1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Xenbus code for blkif backend
3 Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au>
4 Copyright (C) 2005 XenSource Ltd
9 #define pr_fmt(fmt) "xen-blkback: " fmt
11 #include <linux/module.h>
12 #include <linux/kthread.h>
13 #include <linux/pagemap.h>
14 #include <xen/events.h>
15 #include <xen/grant_table.h>
18 /* On the XenBus the max length of 'ring-ref%u'. */
19 #define RINGREF_NAME_LEN (20)
22 struct xenbus_device *dev;
23 struct xen_blkif *blkif;
24 struct xenbus_watch backend_watch;
30 static struct kmem_cache *xen_blkif_cachep;
31 static void connect(struct backend_info *);
32 static int connect_ring(struct backend_info *);
33 static void backend_changed(struct xenbus_watch *, const char *,
35 static void xen_blkif_free(struct xen_blkif *blkif);
36 static void xen_vbd_free(struct xen_vbd *vbd);
38 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be)
44 * The last request could free the device from softirq context and
45 * xen_blkif_free() can sleep.
47 static void xen_blkif_deferred_free(struct work_struct *work)
49 struct xen_blkif *blkif;
51 blkif = container_of(work, struct xen_blkif, free_work);
52 xen_blkif_free(blkif);
55 static int blkback_name(struct xen_blkif *blkif, char *buf)
57 char *devpath, *devname;
58 struct xenbus_device *dev = blkif->be->dev;
60 devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL);
62 return PTR_ERR(devpath);
64 devname = strstr(devpath, "/dev/");
66 devname += strlen("/dev/");
70 snprintf(buf, TASK_COMM_LEN, "%d.%s", blkif->domid, devname);
76 static void xen_update_blkif_status(struct xen_blkif *blkif)
79 char name[TASK_COMM_LEN];
80 struct xen_blkif_ring *ring;
83 /* Not ready to connect? */
84 if (!blkif->rings || !blkif->rings[0].irq || !blkif->vbd.bdev)
87 /* Already connected? */
88 if (blkif->be->dev->state == XenbusStateConnected)
91 /* Attempt to connect: exit if we fail to. */
93 if (blkif->be->dev->state != XenbusStateConnected)
96 err = blkback_name(blkif, name);
98 xenbus_dev_error(blkif->be->dev, err, "get blkback dev name");
102 err = sync_blockdev(blkif->vbd.bdev);
104 xenbus_dev_error(blkif->be->dev, err, "block flush");
107 invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
109 for (i = 0; i < blkif->nr_rings; i++) {
110 ring = &blkif->rings[i];
111 ring->xenblkd = kthread_run(xen_blkif_schedule, ring, "%s-%d", name, i);
112 if (IS_ERR(ring->xenblkd)) {
113 err = PTR_ERR(ring->xenblkd);
114 ring->xenblkd = NULL;
115 xenbus_dev_fatal(blkif->be->dev, err,
116 "start %s-%d xenblkd", name, i);
124 ring = &blkif->rings[i];
125 kthread_stop(ring->xenblkd);
130 static int xen_blkif_alloc_rings(struct xen_blkif *blkif)
134 blkif->rings = kcalloc(blkif->nr_rings, sizeof(struct xen_blkif_ring),
139 for (r = 0; r < blkif->nr_rings; r++) {
140 struct xen_blkif_ring *ring = &blkif->rings[r];
142 spin_lock_init(&ring->blk_ring_lock);
143 init_waitqueue_head(&ring->wq);
144 INIT_LIST_HEAD(&ring->pending_free);
145 INIT_LIST_HEAD(&ring->persistent_purge_list);
146 INIT_WORK(&ring->persistent_purge_work, xen_blkbk_unmap_purged_grants);
147 gnttab_page_cache_init(&ring->free_pages);
149 spin_lock_init(&ring->pending_free_lock);
150 init_waitqueue_head(&ring->pending_free_wq);
151 init_waitqueue_head(&ring->shutdown_wq);
153 ring->st_print = jiffies;
160 static struct xen_blkif *xen_blkif_alloc(domid_t domid)
162 struct xen_blkif *blkif;
164 BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
166 blkif = kmem_cache_zalloc(xen_blkif_cachep, GFP_KERNEL);
168 return ERR_PTR(-ENOMEM);
170 blkif->domid = domid;
171 atomic_set(&blkif->refcnt, 1);
172 init_completion(&blkif->drain_complete);
175 * Because freeing back to the cache may be deferred, it is not
176 * safe to unload the module (and hence destroy the cache) until
177 * this has completed. To prevent premature unloading, take an
178 * extra module reference here and release only when the object
179 * has been freed back to the cache.
