hw/virtio-blk.c

   1 /*
   2  * Virtio Block Device
   3  *
   4  * Copyright IBM, Corp. 2007
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include <qemu-common.h>
  15 #include "qemu-error.h"
  16 #include "trace.h"
  17 #include "blockdev.h"
  18 #include "virtio-blk.h"
  19 #ifdef __linux__
  20 # include <scsi/sg.h>
  21 #endif
  22
  23 typedef struct VirtIOBlock
  24 {
  25     VirtIODevice vdev;
  26     BlockDriverState *bs;
  27     VirtQueue *vq;
  28     void *rq;
  29     QEMUBH *bh;
  30     BlockConf *conf;
  31     unsigned short sector_mask;
  32     char sn[BLOCK_SERIAL_STRLEN];
  33     DeviceState *qdev;
  34 } VirtIOBlock;
  35
  36 static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
  37 {
  38     return (VirtIOBlock *)vdev;
  39 }
  40
  41 typedef struct VirtIOBlockReq
  42 {
  43     VirtIOBlock *dev;
  44     VirtQueueElement elem;
  45     struct virtio_blk_inhdr *in;
  46     struct virtio_blk_outhdr *out;
  47     struct virtio_scsi_inhdr *scsi;
  48     QEMUIOVector qiov;
  49     struct VirtIOBlockReq *next;
  50 } VirtIOBlockReq;
  51
  52 static void virtio_blk_req_complete(VirtIOBlockReq *req, int status)
  53 {
  54     VirtIOBlock *s = req->dev;
  55
  56     trace_virtio_blk_req_complete(req, status);
  57
  58     stb_p(&req->in->status, status);
  59     virtqueue_push(s->vq, &req->elem, req->qiov.size + sizeof(*req->in));
  60     virtio_notify(&s->vdev, s->vq);
  61
  62     qemu_free(req);
  63 }
  64
  65 static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error,
  66     int is_read)
  67 {
  68     BlockErrorAction action = bdrv_get_on_error(req->dev->bs, is_read);
  69     VirtIOBlock *s = req->dev;
  70
  71     if (action == BLOCK_ERR_IGNORE) {
  72         bdrv_mon_event(s->bs, BDRV_ACTION_IGNORE, is_read);
  73         return 0;
  74     }
  75
  76     if ((error == ENOSPC && action == BLOCK_ERR_STOP_ENOSPC)
  77             || action == BLOCK_ERR_STOP_ANY) {
  78         req->next = s->rq;
  79         s->rq = req;
  80         bdrv_mon_event(s->bs, BDRV_ACTION_STOP, is_read);
  81         vm_stop(VMSTOP_DISKFULL);
  82     } else {
  83         virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
  84         bdrv_mon_event(s->bs, BDRV_ACTION_REPORT, is_read);
  85     }
  86
  87     return 1;
  88 }
  89
  90 static void virtio_blk_rw_complete(void *opaque, int ret)
  91 {
  92     VirtIOBlockReq *req = opaque;
  93
  94     trace_virtio_blk_rw_complete(req, ret);
  95
  96     if (ret) {
  97         int is_read = !(ldl_p(&req->out->type) & VIRTIO_BLK_T_OUT);
  98         if (virtio_blk_handle_rw_error(req, -ret, is_read))
  99             return;
 100     }
 101
 102     virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
 103 }
 104
 105 static void virtio_blk_flush_complete(void *opaque, int ret)
 106 {
 107     VirtIOBlockReq *req = opaque;
 108
 109     if (ret) {
 110         if (virtio_blk_handle_rw_error(req, -ret, 0)) {
 111             return;
 112         }
 113     }
 114
 115     virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
 116 }
 117
 118 static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
 119 {
 120     VirtIOBlockReq *req = qemu_malloc(sizeof(*req));
 121     req->dev = s;
 122     req->qiov.size = 0;
 123     req->next = NULL;
 124     return req;
 125 }
 126
 127 static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)
 128 {
 129     VirtIOBlockReq *req = virtio_blk_alloc_request(s);
 130
 131     if (req != NULL) {
 132         if (!virtqueue_pop(s->vq, &req->elem)) {
 133             qemu_free(req);
 134             return NULL;
 135         }
 136     }
 137
 138     return req;
 139 }
 140
 141 #ifdef __linux__
 142 static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
 143 {
 144     struct sg_io_hdr hdr;
 145     int ret;
 146     int status;
 147     int i;
 148
 149     /*
 150      * We require at least one output segment each for the virtio_blk_outhdr
 151      * and the SCSI command block.
