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 int virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr) 105 { 106 struct scatterlist hdr, status, *sgs[3]; 107 unsigned int num_out = 0, num_in = 0; 108 109 sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr)); 110 sgs[num_out++] = &hdr; 111 112 if (vbr->sg_table.nents) { 113 if (vbr->out_hdr.type & cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT)) 114 sgs[num_out++] = vbr->sg_table.sgl; 115 else 116 sgs[num_out + num_in++] = vbr->sg_table.sgl; 117 } 118 119 sg_init_one(&status, &vbr->status, sizeof(vbr->status)); 120 sgs[num_out + num_in++] = &status; 121 122 return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC); 123 } 124 125 static int virtblk_setup_discard_write_zeroes(struct request *req, bool unmap) 126 { 127 unsigned short segments = blk_rq_nr_discard_segments(req); 128 unsigned short n = 0; 129 struct virtio_blk_discard_write_zeroes *range; 130 struct bio *bio; 131 u32 flags = 0; 132 133 if (unmap) 134 flags |= VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP; 135 136 range = kmalloc_array(segments, sizeof(*range), GFP_ATOMIC); 137 if (!range) 138 return -ENOMEM; 139 140 /* 141 * Single max discard segment means multi-range discard isn't 142 * supported, and block layer only runs contiguity merge like 143 * normal RW request. So we can't reply on bio for retrieving 144 * each range info. 145 */ 146 if (queue_max_discard_segments(req->q) == 1) { 147 range[0].flags = cpu_to_le32(flags); 148 range[0].num_sectors = cpu_to_le32(blk_rq_sectors(req)); 149 range[0].sector = cpu_to_le64(blk_rq_pos(req)); 150 n = 1; 151 } else { 152 __rq_for_each_bio(bio, req) { 153 u64 sector = bio->bi_iter.bi_sector; 154 u32 num_sectors = bio->bi_iter.bi_size >> SECTOR_SHIFT; 155 156 range[n].flags = cpu_to_le32(flags); 157 range[n].num_sectors = cpu_to_le32(num_sectors); 158 range[n].sector = cpu_to_le64(sector); 159 n++; 160 } 161 } 162 163 WARN_ON_ONCE(n != segments); 164 165 req->special_vec.bv_page = virt_to_page(range); 166 req->special_vec.bv_offset = offset_in_page(range); 167 req->special_vec.bv_len = sizeof(*range) * segments; 168 req->rq_flags |= RQF_SPECIAL_PAYLOAD; 169 170 return 0; 171 } 172 173 static void virtblk_unmap_data(struct request *req, struct virtblk_req *vbr) 174 { 175 if (blk_rq_nr_phys_segments(req)) 176 sg_free_table_chained(&vbr->sg_table, 177 VIRTIO_BLK_INLINE_SG_CNT); 178 } 179 180 static int virtblk_map_data(struct blk_mq_hw_ctx *hctx, struct request *req, 181 struct virtblk_req *vbr) 182 { 183 int err; 184 185 if (!blk_rq_nr_phys_segments(req)) 186 return 0; 187 188 vbr->sg_table.sgl = vbr->sg; 189 err = sg_alloc_table_chained(&vbr->sg_table, 190 blk_rq_nr_phys_segments(req), 191 vbr->sg_table.sgl, 192 VIRTIO_BLK_INLINE_SG_CNT); 193 if (unlikely(err)) 194 return -ENOMEM; 195 196 return blk_rq_map_sg(hctx->queue, req, vbr->sg_table.sgl); 197 } 198 199 static void virtblk_cleanup_cmd(struct request *req) 200 { 201 if (req->rq_flags & RQF_SPECIAL_PAYLOAD) 202 kfree(bvec_virt(&req->special_vec)); 203 } 204 205 static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev, 206 struct request *req, 207 struct virtblk_req *vbr) 208 { 209 bool unmap = false; 210 u32 type; 211 212 vbr->out_hdr.sector = 0; 213 214 switch (req_op(req)) { 215 case REQ_OP_READ: 216 type = VIRTIO_BLK_T_IN; 217 vbr->out_hdr.sector = cpu_to_virtio64(vdev, 218 blk_rq_pos(req)); 219 break; 220 case REQ_OP_WRITE: 221 type = VIRTIO_BLK_T_OUT; 222 vbr->out_hdr.sector = cpu_to_virtio64(vdev, 223 blk_rq_pos(req)); 224 break; 225 case REQ_OP_FLUSH: 226 type = VIRTIO_BLK_T_FLUSH; 227 break; 228 case REQ_OP_DISCARD: 229 type = VIRTIO_BLK_T_DISCARD; 230 break; 231 case REQ_OP_WRITE_ZEROES: 232 type = VIRTIO_BLK_T_WRITE_ZEROES; 233 unmap = !