qemu/hw/block/xen-block.c
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   1/*
   2 * Copyright (c) 2018  Citrix Systems Inc.
   3 *
   4 * This work is licensed under the terms of the GNU GPL, version 2 or later.
   5 * See the COPYING file in the top-level directory.
   6 */
   7
   8#include "qemu/osdep.h"
   9#include "qemu/cutils.h"
  10#include "qemu/main-loop.h"
  11#include "qemu/module.h"
  12#include "qemu/option.h"
  13#include "qapi/error.h"
  14#include "qapi/qapi-commands-block-core.h"
  15#include "qapi/qapi-commands-qom.h"
  16#include "qapi/qapi-visit-block-core.h"
  17#include "qapi/qobject-input-visitor.h"
  18#include "qapi/visitor.h"
  19#include "qapi/qmp/qdict.h"
  20#include "qapi/qmp/qstring.h"
  21#include "qom/object_interfaces.h"
  22#include "hw/xen/xen_common.h"
  23#include "hw/block/xen_blkif.h"
  24#include "hw/qdev-properties.h"
  25#include "hw/xen/xen-block.h"
  26#include "hw/xen/xen-backend.h"
  27#include "sysemu/blockdev.h"
  28#include "sysemu/block-backend.h"
  29#include "sysemu/iothread.h"
  30#include "dataplane/xen-block.h"
  31#include "trace.h"
  32
  33static char *xen_block_get_name(XenDevice *xendev, Error **errp)
  34{
  35    XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
  36    XenBlockVdev *vdev = &blockdev->props.vdev;
  37
  38    return g_strdup_printf("%lu", vdev->number);
  39}
  40
  41static void xen_block_disconnect(XenDevice *xendev, Error **errp)
  42{
  43    XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
  44    const char *type = object_get_typename(OBJECT(blockdev));
  45    XenBlockVdev *vdev = &blockdev->props.vdev;
  46
  47    trace_xen_block_disconnect(type, vdev->disk, vdev->partition);
  48
  49    xen_block_dataplane_stop(blockdev->dataplane);
  50}
  51
  52static void xen_block_connect(XenDevice *xendev, Error **errp)
  53{
  54    XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
  55    const char *type = object_get_typename(OBJECT(blockdev));
  56    XenBlockVdev *vdev = &blockdev->props.vdev;
  57    BlockConf *conf = &blockdev->props.conf;
  58    unsigned int feature_large_sector_size;
  59    unsigned int order, nr_ring_ref, *ring_ref, event_channel, protocol;
  60    char *str;
  61
  62    trace_xen_block_connect(type, vdev->disk, vdev->partition);
  63
  64    if (xen_device_frontend_scanf(xendev, "feature-large-sector-size", "%u",
  65                                  &feature_large_sector_size) != 1) {
  66        feature_large_sector_size = 0;
  67    }
  68
  69    if (feature_large_sector_size != 1 &&
  70        conf->logical_block_size != XEN_BLKIF_SECTOR_SIZE) {
  71        error_setg(errp, "logical_block_size != %u not supported by frontend",
  72                   XEN_BLKIF_SECTOR_SIZE);
  73        return;
  74    }
  75
  76    if (xen_device_frontend_scanf(xendev, "ring-page-order", "%u",
  77                                  &order) != 1) {
  78        nr_ring_ref = 1;
  79        ring_ref = g_new(unsigned int, nr_ring_ref);
  80
  81        if (xen_device_frontend_scanf(xendev, "ring-ref", "%u",
  82                                      &ring_ref[0]) != 1) {
  83            error_setg(errp, "failed to read ring-ref");
  84            g_free(ring_ref);
  85            return;
  86        }
  87    } else if (order <= blockdev->props.max_ring_page_order) {
  88        unsigned int i;
  89
  90        nr_ring_ref = 1 << order;
  91        ring_ref = g_new(unsigned int, nr_ring_ref);
  92
  93        for (i = 0; i < nr_ring_ref; i++) {
  94            const char *key = g_strdup_printf("ring-ref%u", i);
  95
  96            if (xen_device_frontend_scanf(xendev, key, "%u",
  97                                          &ring_ref[i]) != 1) {
  98                error_setg(errp, "failed to read %s", key);
  99                g_free((gpointer)key);
 100                g_free(ring_ref);
 101                return;
 102            }
 103
 104            g_free((gpointer)key);
 105        }
 106    } else {