 152      *
 153      * We also at least require the virtio_blk_inhdr, the virtio_scsi_inhdr
 154      * and the sense buffer pointer in the input segments.
 155      */
 156     if (req->elem.out_num < 2 || req->elem.in_num < 3) {
 157         virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
 158         return;
 159     }
 160
 161     /*
 162      * No support for bidirection commands yet.
 163      */
 164     if (req->elem.out_num > 2 && req->elem.in_num > 3) {
 165         virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
 166         return;
 167     }
 168
 169     /*
 170      * The scsi inhdr is placed in the second-to-last input segment, just
 171      * before the regular inhdr.
 172      */
 173     req->scsi = (void *)req->elem.in_sg[req->elem.in_num - 2].iov_base;
 174
 175     memset(&hdr, 0, sizeof(struct sg_io_hdr));
 176     hdr.interface_id = 'S';
 177     hdr.cmd_len = req->elem.out_sg[1].iov_len;
 178     hdr.cmdp = req->elem.out_sg[1].iov_base;
 179     hdr.dxfer_len = 0;
 180
 181     if (req->elem.out_num > 2) {
 182         /*
 183          * If there are more than the minimally required 2 output segments
 184          * there is write payload starting from the third iovec.
 185          */
 186         hdr.dxfer_direction = SG_DXFER_TO_DEV;
 187         hdr.iovec_count = req->elem.out_num - 2;
 188
 189         for (i = 0; i < hdr.iovec_count; i++)
 190             hdr.dxfer_len += req->elem.out_sg[i + 2].iov_len;
 191
 192         hdr.dxferp = req->elem.out_sg + 2;
 193
 194     } else if (req->elem.in_num > 3) {
 195         /*
 196          * If we have more than 3 input segments the guest wants to actually
 197          * read data.
 198          */
 199         hdr.dxfer_direction = SG_DXFER_FROM_DEV;
 200         hdr.iovec_count = req->elem.in_num - 3;
 201         for (i = 0; i < hdr.iovec_count; i++)
 202             hdr.dxfer_len += req->elem.in_sg[i].iov_len;
 203
 204         hdr.dxferp = req->elem.in_sg;
 205     } else {
 206         /*
 207          * Some SCSI commands don't actually transfer any data.
 208          */
 209         hdr.dxfer_direction = SG_DXFER_NONE;
 210     }
 211
 212     hdr.sbp = req->elem.in_sg[req->elem.in_num - 3].iov_base;
 213     hdr.mx_sb_len = req->elem.in_sg[req->elem.in_num - 3].iov_len;
 214
 215     ret = bdrv_ioctl(req->dev->bs, SG_IO, &hdr);
 216     if (ret) {
 217         status = VIRTIO_BLK_S_UNSUPP;
 218         hdr.status = ret;
 219         hdr.resid = hdr.dxfer_len;
 220     } else if (hdr.status) {
 221         status = VIRTIO_BLK_S_IOERR;
 222     } else {
 223         status = VIRTIO_BLK_S_OK;
 224     }
 225
 226     stl_p(&req->scsi->errors, hdr.status);
 227     stl_p(&req->scsi->residual, hdr.resid);
 228     stl_p(&req->scsi->sense_len, hdr.sb_len_wr);
 229     stl_p(&req->scsi->data_len, hdr.dxfer_len);
 230
 231     virtio_blk_req_complete(req, status);
 232 }
 233 #else
 234 static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
 235 {
 236     virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
 237 }
 238 #endif /* __linux__ */
 239
 240 typedef struct MultiReqBuffer {
 241     BlockRequest        blkreq[32];
 242     unsigned int        num_writes;
 243 } MultiReqBuffer;
 244
 245 static void virtio_submit_multiwrite(BlockDriverState *bs, MultiReqBuffer *mrb)
 246 {
 247     int i, ret;
 248
 249     if (!mrb->num_writes) {
 250         return;
 251     }
 252
 253     ret = bdrv_aio_multiwrite(bs, mrb->blkreq, mrb->num_writes);
 254     if (ret != 0) {
 255         for (i = 0; i < mrb->num_writes; i++) {
 256             if (mrb->blkreq[i].error) {
 257                 virtio_blk_rw_complete(mrb->blkreq[i].opaque, -EIO);
 258             }
 259         }
 260     }
 261
 262     mrb->num_writes = 0;
 263 }
 264
 265 static void virtio_blk_handle_flush(VirtIOBlockReq *req, MultiReqBuffer *mrb)
 266 {
 267     BlockDriverAIOCB *acb;
 268
 269     /*
 270      * Make sure all outstanding writes are posted to the backing device.