(req->cmd_flags & REQ_NOUNMAP); 234 break; 235 case REQ_OP_DRV_IN: 236 type = VIRTIO_BLK_T_GET_ID; 237 break; 238 default: 239 WARN_ON_ONCE(1); 240 return BLK_STS_IOERR; 241 } 242 243 vbr->out_hdr.type = cpu_to_virtio32(vdev, type); 244 vbr->out_hdr.ioprio = cpu_to_virtio32(vdev, req_get_ioprio(req)); 245 246 if (type == VIRTIO_BLK_T_DISCARD || type == VIRTIO_BLK_T_WRITE_ZEROES) { 247 if (virtblk_setup_discard_write_zeroes(req, unmap)) 248 return BLK_STS_RESOURCE; 249 } 250 251 return 0; 252 } 253 254 static inline void virtblk_request_done(struct request *req) 255 { 256 struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); 257 258 virtblk_unmap_data(req, vbr); 259 virtblk_cleanup_cmd(req); 260 blk_mq_end_request(req, virtblk_result(vbr)); 261 } 262 263 static void virtblk_done(struct virtqueue *vq) 264 { 265 struct virtio_blk *vblk = vq->vdev->priv; 266 bool req_done = false; 267 int qid = vq->index; 268 struct virtblk_req *vbr; 269 unsigned long flags; 270 unsigned int len; 271 272 spin_lock_irqsave(&vblk->vqs[qid].lock, flags); 273 do { 274 virtqueue_disable_cb(vq); 275 while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) { 276 struct request *req = blk_mq_rq_from_pdu(vbr); 277 278 if (likely(!blk_should_fake_timeout(req->q))) 279 blk_mq_complete_request(req); 280 req_done = true; 281 } 282 if (unlikely(virtqueue_is_broken(vq))) 283 break; 284 } while (!virtqueue_enable_cb(vq)); 285 286 /* In case queue is stopped waiting for more buffers. */ 287 if (req_done) 288 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true); 289 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags); 290 } 291 292 static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx) 293 { 294 struct virtio_blk *vblk = hctx->queue->queuedata; 295 struct virtio_blk_vq *vq = &vblk->vqs[hctx->queue_num]; 296 bool kick; 297 298 spin_lock_irq(&vq->lock); 299 kick = virtqueue_kick_prepare(vq->vq); 300 spin_unlock_irq(&vq->lock); 301 302 if (kick) 303 virtqueue_notify(vq->vq); 304 } 305 306 static blk_status_t virtblk_prep_rq(struct blk_mq_hw_ctx *hctx, 307 struct virtio_blk *vblk, 308 struct request *req, 309 struct virtblk_req *vbr) 310 { 311 blk_status_t status; 312 313 status = virtblk_setup_cmd(vblk->vdev, req, vbr); 314 if (unlikely(status)) 315 return status; 316 317 blk_mq_start_request(req); 318 319 vbr->sg_table.nents = virtblk_map_data(hctx, req, vbr); 320 if (unlikely(vbr->sg_table.nents < 0)) { 321 virtblk_cleanup_cmd(req); 322 return BLK_STS_RESOURCE; 323 } 324 325 return BLK_STS_OK; 326 } 327 328 static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, 329 const struct blk_mq_queue_data *bd) 330 { 331 struct virtio_blk *vblk = hctx->queue->queuedata; 332 struct request *req = bd->rq; 333 struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); 334 unsigned long flags; 335 int qid = hctx->queue_num; 336 bool notify = false; 337 blk_status_t status; 338 int err; 339 340 status = virtblk_prep_rq(hctx, vblk, req, vbr); 341 if (unlikely(status)) 342 return status; 343 344 spin_lock_irqsave(&vblk->vqs[qid].lock, flags); 345 err = virtblk_add_req(vblk->vqs[qid].vq, vbr); 346 if (err) { 347 virtqueue_kick(vblk->vqs[qid].vq); 348 /* Don't stop the queue if -ENOMEM: we may have failed to 349 * bounce the buffer due to global resource outage. 350 */ 351 if (err == -ENOSPC) 352 blk_mq_stop_hw_queue(hctx); 353 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags); 354 virtblk_unmap_data(req, vbr); 355 virtblk_cleanup_cmd(req); 356 switch (err) { 357 case -ENOSPC: 358 return BLK_STS_DEV_RESOURCE; 359 case -ENOMEM: 360 return BLK_STS_RESOURCE; 361 default: 362 return BLK_STS_IOERR; 363 } 364 } 365 366 if (bd->last && virtqueue_kick_prepare(vblk->vqs[qid].vq)) 367 notify = true; 368 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags); 369 370 if (notify) 371 virtqueue_notify(vblk->vqs[qid].vq); 372 return BLK_STS_OK; 373 } 374 375 static bool virtblk_prep_rq_batch(struct request *req) 376 { 377 struct virtio_blk *vblk = req->mq_hctx->queue->queuedata; 378 struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); 379 380 req->mq_hctx->tags->rqs[req->tag] = req; 381 382 return virtblk_prep_rq(req->mq_hctx, vblk, req, vbr) == BLK_STS_OK; 383 } 384 