xref: /openbmc/qemu/hw/block/xen-block.c (revision 31cf4b97)
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/option.h"
11 #include "qapi/error.h"
12 #include "qapi/qapi-commands-block-core.h"
13 #include "qapi/qapi-commands-misc.h"
14 #include "qapi/qapi-visit-block-core.h"
15 #include "qapi/qobject-input-visitor.h"
16 #include "qapi/visitor.h"
17 #include "qapi/qmp/qdict.h"
18 #include "qapi/qmp/qstring.h"
19 #include "hw/hw.h"
20 #include "hw/xen/xen_common.h"
21 #include "hw/block/xen_blkif.h"
22 #include "hw/xen/xen-block.h"
23 #include "hw/xen/xen-backend.h"
24 #include "sysemu/blockdev.h"
25 #include "sysemu/block-backend.h"
26 #include "sysemu/iothread.h"
27 #include "dataplane/xen-block.h"
28 #include "trace.h"
29 
30 static char *xen_block_get_name(XenDevice *xendev, Error **errp)
31 {
32     XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
33     XenBlockVdev *vdev = &blockdev->props.vdev;
34 
35     return g_strdup_printf("%lu", vdev->number);
36 }
37 
38 static void xen_block_disconnect(XenDevice *xendev, Error **errp)
39 {
40     XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
41     const char *type = object_get_typename(OBJECT(blockdev));
42     XenBlockVdev *vdev = &blockdev->props.vdev;
43 
44     trace_xen_block_disconnect(type, vdev->disk, vdev->partition);
45 
46     xen_block_dataplane_stop(blockdev->dataplane);
47 }
48 
49 static void xen_block_connect(XenDevice *xendev, Error **errp)
50 {
51     XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
52     const char *type = object_get_typename(OBJECT(blockdev));
53     XenBlockVdev *vdev = &blockdev->props.vdev;
54     unsigned int order, nr_ring_ref, *ring_ref, event_channel, protocol;
55     char *str;
56 
57     trace_xen_block_connect(type, vdev->disk, vdev->partition);
58 
59     if (xen_device_frontend_scanf(xendev, "ring-page-order", "%u",
60                                   &order) != 1) {
61         nr_ring_ref = 1;
62         ring_ref = g_new(unsigned int, nr_ring_ref);
63 
64         if (xen_device_frontend_scanf(xendev, "ring-ref", "%u",
65                                       &ring_ref[0]) != 1) {
66             error_setg(errp, "failed to read ring-ref");
67             g_free(ring_ref);
68             return;
69         }
70     } else if (order <= blockdev->props.max_ring_page_order) {
71         unsigned int i;
72 
73         nr_ring_ref = 1 << order;
74         ring_ref = g_new(unsigned int, nr_ring_ref);
75 
76         for (i = 0; i < nr_ring_ref; i++) {
77             const char *key = g_strdup_printf("ring-ref%u", i);
78 
79             if (xen_device_frontend_scanf(xendev, key, "%u",
80                                           &ring_ref[i]) != 1) {
81                 error_setg(errp, "failed to read %s", key);
82                 g_free((gpointer)key);
83                 g_free(ring_ref);
84                 return;
85             }
86 
87             g_free((gpointer)key);
88         }
89     } else {
90         error_setg(errp, "invalid ring-page-order (%d)", order);
91         return;
92     }
93 
94     if (xen_device_frontend_scanf(xendev, "event-channel", "%u",
95                                   &event_channel) != 1) {
96         error_setg(errp, "failed to read event-channel");
97         g_free(ring_ref);
98         return;
99     }
100 
101     if (xen_device_frontend_scanf(xendev, "protocol", "%ms",
102                                   &str) != 1) {
103         protocol = BLKIF_PROTOCOL_NATIVE;
104     } else {
