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