 107        error_setg(errp, "invalid ring-page-order (%d)", order);
 108        return;
 109    }
 110
 111    if (xen_device_frontend_scanf(xendev, "event-channel", "%u",
 112                                  &event_channel) != 1) {
 113        error_setg(errp, "failed to read event-channel");
 114        g_free(ring_ref);
 115        return;
 116    }
 117
 118    if (xen_device_frontend_scanf(xendev, "protocol", "%ms",
 119                                  &str) != 1) {
 120        protocol = BLKIF_PROTOCOL_NATIVE;
 121    } else {
 122        if (strcmp(str, XEN_IO_PROTO_ABI_X86_32) == 0) {
 123            protocol = BLKIF_PROTOCOL_X86_32;
 124        } else if (strcmp(str, XEN_IO_PROTO_ABI_X86_64) == 0) {
 125            protocol = BLKIF_PROTOCOL_X86_64;
 126        } else {
 127            protocol = BLKIF_PROTOCOL_NATIVE;
 128        }
 129
 130        free(str);
 131    }
 132
 133    xen_block_dataplane_start(blockdev->dataplane, ring_ref, nr_ring_ref,
 134                              event_channel, protocol, errp);
 135
 136    g_free(ring_ref);
 137}
 138
 139static void xen_block_unrealize(XenDevice *xendev)
 140{
 141    XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
 142    XenBlockDeviceClass *blockdev_class =
 143        XEN_BLOCK_DEVICE_GET_CLASS(xendev);
 144    const char *type = object_get_typename(OBJECT(blockdev));
 145    XenBlockVdev *vdev = &blockdev->props.vdev;
 146
 147    if (vdev->type == XEN_BLOCK_VDEV_TYPE_INVALID) {
 148        return;
 149    }
 150
 151    trace_xen_block_unrealize(type, vdev->disk, vdev->partition);
 152
 153    /* Disconnect from the frontend in case this has not already happened */
 154    xen_block_disconnect(xendev, NULL);
 155
 156    xen_block_dataplane_destroy(blockdev->dataplane);
 157    blockdev->dataplane = NULL;
 158
 159    if (blockdev_class->unrealize) {
 160        blockdev_class->unrealize(blockdev);
 161    }
 162}
 163
 164static void xen_block_set_size(XenBlockDevice *blockdev)
 165{
 166    const char *type = object_get_typename(OBJECT(blockdev));
 167    XenBlockVdev *vdev = &blockdev->props.vdev;
 168    BlockConf *conf = &blockdev->props.conf;
 169    int64_t sectors = blk_getlength(conf->blk) / conf->logical_block_size;
 170    XenDevice *xendev = XEN_DEVICE(blockdev);
 171
 172    trace_xen_block_size(type, vdev->disk, vdev->partition, sectors);
 173
 174    xen_device_backend_printf(xendev, "sectors", "%"PRIi64, sectors);
 175}
 176
 177static void xen_block_resize_cb(void *opaque)
 178{
 179    XenBlockDevice *blockdev = opaque;
 180    XenDevice *xendev = XEN_DEVICE(blockdev);
 181    enum xenbus_state state = xen_device_backend_get_state(xendev);
 182
 183    xen_block_set_size(blockdev);
 184
 185    /*
 186     * Mimic the behaviour of Linux xen-blkback and re-write the state
 187     * to trigger the frontend watch.
 188     */
 189    xen_device_backend_printf(xendev, "state", "%u", state);
 190}
 191
 192static const BlockDevOps xen_block_dev_ops = {
 193    .resize_cb = xen_block_resize_cb,
 194};
 195
 196static void xen_block_realize(XenDevice *xendev, Error **errp)
 197{
 198    ERRP_GUARD();
 199    XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
 200    XenBlockDeviceClass *blockdev_class =
 201        XEN_BLOCK_DEVICE_GET_CLASS(xendev);
 202    const char *type = object_get_typename(OBJECT(blockdev));
 203    XenBlockVdev *vdev = &blockdev->props.vdev;
 204    BlockConf *conf = &blockdev->props.conf;
 205    BlockBackend *blk = conf->blk;
 206
 207    if (vdev->type == XEN_BLOCK_VDEV_TYPE_INVALID) {
 208        error_setg(errp, "vdev property not set");
 209        return;
 210    }
 211
 212    trace_xen_block_realize(type, vdev->disk, vdev->partition);
 213
 214    if (blockdev_class->realize) {
 215        blockdev_class->realize(blockdev, errp);
 216        if (*errp) {
 217            return;
 218        }
 219    }
 220
 221    /*
 222     * The blkif protocol does not deal with removable media, so it must
 223     * always be present, even for CDRom devices.
