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         vbr->sg_table.nents = virtblk_map_data(hctx, req, vbr);
 326         if (unlikely(vbr->sg_table.nents < 0)) {
 327                 virtblk_cleanup_cmd(req);
 328                 return BLK_STS_RESOURCE;
 329         }
 330
 331         blk_mq_start_request(req);
 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 {
 396         unsigned long flags;
 397         int err;
 398         bool kick;
 399
 400         spin_lock_irqsave(&vq->lock, flags);
 401
 402         while (!rq_list_empty(*rqlist)) {
 403                 struct request *req = rq_list_pop(rqlist);
 404                 struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
 405
 406                 err = virtblk_add_req(vq->vq, vbr);
 407                 if (err) {
 408                         virtblk_unmap_data(req, vbr);
 409                         virtblk_cleanup_cmd(req);
 410                         blk_mq_requeue_request(req, true);
 411                 }
 412         }
 413
 414         kick = virtqueue_kick_prepare(vq->vq);
 415         spin_unlock_irqrestore(&vq->lock, flags);
 416
 417         return kick;
 418 }
 419
 420 static void virtio_queue_rqs(struct request **rqlist)
 421 {
 422         struct request *req, *next, *prev = NULL;
 423         struct request *requeue_list = NULL;
 424
 425         rq_list_for_each_safe(rqlist, req, next) {
 426                 struct virtio_blk_vq *vq = get_virtio_blk_vq(req->mq_hctx);
 427                 bool kick;
 428
 429                 if (!virtblk_prep_rq_batch(req)) {
 430                         rq_list_move(rqlist, &requeue_list, req, prev);
 431                         req = prev;
 432                         if (!req)
 433                                 continue;
 434                 }
 435
 436                 if (!next || req->mq_hctx != next->mq_hctx) {
 437                         req->rq_next = NULL;
 438                         kick = virtblk_add_req_batch(vq, rqlist);
 439                         if (kick)
 440                                 virtqueue_notify(vq->vq);
 441
 442                         *rqlist = next;
 443                         prev = NULL;
 444                 } else
 445                         prev = req;
 446         }
 447
 448         *rqlist = requeue_list;
 449 }
 450
 451 /* return id (s/n) string for *disk to *id_str
 452  */
 453 static int virtblk_get_id(struct gendisk *disk, char *id_str)
 454 {
 455         struct virtio_blk *vblk = disk->private_data;
 456         struct request_queue *q = vblk->disk->queue;
 457         struct request *req;
 458         int err;
 459
 460         req = blk_mq_alloc_request(q, REQ_OP_DRV_IN, 0);
 461         if (IS_ERR(req))
 462                 return PTR_ERR(req);
 463
 464         err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
 465         if (err)
 466                 goto out;
 467
 468         blk_execute_rq(req, false);
 469         err = blk_status_to_errno(virtblk_result(blk_mq_rq_to_pdu(req)));
 470 out:
 471         blk_mq_free_request(req);
 472         return err;
 473 }
 474
 475 /* We provide getgeo only to please some old bootloader/partitioning tools */
 476 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
 477 {
 478         struct virtio_blk *vblk = bd->bd_disk->private_data;
 479         int ret = 0;
 480
 481         mutex_lock(&vblk->vdev_mutex);
 482
 483         if (!vblk->vdev) {
 484                 ret = -ENXIO;
 485                 goto out;
 486         }
 487
 488         /* see if the host passed in geometry config */
 489         if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) {
 490                 virtio_cread(vblk->vdev, struct virtio_blk_config,
 491                              geometry.cylinders, &geo->cylinders);
 492                 virtio_cread(vblk->vdev, struct virtio_blk_config,
 493                              geometry.heads, &geo->heads);
 494                 virtio_cread(vblk->vdev, struct virtio_blk_config,
