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    blk_set_guest_block_size(blk, conf->logical_block_size);
 247
 248    if (conf->discard_granularity == -1) {
 249        conf->discard_granularity = conf->physical_block_size;
 250    }
 251
 252    if (blk_get_flags(blk) & BDRV_O_UNMAP) {
 253        xen_device_backend_printf(xendev, "feature-discard", "%u", 1);
 254        xen_device_backend_printf(xendev, "discard-granularity", "%u",
 255                                  conf->discard_granularity);
 256        xen_device_backend_printf(xendev, "discard-alignment", "%u", 0);
 257    }
 258
 259    xen_device_backend_printf(xendev, "feature-flush-cache", "%u", 1);
 260    xen_device_backend_printf(xendev, "max-ring-page-order", "%u",
 261                              blockdev->props.max_ring_page_order);
 262    xen_device_backend_printf(xendev, "info", "%u", blockdev->info);
 263
 264    xen_device_frontend_printf(xendev, "virtual-device", "%lu",
 265                               vdev->number);
 266    xen_device_frontend_printf(xendev, "device-type", "%s",
 267                               blockdev->device_type);
 268
 269    xen_device_backend_printf(xendev, "sector-size", "%u",
 270                              conf->logical_block_size);
 271
 272    xen_block_set_size(blockdev);
 273
 274    blockdev->dataplane =
 275        xen_block_dataplane_create(xendev, blk, conf->logical_block_size,
 276                                   blockdev->props.iothread);
 277}
 278
 279static void xen_block_frontend_changed(XenDevice *xendev,
 280                                       enum xenbus_state frontend_state,
 281                                       Error **errp)
 282{
 283    ERRP_GUARD();
 284    enum xenbus_state backend_state = xen_device_backend_get_state(xendev);
 285
 286    switch (frontend_state) {
 287    case XenbusStateInitialised:
 288    case XenbusStateConnected:
 289        if (backend_state == XenbusStateConnected) {
 290            break;
 291        }
 292
 293        xen_block_disconnect(xendev, errp);
 294        if (*errp) {
 295            break;
 296        }
 297
 298        xen_block_connect(xendev, errp);
 299        if (*errp) {
 300            break;
 301        }
 302
 303        xen_device_backend_set_state(xendev, XenbusStateConnected);
 304        break;
 305
 306    case XenbusStateClosing:
 307        xen_device_backend_set_state(xendev, XenbusStateClosing);
 308        break;
 309
 310    case XenbusStateClosed:
 311    case XenbusStateUnknown:
 312        xen_block_disconnect(xendev, errp);
 313        if (*errp) {
 314            break;
 315        }
 316
 317        xen_device_backend_set_state(xendev, XenbusStateClosed);
 318        break;
 319
 320    default:
 321        break;
 322    }
 323}
 324
 325static char *disk_to_vbd_name(unsigned int disk)
 326{
 327    char *name, *prefix = (disk >= 26) ?
 328        disk_to_vbd_name((disk / 26) - 1) : g_strdup("");
 329
 330    name = g_strdup_printf("%s%c", prefix, 'a' + disk % 26);
 331    g_free(prefix);
 332
 333    return name;
 334}
 335
 336static void xen_block_get_vdev(Object *obj, Visitor *v, const char *name,
 337                               void *opaque, Error **errp)
 338{
 339    Property *prop = opaque;
 340    XenBlockVdev *vdev = object_field_prop_ptr(obj, prop);
 341    char *str;
 342
 343    switch (vdev->type) {
 344    case XEN_BLOCK_VDEV_TYPE_DP:
 345        str = g_strdup_printf("d%lup%lu", vdev->disk, vdev->partition);
 346        break;
 347
 348    case XEN_BLOCK_VDEV_TYPE_XVD:
 349    case XEN_BLOCK_VDEV_TYPE_HD:
 350    case XEN_BLOCK_VDEV_TYPE_SD: {
 351        char *name = disk_to_vbd_name(vdev->disk);
 352
 353        str = g_strdup_printf("%s%s%lu",
 354                              (vdev->type == XEN_BLOCK_VDEV_TYPE_XVD) ?