385 static bool virtblk_add_req_batch(struct virtio_blk_vq *vq, 386 struct request **rqlist, 387 struct request **requeue_list) 388 { 389 unsigned long flags; 390 int err; 391 bool kick; 392 393 spin_lock_irqsave(&vq->lock, flags); 394 395 while (!rq_list_empty(*rqlist)) { 396 struct request *req = rq_list_pop(rqlist); 397 struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); 398 399 err = virtblk_add_req(vq->vq, vbr); 400 if (err) { 401 virtblk_unmap_data(req, vbr); 402 virtblk_cleanup_cmd(req); 403 rq_list_add(requeue_list, req); 404 } 405 } 406 407 kick = virtqueue_kick_prepare(vq->vq); 408 spin_unlock_irqrestore(&vq->lock, flags); 409 410 return kick; 411 } 412 413 static void virtio_queue_rqs(struct request **rqlist) 414 { 415 struct request *req, *next, *prev = NULL; 416 struct request *requeue_list = NULL; 417 418 rq_list_for_each_safe(rqlist, req, next) { 419 struct virtio_blk_vq *vq = req->mq_hctx->driver_data; 420 bool kick; 421 422 if (!virtblk_prep_rq_batch(req)) { 423 rq_list_move(rqlist, &requeue_list, req, prev); 424 req = prev; 425 if (!req) 426 continue; 427 } 428 429 if (!next || req->mq_hctx != next->mq_hctx) { 430 req->rq_next = NULL; 431 kick = virtblk_add_req_batch(vq, rqlist, &requeue_list); 432 if (kick) 433 virtqueue_notify(vq->vq); 434 435 *rqlist = next; 436 prev = NULL; 437 } else 438 prev = req; 439 } 440 441 *rqlist = requeue_list; 442 } 443 444 /* return id (s/n) string for *disk to *id_str 445 */ 446 static int virtblk_get_id(struct gendisk *disk, char *id_str) 447 { 448 struct virtio_blk *vblk = disk->private_data; 449 struct request_queue *q = vblk->disk->queue; 450 struct request *req; 451 int err; 452 453 req = blk_mq_alloc_request(q, REQ_OP_DRV_IN, 0); 454 if (IS_ERR(req)) 455 return PTR_ERR(req); 456 457 err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL); 458 if (err) 459 goto out; 460 461 blk_execute_rq(req, false); 462 err = blk_status_to_errno(virtblk_result(blk_mq_rq_to_pdu(req))); 463 out: 464 blk_mq_free_request(req); 465 return err; 466 } 467 468 /* We provide getgeo only to please some old bootloader/partitioning tools */ 469 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) 470 { 471 struct virtio_blk *vblk = bd->bd_disk->private_data; 472 int ret = 0; 473 474 mutex_lock(&vblk->vdev_mutex); 475 476 if (!vblk->vdev) { 477 ret = -ENXIO; 478 goto out; 479 } 480 481 /* see if the host passed in geometry config */ 482 if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) { 483 virtio_cread(vblk->vdev, struct virtio_blk_config, 484 geometry.cylinders, &geo->cylinders); 485 virtio_cread(vblk->vdev, struct virtio_blk_config, 486 geometry.heads, &geo->heads); 487 virtio_cread(vblk->vdev, struct virtio_blk_config, 488 geometry.sectors, &geo->sectors); 489 } else { 490 /* some standard values, similar to sd */ 491 geo->heads = 1 << 6; 492 geo->sectors = 1 << 5; 493 geo->cylinders = get_capacity(bd->bd_disk) >> 11; 494 } 495 out: 496 mutex_unlock(&vblk->vdev_mutex); 497 return ret; 498 } 499 500 static void virtblk_free_disk(struct gendisk *disk) 501 { 502 struct virtio_blk *vblk = disk->private_data; 503 504 ida_simple_remove(&vd_index_ida, vblk->index); 505 mutex_destroy(&vblk->vdev_mutex); 506 kfree(vblk); 507 } 508 509 static const struct block_device_operations virtblk_fops = { 510 .owner = THIS_MODULE, 511 .getgeo = virtblk_getgeo, 512 .free_disk = virtblk_free_disk, 513 }; 514 515 static int index_to_minor(int index) 516 { 517 return index << PART_BITS; 518 } 519 520 static int minor_to_index(int minor) 521 { 522 return minor >> PART_BITS; 523 } 524 525 static ssize_t serial_show(struct device *dev, 526 struct device_attribute *attr, char *buf) 527 { 528 struct gendisk *disk = dev_to_disk(dev); 529 int err; 530 531 /* sysfs gives us a PAGE_SIZE buffer */ 532 BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES); 533 534 buf[VIRTIO_BLK_ID_BYTES] = '\0'; 535 err = virtblk_get_id(disk, buf); 536 if (!err) 537 return strlen(buf); 538 539 if (err == -EIO) /* Unsupported? Make