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