 224     */
 225    assert(blk);
 226    if (!blk_is_inserted(blk)) {
 227        error_setg(errp, "device needs media, but drive is empty");
 228        return;
 229    }
 230
 231    if (!blkconf_apply_backend_options(conf, blockdev->info & VDISK_READONLY,
 232                                       true, errp)) {
 233        return;
 234    }
 235
 236    if (!(blockdev->info & VDISK_CDROM) &&
 237        !blkconf_geometry(conf, NULL, 65535, 255, 255, errp)) {
 238        return;
 239    }
 240
 241    if (!blkconf_blocksizes(conf, errp)) {
 242        return;
 243    }
 244
 245    blk_set_dev_ops(blk, &xen_block_dev_ops, blockdev);
 246
 247    if (conf->discard_granularity == -1) {
 248        conf->discard_granularity = conf->physical_block_size;
 249    }
 250
 251    if (blk_get_flags(blk) & BDRV_O_UNMAP) {
 252        xen_device_backend_printf(xendev, "feature-discard", "%u", 1);
 253        xen_device_backend_printf(xendev, "discard-granularity", "%u",
 254                                  conf->discard_granularity);
 255        xen_device_backend_printf(xendev, "discard-alignment", "%u", 0);
 256    }
 257
 258    xen_device_backend_printf(xendev, "feature-flush-cache", "%u", 1);
 259    xen_device_backend_printf(xendev, "max-ring-page-order", "%u",
 260                              blockdev->props.max_ring_page_order);
 261    xen_device_backend_printf(xendev, "info", "%u", blockdev->info);
 262
 263    xen_device_frontend_printf(xendev, "virtual-device", "%lu",
 264                               vdev->number);
 265    xen_device_frontend_printf(xendev, "device-type", "%s",
 266                               blockdev->device_type);
 267
 268    xen_device_backend_printf(xendev, "sector-size", "%u",
 269                              conf->logical_block_size);
 270
 271    xen_block_set_size(blockdev);
 272
 273    blockdev->dataplane =
 274        xen_block_dataplane_create(xendev, blk, conf->logical_block_size,
 275                                   blockdev->props.iothread);
 276}
 277
 278static void xen_block_frontend_changed(XenDevice *xendev,
 279                                       enum xenbus_state frontend_state,
 280                                       Error **errp)
 281{
 282    ERRP_GUARD();
 283    enum xenbus_state backend_state = xen_device_backend_get_state(xendev);
 284
 285    switch (frontend_state) {
 286    case XenbusStateInitialised:
 287    case XenbusStateConnected:
 288        if (backend_state == XenbusStateConnected) {
 289            break;
 290        }
 291
 292        xen_block_disconnect(xendev, errp);
 293        if (*errp) {
 294            break;
 295        }
 296
 297        xen_block_connect(xendev, errp);
 298        if (*errp) {
 299            break;
 300        }
 301
 302        xen_device_backend_set_state(xendev, XenbusStateConnected);
 303        break;
 304
 305    case XenbusStateClosing:
 306        xen_device_backend_set_state(xendev, XenbusStateClosing);
 307        break;
 308
 309    case XenbusStateClosed:
 310    case XenbusStateUnknown:
 311        xen_block_disconnect(xendev, errp);
 312        if (*errp) {
 313            break;
 314        }
 315
 316        xen_device_backend_set_state(xendev, XenbusStateClosed);
 317        break;
 318
 319    default:
 320        break;
 321    }
 322}
 323
 324static char *disk_to_vbd_name(unsigned int disk)
 325{
 326    char *name, *prefix = (disk >= 26) ?
 327        disk_to_vbd_name((disk / 26) - 1) : g_strdup("");
 328
 329    name = g_strdup_printf("%s%c", prefix, 'a' + disk % 26);
 330    g_free(prefix);
 331
 332    return name;
 333}
 334
 335static void xen_block_get_vdev(Object *obj, Visitor *v, const char *name,
 336                               void *opaque, Error **errp)
 337{
 338    Property *prop = opaque;
 339    XenBlockVdev *vdev = object_field_prop_ptr(obj, prop);
 340    char *str;
 341
 342    switch (vdev->type) {
 343    case XEN_BLOCK_VDEV_TYPE_DP:
 344        str = g_strdup_printf("d%lup%lu", vdev->disk, vdev->partition);
 345        break;
 346
 347    case XEN_BLOCK_VDEV_TYPE_XVD:
 348    case XEN_BLOCK_VDEV_TYPE_HD:
 349    case XEN_BLOCK_VDEV_TYPE_SD: {
 350        char *name = disk_to_vbd_name(vdev->disk);
 351
 352        str = g_strdup_printf("%s%s%lu",
 353                              (vdev->type == XEN_BLOCK_VDEV_TYPE_XVD) ?