105         if (strcmp(str, XEN_IO_PROTO_ABI_X86_32) == 0) {
106             protocol = BLKIF_PROTOCOL_X86_32;
107         } else if (strcmp(str, XEN_IO_PROTO_ABI_X86_64) == 0) {
108             protocol = BLKIF_PROTOCOL_X86_64;
109         } else {
110             protocol = BLKIF_PROTOCOL_NATIVE;
111         }
112 
113         free(str);
114     }
115 
116     xen_block_dataplane_start(blockdev->dataplane, ring_ref, nr_ring_ref,
117                               event_channel, protocol, errp);
118 
119     g_free(ring_ref);
120 }
121 
122 static void xen_block_unrealize(XenDevice *xendev, Error **errp)
123 {
124     XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
125     XenBlockDeviceClass *blockdev_class =
126         XEN_BLOCK_DEVICE_GET_CLASS(xendev);
127     const char *type = object_get_typename(OBJECT(blockdev));
128     XenBlockVdev *vdev = &blockdev->props.vdev;
129 
130     if (vdev->type == XEN_BLOCK_VDEV_TYPE_INVALID) {
131         return;
132     }
133 
134     trace_xen_block_unrealize(type, vdev->disk, vdev->partition);
135 
136     /* Disconnect from the frontend in case this has not already happened */
137     xen_block_disconnect(xendev, NULL);
138 
139     xen_block_dataplane_destroy(blockdev->dataplane);
140     blockdev->dataplane = NULL;
141 
142     if (blockdev_class->unrealize) {
143         blockdev_class->unrealize(blockdev, errp);
144     }
145 }
146 
147 static void xen_block_realize(XenDevice *xendev, Error **errp)
148 {
149     XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
150     XenBlockDeviceClass *blockdev_class =
151         XEN_BLOCK_DEVICE_GET_CLASS(xendev);
152     const char *type = object_get_typename(OBJECT(blockdev));
153     XenBlockVdev *vdev = &blockdev->props.vdev;
154     BlockConf *conf = &blockdev->props.conf;
155     Error *local_err = NULL;
156 
157     if (vdev->type == XEN_BLOCK_VDEV_TYPE_INVALID) {
158         error_setg(errp, "vdev property not set");
159         return;
160     }
161 
162     trace_xen_block_realize(type, vdev->disk, vdev->partition);
163 
164     if (blockdev_class->realize) {
165         blockdev_class->realize(blockdev, &local_err);
166         if (local_err) {
167             error_propagate(errp, local_err);
168             return;
169         }
170     }
171 
172     /*
173      * The blkif protocol does not deal with removable media, so it must
174      * always be present, even for CDRom devices.
175      */
176     assert(conf->blk);
177     if (!blk_is_inserted(conf->blk)) {
178         error_setg(errp, "device needs media, but drive is empty");
179         return;
180     }
181 
182     if (!blkconf_apply_backend_options(conf, blockdev->info & VDISK_READONLY,
183                                        false, errp)) {
184         return;
185     }
186 
187     if (!(blockdev->info & VDISK_CDROM) &&
188         !blkconf_geometry(conf, NULL, 65535, 255, 255, errp)) {
189         return;
190     }
191 
192     blkconf_blocksizes(conf);
193 
194     if (conf->logical_block_size > conf->physical_block_size) {
195         error_setg(
196             errp, "logical_block_size > physical_block_size not supported");
197         return;
198     }
199 
200     blk_set_guest_block_size(conf->blk, conf->logical_block_size);
201 
202     if (conf->discard_granularity > 0) {
203         xen_device_backend_printf(xendev, "feature-discard", "%u", 1);
204     }
205 
206     xen_device_backend_printf(xendev, "feature-flush-cache", "%u", 1);