181 __module_get(THIS_MODULE);
182 INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
187 static int xen_blkif_map(struct xen_blkif_ring *ring, grant_ref_t *gref,
188 unsigned int nr_grefs, unsigned int evtchn)
191 struct xen_blkif *blkif = ring->blkif;
192 const struct blkif_common_sring *sring_common;
193 RING_IDX rsp_prod, req_prod;
196 /* Already connected through? */
200 err = xenbus_map_ring_valloc(blkif->be->dev, gref, nr_grefs,
205 sring_common = (struct blkif_common_sring *)ring->blk_ring;
206 rsp_prod = READ_ONCE(sring_common->rsp_prod);
207 req_prod = READ_ONCE(sring_common->req_prod);
209 switch (blkif->blk_protocol) {
210 case BLKIF_PROTOCOL_NATIVE:
212 struct blkif_sring *sring_native =
213 (struct blkif_sring *)ring->blk_ring;
215 BACK_RING_ATTACH(&ring->blk_rings.native, sring_native,
216 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
217 size = __RING_SIZE(sring_native, XEN_PAGE_SIZE * nr_grefs);
220 case BLKIF_PROTOCOL_X86_32:
222 struct blkif_x86_32_sring *sring_x86_32 =
223 (struct blkif_x86_32_sring *)ring->blk_ring;
225 BACK_RING_ATTACH(&ring->blk_rings.x86_32, sring_x86_32,
226 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
227 size = __RING_SIZE(sring_x86_32, XEN_PAGE_SIZE * nr_grefs);
230 case BLKIF_PROTOCOL_X86_64:
232 struct blkif_x86_64_sring *sring_x86_64 =
233 (struct blkif_x86_64_sring *)ring->blk_ring;
235 BACK_RING_ATTACH(&ring->blk_rings.x86_64, sring_x86_64,
236 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
237 size = __RING_SIZE(sring_x86_64, XEN_PAGE_SIZE * nr_grefs);
245 if (req_prod - rsp_prod > size)
248 err = bind_interdomain_evtchn_to_irqhandler_lateeoi(blkif->be->dev,
249 evtchn, xen_blkif_be_int, 0, "blkif-backend", ring);
257 xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
258 ring->blk_rings.common.sring = NULL;
262 static int xen_blkif_disconnect(struct xen_blkif *blkif)
264 struct pending_req *req, *n;
268 for (r = 0; r < blkif->nr_rings; r++) {
269 struct xen_blkif_ring *ring = &blkif->rings[r];
276 kthread_stop(ring->xenblkd);
277 ring->xenblkd = NULL;
278 wake_up(&ring->shutdown_wq);
281 /* The above kthread_stop() guarantees that at this point we
282 * don't have any discard_io or other_io requests. So, checking
283 * for inflight IO is enough.
285 if (atomic_read(&ring->inflight) > 0) {
291 unbind_from_irqhandler(ring->irq, ring);
295 if (ring->blk_rings.common.sring) {
296 xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
297 ring->blk_rings.common.sring = NULL;
300 /* Remove all persistent grants and the cache of ballooned pages. */
301 xen_blkbk_free_caches(ring);
303 /* Check that there is no request in use */
304 list_for_each_entry_safe(req, n, &ring->pending_free, free_list) {
305 list_del(&req->free_list);
307 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++)
308 kfree(req->segments[j]);
310 for (j = 0; j < MAX_INDIRECT_PAGES; j++)
311 kfree(req->indirect_pages[j]);
317 BUG_ON(atomic_read(&ring->persistent_gnt_in_use) != 0);
318 BUG_ON(!list_empty(&ring->persistent_purge_list));
319 BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts));
320 BUG_ON(ring->free_pages.num_pages != 0);
321 BUG_ON(ring->persistent_gnt_c != 0);
322 WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
323 ring->active = false;
328 blkif->nr_ring_pages = 0;
330 * blkif->rings was allocated in connect_ring, so we should free it in
340 static void xen_blkif_free(struct xen_blkif *blkif)
342 WARN_ON(xen_blkif_disconnect(blkif));
343 xen_vbd_free(&blkif->vbd);
344 kfree(blkif->be->mode);
347 /* Make sure everything is drained before shutting down */
348 kmem_cache_free(xen_blkif_cachep, blkif);
349 module_put(THIS_MODULE);
352 int __init xen_blkif_interface_init(void)
354 xen_blkif_cachep = kmem_cache_create("blkif_cache",
355 sizeof(struct xen_blkif),
357 if (!xen_blkif_cachep)
363 void xen_blkif_interface_fini(void)
365 kmem_cache_destroy(xen_blkif_cachep);
366 xen_blkif_cachep = NULL;
370 * sysfs interface for VBD I/O requests
373 #define VBD_SHOW_ALLRING(name, format) \