 354                              "xvd" :
 355                              (vdev->type == XEN_BLOCK_VDEV_TYPE_HD) ?
 356                              "hd" :
 357                              "sd",
 358                              name, vdev->partition);
 359        g_free(name);
 360        break;
 361    }
 362    default:
 363        error_setg(errp, "invalid vdev type");
 364        return;
 365    }
 366
 367    visit_type_str(v, name, &str, errp);
 368    g_free(str);
 369}
 370
 371static int vbd_name_to_disk(const char *name, const char **endp,
 372                            unsigned long *disk)
 373{
 374    unsigned int n = 0;
 375
 376    while (*name != '\0') {
 377        if (!g_ascii_isalpha(*name) || !g_ascii_islower(*name)) {
 378            break;
 379        }
 380
 381        n *= 26;
 382        n += *name++ - 'a' + 1;
 383    }
 384    *endp = name;
 385
 386    if (!n) {
 387        return -1;
 388    }
 389
 390    *disk = n - 1;
 391
 392    return 0;
 393}
 394
 395static void xen_block_set_vdev(Object *obj, Visitor *v, const char *name,
 396                               void *opaque, Error **errp)
 397{
 398    Property *prop = opaque;
 399    XenBlockVdev *vdev = object_field_prop_ptr(obj, prop);
 400    char *str, *p;
 401    const char *end;
 402
 403    if (!visit_type_str(v, name, &str, errp)) {
 404        return;
 405    }
 406
 407    p = strchr(str, 'd');
 408    if (!p) {
 409        goto invalid;
 410    }
 411
 412    *p++ = '\0';
 413    if (*str == '\0') {
 414        vdev->type = XEN_BLOCK_VDEV_TYPE_DP;
 415    } else if (strcmp(str, "xv") == 0) {
 416        vdev->type = XEN_BLOCK_VDEV_TYPE_XVD;
 417    } else if (strcmp(str, "h") == 0) {
 418        vdev->type = XEN_BLOCK_VDEV_TYPE_HD;
 419    } else if (strcmp(str, "s") == 0) {
 420        vdev->type = XEN_BLOCK_VDEV_TYPE_SD;
 421    } else {
 422        goto invalid;
 423    }
 424
 425    if (vdev->type == XEN_BLOCK_VDEV_TYPE_DP) {
 426        if (qemu_strtoul(p, &end, 10, &vdev->disk)) {
 427            goto invalid;
 428        }
 429
 430        if (*end == 'p') {
 431            if (*(++end) == '\0') {
 432                goto invalid;
 433            }
 434        }
 435    } else {
 436        if (vbd_name_to_disk(p, &end, &vdev->disk)) {
 437            goto invalid;
 438        }
 439    }
 440
 441    if (*end != '\0') {
 442        p = (char *)end;
 443
 444        if (qemu_strtoul(p, &end, 10, &vdev->partition)) {
 445            goto invalid;
 446        }
 447
 448        if (*end != '\0') {
 449            goto invalid;
 450        }
 451    } else {
 452        vdev->partition = 0;
 453    }
 454
 455    switch (vdev->type) {
 456    case XEN_BLOCK_VDEV_TYPE_DP:
 457    case XEN_BLOCK_VDEV_TYPE_XVD:
 458        if (vdev->disk < (1 << 4) && vdev->partition < (1 << 4)) {
 459            vdev->number = (202 << 8) | (vdev->disk << 4) |
 460                vdev->partition;
 461        } else if (vdev->disk < (1 << 20) && vdev->partition < (1 << 8)) {
 462            vdev->number = (1 << 28) | (vdev->disk << 8) |
 463                vdev->partition;
 464        } else {
 465            goto invalid;
 466        }
 467        break;
 468
 469    case XEN_BLOCK_VDEV_TYPE_HD:
 470        if ((vdev->disk == 0 || vdev->disk == 1) &&
 471            vdev->partition < (1 << 6)) {
 472            vdev->number = (3 << 8) | (vdev->disk << 6) | vdev->partition;
 473        } else if ((vdev->disk == 2 || vdev->disk == 3) &&
 474                   vdev->partition < (1 << 6)) {
 475            vdev->number = (22 << 8) | ((vdev->disk - 2) << 6) |
 476                vdev->partition;
 477        } else {
 478            goto invalid;
 479        }
 480        break;
 481
 482    case XEN_BLOCK_VDEV_TYPE_SD:
 483        if (vdev->disk < (1 << 4) && vdev->partition < (1 << 4)) {
 484            vdev->number = (8 << 8) | (vdev->disk << 4) | vdev->partition;
 485        } else {
 486            goto invalid;
 487        }
 488        break;
 489
 490    default:
 491        goto invalid;
 492    }