 271      */
 272     virtio_submit_multiwrite(req->dev->bs, mrb);
 273
 274     acb = bdrv_aio_flush(req->dev->bs, virtio_blk_flush_complete, req);
 275     if (!acb) {
 276         virtio_blk_flush_complete(req, -EIO);
 277     }
 278 }
 279
 280 static void virtio_blk_handle_write(VirtIOBlockReq *req, MultiReqBuffer *mrb)
 281 {
 282     BlockRequest *blkreq;
 283     uint64_t sector;
 284
 285     sector = ldq_p(&req->out->sector);
 286
 287     trace_virtio_blk_handle_write(req, sector, req->qiov.size / 512);
 288
 289     if (sector & req->dev->sector_mask) {
 290         virtio_blk_rw_complete(req, -EIO);
 291         return;
 292     }
 293     if (req->qiov.size % req->dev->conf->logical_block_size) {
 294         virtio_blk_rw_complete(req, -EIO);
 295         return;
 296     }
 297
 298     if (mrb->num_writes == 32) {
 299         virtio_submit_multiwrite(req->dev->bs, mrb);
 300     }
 301
 302     blkreq = &mrb->blkreq[mrb->num_writes];
 303     blkreq->sector = sector;
 304     blkreq->nb_sectors = req->qiov.size / BDRV_SECTOR_SIZE;
 305     blkreq->qiov = &req->qiov;
 306     blkreq->cb = virtio_blk_rw_complete;
 307     blkreq->opaque = req;
 308     blkreq->error = 0;
 309
 310     mrb->num_writes++;
 311 }
 312
 313 static void virtio_blk_handle_read(VirtIOBlockReq *req)
 314 {
 315     BlockDriverAIOCB *acb;
 316     uint64_t sector;
 317
 318     sector = ldq_p(&req->out->sector);
 319
 320     if (sector & req->dev->sector_mask) {
 321         virtio_blk_rw_complete(req, -EIO);
 322         return;
 323     }
 324     if (req->qiov.size % req->dev->conf->logical_block_size) {
 325         virtio_blk_rw_complete(req, -EIO);
 326         return;
 327     }
 328
 329     acb = bdrv_aio_readv(req->dev->bs, sector, &req->qiov,
 330                          req->qiov.size / BDRV_SECTOR_SIZE,
 331                          virtio_blk_rw_complete, req);
 332     if (!acb) {
 333         virtio_blk_rw_complete(req, -EIO);
 334     }
 335 }
 336
 337 static void virtio_blk_handle_request(VirtIOBlockReq *req,
 338     MultiReqBuffer *mrb)
 339 {
 340     uint32_t type;
 341
 342     if (req->elem.out_num < 1 || req->elem.in_num < 1) {
 343         error_report("virtio-blk missing headers");
 344         exit(1);
 345     }
 346
 347     if (req->elem.out_sg[0].iov_len < sizeof(*req->out) ||
 348         req->elem.in_sg[req->elem.in_num - 1].iov_len < sizeof(*req->in)) {
 349         error_report("virtio-blk header not in correct element");
 350         exit(1);
 351     }
 352
 353     req->out = (void *)req->elem.out_sg[0].iov_base;
 354     req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
 355
 356     type = ldl_p(&req->out->type);
 357
 358     if (type & VIRTIO_BLK_T_FLUSH) {
 359         virtio_blk_handle_flush(req, mrb);
 360     } else if (type & VIRTIO_BLK_T_SCSI_CMD) {
 361         virtio_blk_handle_scsi(req);
 362     } else if (type & VIRTIO_BLK_T_GET_ID) {
 363         VirtIOBlock *s = req->dev;
 364
 365         memcpy(req->elem.in_sg[0].iov_base, s->sn,
 366                MIN(req->elem.in_sg[0].iov_len, sizeof(s->sn)));
 367         virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
 368     } else if (type & VIRTIO_BLK_T_OUT) {
 369         qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
 370                                  req->elem.out_num - 1);
 371         virtio_blk_handle_write(req, mrb);
 372     } else {
 373         qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
 374                                  req->elem.in_num - 1);
 375         virtio_blk_handle_read(req);
 376     }
 377 }
 378
 379 static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 380 {
 381     VirtIOBlock *s = to_virtio_blk(vdev);
 382     VirtIOBlockReq *req;
 383     MultiReqBuffer mrb = {
 384         .num_writes = 0,
 385     };
 386
 387     while ((req = virtio_blk_get_request(s))) {
 388         virtio_blk_handle_request(req, &mrb);
 389     }
 390
 391     virtio_submit_multiwrite(s->bs, &mrb);
 392
 393     /*
 394      * FIXME: Want to check for completions before returning to guest mode,
 395      * so cached reads and writes are reported as quickly as possible. But
 396      * that should be done in the generic block layer.
