 729
 730 static void virtblk_update_cache_mode(struct virtio_device *vdev)
 731 {
 732         u8 writeback = virtblk_get_cache_mode(vdev);
 733         struct virtio_blk *vblk = vdev->priv;
 734
 735         blk_queue_write_cache(vblk->disk->queue, writeback, false);
 736 }
 737
 738 static const char *const virtblk_cache_types[] = {
 739         "write through", "write back"
 740 };
 741
 742 static ssize_t
 743 cache_type_store(struct device *dev, struct device_attribute *attr,
 744                  const char *buf, size_t count)
 745 {
 746         struct gendisk *disk = dev_to_disk(dev);
 747         struct virtio_blk *vblk = disk->private_data;
 748         struct virtio_device *vdev = vblk->vdev;
 749         int i;
 750
 751         BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
 752         i = sysfs_match_string(virtblk_cache_types, buf);
 753         if (i < 0)
 754                 return i;
 755
 756         virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
 757         virtblk_update_cache_mode(vdev);
 758         return count;
 759 }
 760
 761 static ssize_t
 762 cache_type_show(struct device *dev, struct device_attribute *attr, char *buf)
 763 {
 764         struct gendisk *disk = dev_to_disk(dev);
 765         struct virtio_blk *vblk = disk->private_data;
 766         u8 writeback = virtblk_get_cache_mode(vblk->vdev);
 767
 768         BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
 769         return sysfs_emit(buf, "%s\n", virtblk_cache_types[writeback]);
 770 }
 771
 772 static DEVICE_ATTR_RW(cache_type);
 773
 774 static struct attribute *virtblk_attrs[] = {
 775         &dev_attr_serial.attr,
 776         &dev_attr_cache_type.attr,
 777         NULL,
 778 };
 779
 780 static umode_t virtblk_attrs_are_visible(struct kobject *kobj,
 781                 struct attribute *a, int n)
 782 {
 783         struct device *dev = kobj_to_dev(kobj);
 784         struct gendisk *disk = dev_to_disk(dev);
 785         struct virtio_blk *vblk = disk->private_data;
 786         struct virtio_device *vdev = vblk->vdev;
 787
 788         if (a == &dev_attr_cache_type.attr &&
 789             !virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
 790                 return S_IRUGO;
 791
 792         return a->mode;
 793 }
 794
 795 static const struct attribute_group virtblk_attr_group = {
 796         .attrs = virtblk_attrs,
 797         .is_visible = virtblk_attrs_are_visible,
 798 };
 799
 800 static const struct attribute_group *virtblk_attr_groups[] = {
 801         &virtblk_attr_group,
 802         NULL,
 803 };
 804
 805 static int virtblk_map_queues(struct blk_mq_tag_set *set)
 806 {
 807         struct virtio_blk *vblk = set->driver_data;
 808         int i, qoff;
 809
 810         for (i = 0, qoff = 0; i < set->nr_maps; i++) {
 811                 struct blk_mq_queue_map *map = &set->map[i];
 812
 813                 map->nr_queues = vblk->io_queues[i];
 814                 map->queue_offset = qoff;
 815                 qoff += map->nr_queues;
 816
 817                 if (map->nr_queues == 0)
 818                         continue;
 819
 820                 /*
 821                  * Regular queues have interrupts and hence CPU affinity is
 822                  * defined by the core virtio code, but polling queues have
 823                  * no interrupts so we let the block layer assign CPU affinity.