 493
 494    g_free(str);
 495    return;
 496
 497invalid:
 498    error_setg(errp, "invalid virtual disk specifier");
 499
 500    vdev->type = XEN_BLOCK_VDEV_TYPE_INVALID;
 501    g_free(str);
 502}
 503
 504/*
 505 * This property deals with 'vdev' names adhering to the Xen VBD naming
 506 * scheme described in:
 507 *
 508 * https://xenbits.xen.org/docs/unstable/man/xen-vbd-interface.7.html
 509 */
 510const PropertyInfo xen_block_prop_vdev = {
 511    .name  = "str",
 512    .description = "Virtual Disk specifier: d*p*/xvd*/hd*/sd*",
 513    .get = xen_block_get_vdev,
 514    .set = xen_block_set_vdev,
 515};
 516
 517static Property xen_block_props[] = {
 518    DEFINE_PROP("vdev", XenBlockDevice, props.vdev,
 519                xen_block_prop_vdev, XenBlockVdev),
 520    DEFINE_BLOCK_PROPERTIES(XenBlockDevice, props.conf),
 521    DEFINE_PROP_UINT32("max-ring-page-order", XenBlockDevice,
 522                       props.max_ring_page_order, 4),
 523    DEFINE_PROP_LINK("iothread", XenBlockDevice, props.iothread,
 524                     TYPE_IOTHREAD, IOThread *),
 525    DEFINE_PROP_END_OF_LIST()
 526};
 527
 528static void xen_block_class_init(ObjectClass *class, void *data)
 529{
 530    DeviceClass *dev_class = DEVICE_CLASS(class);
 531    XenDeviceClass *xendev_class = XEN_DEVICE_CLASS(class);
 532
 533    xendev_class->backend = "qdisk";
 534    xendev_class->device = "vbd";
 535    xendev_class->get_name = xen_block_get_name;
 536    xendev_class->realize = xen_block_realize;
 537    xendev_class->frontend_changed = xen_block_frontend_changed;
 538    xendev_class->unrealize = xen_block_unrealize;
 539
 540    device_class_set_props(dev_class, xen_block_props);
 541}
 542
 543static const TypeInfo xen_block_type_info = {
 544    .name = TYPE_XEN_BLOCK_DEVICE,
 545    .parent = TYPE_XEN_DEVICE,
 546    .instance_size = sizeof(XenBlockDevice),
 547    .abstract = true,
 548    .class_size = sizeof(XenBlockDeviceClass),
 549    .class_init = xen_block_class_init,
 550};
 551
 552static void xen_disk_unrealize(XenBlockDevice *blockdev)
 553{
 554    trace_xen_disk_unrealize();
 555}
 556
 557static void xen_disk_realize(XenBlockDevice *blockdev, Error **errp)
 558{
 559    BlockConf *conf = &blockdev->props.conf;
 560
 561    trace_xen_disk_realize();
 562
 563    blockdev->device_type = "disk";
 564
 565    if (!conf->blk) {
 566        error_setg(errp, "drive property not set");
 567        return;
 568    }
 569
 570    blockdev->info = blk_supports_write_perm(conf->blk) ? 0 : VDISK_READONLY;
 571}
 572
 573static void xen_disk_class_init(ObjectClass *class, void *data)
 574{
 575    DeviceClass *dev_class = DEVICE_CLASS(class);
 576    XenBlockDeviceClass *blockdev_class = XEN_BLOCK_DEVICE_CLASS(class);
 577
 578    blockdev_class->realize = xen_disk_realize;
 579    blockdev_class->unrealize = xen_disk_unrealize;
 580
 581    dev_class->desc = "Xen Disk Device";
 582}
 583
 584static const TypeInfo xen_disk_type_info = {
 585    .name = TYPE_XEN_DISK_DEVICE,
 586    .parent = TYPE_XEN_BLOCK_DEVICE,
 587    .instance_size = sizeof(XenDiskDevice),
 588    .class_init = xen_disk_class_init,
 589};
 590
 591static void xen_cdrom_unrealize(XenBlockDevice *blockdev)
 592{
 593    trace_xen_cdrom_unrealize();
 594}
 595
 596static void xen_cdrom_realize(XenBlockDevice *blockdev, Error **errp)
 597{
 598    BlockConf *conf = &blockdev->props.conf;
 599
 600    trace_xen_cdrom_realize();
 601
 602    blockdev->device_type = "cdrom";
 603
 604    if (!conf->blk) {
 605        int rc;
 606
 607        /* Set up an empty drive */
 608        conf->blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
 609
 610        rc = blk_attach_dev(conf->blk, DEVICE(blockdev));
 611        if (!rc) {
 612            error_setg_errno(errp, -rc, "failed to create drive");
 613            return;
 614        }
 615    }
 616
 617    blockdev->info = VDISK_READONLY | VDISK_CDROM;
 618}
 619
 620static void xen_cdrom_class_init(ObjectClass *class, void *data)
 621{