 397      */
 398 }
 399
 400 static void virtio_blk_dma_restart_bh(void *opaque)
 401 {
 402     VirtIOBlock *s = opaque;
 403     VirtIOBlockReq *req = s->rq;
 404     MultiReqBuffer mrb = {
 405         .num_writes = 0,
 406     };
 407
 408     qemu_bh_delete(s->bh);
 409     s->bh = NULL;
 410
 411     s->rq = NULL;
 412
 413     while (req) {
 414         virtio_blk_handle_request(req, &mrb);
 415         req = req->next;
 416     }
 417
 418     virtio_submit_multiwrite(s->bs, &mrb);
 419 }
 420
 421 static void virtio_blk_dma_restart_cb(void *opaque, int running, int reason)
 422 {
 423     VirtIOBlock *s = opaque;
 424
 425     if (!running)
 426         return;
 427
 428     if (!s->bh) {
 429         s->bh = qemu_bh_new(virtio_blk_dma_restart_bh, s);
 430         qemu_bh_schedule(s->bh);
 431     }
 432 }
 433
 434 static void virtio_blk_reset(VirtIODevice *vdev)
 435 {
 436     /*
 437      * This should cancel pending requests, but can't do nicely until there
 438      * are per-device request lists.
 439      */
 440     qemu_aio_flush();
 441 }
 442
 443 /* coalesce internal state, copy to pci i/o region 0
 444  */
 445 static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
 446 {
 447     VirtIOBlock *s = to_virtio_blk(vdev);
 448     struct virtio_blk_config blkcfg;
 449     uint64_t capacity;
 450     int cylinders, heads, secs;
 451
 452     bdrv_get_geometry(s->bs, &capacity);
 453     bdrv_get_geometry_hint(s->bs, &cylinders, &heads, &secs);
 454     memset(&blkcfg, 0, sizeof(blkcfg));
 455     stq_raw(&blkcfg.capacity, capacity);
 456     stl_raw(&blkcfg.seg_max, 128 - 2);
 457     stw_raw(&blkcfg.cylinders, cylinders);
 458     blkcfg.heads = heads;
 459     blkcfg.sectors = secs & ~s->sector_mask;
 460     blkcfg.blk_size = s->conf->logical_block_size;
 461     blkcfg.size_max = 0;
 462     blkcfg.physical_block_exp = get_physical_block_exp(s->conf);
 463     blkcfg.alignment_offset = 0;
 464     blkcfg.min_io_size = s->conf->min_io_size / blkcfg.blk_size;
 465     blkcfg.opt_io_size = s->conf->opt_io_size / blkcfg.blk_size;
 466     memcpy(config, &blkcfg, sizeof(struct virtio_blk_config));
 467 }
 468
 469 static uint32_t virtio_blk_get_features(VirtIODevice *vdev, uint32_t features)
 470 {
 471     VirtIOBlock *s = to_virtio_blk(vdev);
 472
 473     features |= (1 << VIRTIO_BLK_F_SEG_MAX);
 474     features |= (1 << VIRTIO_BLK_F_GEOMETRY);
 475     features |= (1 << VIRTIO_BLK_F_TOPOLOGY);
 476     features |= (1 << VIRTIO_BLK_F_BLK_SIZE);
 477
 478     if (bdrv_enable_write_cache(s->bs))
 479         features |= (1 << VIRTIO_BLK_F_WCACHE);
 480
 481     if (bdrv_is_read_only(s->bs))
 482         features |= 1 << VIRTIO_BLK_F_RO;
 483
 484     return features;
 485 }
 486
 487 static void virtio_blk_save(QEMUFile *f, void *opaque)
 488 {
 489     VirtIOBlock *s = opaque;
 490     VirtIOBlockReq *req = s->rq;
 491
 492     virtio_save(&s->vdev, f);
 493
 494     while (req) {
 495         qemu_put_sbyte(f, 1);
 496         qemu_put_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