207     xen_device_backend_printf(xendev, "max-ring-page-order", "%u",
208                               blockdev->props.max_ring_page_order);
209     xen_device_backend_printf(xendev, "info", "%u", blockdev->info);
210 
211     xen_device_frontend_printf(xendev, "virtual-device", "%lu",
212                                vdev->number);
213     xen_device_frontend_printf(xendev, "device-type", "%s",
214                                blockdev->device_type);
215 
216     xen_device_backend_printf(xendev, "sector-size", "%u",
217                               conf->logical_block_size);
218     xen_device_backend_printf(xendev, "sectors", "%lu",
219                               blk_getlength(conf->blk) /
220                               conf->logical_block_size);
221 
222     blockdev->dataplane =
223         xen_block_dataplane_create(xendev, conf, blockdev->props.iothread);
224 }
225 
226 static void xen_block_frontend_changed(XenDevice *xendev,
227                                        enum xenbus_state frontend_state,
228                                        Error **errp)
229 {
230     enum xenbus_state backend_state = xen_device_backend_get_state(xendev);
231     Error *local_err = NULL;
232 
233     switch (frontend_state) {
234     case XenbusStateInitialised:
235     case XenbusStateConnected:
236         if (backend_state == XenbusStateConnected) {
237             break;
238         }
239 
240         xen_block_disconnect(xendev, &local_err);
241         if (local_err) {
242             error_propagate(errp, local_err);
243             break;
244         }
245 
246         xen_block_connect(xendev, &local_err);
247         if (local_err) {
248             error_propagate(errp, local_err);
249             break;
250         }
251 
252         xen_device_backend_set_state(xendev, XenbusStateConnected);
253         break;
254 
255     case XenbusStateClosing:
256         xen_device_backend_set_state(xendev, XenbusStateClosing);
257         break;
258 
259     case XenbusStateClosed:
260         xen_block_disconnect(xendev, &local_err);
261         if (local_err) {
262             error_propagate(errp, local_err);
263             break;
264         }
265 
266         xen_device_backend_set_state(xendev, XenbusStateClosed);
267         break;
268 
269     default:
270         break;
271     }
272 }
273 
274 static char *disk_to_vbd_name(unsigned int disk)
275 {
276     char *name, *prefix = (disk >= 26) ?
277         disk_to_vbd_name((disk / 26) - 1) : g_strdup("");
278 
279     name = g_strdup_printf("%s%c", prefix, 'a' + disk % 26);
280     g_free(prefix);
281 
282     return name;
283 }
284 
285 static void xen_block_get_vdev(Object *obj, Visitor *v, const char *name,
286                                void *opaque, Error **errp)
287 {
288     DeviceState *dev = DEVICE(obj);
289     Property *prop = opaque;
290     XenBlockVdev *vdev = qdev_get_prop_ptr(dev, prop);
291     char *str;
292 
293     switch (vdev->type) {
294     case XEN_BLOCK_VDEV_TYPE_DP:
295         str = g_strdup_printf("d%lup%lu", vdev->disk, vdev->partition);
296         break;
297 
298     case XEN_BLOCK_VDEV_TYPE_XVD:
299     case XEN_BLOCK_VDEV_TYPE_HD:
300     case XEN_BLOCK_VDEV_TYPE_SD: {
301         char *name = disk_to_vbd_name(vdev->disk);
302 
303         str = g_strdup_printf("%s%s%lu",
304                               (vdev->type == XEN_BLOCK_VDEV_TYPE_XVD) ?
305                               "xvd" :
306                               (vdev->type == XEN_BLOCK_VDEV_TYPE_HD) ?