 495                              geometry.sectors, &geo->sectors);
 496         } else {
 497                 /* some standard values, similar to sd */
 498                 geo->heads = 1 << 6;
 499                 geo->sectors = 1 << 5;
 500                 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
 501         }
 502 out:
 503         mutex_unlock(&vblk->vdev_mutex);
 504         return ret;
 505 }
 506
 507 static void virtblk_free_disk(struct gendisk *disk)
 508 {
 509         struct virtio_blk *vblk = disk->private_data;
 510
 511         ida_simple_remove(&vd_index_ida, vblk->index);
 512         mutex_destroy(&vblk->vdev_mutex);
 513         kfree(vblk);
 514 }
 515
 516 static const struct block_device_operations virtblk_fops = {
 517         .owner          = THIS_MODULE,
 518         .getgeo         = virtblk_getgeo,
 519         .free_disk      = virtblk_free_disk,
 520 };
 521
 522 static int index_to_minor(int index)
 523 {
 524         return index << PART_BITS;
 525 }
 526
 527 static int minor_to_index(int minor)
 528 {
 529         return minor >> PART_BITS;
 530 }
 531
 532 static ssize_t serial_show(struct device *dev,
 533                            struct device_attribute *attr, char *buf)
 534 {
 535         struct gendisk *disk = dev_to_disk(dev);
 536         int err;
 537
 538         /* sysfs gives us a PAGE_SIZE buffer */
 539         BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
 540
 541         buf[VIRTIO_BLK_ID_BYTES] = '\0';
 542         err = virtblk_get_id(disk, buf);
 543         if (!err)
 544                 return strlen(buf);
 545
 546         if (err == -EIO) /* Unsupported? Make it empty. */
 547                 return 0;
 548
 549         return err;
 550 }
 551
 552 static DEVICE_ATTR_RO(serial);
 553
 554 /* The queue's logical block size must be set before calling this */
 555 static void virtblk_update_capacity(struct virtio_blk *vblk, bool resize)
 556 {
 557         struct virtio_device *vdev = vblk->vdev;
 558         struct request_queue *q = vblk->disk->queue;
 559         char cap_str_2[10], cap_str_10[10];
 560         unsigned long long nblocks;
 561         u64 capacity;
 562
 563         /* Host must always specify the capacity. */
 564         virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
 565
 566         nblocks = DIV_ROUND_UP_ULL(capacity, queue_logical_block_size(q) >> 9);
 567
 568         string_get_size(nblocks, queue_logical_block_size(q),
 569                         STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
 570         string_get_size(nblocks, queue_logical_block_size(q),
 571                         STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
 572
 573         dev_notice(&vdev->dev,
 574                    "[%s] %s%llu %d-byte logical blocks (%s/%s)\n",
 575                    vblk->disk->disk_name,
 576                    resize ? "new size: " : "",
 577                    nblocks,
 578                    queue_logical_block_size(q),
 579                    cap_str_10,
 580                    cap_str_2);
 581
 582         set_capacity_and_notify(vblk->disk, capacity);
 583 }
 584
 585 static void virtblk_config_changed_work(struct work_struct *work)
 586 {
 587         struct virtio_blk *vblk =
 588                 container_of(work, struct virtio_blk, config_work);
 589
 590         virtblk_update_capacity(vblk, true);
 591 }
 592
 593 static void virtblk_config_changed(struct virtio_device *vdev)
 594 {
 595         struct virtio_blk *vblk = vdev->priv;
 596
 597         queue_work(virtblk_wq, &vblk->config_work);
 598 }
 599
 600 static int init_vq(struct virtio_blk *vblk)
 601 {
 602         int err;
 603         int i;
 604         vq_callback_t **callbacks;
 605         const char **names;
 606         struct virtqueue **vqs;
 607         unsigned short num_vqs;
 608         unsigned int num_poll_vqs;
 609         struct virtio_device *vdev = vblk->vdev;
 610         struct irq_affinity desc = { 0, };
 611
 612         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