 622    DeviceClass *dev_class = DEVICE_CLASS(class);
 623    XenBlockDeviceClass *blockdev_class = XEN_BLOCK_DEVICE_CLASS(class);
 624
 625    blockdev_class->realize = xen_cdrom_realize;
 626    blockdev_class->unrealize = xen_cdrom_unrealize;
 627
 628    dev_class->desc = "Xen CD-ROM Device";
 629}
 630
 631static const TypeInfo xen_cdrom_type_info = {
 632    .name = TYPE_XEN_CDROM_DEVICE,
 633    .parent = TYPE_XEN_BLOCK_DEVICE,
 634    .instance_size = sizeof(XenCDRomDevice),
 635    .class_init = xen_cdrom_class_init,
 636};
 637
 638static void xen_block_register_types(void)
 639{
 640    type_register_static(&xen_block_type_info);
 641    type_register_static(&xen_disk_type_info);
 642    type_register_static(&xen_cdrom_type_info);
 643}
 644
 645type_init(xen_block_register_types)
 646
 647static void xen_block_blockdev_del(const char *node_name, Error **errp)
 648{
 649    trace_xen_block_blockdev_del(node_name);
 650
 651    qmp_blockdev_del(node_name, errp);
 652}
 653
 654static char *xen_block_blockdev_add(const char *id, QDict *qdict,
 655                                    Error **errp)
 656{
 657    ERRP_GUARD();
 658    const char *driver = qdict_get_try_str(qdict, "driver");
 659    BlockdevOptions *options = NULL;
 660    char *node_name;
 661    Visitor *v;
 662
 663    if (!driver) {
 664        error_setg(errp, "no 'driver' parameter");
 665        return NULL;
 666    }
 667
 668    node_name = g_strdup_printf("%s-%s", id, driver);
 669    qdict_put_str(qdict, "node-name", node_name);
 670
 671    trace_xen_block_blockdev_add(node_name);
 672
 673    v = qobject_input_visitor_new(QOBJECT(qdict));
 674    visit_type_BlockdevOptions(v, NULL, &options, errp);
 675    visit_free(v);
 676    if (!options) {
 677        goto fail;
 678    }
 679
 680    qmp_blockdev_add(options, errp);
 681
 682    if (*errp) {
 683        goto fail;
 684    }
 685
 686    qapi_free_BlockdevOptions(options);
 687
 688    return node_name;
 689
 690fail:
 691    if (options) {
 692        qapi_free_BlockdevOptions(options);
 693    }
 694    g_free(node_name);
 695
 696    return NULL;
 697}
 698
 699static void xen_block_drive_destroy(XenBlockDrive *drive, Error **errp)
 700{
 701    ERRP_GUARD();
 702    char *node_name = drive->node_name;
 703
 704    if (node_name) {
 705        xen_block_blockdev_del(node_name, errp);
 706        if (*errp) {
 707            return;
 708        }
 709        g_free(node_name);
 710        drive->node_name = NULL;
 711    }
 712    g_free(drive->id);
 713    g_free(drive);
 714}
 715
 716static XenBlockDrive *xen_block_drive_create(const char *id,
 717                                             const char *device_type,
 718                                             QDict *opts, Error **errp)
 719{
 720    ERRP_GUARD();
 721    const char *params = qdict_get_try_str(opts, "params");
 722    const char *mode = qdict_get_try_str(opts, "mode");
 723    const char *direct_io_safe = qdict_get_try_str(opts, "direct-io-safe");
 724    const char *discard_enable = qdict_get_try_str(opts, "discard-enable");
 725    char *driver = NULL;
 726    char *filename = NULL;
 727    XenBlockDrive *drive = NULL;
 728    QDict *file_layer;
 729    QDict *driver_layer;
 730    struct stat st;
 731    int rc;
 732
 733    if (params) {
 734        char **v = g_strsplit(params, ":", 2);
 735
 736        if (v[1] == NULL) {
 737            filename = g_strdup(v[0]);
 738            driver = g_strdup("raw");
 739        } else {
 740            if (strcmp(v[0], "aio") == 0) {
 741                driver = g_strdup("raw");
 742            } else if (strcmp(v[0], "vhd") == 0) {
 743                driver = g_strdup("vpc");
 744            } else {
 745                driver = g_strdup(v[0]);
 746            }
 747            filename = g_strdup(v[1]);
 748        }
 749
 750        g_strfreev(v);
 751    } else {
 752        error_setg(errp, "no params");
 753        goto done;
 754    }
 755
 756    assert(filename);
 757    assert(driver);
 758
 759    drive = g_new0(XenBlockDrive, 1);