it empty. */ 540 return 0; 541 542 return err; 543 } 544 545 static DEVICE_ATTR_RO(serial); 546 547 /* The queue's logical block size must be set before calling this */ 548 static void virtblk_update_capacity(struct virtio_blk *vblk, bool resize) 549 { 550 struct virtio_device *vdev = vblk->vdev; 551 struct request_queue *q = vblk->disk->queue; 552 char cap_str_2[10], cap_str_10[10]; 553 unsigned long long nblocks; 554 u64 capacity; 555 556 /* Host must always specify the capacity. */ 557 virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity); 558 559 nblocks = DIV_ROUND_UP_ULL(capacity, queue_logical_block_size(q) >> 9); 560 561 string_get_size(nblocks, queue_logical_block_size(q), 562 STRING_UNITS_2, cap_str_2, sizeof(cap_str_2)); 563 string_get_size(nblocks, queue_logical_block_size(q), 564 STRING_UNITS_10, cap_str_10, sizeof(cap_str_10)); 565 566 dev_notice(&vdev->dev, 567 "[%s] %s%llu %d-byte logical blocks (%s/%s)\n", 568 vblk->disk->disk_name, 569 resize ? "new size: " : "", 570 nblocks, 571 queue_logical_block_size(q), 572 cap_str_10, 573 cap_str_2); 574 575 set_capacity_and_notify(vblk->disk, capacity); 576 } 577 578 static void virtblk_config_changed_work(struct work_struct *work) 579 { 580 struct virtio_blk *vblk = 581 container_of(work, struct virtio_blk, config_work); 582 583 virtblk_update_capacity(vblk, true); 584 } 585 586 static void virtblk_config_changed(struct virtio_device *vdev) 587 { 588 struct virtio_blk *vblk = vdev->priv; 589 590 queue_work(virtblk_wq, &vblk->config_work); 591 } 592 593 static int init_vq(struct virtio_blk *vblk) 594 { 595 int err; 596 int i; 597 vq_callback_t **callbacks; 598 const char **names; 599 struct virtqueue **vqs; 600 unsigned short num_vqs; 601 unsigned int num_poll_vqs; 602 struct virtio_device *vdev = vblk->vdev; 603 struct irq_affinity desc = { 0, }; 604 605 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ, 606 struct virtio_blk_config, num_queues, 607 &num_vqs); 608 if (err) 609 num_vqs = 1; 610 611 if (!err && !num_vqs) { 612 dev_err(&vdev->dev, "MQ advertised but zero queues reported\n"); 613 return -EINVAL; 614 } 615 616 num_vqs = min_t(unsigned int, 617 min_not_zero(num_request_queues, nr_cpu_ids), 618 num_vqs); 619 620 num_poll_vqs = min_t(unsigned int, poll_queues, num_vqs - 1); 621 622 vblk->io_queues[HCTX_TYPE_DEFAULT] = num_vqs - num_poll_vqs; 623 vblk->io_queues[HCTX_TYPE_READ] = 0; 624 vblk->io_queues[HCTX_TYPE_POLL] = num_poll_vqs; 625 626 dev_info(&vdev->dev, "%d/%d/%d default/read/poll queues\n", 627 vblk->io_queues[HCTX_TYPE_DEFAULT], 628 vblk->io_queues[HCTX_TYPE_READ], 629 vblk->io_queues[HCTX_TYPE_POLL]); 630 631 vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL); 632 if (!vblk->vqs) 633 return -ENOMEM; 634 635 names = kmalloc_array(num_vqs, sizeof(*names), GFP_KERNEL); 636 callbacks = kmalloc_array(num_vqs, sizeof(*callbacks), GFP_KERNEL); 637 vqs = kmalloc_array(num_vqs, sizeof(*vqs), GFP_KERNEL); 638 if (!names || !callbacks || !vqs) { 639 err = -ENOMEM; 640 goto out; 641 } 642 643 for (i = 0; i < num_vqs - num_poll_vqs; i++) { 644 callbacks[i] = virtblk_done; 645 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i); 646 names[i] = vblk->vqs[i].name; 647 } 648 649 for (; i < num_vqs; i++) { 650 callbacks[i] = NULL; 651 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req_poll.%d", i); 652 names[i] = vblk->vqs[i].name; 653 } 654 655 /* Discover virtqueues and write information to configuration. */ 656 err = virtio_find_vqs(vdev, num_vqs, vqs, callbacks, names, &desc); 657 if (err) 658 goto out; 659 660 for (i = 0; i < num_vqs; i++) { 661 spin_lock_init(&vblk->vqs[i].lock); 662 vblk->vqs[i].vq = vqs[i]; 663 } 664 vblk->num_vqs = num_vqs; 665 666 out: 667 kfree(vqs); 668 kfree(callbacks); 669 kfree(names); 670 if (err) 671 kfree(vblk->vqs); 672 return err; 673 } 674 675 /* 676 * Legacy naming scheme used for virtio devices. We are stuck with it for 677 * virtio blk but don't ever use it for any new driver. 