 613                                    struct virtio_blk_config, num_queues,
 614                                    &num_vqs);
 615         if (err)
 616                 num_vqs = 1;
 617
 618         if (!err && !num_vqs) {
 619                 dev_err(&vdev->dev, "MQ advertised but zero queues reported\n");
 620                 return -EINVAL;
 621         }
 622
 623         num_vqs = min_t(unsigned int,
 624                         min_not_zero(num_request_queues, nr_cpu_ids),
 625                         num_vqs);
 626
 627         num_poll_vqs = min_t(unsigned int, poll_queues, num_vqs - 1);
 628
 629         vblk->io_queues[HCTX_TYPE_DEFAULT] = num_vqs - num_poll_vqs;
 630         vblk->io_queues[HCTX_TYPE_READ] = 0;
 631         vblk->io_queues[HCTX_TYPE_POLL] = num_poll_vqs;
 632
 633         dev_info(&vdev->dev, "%d/%d/%d default/read/poll queues\n",
 634                                 vblk->io_queues[HCTX_TYPE_DEFAULT],
 635                                 vblk->io_queues[HCTX_TYPE_READ],
 636                                 vblk->io_queues[HCTX_TYPE_POLL]);
 637
 638         vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL);
 639         if (!vblk->vqs)
 640                 return -ENOMEM;
 641
 642         names = kmalloc_array(num_vqs, sizeof(*names), GFP_KERNEL);
 643         callbacks = kmalloc_array(num_vqs, sizeof(*callbacks), GFP_KERNEL);
 644         vqs = kmalloc_array(num_vqs, sizeof(*vqs), GFP_KERNEL);
 645         if (!names || !callbacks || !vqs) {
 646                 err = -ENOMEM;
 647                 goto out;
 648         }
 649
 650         for (i = 0; i < num_vqs - num_poll_vqs; i++) {
 651                 callbacks[i] = virtblk_done;
 652                 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
 653                 names[i] = vblk->vqs[i].name;
 654         }
 655
 656         for (; i < num_vqs; i++) {
 657                 callbacks[i] = NULL;
 658                 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req_poll.%d", i);
 659                 names[i] = vblk->vqs[i].name;
 660         }
 661
 662         /* Discover virtqueues and write information to configuration.  */
 663         err = virtio_find_vqs(vdev, num_vqs, vqs, callbacks, names, &desc);
 664         if (err)
 665                 goto out;
 666
 667         for (i = 0; i < num_vqs; i++) {
 668                 spin_lock_init(&vblk->vqs[i].lock);
 669                 vblk->vqs[i].vq = vqs[i];
 670         }
 671         vblk->num_vqs = num_vqs;
 672
 673 out:
 674         kfree(vqs);
 675         kfree(callbacks);
 676         kfree(names);
 677         if (err)
 678                 kfree(vblk->vqs);
 679         return err;
 680 }
 681
 682 /*
 683  * Legacy naming scheme used for virtio devices.  We are stuck with it for
 684  * virtio blk but don't ever use it for any new driver.
 685  */
 686 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
 687 {
 688         const int base = 'z' - 'a' + 1;
 689         char *begin = buf + strlen(prefix);
 690         char *end = buf + buflen;
 691         char *p;
 692         int unit;
 693
 694         p = end - 1;
 695         *p = '\0';
 696         unit = base;
 697         do {
 698                 if (p == begin)
 699                         return -EINVAL;
 700                 *--p = 'a' + (index % unit);
 701                 index = (index / unit) - 1;
 702         } while (index >= 0);
 703
 704         memmove(begin, p, end - p);
 705         memcpy(buf, prefix, strlen(prefix));
 706
 707         return 0;
 708 }
 709
 710 static int virtblk_get_cache_mode(struct virtio_device *vdev)
 711 {
 712         u8 writeback;
 713         int err;
 714
 715         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
 716                                    struct virtio_blk_config, wce,
 717                                    &writeback);
 718
 719         /*
 720          * If WCE is not configurable and flush is not available,
 721          * assume no writeback cache is in use.