307                               "hd" :
308                               "sd",
309                               name, vdev->partition);
310         g_free(name);
311         break;
312     }
313     default:
314         error_setg(errp, "invalid vdev type");
315         return;
316     }
317 
318     visit_type_str(v, name, &str, errp);
319     g_free(str);
320 }
321 
322 static unsigned int vbd_name_to_disk(const char *name, const char **endp)
323 {
324     unsigned int disk = 0;
325 
326     while (*name != '\0') {
327         if (!g_ascii_isalpha(*name) || !g_ascii_islower(*name)) {
328             break;
329         }
330 
331         disk *= 26;
332         disk += *name++ - 'a' + 1;
333     }
334     *endp = name;
335 
336     return disk - 1;
337 }
338 
339 static void xen_block_set_vdev(Object *obj, Visitor *v, const char *name,
340                                void *opaque, Error **errp)
341 {
342     DeviceState *dev = DEVICE(obj);
343     Property *prop = opaque;
344     XenBlockVdev *vdev = qdev_get_prop_ptr(dev, prop);
345     Error *local_err = NULL;
346     char *str, *p;
347     const char *end;
348 
349     if (dev->realized) {
350         qdev_prop_set_after_realize(dev, name, errp);
351         return;
352     }
353 
354     visit_type_str(v, name, &str, &local_err);
355     if (local_err) {
356         error_propagate(errp, local_err);
357         return;
358     }
359 
360     p = strchr(str, 'd');
361     if (!p) {
362         goto invalid;
363     }
364 
365     *p++ = '\0';
366     if (*str == '\0') {
367         vdev->type = XEN_BLOCK_VDEV_TYPE_DP;
368     } else if (strcmp(str, "xv") == 0) {
369         vdev->type = XEN_BLOCK_VDEV_TYPE_XVD;
370     } else if (strcmp(str, "h") == 0) {
371         vdev->type = XEN_BLOCK_VDEV_TYPE_HD;
372     } else if (strcmp(str, "s") == 0) {
373         vdev->type = XEN_BLOCK_VDEV_TYPE_SD;
374     } else {
375         goto invalid;
376     }
377 
378     if (vdev->type == XEN_BLOCK_VDEV_TYPE_DP) {
379         if (qemu_strtoul(p, &end, 10, &vdev->disk)) {
380             goto invalid;
381         }
382 
383         if (*end == 'p') {
384             p = (char *) ++end;
385             if (*end == '\0') {
386                 goto invalid;
387             }
388         }
389     } else {
390         vdev->disk = vbd_name_to_disk(p, &end);
391     }
392 
393     if (*end != '\0') {
394         p = (char *)end;
395 
396         if (qemu_strtoul(p, &end, 10, &vdev->partition)) {
397             goto invalid;
398         }
399 
400         if (*end != '\0') {
401             goto invalid;
402         }
403     } else {
404         vdev->partition = 0;
405     }
406 
407     switch (vdev->type) {
408     case XEN_BLOCK_VDEV_TYPE_DP:
409     case XEN_BLOCK_VDEV_TYPE_XVD:
410         if (vdev->disk < (1 << 4) && vdev->partition < (1 << 4)) {
411             vdev->number = (202 << 8) | (vdev->disk << 4) |
412                 vdev->partition;
413         } else if (vdev->disk < (1 << 20) && vdev->partition < (1 << 8)) {
414             vdev->number = (1 << 28) | (vdev->disk << 8) |
415                 vdev->partition;
416         } else {
417             goto invalid;
418         }
419         break;
420 
421     case XEN_BLOCK_VDEV_TYPE_HD:
422         if ((vdev->disk == 0 || vdev->disk == 1) &&
423             vdev->partition < (1 << 6)) {
424             vdev->number = (3 << 8) | (vdev->disk << 6) | vdev->partition;
425         } else if ((vdev->disk == 2 || vdev->disk == 3) &&
426                    vdev->partition < (1 << 6)) {
427             vdev->number = (22 << 8) | ((vdev->disk - 2) << 6) |
428                 vdev->partition;
429         } else {
430             goto invalid;
431         }
432         break;
433 
434     case XEN_BLOCK_VDEV_TYPE_SD:
435         if (vdev->disk < (1 << 4) && vdev->partition < (1 << 4)) {
436             vdev->number = (8 << 8) | (vdev->disk << 4) | vdev->partition;
437         } else {
438             goto invalid;
439         }
440         break;
441 
442     default:
443         goto invalid;
444     }
445 
446     g_free(str);
447     return;
448 
449 invalid:
450     error_setg(errp, "invalid virtual disk specifier");
451 
452     vdev->type = XEN_BLOCK_VDEV_TYPE_INVALID;
453     g_free(str);
454 }
455 
456 /*
457  * This property deals with 'vdev' names adhering to the Xen VBD naming
458  * scheme described in:
459  *
460  * https://xenbits.xen.org/docs/unstable/man/xen-vbd-interface.7.html
461  */
462 const PropertyInfo xen_block_prop_vdev = {
463     .name  = "str",
464     .description = "Virtual Disk specifier: d*p*/xvd*/hd*/sd*",
465     .get = xen_block_get_vdev,
466     .set = xen_block_set_vdev,
467 };
468 
469 static Property xen_block_props[] = {
470     DEFINE_PROP("vdev", XenBlockDevice, props.vdev,
471                 xen_block_prop_vdev, XenBlockVdev),
472     DEFINE_BLOCK_PROPERTIES(XenBlockDevice, props.conf),
473     DEFINE_PROP_UINT32("max-ring-page-order", XenBlockDevice,
474                        props.max_ring_page_order, 4),
475     DEFINE_PROP_LINK("iothread", XenBlockDevice, props.iothread,
476                      TYPE_IOTHREAD, IOThread *),
477     DEFINE_PROP_END_OF_LIST()
478 };
479 
480 static void xen_block_class_init(ObjectClass *class, void *data)
481 {
482     DeviceClass *dev_class = DEVICE_CLASS(class);
483     XenDeviceClass *xendev_class = XEN_DEVICE_CLASS(class);
484 
485     xendev_class->backend = "qdisk";
486     xendev_class->device = "vbd";
487     xendev_class->get_name = xen_block_get_name;
488     xendev_class->realize = xen_block_realize;
489     xendev_class->frontend_changed = xen_block_frontend_changed;
490     xendev_class->unrealize = xen_block_unrealize;
491 
492     dev_class->props = xen_block_props;
493 }
494 
495 static const TypeInfo xen_block_type_info = {
496     .name = TYPE_XEN_BLOCK_DEVICE,
497     .parent = TYPE_XEN_DEVICE,
498     .instance_size = sizeof(XenBlockDevice),
499     .abstract = true,
500     .class_size = sizeof(XenBlockDeviceClass),
501     .class_init = xen_block_class_init,
502 };
503 
504 static void xen_disk_unrealize(XenBlockDevice *blockdev, Error **errp)
505 {
506     trace_xen_disk_unrealize();
507 }
508 
509 static void xen_disk_realize(XenBlockDevice *blockdev, Error **errp)
510 {
511     BlockConf *conf = &blockdev->props.conf;
512 
513     trace_xen_disk_realize();
514 
515     blockdev->device_type = "disk";
516 
517     if (!conf->blk) {
518         error_setg(errp, "drive property not set");
519         return;
520     }
521 
522     blockdev->info = blk_is_read_only(conf->blk) ? VDISK_READONLY : 0;
523 }
524 
525 static void xen_disk_class_init(ObjectClass *class, void *data)
526 {
527     DeviceClass *dev_class = DEVICE_CLASS(class);
528     XenBlockDeviceClass *blockdev_class = XEN_BLOCK_DEVICE_CLASS(class);
529 
530     blockdev_class->realize = xen_disk_realize;
531     blockdev_class->unrealize = xen_disk_unrealize;
532 
533     dev_class->desc = "Xen Disk Device";
534 }
535 
536 static const TypeInfo xen_disk_type_info = {
537     .name = TYPE_XEN_DISK_DEVICE,
538     .parent = TYPE_XEN_BLOCK_DEVICE,
539     .instance_size = sizeof(XenDiskDevice),
540     .class_init = xen_disk_class_init,
541 };
542 
543 static void xen_cdrom_unrealize(XenBlockDevice *blockdev, Error **errp)
544 {
545     trace_xen_cdrom_unrealize();
546 }
547 
548 static void xen_cdrom_realize(XenBlockDevice *blockdev, Error **errp)
549 {
550     BlockConf *conf = &blockdev->props.conf;
551 
552     trace_xen_cdrom_realize();
553 
554     blockdev->device_type = "cdrom";
555 
556     if (!conf->blk) {
557         int rc;
558 
559         /* Set up an empty drive */
560         conf->blk = blk_new(0, BLK_PERM_ALL);
561 
562         rc = blk_attach_dev(conf->blk, DEVICE(blockdev));
563         if (!rc) {
564             error_setg_errno(errp, -rc, "failed to create drive");
565             return;
566         }
567     }
568 
569     blockdev->info = VDISK_READONLY | VDISK_CDROM;
570 }
571 
572 static void xen_cdrom_class_init(ObjectClass *class, void *data)