 824                  */
 825                 if (i == HCTX_TYPE_POLL)
 826                         blk_mq_map_queues(&set->map[i]);
 827                 else
 828                         blk_mq_virtio_map_queues(&set->map[i], vblk->vdev, 0);
 829         }
 830
 831         return 0;
 832 }
 833
 834 static void virtblk_complete_batch(struct io_comp_batch *iob)
 835 {
 836         struct request *req;
 837
 838         rq_list_for_each(&iob->req_list, req) {
 839                 virtblk_unmap_data(req, blk_mq_rq_to_pdu(req));
 840                 virtblk_cleanup_cmd(req);
 841         }
 842         blk_mq_end_request_batch(iob);
 843 }
 844
 845 static int virtblk_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob)
 846 {
 847         struct virtio_blk *vblk = hctx->queue->queuedata;
 848         struct virtio_blk_vq *vq = get_virtio_blk_vq(hctx);
 849         struct virtblk_req *vbr;
 850         unsigned long flags;
 851         unsigned int len;
 852         int found = 0;
 853
 854         spin_lock_irqsave(&vq->lock, flags);
 855
 856         while ((vbr = virtqueue_get_buf(vq->vq, &len)) != NULL) {
 857                 struct request *req = blk_mq_rq_from_pdu(vbr);
 858
 859                 found++;
 860                 if (!blk_mq_add_to_batch(req, iob, vbr->status,
 861                                                 virtblk_complete_batch))
 862                         blk_mq_complete_request(req);
 863         }
 864
 865         if (found)
 866                 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
 867
 868         spin_unlock_irqrestore(&vq->lock, flags);
 869
 870         return found;
 871 }
 872
 873 static const struct blk_mq_ops virtio_mq_ops = {
 874         .queue_rq       = virtio_queue_rq,
 875         .queue_rqs      = virtio_queue_rqs,
 876         .commit_rqs     = virtio_commit_rqs,
 877         .complete       = virtblk_request_done,
 878         .map_queues     = virtblk_map_queues,
 879         .poll           = virtblk_poll,
 880 };
 881
 882 static unsigned int virtblk_queue_depth;
 883 module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
 884
 885 static int virtblk_probe(struct virtio_device *vdev)
 886 {
 887         struct virtio_blk *vblk;
 888         struct request_queue *q;
 889         int err, index;
 890
 891         u32 v, blk_size, max_size, sg_elems, opt_io_size;
 892         u16 min_io_size;
 893         u8 physical_block_exp, alignment_offset;
 894         unsigned int queue_depth;
 895
 896         if (!vdev->config->get) {
 897                 dev_err(&vdev->dev, "%s failure: config access disabled\n",
 898                         __func__);
 899                 return -EINVAL;
 900         }
 901
 902         err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
 903                              GFP_KERNEL);
 904         if (err < 0)
 905                 goto out;
 906         index = err;
 907
 908         /* We need to know how many segments before we allocate. */
 909         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
 910                                    struct virtio_blk_config, seg_max,
 911                                    &sg_elems);
 912
 913         /* We need at least one SG element, whatever they say. */
 914         if (err || !sg_elems)
 915                 sg_elems = 1;
 916
 917         /* Prevent integer overflows and honor max vq size */
 918         sg_elems = min_t(u32, sg_elems, VIRTIO_BLK_MAX_SG_ELEMS - 2);
 919
 920         vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
 921         if (!vblk) {
 922                 err = -ENOMEM;
 923                 goto out_free_index;
 924         }
 925
 926         mutex_init(&vblk->vdev_mutex);
 927
 928         vblk->vdev = vdev;
 929
 930         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
 931
 932         err = init_vq(vblk);
 933         if (err)
 934                 goto out_free_vblk;
 935
 936         /* Default queue sizing is to fill the ring. */
 937         if (!virtblk_queue_depth) {
 938                 queue_depth = vblk->vqs[0].vq->num_free;
 939                 /* ... but without indirect descs, we use 2 descs per req */
 940                 if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
 941                         queue_depth /= 2;
 942         } else {
 943                 queue_depth = virtblk_queue_depth;
 944         }
 945
 946         memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
 947         vblk->tag_set.ops = &virtio_mq_ops;
 948         vblk->tag_set.queue_depth = queue_depth;
 949         vblk->tag_set.numa_node = NUMA_NO_NODE;
 950         vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
 951         vblk->tag_set.cmd_size =
 952                 sizeof(struct virtblk_req) +
 953                 sizeof(struct scatterlist) * VIRTIO_BLK_INLINE_SG_CNT;
 954         vblk->tag_set.driver_data = vblk;
 955         vblk->tag_set.nr_hw_queues = vblk->num_vqs;