 760    drive->id = g_strdup(id);
 761
 762    file_layer = qdict_new();
 763    driver_layer = qdict_new();
 764
 765    rc = stat(filename, &st);
 766    if (rc) {
 767        error_setg_errno(errp, errno, "Could not stat file '%s'", filename);
 768        goto done;
 769    }
 770    if (S_ISBLK(st.st_mode)) {
 771        qdict_put_str(file_layer, "driver", "host_device");
 772    } else {
 773        qdict_put_str(file_layer, "driver", "file");
 774    }
 775
 776    qdict_put_str(file_layer, "filename", filename);
 777    g_free(filename);
 778
 779    if (mode && *mode != 'w') {
 780        qdict_put_bool(file_layer, "read-only", true);
 781    }
 782
 783    if (direct_io_safe) {
 784        unsigned long value;
 785
 786        if (!qemu_strtoul(direct_io_safe, NULL, 2, &value) && !!value) {
 787            QDict *cache_qdict = qdict_new();
 788
 789            qdict_put_bool(cache_qdict, "direct", true);
 790            qdict_put(file_layer, "cache", cache_qdict);
 791
 792            qdict_put_str(file_layer, "aio", "native");
 793        }
 794    }
 795
 796    if (discard_enable) {
 797        unsigned long value;
 798
 799        if (!qemu_strtoul(discard_enable, NULL, 2, &value) && !!value) {
 800            qdict_put_str(file_layer, "discard", "unmap");
 801            qdict_put_str(driver_layer, "discard", "unmap");
 802        }
 803    }
 804
 805    /*
 806     * It is necessary to turn file locking off as an emulated device
 807     * may have already opened the same image file.
 808     */
 809    qdict_put_str(file_layer, "locking", "off");
 810
 811    qdict_put_str(driver_layer, "driver", driver);
 812    g_free(driver);
 813
 814    qdict_put(driver_layer, "file", file_layer);
 815
 816    g_assert(!drive->node_name);
 817    drive->node_name = xen_block_blockdev_add(drive->id, driver_layer,
 818                                              errp);
 819
 820    qobject_unref(driver_layer);
 821
 822done:
 823    if (*errp) {
 824        xen_block_drive_destroy(drive, NULL);
 825        return NULL;
 826    }
 827
 828    return drive;
 829}
 830
 831static const char *xen_block_drive_get_node_name(XenBlockDrive *drive)
 832{
 833    return drive->node_name ? drive->node_name : "";
 834}
 835
 836static void xen_block_iothread_destroy(XenBlockIOThread *iothread,
 837                                       Error **errp)
 838{
 839    qmp_object_del(iothread->id, errp);
 840
 841    g_free(iothread->id);
 842    g_free(iothread);
 843}
 844
 845static XenBlockIOThread *xen_block_iothread_create(const char *id,
 846                                                   Error **errp)
 847{
 848    ERRP_GUARD();
 849    XenBlockIOThread *iothread = g_new(XenBlockIOThread, 1);
 850    ObjectOptions *opts;
 851
 852    iothread->id = g_strdup(id);
 853
 854    opts = g_new(ObjectOptions, 1);
 855    *opts = (ObjectOptions) {
 856        .qom_type = OBJECT_TYPE_IOTHREAD,
 857        .id = g_strdup(id),
 858    };
 859    qmp_object_add(opts, errp);
 860    qapi_free_ObjectOptions(opts);
 861
 862    if (*errp) {
 863        g_free(iothread->id);
 864        g_free(iothread);
 865        return NULL;
 866    }
 867
 868    return iothread;
 869}
 870
 871static void xen_block_device_create(XenBackendInstance *backend,
 872                                    QDict *opts, Error **errp)
 873{
 874    ERRP_GUARD();
 875    XenBus *xenbus = xen_backend_get_bus(backend);
 876    const char *name = xen_backend_get_name(backend);
 877    unsigned long number;
 878    const char *vdev, *device_type;
 879    XenBlockDrive *drive = NULL;
 880    XenBlockIOThread *iothread = NULL;
 881    XenDevice *xendev = NULL;
 882    const char *type;
 883    XenBlockDevice *blockdev;
 884
 885    if (qemu_strtoul(name, NULL, 10, &number)) {
 886        error_setg(errp, "failed to parse name '%s'", name);
 887        goto fail;
 888    }
 889
 890    trace_xen_block_device_create(number);
 891
 892    vdev = qdict_get_try_str(opts, "dev");
 893    if (!vdev) {
 894        error_setg(errp, "no dev parameter");