374 static ssize_t show_##name(struct device *_dev, \
375 struct device_attribute *attr, \
378 struct xenbus_device *dev = to_xenbus_device(_dev); \
379 struct backend_info *be = dev_get_drvdata(&dev->dev); \
380 struct xen_blkif *blkif = be->blkif; \
382 unsigned long long result = 0; \
387 for (i = 0; i < blkif->nr_rings; i++) { \
388 struct xen_blkif_ring *ring = &blkif->rings[i]; \
390 result += ring->st_##name; \
394 return sprintf(buf, format, result); \
396 static DEVICE_ATTR(name, 0444, show_##name, NULL)
398 VBD_SHOW_ALLRING(oo_req, "%llu\n");
399 VBD_SHOW_ALLRING(rd_req, "%llu\n");
400 VBD_SHOW_ALLRING(wr_req, "%llu\n");
401 VBD_SHOW_ALLRING(f_req, "%llu\n");
402 VBD_SHOW_ALLRING(ds_req, "%llu\n");
403 VBD_SHOW_ALLRING(rd_sect, "%llu\n");
404 VBD_SHOW_ALLRING(wr_sect, "%llu\n");
406 static struct attribute *xen_vbdstat_attrs[] = {
407 &dev_attr_oo_req.attr,
408 &dev_attr_rd_req.attr,
409 &dev_attr_wr_req.attr,
410 &dev_attr_f_req.attr,
411 &dev_attr_ds_req.attr,
412 &dev_attr_rd_sect.attr,
413 &dev_attr_wr_sect.attr,
417 static const struct attribute_group xen_vbdstat_group = {
418 .name = "statistics",
419 .attrs = xen_vbdstat_attrs,
422 #define VBD_SHOW(name, format, args...) \
423 static ssize_t show_##name(struct device *_dev, \
424 struct device_attribute *attr, \
427 struct xenbus_device *dev = to_xenbus_device(_dev); \
428 struct backend_info *be = dev_get_drvdata(&dev->dev); \
430 return sprintf(buf, format, ##args); \
432 static DEVICE_ATTR(name, 0444, show_##name, NULL)
434 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
435 VBD_SHOW(mode, "%s\n", be->mode);
437 static int xenvbd_sysfs_addif(struct xenbus_device *dev)
441 error = device_create_file(&dev->dev, &dev_attr_physical_device);
445 error = device_create_file(&dev->dev, &dev_attr_mode);
449 error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group);
455 fail3: sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
456 fail2: device_remove_file(&dev->dev, &dev_attr_mode);
457 fail1: device_remove_file(&dev->dev, &dev_attr_physical_device);
461 static void xenvbd_sysfs_delif(struct xenbus_device *dev)
463 sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
464 device_remove_file(&dev->dev, &dev_attr_mode);
465 device_remove_file(&dev->dev, &dev_attr_physical_device);
468 static void xen_vbd_free(struct xen_vbd *vbd)
471 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
475 /* Enable the persistent grants feature. */
476 static bool feature_persistent = true;
477 module_param(feature_persistent, bool, 0644);
478 MODULE_PARM_DESC(feature_persistent,
479 "Enables the persistent grants feature");
481 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
482 unsigned major, unsigned minor, int readonly,
486 struct block_device *bdev;
487 struct request_queue *q;
490 vbd->handle = handle;
491 vbd->readonly = readonly;
494 vbd->pdevice = MKDEV(major, minor);
496 bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
497 FMODE_READ : FMODE_WRITE, NULL);
500 pr_warn("xen_vbd_create: device %08x could not be opened\n",
506 if (vbd->bdev->bd_disk == NULL) {
507 pr_warn("xen_vbd_create: device %08x doesn't exist\n",
512 vbd->size = vbd_sz(vbd);
514 if (cdrom || disk_to_cdi(vbd->bdev->bd_disk))
515 vbd->type |= VDISK_CDROM;
516 if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
517 vbd->type |= VDISK_REMOVABLE;
519 q = bdev_get_queue(bdev);
520 if (q && test_bit(QUEUE_FLAG_WC, &q->queue_flags))
521 vbd->flush_support = true;
523 if (q && blk_queue_secure_erase(q))
524 vbd->discard_secure = true;
526 vbd->feature_gnt_persistent = feature_persistent;
528 pr_debug("Successful creation of handle=%04x (dom=%u)\n",
529 handle, blkif->domid);
533 static int xen_blkbk_remove(struct xenbus_device *dev)
535 struct backend_info *be = dev_get_drvdata(&dev->dev);
537 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
539 if (be->major || be->minor)
540 xenvbd_sysfs_delif(dev);
542 if (be->backend_watch.node) {
543 unregister_xenbus_watch(&be->backend_watch);
544 kfree(be->backend_watch.node);