573 {
574     DeviceClass *dev_class = DEVICE_CLASS(class);
575     XenBlockDeviceClass *blockdev_class = XEN_BLOCK_DEVICE_CLASS(class);
576 
577     blockdev_class->realize = xen_cdrom_realize;
578     blockdev_class->unrealize = xen_cdrom_unrealize;
579 
580     dev_class->desc = "Xen CD-ROM Device";
581 }
582 
583 static const TypeInfo xen_cdrom_type_info = {
584     .name = TYPE_XEN_CDROM_DEVICE,
585     .parent = TYPE_XEN_BLOCK_DEVICE,
586     .instance_size = sizeof(XenCDRomDevice),
587     .class_init = xen_cdrom_class_init,
588 };
589 
590 static void xen_block_register_types(void)
591 {
592     type_register_static(&xen_block_type_info);
593     type_register_static(&xen_disk_type_info);
594     type_register_static(&xen_cdrom_type_info);
595 }
596 
597 type_init(xen_block_register_types)
598 
599 static void xen_block_blockdev_del(const char *node_name, Error **errp)
600 {
601     trace_xen_block_blockdev_del(node_name);
602 
603     qmp_blockdev_del(node_name, errp);
604 }
605 
606 static char *xen_block_blockdev_add(const char *id, QDict *qdict,
607                                     Error **errp)
608 {
609     const char *driver = qdict_get_try_str(qdict, "driver");
610     BlockdevOptions *options = NULL;
611     Error *local_err = NULL;
612     char *node_name;
613     Visitor *v;
614 
615     if (!driver) {
616         error_setg(errp, "no 'driver' parameter");
617         return NULL;
618     }
619 
620     node_name = g_strdup_printf("%s-%s", id, driver);
621     qdict_put_str(qdict, "node-name", node_name);
622 
623     trace_xen_block_blockdev_add(node_name);
624 
625     v = qobject_input_visitor_new(QOBJECT(qdict));
626     visit_type_BlockdevOptions(v, NULL, &options, &local_err);
627     visit_free(v);
628 
629     if (local_err) {
630         error_propagate(errp, local_err);
631         goto fail;
632     }
633 
634     qmp_blockdev_add(options, &local_err);
635 
636     if (local_err) {
637         error_propagate(errp, local_err);
638         goto fail;
639     }
640 
641     qapi_free_BlockdevOptions(options);
642 
643     return node_name;
644 
645 fail:
646     if (options) {
647         qapi_free_BlockdevOptions(options);
648     }
649     g_free(node_name);
650 
651     return NULL;
652 }
653 
654 static void xen_block_drive_destroy(XenBlockDrive *drive, Error **errp)
655 {
656     char *node_name = drive->node_name;
657 
658     if (node_name) {
659         Error *local_err = NULL;
660 
661         xen_block_blockdev_del(node_name, &local_err);
662         if (local_err) {
663             error_propagate(errp, local_err);
664             return;
665         }
666         g_free(node_name);
667         drive->node_name = NULL;
668     }
669     g_free(drive->id);
670     g_free(drive);
671 }
672 
673 static XenBlockDrive *xen_block_drive_create(const char *id,
674                                              const char *device_type,
675                                              QDict *opts, Error **errp)
676 {
677     const char *params = qdict_get_try_str(opts, "params");
678     const char *mode = qdict_get_try_str(opts, "mode");
679     const char *direct_io_safe = qdict_get_try_str(opts, "direct-io-safe");
680     const char *discard_enable = qdict_get_try_str(opts, "discard-enable");
681     char *driver = NULL;
682     char *filename = NULL;
683     XenBlockDrive *drive = NULL;
684     Error *local_err = NULL;
685     QDict *file_layer;
686     QDict *driver_layer;
687 
688     if (params) {
689         char **v = g_strsplit(params, ":", 2);
690 
691         if (v[1] == NULL) {
692             filename = g_strdup(v[0]);
693             driver = g_strdup("raw");
694         } else {
695             if (strcmp(v[0], "aio") == 0) {
696                 driver = g_strdup("raw");
697             } else if (strcmp(v[0], "vhd") == 0) {
698                 driver = g_strdup("vpc");
699             } else {
700                 driver = g_strdup(v[0]);
701             }
702             filename = g_strdup(v[1]);