 722          */
 723         if (err)
 724                 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH);
 725
 726         return writeback;
 727 }
 728
 729 static void virtblk_update_cache_mode(struct virtio_device *vdev)
 730 {
 731         u8 writeback = virtblk_get_cache_mode(vdev);
 732         struct virtio_blk *vblk = vdev->priv;
 733
 734         blk_queue_write_cache(vblk->disk->queue, writeback, false);
 735 }
 736
 737 static const char *const virtblk_cache_types[] = {
 738         "write through", "write back"
 739 };
 740
 741 static ssize_t
 742 cache_type_store(struct device *dev, struct device_attribute *attr,
 743                  const char *buf, size_t count)
 744 {
 745         struct gendisk *disk = dev_to_disk(dev);
 746         struct virtio_blk *vblk = disk->private_data;
 747         struct virtio_device *vdev = vblk->vdev;
 748         int i;
 749
 750         BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
 751         i = sysfs_match_string(virtblk_cache_types, buf);
 752         if (i < 0)
 753                 return i;
 754
 755         virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
 756         virtblk_update_cache_mode(vdev);
 757         return count;
 758 }
 759
 760 static ssize_t
 761 cache_type_show(struct device *dev, struct device_attribute *attr, char *buf)
 762 {
 763         struct gendisk *disk = dev_to_disk(dev);
 764         struct virtio_blk *vblk = disk->private_data;
 765         u8 writeback = virtblk_get_cache_mode(vblk->vdev);
 766
 767         BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
 768         return sysfs_emit(buf, "%s\n", virtblk_cache_types[writeback]);
 769 }
 770
 771 static DEVICE_ATTR_RW(cache_type);
 772
 773 static struct attribute *virtblk_attrs[] = {
 774         &dev_attr_serial.attr,
 775         &dev_attr_cache_type.attr,
 776         NULL,
 777 };
 778
 779 static umode_t virtblk_attrs_are_visible(struct kobject *kobj,
 780                 struct attribute *a, int n)
 781 {
 782         struct device *dev = kobj_to_dev(kobj);
 783         struct gendisk *disk = dev_to_disk(dev);
 784         struct virtio_blk *vblk = disk->private_data;
 785         struct virtio_device *vdev = vblk->vdev;
 786
 787         if (a == &dev_attr_cache_type.attr &&
 788             !virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
 789                 return S_IRUGO;
 790
 791         return a->mode;
 792 }
 793
 794 static const struct attribute_group virtblk_attr_group = {
 795         .attrs = virtblk_attrs,
 796         .is_visible = virtblk_attrs_are_visible,
 797 };
 798
 799 static const struct attribute_group *virtblk_attr_groups[] = {
 800         &virtblk_attr_group,
 801         NULL,
 802 };
 803
 804 static void virtblk_map_queues(struct blk_mq_tag_set *set)
 805 {
 806         struct virtio_blk *vblk = set->driver_data;
 807         int i, qoff;
 808
 809         for (i = 0, qoff = 0; i < set->nr_maps; i++) {
 810                 struct blk_mq_queue_map *map = &set->map[i];
 811
 812                 map->nr_queues = vblk->io_queues[i];
 813                 map->queue_offset = qoff;
 814                 qoff += map->nr_queues;
 815
 816                 if (map->nr_queues == 0)
 817                         continue;
 818
 819                 /*
 820                  * Regular queues have interrupts and hence CPU affinity is
 821                  * defined by the core virtio code, but polling queues have
 822                  * no interrupts so we let the block layer assign CPU affinity.
 823                  */
 824                 if (i == HCTX_TYPE_POLL)
 825                         blk_mq_map_queues(&set->map[i]);
 826                 else
 827                         blk_mq_virtio_map_queues(&set->map[i], vblk->vdev, 0);
 828         }
 829 }
 830
 831 static void virtblk_complete_batch(struct io_comp_batch *iob)
 832 {
 833         struct request *req;
 834
 835         rq_list_for_each(&iob->req_list, req) {
 836                 virtblk_unmap_data(req, blk_mq_rq_to_pdu(req));
 837                 virtblk_cleanup_cmd(req);
 838         }
 839         blk_mq_end_request_batch(iob);
 840 }
 841
 842 static int virtblk_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob)
 843 {
 844         struct virtio_blk *vblk = hctx->queue->queuedata;
 845         struct virtio_blk_vq *vq = get_virtio_blk_vq(hctx);
 846         struct virtblk_req *vbr;
 847         unsigned long flags;
 848         unsigned int len;
 849         int found = 0;
 850
 851         spin_lock_irqsave(&vq->lock, flags);
 852
 853         while ((vbr = virtqueue_get_buf(vq->vq, &len)) != NULL) {
 854                 struct request *req = blk_mq_rq_from_pdu(vbr);
 855
 856                 found++;