 355                              "xvd" :
 356                              (vdev->type == XEN_BLOCK_VDEV_TYPE_HD) ?
 357                              "hd" :
 358                              "sd",
 359                              name, vdev->partition);
 360        g_free(name);
 361        break;
 362    }
 363    default:
 364        error_setg(errp, "invalid vdev type");
 365        return;
 366    }
 367
 368    visit_type_str(v, name, &str, errp);
 369    g_free(str);
 370}
 371
 372static int vbd_name_to_disk(const char *name, const char **endp,
 373                            unsigned long *disk)
 374{
 375    unsigned int n = 0;
 376
 377    while (*name != '\0') {
 378        if (!g_ascii_isalpha(*name) || !g_ascii_islower(*name)) {
 379            break;
 380        }
 381
 382        n *= 26;
 383        n += *name++ - 'a' + 1;
 384    }
 385    *endp = name;
 386
 387    if (!n) {
 388        return -1;
 389    }
 390
 391    *disk = n - 1;
 392
 393    return 0;
 394}
 395
 396static void xen_block_set_vdev(Object *obj, Visitor *v, const char *name,
 397                               void *opaque, Error **errp)
 398{
 399    Property *prop = opaque;
 400    XenBlockVdev *vdev = object_field_prop_ptr(obj, prop);
 401    char *str, *p;
 402    const char *end;
 403
 404    if (!visit_type_str(v, name, &str, errp)) {
 405        return;
 406    }
 407
 408    p = strchr(str, 'd');
 409    if (!p) {
 410        goto invalid;
 411    }
 412
 413    *p++ = '\0';
 414    if (*str == '\0') {
 415        vdev->type = XEN_BLOCK_VDEV_TYPE_DP;
 416    } else if (strcmp(str, "xv") == 0) {
 417        vdev->type = XEN_BLOCK_VDEV_TYPE_XVD;
 418    } else if (strcmp(str, "h") == 0) {
 419        vdev->type = XEN_BLOCK_VDEV_TYPE_HD;
 420    } else if (strcmp(str, "s") == 0) {
 421        vdev->type = XEN_BLOCK_VDEV_TYPE_SD;
 422    } else {
 423        goto invalid;
 424    }
 425
 426    if (vdev->type == XEN_BLOCK_VDEV_TYPE_DP) {
 427        if (qemu_strtoul(p, &end, 10, &vdev->disk)) {
 428            goto invalid;
 429        }
 430
 431        if (*end == 'p') {
 432            if (*(++end) == '\0') {
 433                goto invalid;
 434            }
 435        }
 436    } else {
 437        if (vbd_name_to_disk(p, &end, &vdev->disk)) {
 438            goto invalid;
 439        }
 440    }
 441
 442    if (*end != '\0') {
 443        p = (char *)end;
 444
 445        if (qemu_strtoul(p, &end, 10, &vdev->partition)) {
 446            goto invalid;
 447        }
 448
 449        if (*end != '\0') {
 450            goto invalid;
 451        }
 452    } else {
 453        vdev->partition = 0;
 454    }
 455
 456    switch (vdev->type) {
 457    case XEN_BLOCK_VDEV_TYPE_DP:
 458    case XEN_BLOCK_VDEV_TYPE_XVD:
 459        if (vdev->disk < (1 << 4) && vdev->partition < (1 << 4)) {
 460            vdev->number = (202 << 8) | (vdev->disk << 4) |
 461                vdev->partition;
 462        } else if (vdev->disk < (1 << 20) && vdev->partition < (1 << 8)) {
 463            vdev->number = (1 << 28) | (vdev->disk << 8) |
 464                vdev->partition;
 465        } else {
 466            goto invalid;
 467        }
 468        break;
 469
 470    case XEN_BLOCK_VDEV_TYPE_HD:
 471        if ((vdev->disk == 0 || vdev->disk == 1) &&
 472            vdev->partition < (1 << 6)) {
 473            vdev->number = (3 << 8) | (vdev->disk << 6) | vdev->partition;