545 be->backend_watch.node = NULL;
548 dev_set_drvdata(&dev->dev, NULL);
551 xen_blkif_disconnect(be->blkif);
553 /* Put the reference we set in xen_blkif_alloc(). */
554 xen_blkif_put(be->blkif);
560 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
561 struct backend_info *be, int state)
563 struct xenbus_device *dev = be->dev;
566 err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache",
569 dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err);
574 static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be)
576 struct xenbus_device *dev = be->dev;
577 struct xen_blkif *blkif = be->blkif;
580 struct block_device *bdev = be->blkif->vbd.bdev;
581 struct request_queue *q = bdev_get_queue(bdev);
583 if (!xenbus_read_unsigned(dev->nodename, "discard-enable", 1))
586 if (blk_queue_discard(q)) {
587 err = xenbus_printf(xbt, dev->nodename,
588 "discard-granularity", "%u",
589 q->limits.discard_granularity);
591 dev_warn(&dev->dev, "writing discard-granularity (%d)", err);
594 err = xenbus_printf(xbt, dev->nodename,
595 "discard-alignment", "%u",
596 q->limits.discard_alignment);
598 dev_warn(&dev->dev, "writing discard-alignment (%d)", err);
603 err = xenbus_printf(xbt, dev->nodename,
604 "discard-secure", "%d",
605 blkif->vbd.discard_secure);
607 dev_warn(&dev->dev, "writing discard-secure (%d)", err);
611 err = xenbus_printf(xbt, dev->nodename, "feature-discard",
614 dev_warn(&dev->dev, "writing feature-discard (%d)", err);
617 int xen_blkbk_barrier(struct xenbus_transaction xbt,
618 struct backend_info *be, int state)
620 struct xenbus_device *dev = be->dev;
623 err = xenbus_printf(xbt, dev->nodename, "feature-barrier",
626 dev_warn(&dev->dev, "writing feature-barrier (%d)", err);
632 * Entry point to this code when a new device is created. Allocate the basic
633 * structures, and watch the store waiting for the hotplug scripts to tell us
634 * the device's physical major and minor numbers. Switch to InitWait.
636 static int xen_blkbk_probe(struct xenbus_device *dev,
637 const struct xenbus_device_id *id)
640 struct backend_info *be = kzalloc(sizeof(struct backend_info),
643 /* match the pr_debug in xen_blkbk_remove */
644 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
647 xenbus_dev_fatal(dev, -ENOMEM,
648 "allocating backend structure");
652 dev_set_drvdata(&dev->dev, be);
654 be->blkif = xen_blkif_alloc(dev->otherend_id);
655 if (IS_ERR(be->blkif)) {
656 err = PTR_ERR(be->blkif);
658 xenbus_dev_fatal(dev, err, "creating block interface");
662 err = xenbus_printf(XBT_NIL, dev->nodename,
663 "feature-max-indirect-segments", "%u",
664 MAX_INDIRECT_SEGMENTS);
667 "writing %s/feature-max-indirect-segments (%d)",
670 /* Multi-queue: advertise how many queues are supported by us.*/
671 err = xenbus_printf(XBT_NIL, dev->nodename,
672 "multi-queue-max-queues", "%u", xenblk_max_queues);
674 pr_warn("Error writing multi-queue-max-queues\n");
676 /* setup back pointer */
679 err = xenbus_watch_pathfmt(dev, &be->backend_watch, NULL,
681 "%s/%s", dev->nodename, "physical-device");
685 err = xenbus_printf(XBT_NIL, dev->nodename, "max-ring-page-order", "%u",
686 xen_blkif_max_ring_order);
688 pr_warn("%s write out 'max-ring-page-order' failed\n", __func__);
690 err = xenbus_switch_state(dev, XenbusStateInitWait);
697 pr_warn("%s failed\n", __func__);
698 xen_blkbk_remove(dev);
703 * Callback received when the hotplug scripts have placed the physical-device
704 * node. Read it and the mode node, and create a vbd. If the frontend is
707 static void backend_changed(struct xenbus_watch *watch,
708 const char *path, const char *token)
713 struct backend_info *be
714 = container_of(watch, struct backend_info, backend_watch);
715 struct xenbus_device *dev = be->dev;
717 unsigned long handle;
720 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
722 err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
724 if (XENBUS_EXIST_ERR(err)) {
726 * Since this watch will fire once immediately after it is
727 * registered, we expect this. Ignore it, and wait for the