678 */ 679 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen) 680 { 681 const int base = 'z' - 'a' + 1; 682 char *begin = buf + strlen(prefix); 683 char *end = buf + buflen; 684 char *p; 685 int unit; 686 687 p = end - 1; 688 *p = '\0'; 689 unit = base; 690 do { 691 if (p == begin) 692 return -EINVAL; 693 *--p = 'a' + (index % unit); 694 index = (index / unit) - 1; 695 } while (index >= 0); 696 697 memmove(begin, p, end - p); 698 memcpy(buf, prefix, strlen(prefix)); 699 700 return 0; 701 } 702 703 static int virtblk_get_cache_mode(struct virtio_device *vdev) 704 { 705 u8 writeback; 706 int err; 707 708 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE, 709 struct virtio_blk_config, wce, 710 &writeback); 711 712 /* 713 * If WCE is not configurable and flush is not available, 714 * assume no writeback cache is in use. 715 */ 716 if (err) 717 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH); 718 719 return writeback; 720 } 721 722 static void virtblk_update_cache_mode(struct virtio_device *vdev) 723 { 724 u8 writeback = virtblk_get_cache_mode(vdev); 725 struct virtio_blk *vblk = vdev->priv; 726 727 blk_queue_write_cache(vblk->disk->queue, writeback, false); 728 } 729 730 static const char *const virtblk_cache_types[] = { 731 "write through", "write back" 732 }; 733 734 static ssize_t 735 cache_type_store(struct device *dev, struct device_attribute *attr, 736 const char *buf, size_t count) 737 { 738 struct gendisk *disk = dev_to_disk(dev); 739 struct virtio_blk *vblk = disk->private_data; 740 struct virtio_device *vdev = vblk->vdev; 741 int i; 742 743 BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE)); 744 i = sysfs_match_string(virtblk_cache_types, buf); 745 if (i < 0) 746 return i; 747 748 virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i); 749 virtblk_update_cache_mode(vdev); 750 return count; 751 } 752 753 static ssize_t 754 cache_type_show(struct device *dev, struct device_attribute *attr, char *buf) 755 { 756 struct gendisk *disk = dev_to_disk(dev); 757 struct virtio_blk *vblk = disk->private_data; 758 u8 writeback = virtblk_get_cache_mode(vblk->vdev); 759 760 BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types)); 761 return sysfs_emit(buf, "%s\n", virtblk_cache_types[writeback]); 762 } 763 764 static DEVICE_ATTR_RW(cache_type); 765 766 static struct attribute *virtblk_attrs[] = { 767 &dev_attr_serial.attr, 768 &dev_attr_cache_type.attr, 769 NULL, 770 }; 771 772 static umode_t virtblk_attrs_are_visible(struct kobject *kobj, 773 struct attribute *a, int n) 774 { 775 struct device *dev = kobj_to_dev(kobj); 776 struct gendisk *disk = dev_to_disk(dev); 777 struct virtio_blk *vblk = disk->private_data; 778 struct virtio_device *vdev = vblk->vdev; 779 780 if (a == &dev_attr_cache_type.attr && 781 !virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE)) 782 return S_IRUGO; 783 784 return a->mode; 785 } 786 787 static const struct attribute_group virtblk_attr_group = { 788 .attrs = virtblk_attrs, 789 .is_visible = virtblk_attrs_are_visible, 790 }; 791 792 static const struct attribute_group *virtblk_attr_groups[] = { 793 &virtblk_attr_group, 794 NULL, 795 }; 796 797 static int virtblk_map_queues(struct blk_mq_tag_set *set) 798 { 799 struct virtio_blk *vblk = set->driver_data; 800 int i, qoff; 801 802 for (i = 0, qoff = 0; i < set->nr_maps; i++) { 803 struct blk_mq_queue_map *map = &set->map[i]; 804 805 map->nr_queues = vblk->io_queues[i]; 806 map->queue_offset = qoff; 807 qoff += map->nr_queues; 808 809 if (map->nr_queues == 0) 810 continue; 811 812 /* 813 * Regular queues have interrupts and hence CPU affinity is 814 * defined by the core virtio code, but polling queues have 815 * no interrupts so we let the block layer assign CPU affinity. 