 857                 if (!blk_mq_add_to_batch(req, iob, vbr->status,
 858                                                 virtblk_complete_batch))
 859                         blk_mq_complete_request(req);
 860         }
 861
 862         if (found)
 863                 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
 864
 865         spin_unlock_irqrestore(&vq->lock, flags);
 866
 867         return found;
 868 }
 869
 870 static const struct blk_mq_ops virtio_mq_ops = {
 871         .queue_rq       = virtio_queue_rq,
 872         .queue_rqs      = virtio_queue_rqs,
 873         .commit_rqs     = virtio_commit_rqs,
 874         .complete       = virtblk_request_done,
 875         .map_queues     = virtblk_map_queues,
 876         .poll           = virtblk_poll,
 877 };
 878
 879 static unsigned int virtblk_queue_depth;
 880 module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
 881
 882 static int virtblk_probe(struct virtio_device *vdev)
 883 {
 884         struct virtio_blk *vblk;
 885         struct request_queue *q;
 886         int err, index;
 887
 888         u32 v, blk_size, max_size, sg_elems, opt_io_size;
 889         u16 min_io_size;
 890         u8 physical_block_exp, alignment_offset;
 891         unsigned int queue_depth;
 892
 893         if (!vdev->config->get) {
 894                 dev_err(&vdev->dev, "%s failure: config access disabled\n",
 895                         __func__);
 896                 return -EINVAL;
 897         }
 898
 899         err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
 900                              GFP_KERNEL);
 901         if (err < 0)
 902                 goto out;
 903         index = err;
 904
 905         /* We need to know how many segments before we allocate. */
 906         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
 907                                    struct virtio_blk_config, seg_max,
 908                                    &sg_elems);
 909
 910         /* We need at least one SG element, whatever they say. */
 911         if (err || !sg_elems)
 912                 sg_elems = 1;
 913
 914         /* Prevent integer overflows and honor max vq size */
 915         sg_elems = min_t(u32, sg_elems, VIRTIO_BLK_MAX_SG_ELEMS - 2);
 916
 917         vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
 918         if (!vblk) {
 919                 err = -ENOMEM;
 920                 goto out_free_index;
 921         }
 922
 923         mutex_init(&vblk->vdev_mutex);
 924
 925         vblk->vdev = vdev;
 926
 927         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
 928
 929         err = init_vq(vblk);
 930         if (err)
 931                 goto out_free_vblk;
 932
 933         /* Default queue sizing is to fill the ring. */
 934         if (!virtblk_queue_depth) {
 935                 queue_depth = vblk->vqs[0].vq->num_free;
 936                 /* ... but without indirect descs, we use 2 descs per req */
 937                 if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
 938                         queue_depth /= 2;
 939         } else {
 940                 queue_depth = virtblk_queue_depth;
 941         }
 942
 943         memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
 944         vblk->tag_set.ops = &virtio_mq_ops;
 945         vblk->tag_set.queue_depth = queue_depth;
 946         vblk->tag_set.numa_node = NUMA_NO_NODE;
 947         vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
 948         vblk->tag_set.cmd_size =
 949                 sizeof(struct virtblk_req) +
 950                 sizeof(struct scatterlist) * VIRTIO_BLK_INLINE_SG_CNT;
 951         vblk->tag_set.driver_data = vblk;
 952         vblk->tag_set.nr_hw_queues = vblk->num_vqs;
 953         vblk->tag_set.nr_maps = 1;
 954         if (vblk->io_queues[HCTX_TYPE_POLL])
 955                 vblk->tag_set.nr_maps = 3;
 956
 957         err = blk_mq_alloc_tag_set(&vblk->tag_set);
 958         if (err)
 959                 goto out_free_vq;
 960
 961         vblk->disk = blk_mq_alloc_disk(&vblk->tag_set, vblk);
 962         if (IS_ERR(vblk->disk)) {
 963                 err = PTR_ERR(vblk->disk);
 964                 goto out_free_tags;
 965         }
 966         q = vblk->disk->queue;
 967
 968         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
 969
 970         vblk->disk->major = major;
 971         vblk->disk->first_minor = index_to_minor(index);
 972         vblk->disk->minors = 1 << PART_BITS;
 973         vblk->disk->private_data = vblk;
 974         vblk->disk->fops = &virtblk_fops;
 975         vblk->index = index;
 976
 977         /* configure queue flush support */
 978         virtblk_update_cache_mode(vdev);
 979
 980         /* If disk is read-only in the host, the guest should obey */
 981         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