 895        goto fail;
 896    }
 897
 898    device_type = qdict_get_try_str(opts, "device-type");
 899    if (!device_type) {
 900        error_setg(errp, "no device-type parameter");
 901        goto fail;
 902    }
 903
 904    if (!strcmp(device_type, "disk")) {
 905        type = TYPE_XEN_DISK_DEVICE;
 906    } else if (!strcmp(device_type, "cdrom")) {
 907        type = TYPE_XEN_CDROM_DEVICE;
 908    } else {
 909        error_setg(errp, "invalid device-type parameter '%s'", device_type);
 910        goto fail;
 911    }
 912
 913    drive = xen_block_drive_create(vdev, device_type, opts, errp);
 914    if (!drive) {
 915        error_prepend(errp, "failed to create drive: ");
 916        goto fail;
 917    }
 918
 919    iothread = xen_block_iothread_create(vdev, errp);
 920    if (*errp) {
 921        error_prepend(errp, "failed to create iothread: ");
 922        goto fail;
 923    }
 924
 925    xendev = XEN_DEVICE(qdev_new(type));
 926    blockdev = XEN_BLOCK_DEVICE(xendev);
 927
 928    if (!object_property_set_str(OBJECT(xendev), "vdev", vdev,
 929                                 errp)) {
 930        error_prepend(errp, "failed to set 'vdev': ");
 931        goto fail;
 932    }
 933
 934    if (!object_property_set_str(OBJECT(xendev), "drive",
 935                                 xen_block_drive_get_node_name(drive),
 936                                 errp)) {
 937        error_prepend(errp, "failed to set 'drive': ");
 938        goto fail;
 939    }
 940
 941    if (!object_property_set_str(OBJECT(xendev), "iothread", iothread->id,
 942                                 errp)) {
 943        error_prepend(errp, "failed to set 'iothread': ");
 944        goto fail;
 945    }
 946
 947    blockdev->iothread = iothread;
 948    blockdev->drive = drive;
 949
 950    if (!qdev_realize_and_unref(DEVICE(xendev), BUS(xenbus), errp)) {
 951        error_prepend(errp, "realization of device %s failed: ", type);
 952        goto fail;
 953    }
 954
 955    xen_backend_set_device(backend, xendev);
 956    return;
 957
 958fail:
 959    if (xendev) {
 960        object_unparent(OBJECT(xendev));
 961    }
 962
 963    if (iothread) {
 964        xen_block_iothread_destroy(iothread, NULL);
 965    }
 966
 967    if (drive) {
 968        xen_block_drive_destroy(drive, NULL);
 969    }
 970}
 971
 972static void xen_block_device_destroy(XenBackendInstance *backend,
 973                                     Error **errp)
 974{
 975    ERRP_GUARD();
 976    XenDevice *xendev = xen_backend_get_device(backend);
 977    XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
 978    XenBlockVdev *vdev = &blockdev->props.vdev;
 979    XenBlockDrive *drive = blockdev->drive;
 980    XenBlockIOThread *iothread = blockdev->iothread;
 981
 982    trace_xen_block_device_destroy(vdev->number);
 983
 984    object_unparent(OBJECT(xendev));
 985
 986    /*
 987     * Drain all pending RCU callbacks as object_unparent() frees `xendev'
 988     * in a RCU callback.
 989     * And due to the property "drive" still existing in `xendev', we
 990     * can't destroy the XenBlockDrive associated with `xendev' with
 991     * xen_block_drive_destroy() below.
 992     */
 993    drain_call_rcu();
 994
 995    if (iothread) {
 996        xen_block_iothread_destroy(iothread, errp);
 997        if (*errp) {
 998            error_prepend(errp, "failed to destroy iothread: ");
 999            return;
1000        }
1001    }
1002
1003    if (drive) {
1004        xen_block_drive_destroy(drive, errp);
1005        if (*errp) {
1006            error_prepend(errp, "failed to destroy drive: ");
1007            return;
1008        }
1009    }
1010}
1011
1012static const XenBackendInfo xen_block_backend_info = {
1013    .type = "qdisk",
1014    .create = xen_block_device_create,
1015    .destroy = xen_block_device_destroy,
1016};
1017
1018static void xen_block_register_backend(void)
1019{
1020    xen_backend_register(&xen_block_backend_info);
1021}
1022
1023xen_backend_init(xen_block_register_backend);
1024