816 */ 817 if (i == HCTX_TYPE_POLL) 818 blk_mq_map_queues(&set->map[i]); 819 else 820 blk_mq_virtio_map_queues(&set->map[i], vblk->vdev, 0); 821 } 822 823 return 0; 824 } 825 826 static void virtblk_complete_batch(struct io_comp_batch *iob) 827 { 828 struct request *req; 829 830 rq_list_for_each(&iob->req_list, req) { 831 virtblk_unmap_data(req, blk_mq_rq_to_pdu(req)); 832 virtblk_cleanup_cmd(req); 833 } 834 blk_mq_end_request_batch(iob); 835 } 836 837 static int virtblk_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob) 838 { 839 struct virtio_blk *vblk = hctx->queue->queuedata; 840 struct virtio_blk_vq *vq = hctx->driver_data; 841 struct virtblk_req *vbr; 842 unsigned long flags; 843 unsigned int len; 844 int found = 0; 845 846 spin_lock_irqsave(&vq->lock, flags); 847 848 while ((vbr = virtqueue_get_buf(vq->vq, &len)) != NULL) { 849 struct request *req = blk_mq_rq_from_pdu(vbr); 850 851 found++; 852 if (!blk_mq_add_to_batch(req, iob, vbr->status, 853 virtblk_complete_batch)) 854 blk_mq_complete_request(req); 855 } 856 857 if (found) 858 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true); 859 860 spin_unlock_irqrestore(&vq->lock, flags); 861 862 return found; 863 } 864 865 static int virtblk_init_hctx(struct blk_mq_hw_ctx *hctx, void *data, 866 unsigned int hctx_idx) 867 { 868 struct virtio_blk *vblk = data; 869 struct virtio_blk_vq *vq = &vblk->vqs[hctx_idx]; 870 871 WARN_ON(vblk->tag_set.tags[hctx_idx] != hctx->tags); 872 hctx->driver_data = vq; 873 return 0; 874 } 875 876 static const struct blk_mq_ops virtio_mq_ops = { 877 .queue_rq = virtio_queue_rq, 878 .queue_rqs = virtio_queue_rqs, 879 .commit_rqs = virtio_commit_rqs, 880 .init_hctx = virtblk_init_hctx, 881 .complete = virtblk_request_done, 882 .map_queues = virtblk_map_queues, 883 .poll = virtblk_poll, 884 }; 885 886 static unsigned int virtblk_queue_depth; 887 module_param_named(queue_depth, virtblk_queue_depth, uint, 0444); 888 889 static int virtblk_probe(struct virtio_device *vdev) 890 { 891 struct virtio_blk *vblk; 892 struct request_queue *q; 893 int err, index; 894 895 u32 v, blk_size, max_size, sg_elems, opt_io_size; 896 u16 min_io_size; 897 u8 physical_block_exp, alignment_offset; 898 unsigned int queue_depth; 899 900 if (!vdev->config->get) { 901 dev_err(&vdev->dev, "%s failure: config access disabled\n", 902 __func__); 903 return -EINVAL; 904 } 905 906 err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS), 907 GFP_KERNEL); 908 if (err < 0) 909 goto out; 910 index = err; 911 912 /* We need to know how many segments before we allocate. */ 913 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX, 914 struct virtio_blk_config, seg_max, 915 &sg_elems); 916 917 /* We need at least one SG element, whatever they say. */ 918 if (err || !sg_elems) 919 sg_elems = 1; 920 921 /* Prevent integer overflows and honor max vq size */ 922 sg_elems = min_t(u32, sg_elems, VIRTIO_BLK_MAX_SG_ELEMS - 2); 923 924 vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL); 925 if (!vblk) { 926 err = -ENOMEM; 927 goto out_free_index; 928 } 929 930 mutex_init(&vblk->vdev_mutex); 931 932 vblk->vdev = vdev; 933 934 INIT_WORK(&vblk->config_work, virtblk_config_changed_work); 935 936 err = init_vq(vblk); 937 if (err) 938 goto out_free_vblk; 939 940 /* Default queue sizing is to fill the ring. */ 941 if (!virtblk_queue_depth) { 942 queue_depth = vblk->vqs[0].vq->num_free; 943 /* ... but without indirect descs, we use 2 descs per req */ 944 if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)) 945 queue_depth /= 2; 946 } else { 947 queue_depth = virtblk_queue_depth; 948 } 949 950 memset(&vblk->tag_set, 0, sizeof(vblk->tag_set)); 951 vblk->tag_set.ops = &virtio_mq_ops; 952 vblk->tag_set.queue_depth = queue_depth; 953 vblk->tag_set.numa_node = NUMA_NO_NODE; 954 vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE; 955 vblk->tag_set.cmd_size = 956 sizeof(struct virtblk_req) + 957 sizeof(struct scatterlist) * VIRTIO_BLK_INLINE_SG_CNT; 958 vblk->tag_set.driver_data = vblk; 959 vblk->tag_set.nr_hw_queues = vblk->num_vqs; 960 vblk->tag_set.nr_maps = 1; 961 if (vblk->io_queues[HCTX_TYPE_POLL]) 962 vblk->tag_set.nr_maps = 3; 963 964 err = blk_mq_alloc_tag_set(&vblk->tag_set); 965 if (err) 966 goto out_free_vq; 967 968 