 982                 set_disk_ro(vblk->disk, 1);
 983
 984         /* We can handle whatever the host told us to handle. */
 985         blk_queue_max_segments(q, sg_elems);
 986
 987         /* No real sector limit. */
 988         blk_queue_max_hw_sectors(q, -1U);
 989
 990         max_size = virtio_max_dma_size(vdev);
 991
 992         /* Host can optionally specify maximum segment size and number of
 993          * segments. */
 994         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
 995                                    struct virtio_blk_config, size_max, &v);
 996         if (!err)
 997                 max_size = min(max_size, v);
 998
 999         blk_queue_max_segment_size(q, max_size);
1000
1001         /* Host can optionally specify the block size of the device */
1002         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
1003                                    struct virtio_blk_config, blk_size,
1004                                    &blk_size);
1005         if (!err) {
1006                 err = blk_validate_block_size(blk_size);
1007                 if (err) {
1008                         dev_err(&vdev->dev,
1009                                 "virtio_blk: invalid block size: 0x%x\n",
1010                                 blk_size);
1011                         goto out_cleanup_disk;
1012                 }
1013
1014                 blk_queue_logical_block_size(q, blk_size);
1015         } else
1016                 blk_size = queue_logical_block_size(q);
1017
1018         /* Use topology information if available */
1019         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
1020                                    struct virtio_blk_config, physical_block_exp,
1021                                    &physical_block_exp);
1022         if (!err && physical_block_exp)
1023                 blk_queue_physical_block_size(q,
1024                                 blk_size * (1 << physical_block_exp));
1025
1026         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
1027                                    struct virtio_blk_config, alignment_offset,
1028                                    &alignment_offset);
1029         if (!err && alignment_offset)
1030                 blk_queue_alignment_offset(q, blk_size * alignment_offset);
1031
1032         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
1033                                    struct virtio_blk_config, min_io_size,
1034                                    &min_io_size);
1035         if (!err && min_io_size)
1036                 blk_queue_io_min(q, blk_size * min_io_size);
1037
1038         err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
1039                                    struct virtio_blk_config, opt_io_size,
1040                                    &opt_io_size);
1041         if (!err && opt_io_size)
1042                 blk_queue_io_opt(q, blk_size * opt_io_size);
1043
1044         if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) {
1045                 virtio_cread(vdev, struct virtio_blk_config,
1046                              discard_sector_alignment, &v);
1047                 if (v)
1048                         q->limits.discard_granularity = v << SECTOR_SHIFT;
1049                 else
1050                         q->limits.discard_granularity = blk_size;
1051
1052                 virtio_cread(vdev, struct virtio_blk_config,
1053                              max_discard_sectors, &v);
1054                 blk_queue_max_discard_sectors(q, v ? v : UINT_MAX);
1055
1056                 virtio_cread(vdev, struct virtio_blk_config, max_discard_seg,
1057                              &v);
1058
1059                 /*
1060                  * max_discard_seg == 0 is out of spec but we always
1061                  * handled it.
1062                  */
1063                 if (!v)
1064                         v = sg_elems;
1065                 blk_queue_max_discard_segments(q,
1066                                                min(v, MAX_DISCARD_SEGMENTS));
1067         }
1068
1069         if (virtio_has_feature(vdev, VIRTIO_BLK_F_WRITE_ZEROES)) {
1070                 virtio_cread(vdev, struct virtio_blk_config,
1071                              max_write_zeroes_sectors, &v);
1072                 blk_queue_max_write_zeroes_sectors(q, v ? v : UINT_MAX);
1073         }
1074
1075         virtblk_update_capacity(vblk, false);
1076         virtio_device_ready(vdev);
1077
1078         err = device_add_disk(&vdev->dev, vblk->disk, virtblk_attr_groups);
1079         if (err)
1080                 goto out_cleanup_disk;
1081
1082         return 0;
1083
1084 out_cleanup_disk:
1085         put_disk(vblk->disk);
1086 out_free_tags:
1087         blk_mq_free_tag_set(&vblk->tag_set);