 956         vblk->tag_set.nr_maps = 1;
 957         if (vblk->io_queues[HCTX_TYPE_POLL])
 958                 vblk->tag_set.nr_maps = 3;
 959
 960         err = blk_mq_alloc_tag_set(&vblk->tag_set);
 961         if (err)
 962                 goto out_free_vq;
 963
 964         vblk->disk = blk_mq_alloc_disk(&vblk->tag_set, vblk);
 965         if (IS_ERR(vblk->disk)) {
 966                 err = PTR_ERR(vblk->disk);
 967                 goto out_free_tags;
 968         }
 969         q = vblk->disk->queue;
 970
 971         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
 972
 973         vblk->disk->major = major;
 974         vblk->disk->first_minor = index_to_minor(index);
 975         vblk->disk->minors = 1 << PART_BITS;
 976         vblk->disk->private_data = vblk;
 977         vblk->disk->fops = &virtblk_fops;
 978         vblk->index = index;
 979
 980         /* configure queue flush support */
 981         virtblk_update_cache_mode(vdev);
 982
 983         /* If disk is read-only in the host, the guest should obey */
 984         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
 985                 set_disk_ro(vblk->disk, 1);
 986
 987         /* We can handle whatever the host told us to handle. */
 988         blk_queue_max_segments(q, sg_elems);
 989
 990         /* No real sector limit. */
 991         blk_queue_max_hw_sectors(q, -1U);
 992
 993         max_size = virtio_max_dma_size(vdev);
 994
 995         /* Host can optionally specify maximum segment size and number of
 996          * segments. */
 997         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
 998                                    struct virtio_blk_config, size_max, &v);
 999         if (!err)
1000                 max_size = min(max_size, v);
1001
1002         blk_queue_max_segment_size(q, max_size);
1003
1004         /* Host can optionally specify the block size of the device */
1005         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
1006                                    struct virtio_blk_config, blk_size,
1007                                    &blk_size);
1008         if (!err) {
1009                 err = blk_validate_block_size(blk_size);
1010                 if (err) {
1011                         dev_err(&vdev->dev,
1012                                 "virtio_blk: invalid block size: 0x%x\n",
1013                                 blk_size);
1014                         goto out_cleanup_disk;
1015                 }
1016
1017                 blk_queue_logical_block_size(q, blk_size);
1018         } else
1019                 blk_size = queue_logical_block_size(q);
1020
1021         /* Use topology information if available */
1022         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
1023                                    struct virtio_blk_config, physical_block_exp,
1024                                    &physical_block_exp);
1025         if (!err && physical_block_exp)
1026                 blk_queue_physical_block_size(q,
1027                                 blk_size * (1 << physical_block_exp));
1028
1029         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
1030                                    struct virtio_blk_config, alignment_offset,
1031                                    &alignment_offset);
1032         if (!err && alignment_offset)
1033                 blk_queue_alignment_offset(q, blk_size * alignment_offset);
1034
1035         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
1036                                    struct virtio_blk_config, min_io_size,
1037                                    &min_io_size);
1038         if (!err && min_io_size)
1039                 blk_queue_io_min(q, blk_size * min_io_size);
1040
1041         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
1042                                    struct virtio_blk_config, opt_io_size,
1043                                    &opt_io_size);
1044         if (!err && opt_io_size)
1045                 blk_queue_io_opt(q, blk_size * opt_io_size);
1046
1047         if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) {
1048                 virtio_cread(vdev, struct virtio_blk_config,
1049                              discard_sector_alignment, &v);
1050                 if (v)
1051                         q->limits.discard_granularity = v << SECTOR_SHIFT;
1052                 else
1053                         q->limits.discard_granularity = blk_size;
1054
1055                 virtio_cread(vdev, struct virtio_blk_config,
1056                              max_discard_sectors, &v);
1057                 blk_queue_max_discard_sectors(q, v ? v : UINT_MAX);
1058
1059                 virtio_cread(vdev, struct virtio_blk_config, max_discard_seg,
1060                              &v);
1061
1062                 /*
1063                  * max_discard_seg == 0 is out of spec but we always
1064                  * handled it.