vblk->disk = blk_mq_alloc_disk(&vblk->tag_set, vblk); 969 if (IS_ERR(vblk->disk)) { 970 err = PTR_ERR(vblk->disk); 971 goto out_free_tags; 972 } 973 q = vblk->disk->queue; 974 975 virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN); 976 977 vblk->disk->major = major; 978 vblk->disk->first_minor = index_to_minor(index); 979 vblk->disk->minors = 1 << PART_BITS; 980 vblk->disk->private_data = vblk; 981 vblk->disk->fops = &virtblk_fops; 982 vblk->index = index; 983 984 /* configure queue flush support */ 985 virtblk_update_cache_mode(vdev); 986 987 /* If disk is read-only in the host, the guest should obey */ 988 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) 989 set_disk_ro(vblk->disk, 1); 990 991 /* We can handle whatever the host told us to handle. */ 992 blk_queue_max_segments(q, sg_elems); 993 994 /* No real sector limit. */ 995 blk_queue_max_hw_sectors(q, -1U); 996 997 max_size = virtio_max_dma_size(vdev); 998 999 /* Host can optionally specify maximum segment size and number of 1000 * segments. */ 1001 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX, 1002 struct virtio_blk_config, size_max, &v); 1003 if (!err) 1004 max_size = min(max_size, v); 1005 1006 blk_queue_max_segment_size(q, max_size); 1007 1008 /* Host can optionally specify the block size of the device */ 1009 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE, 1010 struct virtio_blk_config, blk_size, 1011 &blk_size); 1012 if (!err) { 1013 err = blk_validate_block_size(blk_size); 1014 if (err) { 1015 dev_err(&vdev->dev, 1016 "virtio_blk: invalid block size: 0x%x\n", 1017 blk_size); 1018 goto out_cleanup_disk; 1019 } 1020 1021 blk_queue_logical_block_size(q, blk_size); 1022 } else 1023 blk_size = queue_logical_block_size(q); 1024 1025 /* Use topology information if available */ 1026 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY, 1027 struct virtio_blk_config, physical_block_exp, 1028 &physical_block_exp); 1029 if (!err && physical_block_exp) 1030 blk_queue_physical_block_size(q, 1031 blk_size * (1 << physical_block_exp)); 1032 1033 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY, 1034 struct virtio_blk_config, alignment_offset, 1035 &alignment_offset); 1036 if (!err && alignment_offset) 1037 blk_queue_alignment_offset(q, blk_size * alignment_offset); 1038 1039 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY, 1040 struct virtio_blk_config, min_io_size, 1041 &min_io_size); 1042 if (!err && min_io_size) 1043 blk_queue_io_min(q, blk_size * min_io_size); 1044 1045 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY, 1046 struct virtio_blk_config, opt_io_size, 1047 &opt_io_size); 1048 if (!err && opt_io_size) 1049 blk_queue_io_opt(q, blk_size * opt_io_size); 1050 1051 if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) { 1052 virtio_cread(vdev, struct virtio_blk_config, 1053 discard_sector_alignment, &v); 1054 if (v) 1055 q->limits.discard_granularity = v << SECTOR_SHIFT; 1056 else 1057 q->limits.discard_granularity = blk_size; 1058 1059 virtio_cread(vdev, struct virtio_blk_config, 1060 max_discard_sectors, &v); 1061 blk_queue_max_discard_sectors(q, v ? v : UINT_MAX); 1062 1063 virtio_cread(vdev, struct virtio_blk_config, max_discard_seg, 1064 &v); 1065 1066 /* 1067 * max_discard_seg == 0 is out of spec but we always 1068 * handled it. 1069 */ 1070 if (!v) 1071 v = sg_elems; 1072 blk_queue_max_discard_segments(q, 1073 min(v, MAX_DISCARD_SEGMENTS)); 1074 } 1075 1076 if (virtio_has_feature(vdev, VIRTIO_BLK_F_WRITE_ZEROES)) { 1077 virtio_cread(vdev, struct virtio_blk_config, 1078 max_write_zeroes_sectors, &v); 1079 blk_queue_max_write_zeroes_sectors(q, v ? v : UINT_MAX); 1080 } 1081 1082 virtblk_update_capacity(vblk, false); 1083 virtio_device_ready(vdev); 1084 1085 err = device_add_disk(&vdev->dev, vblk->disk, virtblk_attr_groups); 1086 if (err) 1087 goto out_cleanup_disk; 1088 1089 return 0; 1090 1091 out_cleanup_disk: 1092 blk_cleanup_disk(vblk->disk); 1093 out_free_tags: 1094 blk_mq_free_tag_set(&vblk->tag_set); 