1 //#define DEBUG 2 #include <linux/spinlock.h> 3 #include <linux/blkdev.h> 4 #include <linux/hdreg.h> 5 #include <linux/virtio.h> 6 #include <linux/virtio_blk.h> 7 #include <linux/scatterlist.h> 8 9 #define PART_BITS 4 10 11 static int major, index; 12 13 struct virtio_blk 14 { 15 spinlock_t lock; 16 17 struct virtio_device *vdev; 18 struct virtqueue *vq; 19 20 /* The disk structure for the kernel. */ 21 struct gendisk *disk; 22 23 /* Request tracking. */ 24 struct list_head reqs; 25 26 mempool_t *pool; 27 28 /* What host tells us, plus 2 for header & tailer. */ 29 unsigned int sg_elems; 30 31 /* Scatterlist: can be too big for stack. */ 32 struct scatterlist sg[/*sg_elems*/]; 33 }; 34 35 struct virtblk_req 36 { 37 struct list_head list; 38 struct request *req; 39 struct virtio_blk_outhdr out_hdr; 40 struct virtio_scsi_inhdr in_hdr; 41 u8 status; 42 }; 43 44 static void blk_done(struct virtqueue *vq) 45 { 46 struct virtio_blk *vblk = vq->vdev->priv; 47 struct virtblk_req *vbr; 48 unsigned int len; 49 unsigned long flags; 50 51 spin_lock_irqsave(&vblk->lock, flags); 52 while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) { 53 int error; 54 55 switch (vbr->status) { 56 case VIRTIO_BLK_S_OK: 57 error = 0; 58 break; 59 case VIRTIO_BLK_S_UNSUPP: 60 error = -ENOTTY; 61 break; 62 default: 63 error = -EIO; 64 break; 65 } 66 67 if (blk_pc_request(vbr->req)) { 68 vbr->req->resid_len = vbr->in_hdr.residual; 69 vbr->req->sense_len = vbr->in_hdr.sense_len; 70 vbr->req->errors = vbr->in_hdr.errors; 71 } 72 73 __blk_end_request_all(vbr->req, error); 74 list_del(&vbr->list); 75 mempool_free(vbr, vblk->pool); 76 } 77 /* In case queue is stopped waiting for more buffers. */ 78 blk_start_queue(vblk->disk->queue); 79 spin_unlock_irqrestore(&vblk->lock, flags); 80 } 81 82 static bool do_req(struct request_queue *q, struct virtio_blk *vblk, 83 struct request *req) 84 { 85 unsigned long num, out = 0, in = 0; 86 struct virtblk_req *vbr; 87 88 vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); 89 if (!vbr) 90 /* When another request finishes we'll try again. */ 91 return false; 92 93 vbr->req = req; 94 if (blk_fs_request(vbr->req)) { 95 vbr->out_hdr.type = 0; 96 vbr->out_hdr.sector = blk_rq_pos(vbr->req); 97 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 98 } else if (blk_pc_request(vbr->req)) { 99 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; 100 vbr->out_hdr.sector = 0; 101 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 102 } else { 103 /* We don't put anything else in the queue. */ 104 BUG(); 105 } 106 107 if (blk_barrier_rq(vbr->req)) 108 vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER; 109 110 sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr)); 111 112 /* 113 * If this is a packet command we need a couple of additional headers. 114 * Behind the normal outhdr we put a segment with the scsi command 115 * block, and before the normal inhdr we put the sense data and the 116 * inhdr with additional status information before the normal inhdr. 117 */ 118 if (blk_pc_request(vbr->req)) 119 sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len); 120 121 num = blk_rq_map_sg(q, vbr->req, vblk->sg + out); 122 123 if (blk_pc_request(vbr->req)) { 124 sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, 96); 125 sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr, 126 sizeof(vbr->in_hdr)); 127 } 128 129 sg_set_buf(&vblk->sg[num + out + in++], &vbr->status, 130 sizeof(vbr->status)); 131 132 if (num) { 133 if (rq_data_dir(vbr->req) == WRITE) { 134 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; 135 out += num; 136 } else { 137 vbr->out_hdr.type |= VIRTIO_BLK_T_IN; 138 in += num; 139 } 140 } 141 142 if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) { 143 mempool_free(vbr, vblk->pool); 144 return false; 145 } 146 147 list_add_tail(&vbr->list, &vblk->reqs); 148 return true; 149 } 150 151 static void do_virtblk_request(struct request_queue *q) 152 { 153 struct virtio_blk *vblk = q->queuedata; 154 struct request *req; 155 unsigned int issued = 0; 156 157 while ((req = blk_peek_request(q)) != NULL) { 158 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems); 