 474        } else if ((vdev->disk == 2 || vdev->disk == 3) &&
 475                   vdev->partition < (1 << 6)) {
 476            vdev->number = (22 << 8) | ((vdev->disk - 2) << 6) |
 477                vdev->partition;
 478        } else {
 479            goto invalid;
 480        }
 481        break;
 482
 483    case XEN_BLOCK_VDEV_TYPE_SD:
 484        if (vdev->disk < (1 << 4) && vdev->partition < (1 << 4)) {
 485            vdev->number = (8 << 8) | (vdev->disk << 4) | vdev->partition;
 486        } else {
 487            goto invalid;
 488        }
 489        break;
 490
 491    default:
 492        goto invalid;
 493    }
 494
 495    g_free(str);
 496    return;
 497
 498invalid:
 499    error_setg(errp, "invalid virtual disk specifier");
 500
 501    vdev->type = XEN_BLOCK_VDEV_TYPE_INVALID;
 502    g_free(str);
 503}
 504
 505/*
 506 * This property deals with 'vdev' names adhering to the Xen VBD naming
 507 * scheme described in:
 508 *
 509 * https://xenbits.xen.org/docs/unstable/man/xen-vbd-interface.7.html
 510 */
 511const PropertyInfo xen_block_prop_vdev = {
 512    .name  = "str",
 513    .description = "Virtual Disk specifier: d*p*/xvd*/hd*/sd*",
 514    .get = xen_block_get_vdev,
 515    .set = xen_block_set_vdev,
 516};
 517
 518static Property xen_block_props[] = {
 519    DEFINE_PROP("vdev", XenBlockDevice, props.vdev,
 520                xen_block_prop_vdev, XenBlockVdev),
 521    DEFINE_BLOCK_PROPERTIES(XenBlockDevice, props.conf),
 522    DEFINE_PROP_UINT32("max-ring-page-order", XenBlockDevice,
 523                       props.max_ring_page_order, 4),
 524    DEFINE_PROP_LINK("iothread", XenBlockDevice, props.iothread,
 525                     TYPE_IOTHREAD, IOThread *),
 526    DEFINE_PROP_END_OF_LIST()
 527};
 528
 529static void xen_block_class_init(ObjectClass *class, void *data)
 530{
 531    DeviceClass *dev_class = DEVICE_CLASS(class);
 532    XenDeviceClass *xendev_class = XEN_DEVICE_CLASS(class);
 533
 534    xendev_class->backend = "qdisk";
 535    xendev_class->device = "vbd";
 536    xendev_class->get_name = xen_block_get_name;
 537    xendev_class->realize = xen_block_realize;
 538    xendev_class->frontend_changed = xen_block_frontend_changed;
 539    xendev_class->unrealize = xen_block_unrealize;
 540
 541    device_class_set_props(dev_class, xen_block_props);
 542}
 543
 544static const TypeInfo xen_block_type_info = {
 545    .name = TYPE_XEN_BLOCK_DEVICE,
 546    .parent = TYPE_XEN_DEVICE,
 547    .instance_size = sizeof(XenBlockDevice),
 548    .abstract = true,
 549    .class_size = sizeof(XenBlockDeviceClass),
 550    .class_init = xen_block_class_init,
 551};
 552
 553static void xen_disk_unrealize(XenBlockDevice *blockdev)
 554{
 555    trace_xen_disk_unrealize();
 556}
 557
 558static void xen_disk_realize(XenBlockDevice *blockdev, Error **errp)
 559{
 560    BlockConf *conf = &blockdev->props.conf;
 561
 562    trace_xen_disk_realize();
 563
 564    blockdev->device_type = "disk";
 565
 566    if (!conf->blk) {
 567        error_setg(errp, "drive property not set");
 568        return;
 569    }
 570
 571    blockdev->info = blk_supports_write_perm(conf->blk) ? 0 : VDISK_READONLY;
 572}
 573
 574static void xen_disk_class_init(ObjectClass *class, void *data)
 575{
 576    DeviceClass *dev_class = DEVICE_CLASS(class);
 577    XenBlockDeviceClass *blockdev_class = XEN_BLOCK_DEVICE_CLASS(class);
 578