703         }
704 
705         g_strfreev(v);
706     }
707 
708     if (!filename) {
709         error_setg(errp, "no filename");
710         goto done;
711     }
712     assert(driver);
713 
714     drive = g_new0(XenBlockDrive, 1);
715     drive->id = g_strdup(id);
716 
717     file_layer = qdict_new();
718 
719     qdict_put_str(file_layer, "driver", "file");
720     qdict_put_str(file_layer, "filename", filename);
721 
722     if (mode && *mode != 'w') {
723         qdict_put_bool(file_layer, "read-only", true);
724     }
725 
726     if (direct_io_safe) {
727         unsigned long value;
728 
729         if (!qemu_strtoul(direct_io_safe, NULL, 2, &value) && !!value) {
730             QDict *cache_qdict = qdict_new();
731 
732             qdict_put_bool(cache_qdict, "direct", true);
733             qdict_put_obj(file_layer, "cache", QOBJECT(cache_qdict));
734 
735             qdict_put_str(file_layer, "aio", "native");
736         }
737     }
738 
739     if (discard_enable) {
740         unsigned long value;
741 
742         if (!qemu_strtoul(discard_enable, NULL, 2, &value) && !!value) {
743             qdict_put_str(file_layer, "discard", "unmap");
744         }
745     }
746 
747     /*
748      * It is necessary to turn file locking off as an emulated device
749      * may have already opened the same image file.
750      */
751     qdict_put_str(file_layer, "locking", "off");
752 
753     driver_layer = qdict_new();
754 
755     qdict_put_str(driver_layer, "driver", driver);
756     qdict_put_obj(driver_layer, "file", QOBJECT(file_layer));
757 
758     g_assert(!drive->node_name);
759     drive->node_name = xen_block_blockdev_add(drive->id, driver_layer,
760                                               &local_err);
761 
762 done:
763     g_free(driver);
764     g_free(filename);
765 
766     if (local_err) {
767         error_propagate(errp, local_err);
768         xen_block_drive_destroy(drive, NULL);
769         return NULL;
770     }
771 
772     return drive;
773 }
774 
775 static const char *xen_block_drive_get_node_name(XenBlockDrive *drive)
776 {
777     return drive->node_name ? drive->node_name : "";
778 }
779 
780 static void xen_block_iothread_destroy(XenBlockIOThread *iothread,
781                                        Error **errp)
782 {
783     qmp_object_del(iothread->id, errp);
784 
785     g_free(iothread->id);
786     g_free(iothread);
787 }
788 
789 static XenBlockIOThread *xen_block_iothread_create(const char *id,
790                                                    Error **errp)
791 {
792     XenBlockIOThread *iothread = g_new(XenBlockIOThread, 1);
793     Error *local_err = NULL;
794 
795     iothread->id = g_strdup(id);
796 
797     qmp_object_add(TYPE_IOTHREAD, id, false, NULL, &local_err);
798     if (local_err) {
799         error_propagate(errp, local_err);
800 
801         g_free(iothread->id);
802         g_free(iothread);
803         return NULL;
804     }
805 
806     return iothread;
807 }
808 
809 static void xen_block_device_create(XenBackendInstance *backend,
810                                     QDict *opts, Error **errp)
811 {
812     XenBus *xenbus = xen_backend_get_bus(backend);
813     const char *name = xen_backend_get_name(backend);
814     unsigned long number;
815     const char *vdev, *device_type;
816     XenBlockDrive *drive = NULL;
817     XenBlockIOThread *iothread = NULL;
818     XenDevice *xendev = NULL;
819     Error *local_err = NULL;
820     const char *type;
821     XenBlockDevice *blockdev;
822 
823     if (qemu_strtoul(name, NULL, 10, &number)) {
824         error_setg(errp, "failed to parse name '%s'", name);
825         goto fail;
826     }
827 
828     trace_xen_block_device_create(number);
829 
830     vdev = qdict_get_try_str(opts, "dev");
831     if (!vdev) {
832         error_setg(errp, "no dev parameter");
833         goto fail;
834     }
835 
836     device_type = qdict_get_try_str(opts, "device-type");
837     if (!device_type) {
838         error_setg(errp, "no device-type parameter");