159 160 /* If this request fails, stop queue and wait for something to 161 finish to restart it. */ 162 if (!do_req(q, vblk, req)) { 163 blk_stop_queue(q); 164 break; 165 } 166 blk_start_request(req); 167 issued++; 168 } 169 170 if (issued) 171 vblk->vq->vq_ops->kick(vblk->vq); 172 } 173 174 /* return ATA identify data 175 */ 176 static int virtblk_identify(struct gendisk *disk, void *argp) 177 { 178 struct virtio_blk *vblk = disk->private_data; 179 void *opaque; 180 int err = -ENOMEM; 181 182 opaque = kmalloc(VIRTIO_BLK_ID_BYTES, GFP_KERNEL); 183 if (!opaque) 184 goto out; 185 186 err = virtio_config_buf(vblk->vdev, VIRTIO_BLK_F_IDENTIFY, 187 offsetof(struct virtio_blk_config, identify), opaque, 188 VIRTIO_BLK_ID_BYTES); 189 190 if (err) 191 goto out_kfree; 192 193 if (copy_to_user(argp, opaque, VIRTIO_BLK_ID_BYTES)) 194 err = -EFAULT; 195 196 out_kfree: 197 kfree(opaque); 198 out: 199 return err; 200 } 201 202 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, 203 unsigned cmd, unsigned long data) 204 { 205 struct gendisk *disk = bdev->bd_disk; 206 struct virtio_blk *vblk = disk->private_data; 207 void __user *argp = (void __user *)data; 208 209 if (cmd == HDIO_GET_IDENTITY) 210 return virtblk_identify(disk, argp); 211 212 /* 213 * Only allow the generic SCSI ioctls if the host can support it. 214 */ 215 if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI)) 216 return -ENOIOCTLCMD; 217 218 return scsi_cmd_ioctl(disk->queue, disk, mode, cmd, argp); 219 } 220 221 /* We provide getgeo only to please some old bootloader/partitioning tools */ 222 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) 223 { 224 struct virtio_blk *vblk = bd->bd_disk->private_data; 225 struct virtio_blk_geometry vgeo; 226 int err; 227 228 /* see if the host passed in geometry config */ 229 err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY, 230 offsetof(struct virtio_blk_config, geometry), 231 &vgeo); 232 233 if (!err) { 234 geo->heads = vgeo.heads; 235 geo->sectors = vgeo.sectors; 236 geo->cylinders = vgeo.cylinders; 237 } else { 238 /* some standard values, similar to sd */ 239 geo->heads = 1 << 6; 240 geo->sectors = 1 << 5; 241 geo->cylinders = get_capacity(bd->bd_disk) >> 11; 242 } 243 return 0; 244 } 245 246 static struct block_device_operations virtblk_fops = { 247 .locked_ioctl = virtblk_ioctl, 248 .owner = THIS_MODULE, 249 .getgeo = virtblk_getgeo, 250 }; 251 252 static int index_to_minor(int index) 253 { 254 return index << PART_BITS; 255 } 256 257 static int virtblk_probe(struct virtio_device *vdev) 258 { 259 struct virtio_blk *vblk; 260 int err; 261 u64 cap; 262 u32 v; 263 u32 blk_size, sg_elems; 264 265 if (index_to_minor(index) >= 1 << MINORBITS) 266 return -ENOSPC; 267 268 /* We need to know how many segments before we allocate. */ 269 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, 270 offsetof(struct virtio_blk_config, seg_max), 271 &sg_elems); 272 if (err) 273 sg_elems = 1; 274 275 /* We need an extra sg elements at head and tail. */ 276 sg_elems += 2; 277 vdev->priv = vblk = kmalloc(sizeof(*vblk) + 278 sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL); 279 if (!vblk) { 280 err = -ENOMEM; 281 goto out; 282 } 283 284 INIT_LIST_HEAD(&vblk->reqs); 285 spin_lock_init(&vblk->lock); 286 vblk->vdev = vdev; 287 vblk->sg_elems = sg_elems; 288 sg_init_table(vblk->sg, vblk->sg_elems); 289 290 /* We expect one virtqueue, for output. */ 291 vblk->vq = vdev->config->find_vq(vdev, 0, blk_done); 292 if (IS_ERR(vblk->vq)) { 293 err = PTR_ERR(vblk->vq); 294 goto out_free_vblk; 295 } 296 297 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); 298 if (!vblk->pool) { 299 err = -ENOMEM; 300 goto out_free_vq; 301 } 302 303 /* FIXME: How many partitions? How long is a piece of string? */ 304 vblk->disk = alloc_disk(1 << PART_BITS); 305 if (!vblk->disk) { 306 err = -ENOMEM; 307 goto out_mempool; 308 } 309 310 vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); 311 if (!vblk->disk->queue) { 312 err = -ENOMEM; 313 goto out_put_disk; 314 } 315 316 vblk->disk->queue->queuedata = vblk; 317 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, vblk->disk->queue); 318 319 if (index < 26) { 320 sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); 321 } else if (index < (26 + 1) * 26) { 322 sprintf(vblk->disk->disk_name, "vd%c%c", 323 'a' + index / 26 - 1, 'a' + index % 26); 324 } else { 325 const unsigned int m1 = (index / 26 - 1) / 26 - 1; 326 const unsigned int m2 = (index / 26 - 1) % 26; 327 const unsigned int m3 = index % 26; 328 sprintf(vblk->disk->disk_name, "vd%c%c%c", 329 'a' + m1, 'a' + m2, 'a' + m3); 330 } 331 332 vblk->disk->major = major; 333 vblk->disk->first_minor = index_to_minor(index); 334 vblk->disk->private_data = vblk; 335 vblk->disk->fops = &virtblk_fops; 336 vblk->disk->driverfs_dev = &vdev->dev; 337 index++; 338 339 /* If barriers are supported, tell block layer that queue is ordered */ 340 if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) 341 blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); 342 343 /* If disk is read-only in the host, the guest should obey */ 344 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) 345 set_disk_ro(vblk->disk, 1); 346 347 /* Host must always specify the capacity. */ 348 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 349 &cap, sizeof(cap)); 350 351 /* If capacity is too big, truncate with warning. */ 352 if ((sector_t)cap != cap) { 353 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 354 (unsigned long long)cap); 355 cap = (sector_t)-1; 356 } 357 set_capacity(vblk->disk, cap); 358 359 /* We can handle whatever the host told us to handle. */ 360 blk_queue_max_phys_segments(vblk->disk->queue, vblk->sg_elems-2); 361 blk_queue_max_hw_segments(vblk->disk->queue, vblk->sg_elems-2); 362 363 /* No real sector limit. */ 364 blk_queue_max_sectors(vblk->disk->queue, -1U); 365 366 /* Host can optionally specify maximum segment size and number of 367 * segments. */ 368 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, 369 offsetof(struct virtio_blk_config, size_max), 370 &v); 371 if (!err) 372 blk_queue_max_segment_size(vblk->disk->queue, v); 373 else 374 blk_queue_max_segment_size(vblk->disk->queue, -1U); 375 376 /* Host can optionally specify the block size of the device */ 377 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, 378 offsetof(struct virtio_blk_config, blk_size), 379 &blk_size); 380 if (!err) 381 blk_queue_logical_block_size(vblk->disk->queue, blk_size); 382 383 add_disk(vblk->disk); 384 return 0; 385 386 out_put_disk: 387 put_disk(vblk->disk); 388 out_mempool: 389 mempool_destroy(vblk->pool); 390 out_free_vq: 391 vdev->config->del_vq(vblk->vq); 392 out_free_vblk: 393 kfree(vblk); 394 out: 395 return err; 396 } 397 398 static void virtblk_remove(struct virtio_device *vdev) 399 { 400 struct virtio_blk *vblk = vdev->priv; 401 402 /* Nothing should be pending. */ 403 BUG_ON(!list_empty(&vblk->reqs)); 404 405 /* Stop all the virtqueues. */ 406 vdev->config->reset(vdev); 407 408 del_gendisk(vblk->disk); 409 blk_cleanup_queue(vblk->disk->queue); 410 put_disk(vblk->disk); 411 mempool_destroy(vblk->pool); 412 vdev->config->del_vq(vblk->vq); 413 kfree(vblk); 414 } 415 416 static struct virtio_device_id id_table[] = { 417 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, 418 { 0 }, 419 }; 420 421 static unsigned int features[] = { 422 VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, 423 VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, 424 VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_IDENTIFY 425 }; 426 427 static struct virtio_driver virtio_blk = { 428 .feature_table = features, 429 .feature_table_size = ARRAY_SIZE(features), 430 .driver.name = KBUILD_MODNAME, 431 .driver.owner = THIS_MODULE, 432 .id_table = id_table, 433 .probe = virtblk_probe, 434 .remove = __devexit_p(virtblk_remove), 435 }; 436 437 static int __init init(void) 438 { 439 major = register_blkdev(0, "virtblk"); 440 if (major < 0) 441 return major; 442 return register_virtio_driver(&virtio_blk); 443 } 444 445 static void __exit fini(void) 446 { 447 unregister_blkdev(major, "virtblk"); 448 unregister_virtio_driver(&virtio_blk); 449 } 450 module_init(init); 451 module_exit(fini); 452 453 MODULE_DEVICE_TABLE(virtio, id_table); 454 MODULE_DESCRIPTION("Virtio block driver"); 455 MODULE_LICENSE("GPL"); 456