 579    blockdev_class->realize = xen_disk_realize;
 580    blockdev_class->unrealize = xen_disk_unrealize;
 581
 582    dev_class->desc = "Xen Disk Device";
 583}
 584
 585static const TypeInfo xen_disk_type_info = {
 586    .name = TYPE_XEN_DISK_DEVICE,
 587    .parent = TYPE_XEN_BLOCK_DEVICE,
 588    .instance_size = sizeof(XenDiskDevice),
 589    .class_init = xen_disk_class_init,
 590};
 591
 592static void xen_cdrom_unrealize(XenBlockDevice *blockdev)
 593{
 594    trace_xen_cdrom_unrealize();
 595}
 596
 597static void xen_cdrom_realize(XenBlockDevice *blockdev, Error **errp)
 598{
 599    BlockConf *conf = &blockdev->props.conf;
 600
 601    trace_xen_cdrom_realize();
 602
 603    blockdev->device_type = "cdrom";
 604
 605    if (!conf->blk) {
 606        int rc;
 607
 608        /* Set up an empty drive */
 609        conf->blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
 610
 611        rc = blk_attach_dev(conf->blk, DEVICE(blockdev));
 612        if (!rc) {
 613            error_setg_errno(errp, -rc, "failed to create drive");
 614            return;
 615        }
 616    }
 617
 618    blockdev->info = VDISK_READONLY | VDISK_CDROM;
 619}
 620
 621static void xen_cdrom_class_init(ObjectClass *class, void *data)
 622{
 623    DeviceClass *dev_class = DEVICE_CLASS(class);
 624    XenBlockDeviceClass *blockdev_class = XEN_BLOCK_DEVICE_CLASS(class);
 625
 626    blockdev_class->realize = xen_cdrom_realize;
 627    blockdev_class->unrealize = xen_cdrom_unrealize;
 628
 629    dev_class->desc = "Xen CD-ROM Device";
 630}
 631
 632static const TypeInfo xen_cdrom_type_info = {
 633    .name = TYPE_XEN_CDROM_DEVICE,
 634    .parent = TYPE_XEN_BLOCK_DEVICE,
 635    .instance_size = sizeof(XenCDRomDevice),
 636    .class_init = xen_cdrom_class_init,
 637};
 638
 639static void xen_block_register_types(void)
 640{
 641    type_register_static(&xen_block_type_info);
 642    type_register_static(&xen_disk_type_info);
 643    type_register_static(&xen_cdrom_type_info);
 644}
 645
 646type_init(xen_block_register_types)
 647
 648static void xen_block_blockdev_del(const char *node_name, Error **errp)
 649{
 650    trace_xen_block_blockdev_del(node_name);
 651
 652    qmp_blockdev_del(node_name, errp);
 653}
 654
 655static char *xen_block_blockdev_add(const char *id, QDict *qdict,
 656                                    Error **errp)
 657{
 658    ERRP_GUARD();
 659    const char *driver = qdict_get_try_str(qdict, "driver");
 660    BlockdevOptions *options = NULL;
 661    char *node_name;
 662    Visitor *v;
 663
 664    if (!driver) {
 665        error_setg(errp, "no 'driver' parameter");
 666        return NULL;
 667    }
 668
 669    node_name = g_strdup_printf("%s-%s", id, driver);
 670    qdict_put_str(qdict, "node-name", node_name);
 671
 672    trace_xen_block_blockdev_add(node_name);
 673
 674    v = qobject_input_visitor_new(QOBJECT(qdict));
 675    visit_type_BlockdevOptions(v, NULL, &options, errp);
 676    visit_free(v);
 677    if (!options) {
 678        goto fail;
 679    }
 680
 681    qmp_blockdev_add(options, errp);
 682
 683    if (*errp) {
 684        goto fail;
 685    }
 686
 687    qapi_free_BlockdevOptions(options);
 688
 689    return node_name;
 690
 691fail:
 692    if (options) {
 693        qapi_free_BlockdevOptions(options);
 694    }
 695    g_free(node_name);
 696
 697    return NULL;
 698}
 699
 700static void xen_block_drive_destroy(XenBlockDrive *drive, Error **errp)