1065                  */
1066                 if (!v)
1067                         v = sg_elems;
1068                 blk_queue_max_discard_segments(q,
1069                                                min(v, MAX_DISCARD_SEGMENTS));
1070         }
1071
1072         if (virtio_has_feature(vdev, VIRTIO_BLK_F_WRITE_ZEROES)) {
1073                 virtio_cread(vdev, struct virtio_blk_config,
1074                              max_write_zeroes_sectors, &v);
1075                 blk_queue_max_write_zeroes_sectors(q, v ? v : UINT_MAX);
1076         }
1077
1078         virtblk_update_capacity(vblk, false);
1079         virtio_device_ready(vdev);
1080
1081         err = device_add_disk(&vdev->dev, vblk->disk, virtblk_attr_groups);
1082         if (err)
1083                 goto out_cleanup_disk;
1084
1085         return 0;
1086
1087 out_cleanup_disk:
1088         put_disk(vblk->disk);
1089 out_free_tags:
1090         blk_mq_free_tag_set(&vblk->tag_set);
1091 out_free_vq:
1092         vdev->config->del_vqs(vdev);
1093         kfree(vblk->vqs);
1094 out_free_vblk:
1095         kfree(vblk);
1096 out_free_index:
1097         ida_simple_remove(&vd_index_ida, index);
1098 out:
1099         return err;
1100 }
1101
1102 static void virtblk_remove(struct virtio_device *vdev)
1103 {
1104         struct virtio_blk *vblk = vdev->priv;
1105
1106         /* Make sure no work handler is accessing the device. */
1107         flush_work(&vblk->config_work);
1108
1109         del_gendisk(vblk->disk);
1110         blk_mq_free_tag_set(&vblk->tag_set);
1111
1112         mutex_lock(&vblk->vdev_mutex);
1113
1114         /* Stop all the virtqueues. */
1115         virtio_reset_device(vdev);
1116
1117         /* Virtqueues are stopped, nothing can use vblk->vdev anymore. */
1118         vblk->vdev = NULL;
1119
1120         vdev->config->del_vqs(vdev);
1121         kfree(vblk->vqs);
1122
1123         mutex_unlock(&vblk->vdev_mutex);
1124
1125         put_disk(vblk->disk);
1126 }
1127
1128 #ifdef CONFIG_PM_SLEEP
1129 static int virtblk_freeze(struct virtio_device *vdev)
1130 {
1131         struct virtio_blk *vblk = vdev->priv;
1132
1133         /* Ensure we don't receive any more interrupts */
1134         virtio_reset_device(vdev);
1135
1136         /* Make sure no work handler is accessing the device. */
1137         flush_work(&vblk->config_work);
1138
1139         blk_mq_quiesce_queue(vblk->disk->queue);
1140
1141         vdev->config->del_vqs(vdev);
1142         kfree(vblk->vqs);
1143
1144         return 0;
1145 }
1146
1147 static int virtblk_restore(struct virtio_device *vdev)
1148 {
1149         struct virtio_blk *vblk = vdev->priv;
1150         int ret;
1151
1152         ret = init_vq(vdev->priv);
1153         if (ret)
1154                 return ret;
1155
1156         virtio_device_ready(vdev);
1157
1158         blk_mq_unquiesce_queue(vblk->disk->queue);
1159         return 0;
1160 }
1161 #endif
1162
1163 static const struct virtio_device_id id_table[] = {
1164         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
1165         { 0 },
1166 };
1167
1168 static unsigned int features_legacy[] = {
1169         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
1170         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
1171         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
1172         VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
1173 }
1174 ;
1175 static unsigned int features[] = {
1176         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
1177         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
1178         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
1179         VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
1180 };
1181
1182 static struct virtio_driver virtio_blk = {
1183         .feature_table                  = features,
1184         .feature_table_size             = ARRAY_SIZE(features),
1185         .feature_table_legacy           = features_legacy,
1186         .feature_table_size_legacy      = ARRAY_SIZE(features_legacy),
1187         .driver.name                    = KBUILD_MODNAME,
1188         .driver.owner                   = THIS_MODULE,
1189         .id_table                       = id_table,
1190         .probe                          = virtblk_probe,
1191         .remove                         = virtblk_remove,
1192         .config_changed                 = virtblk_config_changed,
1193 #ifdef CONFIG_PM_SLEEP
1194         .freeze                         = virtblk_freeze,
1195         .restore                        = virtblk_restore,
1196 #endif
1197 };
1198
1199 static int __init virtio_blk_init(void)
1200 {
1201         int error;
1202
1203         virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
1204         if (!virtblk_wq)
1205                 return -ENOMEM;
1206
1207         major = register_blkdev(0, "virtblk");
1208         if (major < 0) {
1209                 error = major;
1210                 goto out_destroy_workqueue;
1211         }
1212
1213         error = register_virtio_driver(&virtio_blk);
1214         if (error)
1215                 goto out_unregister_blkdev;
1216         return 0;
1217
1218 out_unregister_blkdev:
1219         unregister_blkdev(major, "virtblk");
1220 out_destroy_workqueue:
1221         destroy_workqueue(virtblk_wq);
1222         return error;
1223 }
1224
1225 static void __exit virtio_blk_fini(void)
1226 {
1227         unregister_virtio_driver(&virtio_blk);
1228         unregister_blkdev(major, "virtblk");
1229         destroy_workqueue(virtblk_wq);
1230 }
1231 module_init(virtio_blk_init);
1232 module_exit(virtio_blk_fini);
1233
1234 MODULE_DEVICE_TABLE(virtio, id_table);
1235 MODULE_DESCRIPTION("Virtio block driver");
1236 MODULE_LICENSE("GPL");