1088 out_free_vq:
1089         vdev->config->del_vqs(vdev);
1090         kfree(vblk->vqs);
1091 out_free_vblk:
1092         kfree(vblk);
1093 out_free_index:
1094         ida_simple_remove(&vd_index_ida, index);
1095 out:
1096         return err;
1097 }
1098
1099 static void virtblk_remove(struct virtio_device *vdev)
1100 {
1101         struct virtio_blk *vblk = vdev->priv;
1102
1103         /* Make sure no work handler is accessing the device. */
1104         flush_work(&vblk->config_work);
1105
1106         del_gendisk(vblk->disk);
1107         blk_mq_free_tag_set(&vblk->tag_set);
1108
1109         mutex_lock(&vblk->vdev_mutex);
1110
1111         /* Stop all the virtqueues. */
1112         virtio_reset_device(vdev);
1113
1114         /* Virtqueues are stopped, nothing can use vblk->vdev anymore. */
1115         vblk->vdev = NULL;
1116
1117         vdev->config->del_vqs(vdev);
1118         kfree(vblk->vqs);
1119
1120         mutex_unlock(&vblk->vdev_mutex);
1121
1122         put_disk(vblk->disk);
1123 }
1124
1125 #ifdef CONFIG_PM_SLEEP
1126 static int virtblk_freeze(struct virtio_device *vdev)
1127 {
1128         struct virtio_blk *vblk = vdev->priv;
1129
1130         /* Ensure we don't receive any more interrupts */
1131         virtio_reset_device(vdev);
1132
1133         /* Make sure no work handler is accessing the device. */
1134         flush_work(&vblk->config_work);
1135
1136         blk_mq_quiesce_queue(vblk->disk->queue);
1137
1138         vdev->config->del_vqs(vdev);
1139         kfree(vblk->vqs);
1140
1141         return 0;
1142 }
1143
1144 static int virtblk_restore(struct virtio_device *vdev)
1145 {
1146         struct virtio_blk *vblk = vdev->priv;
1147         int ret;
1148
1149         ret = init_vq(vdev->priv);
1150         if (ret)
1151                 return ret;
1152
1153         virtio_device_ready(vdev);
1154
1155         blk_mq_unquiesce_queue(vblk->disk->queue);
1156         return 0;
1157 }
1158 #endif
1159
1160 static const struct virtio_device_id id_table[] = {
1161         { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
1162         { 0 },
1163 };
1164
1165 static unsigned int features_legacy[] = {
1166         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
1167         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
1168         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
1169         VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
1170 }
1171 ;
1172 static unsigned int features[] = {
1173         VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
1174         VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
1175         VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
1176         VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
1177 };
1178
1179 static struct virtio_driver virtio_blk = {
1180         .feature_table                  = features,
1181         .feature_table_size             = ARRAY_SIZE(features),
1182         .feature_table_legacy           = features_legacy,
1183         .feature_table_size_legacy      = ARRAY_SIZE(features_legacy),
1184         .driver.name                    = KBUILD_MODNAME,
1185         .driver.owner                   = THIS_MODULE,
1186         .id_table                       = id_table,
1187         .probe                          = virtblk_probe,
1188         .remove                         = virtblk_remove,
1189         .config_changed                 = virtblk_config_changed,
1190 #ifdef CONFIG_PM_SLEEP
1191         .freeze                         = virtblk_freeze,
1192         .restore                        = virtblk_restore,
1193 #endif
1194 };
1195
1196 static int __init virtio_blk_init(void)
1197 {
1198         int error;
1199
1200         virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
1201         if (!virtblk_wq)
1202                 return -ENOMEM;
1203
1204         major = register_blkdev(0, "virtblk");
1205         if (major < 0) {
1206                 error = major;
1207                 goto out_destroy_workqueue;
1208         }
1209
1210         error = register_virtio_driver(&virtio_blk);
1211         if (error)
1212                 goto out_unregister_blkdev;
1213         return 0;
1214
1215 out_unregister_blkdev:
1216         unregister_blkdev(major, "virtblk");
1217 out_destroy_workqueue:
1218         destroy_workqueue(virtblk_wq);
1219         return error;
1220 }
1221
1222 static void __exit virtio_blk_fini(void)
1223 {
1224         unregister_virtio_driver(&virtio_blk);
1225         unregister_blkdev(major, "virtblk");
1226         destroy_workqueue(virtblk_wq);
1227 }
1228 module_init(virtio_blk_init);
1229 module_exit(virtio_blk_fini);
1230
1231 MODULE_DEVICE_TABLE(virtio, id_table);
1232 MODULE_DESCRIPTION("Virtio block driver");
1233 MODULE_LICENSE("GPL");