1095 out_free_vq: 1096 vdev->config->del_vqs(vdev); 1097 kfree(vblk->vqs); 1098 out_free_vblk: 1099 kfree(vblk); 1100 out_free_index: 1101 ida_simple_remove(&vd_index_ida, index); 1102 out: 1103 return err; 1104 } 1105 1106 static void virtblk_remove(struct virtio_device *vdev) 1107 { 1108 struct virtio_blk *vblk = vdev->priv; 1109 1110 /* Make sure no work handler is accessing the device. */ 1111 flush_work(&vblk->config_work); 1112 1113 del_gendisk(vblk->disk); 1114 blk_cleanup_queue(vblk->disk->queue); 1115 blk_mq_free_tag_set(&vblk->tag_set); 1116 1117 mutex_lock(&vblk->vdev_mutex); 1118 1119 /* Stop all the virtqueues. */ 1120 virtio_reset_device(vdev); 1121 1122 /* Virtqueues are stopped, nothing can use vblk->vdev anymore. */ 1123 vblk->vdev = NULL; 1124 1125 vdev->config->del_vqs(vdev); 1126 kfree(vblk->vqs); 1127 1128 mutex_unlock(&vblk->vdev_mutex); 1129 1130 put_disk(vblk->disk); 1131 } 1132 1133 #ifdef CONFIG_PM_SLEEP 1134 static int virtblk_freeze(struct virtio_device *vdev) 1135 { 1136 struct virtio_blk *vblk = vdev->priv; 1137 1138 /* Ensure we don't receive any more interrupts */ 1139 virtio_reset_device(vdev); 1140 1141 /* Make sure no work handler is accessing the device. */ 1142 flush_work(&vblk->config_work); 1143 1144 blk_mq_quiesce_queue(vblk->disk->queue); 1145 1146 vdev->config->del_vqs(vdev); 1147 kfree(vblk->vqs); 1148 1149 return 0; 1150 } 1151 1152 static int virtblk_restore(struct virtio_device *vdev) 1153 { 1154 struct virtio_blk *vblk = vdev->priv; 1155 int ret; 1156 1157 ret = init_vq(vdev->priv); 1158 if (ret) 1159 return ret; 1160 1161 virtio_device_ready(vdev); 1162 1163 blk_mq_unquiesce_queue(vblk->disk->queue); 1164 return 0; 1165 } 1166 #endif 1167 1168 static const struct virtio_device_id id_table[] = { 1169 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, 1170 { 0 }, 1171 }; 1172 1173 static unsigned int features_legacy[] = { 1174 VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY, 1175 VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, 1176 VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE, 1177 VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES, 1178 } 1179 ; 1180 static unsigned int features[] = { 1181 VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY, 1182 VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, 1183 VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE, 1184 VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES, 1185 }; 1186 1187 static struct virtio_driver virtio_blk = { 1188 .feature_table = features, 1189 .feature_table_size = ARRAY_SIZE(features), 1190 .feature_table_legacy = features_legacy, 1191 .feature_table_size_legacy = ARRAY_SIZE(features_legacy), 1192 .driver.name = KBUILD_MODNAME, 1193 .driver.owner = THIS_MODULE, 1194 .id_table = id_table, 1195 .probe = virtblk_probe, 1196 .remove = virtblk_remove, 1197 .config_changed = virtblk_config_changed, 1198 #ifdef CONFIG_PM_SLEEP 1199 .freeze = virtblk_freeze, 1200 .restore = virtblk_restore, 1201 #endif 1202 }; 1203 1204 static int __init virtio_blk_init(void) 1205 { 1206 int error; 1207 1208 virtblk_wq = alloc_workqueue("virtio-blk", 0, 0); 1209 if (!virtblk_wq) 1210 return -ENOMEM; 1211 1212 major = register_blkdev(0, "virtblk"); 1213 if (major < 0) { 1214 error = major; 1215 goto out_destroy_workqueue; 1216 } 1217 1218 error = register_virtio_driver(&virtio_blk); 1219 if (error) 1220 goto out_unregister_blkdev; 1221 return 0; 1222 1223 out_unregister_blkdev: 1224 unregister_blkdev(major, "virtblk"); 1225 out_destroy_workqueue: 1226 destroy_workqueue(virtblk_wq); 1227 return error; 1228 } 1229 1230 static void __exit virtio_blk_fini(void) 1231 { 1232 unregister_virtio_driver(&virtio_blk); 1233 unregister_blkdev(major, "virtblk"); 1234 destroy_workqueue(virtblk_wq); 1235 } 1236 module_init(virtio_blk_init); 1237 module_exit(virtio_blk_fini); 1238 1239 MODULE_DEVICE_TABLE(virtio, id_table); 1240 MODULE_DESCRIPTION("Virtio block driver"); 1241 MODULE_LICENSE("GPL"); 1242