 497         req = req->next;
 498     }
 499     qemu_put_sbyte(f, 0);
 500 }
 501
 502 static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id)
 503 {
 504     VirtIOBlock *s = opaque;
 505
 506     if (version_id != 2)
 507         return -EINVAL;
 508
 509     virtio_load(&s->vdev, f);
 510     while (qemu_get_sbyte(f)) {
 511         VirtIOBlockReq *req = virtio_blk_alloc_request(s);
 512         qemu_get_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
 513         req->next = s->rq;
 514         s->rq = req;
 515
 516         virtqueue_map_sg(req->elem.in_sg, req->elem.in_addr,
 517             req->elem.in_num, 1);
 518         virtqueue_map_sg(req->elem.out_sg, req->elem.out_addr,
 519             req->elem.out_num, 0);
 520     }
 521
 522     return 0;
 523 }
 524
 525 static void virtio_blk_change_cb(void *opaque, int reason)
 526 {
 527     VirtIOBlock *s = opaque;
 528
 529     if (reason & CHANGE_SIZE) {
 530         virtio_notify_config(&s->vdev);
 531     }
 532 }
 533
 534 VirtIODevice *virtio_blk_init(DeviceState *dev, BlockConf *conf)
 535 {
 536     VirtIOBlock *s;
 537     int cylinders, heads, secs;
 538     static int virtio_blk_id;
 539     DriveInfo *dinfo;
 540
 541     if (!conf->bs) {
 542         error_report("virtio-blk-pci: drive property not set");
 543         return NULL;
 544     }
 545     if (!bdrv_is_inserted(conf->bs)) {
 546         error_report("Device needs media, but drive is empty");
 547         return NULL;
 548     }
 549
 550     s = (VirtIOBlock *)virtio_common_init("virtio-blk", VIRTIO_ID_BLOCK,
 551                                           sizeof(struct virtio_blk_config),
 552                                           sizeof(VirtIOBlock));
 553
 554     s->vdev.get_config = virtio_blk_update_config;
 555     s->vdev.get_features = virtio_blk_get_features;
 556     s->vdev.reset = virtio_blk_reset;
 557     s->bs = conf->bs;
 558     s->conf = conf;
 559     s->rq = NULL;
 560     s->sector_mask = (s->conf->logical_block_size / BDRV_SECTOR_SIZE) - 1;
 561     bdrv_guess_geometry(s->bs, &cylinders, &heads, &secs);
 562
 563     /* NB: per existing s/n string convention the string is terminated
 564      * by '\0' only when less than sizeof (s->sn)
 565      */
 566     dinfo = drive_get_by_blockdev(s->bs);
 567     strncpy(s->sn, dinfo->serial, sizeof (s->sn));
 568
 569     s->vq = virtio_add_queue(&s->vdev, 128, virtio_blk_handle_output);
 570
 571     qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
 572     s->qdev = dev;
 573     register_savevm(dev, "virtio-blk", virtio_blk_id++, 2,
 574                     virtio_blk_save, virtio_blk_load, s);
 575     bdrv_set_removable(s->bs, 0);
 576     bdrv_set_change_cb(s->bs, virtio_blk_change_cb, s);
 577     s->bs->buffer_alignment = conf->logical_block_size;
 578
 579     add_boot_device_path(conf->bootindex, dev, "/disk@0,0");
 580
 581     return &s->vdev;
 582 }
 583
 584 void virtio_blk_exit(VirtIODevice *vdev)
 585 {
 586     VirtIOBlock *s = to_virtio_blk(vdev);
 587     unregister_savevm(s->qdev, "virtio-blk", s);
 588 }