 701{
 702    ERRP_GUARD();
 703    char *node_name = drive->node_name;
 704
 705    if (node_name) {
 706        xen_block_blockdev_del(node_name, errp);
 707        if (*errp) {
 708            return;
 709        }
 710        g_free(node_name);
 711        drive->node_name = NULL;
 712    }
 713    g_free(drive->id);
 714    g_free(drive);
 715}
 716
 717static XenBlockDrive *xen_block_drive_create(const char *id,
 718                                             const char *device_type,
 719                                             QDict *opts, Error **errp)
 720{
 721    ERRP_GUARD();
 722    const char *params = qdict_get_try_str(opts, "params");
 723    const char *mode = qdict_get_try_str(opts, "mode");
 724    const char *direct_io_safe = qdict_get_try_str(opts, "direct-io-safe");
 725    const char *discard_enable = qdict_get_try_str(opts, "discard-enable");
 726    char *driver = NULL;
 727    char *filename = NULL;
 728    XenBlockDrive *drive = NULL;
 729    QDict *file_layer;
 730    QDict *driver_layer;
 731    struct stat st;
 732    int rc;
 733
 734    if (params) {
 735        char **v = g_strsplit(params, ":", 2);
 736
 737        if (v[1] == NULL) {
 738            filename = g_strdup(v[0]);
 739            driver = g_strdup("raw");
 740        } else {
 741            if (strcmp(v[0], "aio") == 0) {
 742                driver = g_strdup("raw");
 743            } else if (strcmp(v[0], "vhd") == 0) {
 744                driver = g_strdup("vpc");
 745            } else {
 746                driver = g_strdup(v[0]);
 747            }
 748            filename = g_strdup(v[1]);
 749        }
 750
 751        g_strfreev(v);
 752    } else {
 753        error_setg(errp, "no params");
 754        goto done;
 755    }
 756
 757    assert(filename);
 758    assert(driver);
 759
 760    drive = g_new0(XenBlockDrive, 1);
 761    drive->id = g_strdup(id);
 762
 763    file_layer = qdict_new();
 764    driver_layer = qdict_new();
 765
 766    rc = stat(filename, &st);
 767    if (rc) {
 768        error_setg_errno(errp, errno, "Could not stat file '%s'", filename);
 769        goto done;
 770    }
 771    if (S_ISBLK(st.st_mode)) {
 772        qdict_put_str(file_layer, "driver", "host_device");
 773    } else {
 774        qdict_put_str(file_layer, "driver", "file");
 775    }
 776
 777    qdict_put_str(file_layer, "filename", filename);
 778    g_free(filename);
 779
 780    if (mode && *mode != 'w') {
 781        qdict_put_bool(file_layer, "read-only", true);
 782    }
 783
 784    if (direct_io_safe) {
 785        unsigned long value;
 786
 787        if (!qemu_strtoul(direct_io_safe, NULL, 2, &value) && !!value) {
 788            QDict *cache_qdict = qdict_new();
 789
 790            qdict_put_bool(cache_qdict, "direct", true);
 791            qdict_put(file_layer, "cache", cache_qdict);
 792
 793            qdict_put_str(file_layer, "aio", "native");
 794        }
 795    }
 796
 797    if (discard_enable) {
 798        unsigned long value;
 799
 800        if (!qemu_strtoul(discard_enable, NULL, 2, &value) && !!value) {
 801            qdict_put_str(file_layer, "discard", "unmap");
 802            qdict_put_str(driver_layer, "discard", "unmap");
 803        }
 804    }
 805
 806    /*
 807     * It is necessary to turn file locking off as an emulated device
 808     * may have already opened the same image file.