839         goto fail;
840     }
841 
842     if (!strcmp(device_type, "disk")) {
843         type = TYPE_XEN_DISK_DEVICE;
844     } else if (!strcmp(device_type, "cdrom")) {
845         type = TYPE_XEN_CDROM_DEVICE;
846     } else {
847         error_setg(errp, "invalid device-type parameter '%s'", device_type);
848         goto fail;
849     }
850 
851     drive = xen_block_drive_create(vdev, device_type, opts, &local_err);
852     if (!drive) {
853         error_propagate_prepend(errp, local_err, "failed to create drive: ");
854         goto fail;
855     }
856 
857     iothread = xen_block_iothread_create(vdev, &local_err);
858     if (local_err) {
859         error_propagate_prepend(errp, local_err,
860                                 "failed to create iothread: ");
861         goto fail;
862     }
863 
864     xendev = XEN_DEVICE(qdev_create(BUS(xenbus), type));
865     blockdev = XEN_BLOCK_DEVICE(xendev);
866 
867     object_property_set_str(OBJECT(xendev), vdev, "vdev", &local_err);
868     if (local_err) {
869         error_propagate_prepend(errp, local_err, "failed to set 'vdev': ");
870         goto fail;
871     }
872 
873     object_property_set_str(OBJECT(xendev),
874                             xen_block_drive_get_node_name(drive), "drive",
875                             &local_err);
876     if (local_err) {
877         error_propagate_prepend(errp, local_err, "failed to set 'drive': ");
878         goto fail;
879     }
880 
881     object_property_set_str(OBJECT(xendev), iothread->id, "iothread",
882                             &local_err);
883     if (local_err) {
884         error_propagate_prepend(errp, local_err,
885                                 "failed to set 'iothread': ");
886         goto fail;
887     }
888 
889     blockdev->iothread = iothread;
890     blockdev->drive = drive;
891 
892     object_property_set_bool(OBJECT(xendev), true, "realized", &local_err);
893     if (local_err) {
894         error_propagate_prepend(errp, local_err,
895                                 "realization of device %s failed: ",
896                                 type);
897         goto fail;
898     }
899 
900     xen_backend_set_device(backend, xendev);
901     return;
902 
903 fail:
904     if (xendev) {
905         object_unparent(OBJECT(xendev));
906     }
907 
908     if (iothread) {
909         xen_block_iothread_destroy(iothread, NULL);
910     }
911 
912     if (drive) {
913         xen_block_drive_destroy(drive, NULL);
914     }
915 }
916 
917 static void xen_block_device_destroy(XenBackendInstance *backend,
918                                      Error **errp)
919 {
920     XenDevice *xendev = xen_backend_get_device(backend);
921     XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
922     XenBlockVdev *vdev = &blockdev->props.vdev;
923     XenBlockDrive *drive = blockdev->drive;
924     XenBlockIOThread *iothread = blockdev->iothread;
925 
926     trace_xen_block_device_destroy(vdev->number);
927 
928     object_unparent(OBJECT(xendev));
929 
930     if (iothread) {
931         Error *local_err = NULL;
932 
933         xen_block_iothread_destroy(iothread, &local_err);
934         if (local_err) {
935             error_propagate_prepend(errp, local_err,
936                                 "failed to destroy iothread: ");
937             return;
938         }
939     }
940 
941     if (drive) {
942         Error *local_err = NULL;
943 
944         xen_block_drive_destroy(drive, &local_err);
945         if (local_err) {
946             error_propagate_prepend(errp, local_err,
947                                 "failed to destroy drive: ");
948         }
949     }
950 }
951 
952 static const XenBackendInfo xen_block_backend_info = {
953     .type = "qdisk",
954     .create = xen_block_device_create,
955     .destroy = xen_block_device_destroy,
956 };
957 
958 static void xen_block_register_backend(void)
959 {
960     xen_backend_register(&xen_block_backend_info);
961 }
962 
963 xen_backend_init(xen_block_register_backend);
964