 809     */
 810    qdict_put_str(file_layer, "locking", "off");
 811
 812    qdict_put_str(driver_layer, "driver", driver);
 813    g_free(driver);
 814
 815    qdict_put(driver_layer, "file", file_layer);
 816
 817    g_assert(!drive->node_name);
 818    drive->node_name = xen_block_blockdev_add(drive->id, driver_layer,
 819                                              errp);
 820
 821    qobject_unref(driver_layer);
 822
 823done:
 824    if (*errp) {
 825        xen_block_drive_destroy(drive, NULL);
 826        return NULL;
 827    }
 828
 829    return drive;
 830}
 831
 832static const char *xen_block_drive_get_node_name(XenBlockDrive *drive)
 833{
 834    return drive->node_name ? drive->node_name : "";
 835}
 836
 837static void xen_block_iothread_destroy(XenBlockIOThread *iothread,
 838                                       Error **errp)
 839{
 840    qmp_object_del(iothread->id, errp);
 841
 842    g_free(iothread->id);
 843    g_free(iothread);
 844}
 845
 846static XenBlockIOThread *xen_block_iothread_create(const char *id,
 847                                                   Error **errp)
 848{
 849    ERRP_GUARD();
 850    XenBlockIOThread *iothread = g_new(XenBlockIOThread, 1);
 851    ObjectOptions *opts;
 852
 853    iothread->id = g_strdup(id);
 854
 855    opts = g_new(ObjectOptions, 1);
 856    *opts = (ObjectOptions) {
 857        .qom_type = OBJECT_TYPE_IOTHREAD,
 858        .id = g_strdup(id),
 859    };
 860    qmp_object_add(opts, errp);
 861    qapi_free_ObjectOptions(opts);
 862
 863    if (*errp) {
 864        g_free(iothread->id);
 865        g_free(iothread);
 866        return NULL;
 867    }
 868
 869    return iothread;
 870}
 871
 872static void xen_block_device_create(XenBackendInstance *backend,
 873                                    QDict *opts, Error **errp)
 874{
 875    ERRP_GUARD();
 876    XenBus *xenbus = xen_backend_get_bus(backend);
 877    const char *name = xen_backend_get_name(backend);
 878    unsigned long number;
 879    const char *vdev, *device_type;
 880    XenBlockDrive *drive = NULL;
 881    XenBlockIOThread *iothread = NULL;
 882    XenDevice *xendev = NULL;
 883    const char *type;
 884    XenBlockDevice *blockdev;
 885
 886    if (qemu_strtoul(name, NULL, 10, &number)) {
 887        error_setg(errp, "failed to parse name '%s'", name);
 888        goto fail;
 889    }
 890
 891    trace_xen_block_device_create(number);
 892
 893    vdev = qdict_get_try_str(opts, "dev");
 894    if (!vdev) {
 895        error_setg(errp, "no dev parameter");
 896        goto fail;
 897    }
 898
 899    device_type = qdict_get_try_str(opts, "device-type");
 900    if (!device_type) {
 901        error_setg(errp, "no device-type parameter");
 902        goto fail;
 903    }
 904
 905    if (!strcmp(device_type, "disk")) {
 906        type = TYPE_XEN_DISK_DEVICE;
 907    } else if (!strcmp(device_type, "cdrom")) {
 908        type = TYPE_XEN_CDROM_DEVICE;
 909    } else {
 910        error_setg(errp, "invalid device-type parameter '%s'", device_type);
 911        goto fail;
 912    }
 913
 914    drive = xen_block_drive_create(vdev, device_type, opts, errp);
 915    if (!drive) {
 916        error_prepend(errp, "failed to create drive: ");
 917        goto fail;
 918    }
 919
 920    iothread = xen_block_iothread_create(vdev, errp);
 921    if (*errp) {
 922        error_prepend(errp, "failed to create iothread: ");
 923        goto fail;
 924    }
 925
 926    xendev = XEN_DEVICE(qdev_new(type));
 927    blockdev = XEN_BLOCK_DEVICE(xendev);
 928
 929    if (!object_property_set_str(OBJECT(xendev), "vdev", vdev,
 930                                 errp)) {
 931        error_prepend(errp, "failed to set 'vdev': ");
 932        goto fail;
 933    }
 934
 935    if (!object_property_set_str(OBJECT(xendev), "drive",
 936                                 xen_block_drive_get_node_name(drive),
 937                                 errp)) {
 938        error_prepend(errp, "failed to set 'drive': ");
 939        goto fail;
 940    }
 941
 942    if (!object_property_set_str(OBJECT(xendev), "iothread", iothread->id,
 943                                 errp)) {
 944        error_prepend(errp, "failed to set 'iothread': ");
 945        goto fail;
 946    }
 947
 948    blockdev->iothread = iothread;
 949    blockdev->drive = drive;
 950
 951    if (!qdev_realize_and_unref(DEVICE(xendev), BUS(xenbus), errp)) {
 952        error_prepend(errp, "realization of device %s failed: ", type);
 953        goto fail;
 954    }
 955
 956    xen_backend_set_device(backend, xendev);
 957    return;
 958
 959fail:
 960    if (xendev) {
 961        object_unparent(OBJECT(xendev));
 962    }
 963
 964    if (iothread) {
 965        xen_block_iothread_destroy(iothread, NULL);
 966    }
 967
 968    if (drive) {
 969        xen_block_drive_destroy(drive, NULL);
 970    }
 971}
 972
 973static void xen_block_device_destroy(XenBackendInstance *backend,
 974                                     Error **errp)
 975{
 976    ERRP_GUARD();
 977    XenDevice *xendev = xen_backend_get_device(backend);
 978    XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
 979    XenBlockVdev *vdev = &blockdev->props.vdev;
 980    XenBlockDrive *drive = blockdev->drive;
 981    XenBlockIOThread *iothread = blockdev->iothread;
 982
 983    trace_xen_block_device_destroy(vdev->number);
 984
 985    object_unparent(OBJECT(xendev));
 986
 987    /*
 988     * Drain all pending RCU callbacks as object_unparent() frees `xendev'
 989     * in a RCU callback.
 990     * And due to the property "drive" still existing in `xendev', we
 991     * can't destroy the XenBlockDrive associated with `xendev' with
 992     * xen_block_drive_destroy() below.
 993     */
 994    drain_call_rcu();
 995
 996    if (iothread) {
 997        xen_block_iothread_destroy(iothread, errp);
 998        if (*errp) {
 999            error_prepend(errp, "failed to destroy iothread: ");
1000            return;
1001        }
1002    }
1003
1004    if (drive) {
1005        xen_block_drive_destroy(drive, errp);
1006        if (*errp) {
1007            error_prepend(errp, "failed to destroy drive: ");
1008            return;
1009        }
1010    }
1011}
1012
1013static const XenBackendInfo xen_block_backend_info = {
1014    .type = "qdisk",
1015    .create = xen_block_device_create,
1016    .destroy = xen_block_device_destroy,
1017};
1018
1019static void xen_block_register_backend(void)
1020{
1021    xen_backend_register(&xen_block_backend_info);
1022}
1023
1024xen_backend_init(xen_block_register_backend);
1025