733 xenbus_dev_fatal(dev, err, "reading physical-device");
737 if (be->major | be->minor) {
738 if (be->major != major || be->minor != minor)
739 pr_warn("changing physical device (from %x:%x to %x:%x) not supported.\n",
740 be->major, be->minor, major, minor);
744 be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
745 if (IS_ERR(be->mode)) {
746 err = PTR_ERR(be->mode);
748 xenbus_dev_fatal(dev, err, "reading mode");
752 device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
753 if (!IS_ERR(device_type)) {
754 cdrom = strcmp(device_type, "cdrom") == 0;
758 /* Front end dir is a number, which is used as the handle. */
759 err = kstrtoul(strrchr(dev->otherend, '/') + 1, 0, &handle);
769 err = xen_vbd_create(be->blkif, handle, major, minor,
770 !strchr(be->mode, 'w'), cdrom);
773 xenbus_dev_fatal(dev, err, "creating vbd structure");
775 err = xenvbd_sysfs_addif(dev);
777 xen_vbd_free(&be->blkif->vbd);
778 xenbus_dev_fatal(dev, err, "creating sysfs entries");
788 /* We're potentially connected now */
789 xen_update_blkif_status(be->blkif);
794 * Callback received when the frontend's state changes.
796 static void frontend_changed(struct xenbus_device *dev,
797 enum xenbus_state frontend_state)
799 struct backend_info *be = dev_get_drvdata(&dev->dev);
802 pr_debug("%s %p %s\n", __func__, dev, xenbus_strstate(frontend_state));
804 switch (frontend_state) {
805 case XenbusStateInitialising:
806 if (dev->state == XenbusStateClosed) {
807 pr_info("%s: prepare for reconnect\n", dev->nodename);
808 xenbus_switch_state(dev, XenbusStateInitWait);
812 case XenbusStateInitialised:
813 case XenbusStateConnected:
815 * Ensure we connect even when two watches fire in
816 * close succession and we miss the intermediate value
819 if (dev->state == XenbusStateConnected)
823 * Enforce precondition before potential leak point.
824 * xen_blkif_disconnect() is idempotent.
826 err = xen_blkif_disconnect(be->blkif);
828 xenbus_dev_fatal(dev, err, "pending I/O");
832 err = connect_ring(be);
835 * Clean up so that memory resources can be used by
836 * other devices. connect_ring reported already error.
838 xen_blkif_disconnect(be->blkif);
841 xen_update_blkif_status(be->blkif);
844 case XenbusStateClosing:
845 xenbus_switch_state(dev, XenbusStateClosing);
848 case XenbusStateClosed:
849 xen_blkif_disconnect(be->blkif);
850 xenbus_switch_state(dev, XenbusStateClosed);
851 if (xenbus_dev_is_online(dev))
855 case XenbusStateUnknown:
856 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */
857 device_unregister(&dev->dev);
861 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
867 /* Once a memory pressure is detected, squeeze free page pools for a while. */
868 static unsigned int buffer_squeeze_duration_ms = 10;
869 module_param_named(buffer_squeeze_duration_ms,
870 buffer_squeeze_duration_ms, int, 0644);
871 MODULE_PARM_DESC(buffer_squeeze_duration_ms,
872 "Duration in ms to squeeze pages buffer when a memory pressure is detected");
875 * Callback received when the memory pressure is detected.
877 static void reclaim_memory(struct xenbus_device *dev)
879 struct backend_info *be = dev_get_drvdata(&dev->dev);
883 be->blkif->buffer_squeeze_end = jiffies +
884 msecs_to_jiffies(buffer_squeeze_duration_ms);
887 /* ** Connection ** */
890 * Write the physical details regarding the block device to the store, and
891 * switch to Connected state.
893 static void connect(struct backend_info *be)
895 struct xenbus_transaction xbt;
897 struct xenbus_device *dev = be->dev;
899 pr_debug("%s %s\n", __func__, dev->otherend);
901 /* Supply the information about the device the frontend needs */
903 err = xenbus_transaction_start(&xbt);
905 xenbus_dev_fatal(dev, err, "starting transaction");
909 /* If we can't advertise it is OK. */
910 xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
912 xen_blkbk_discard(xbt, be);
914 xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support);
916 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u",
917 be->blkif->vbd.feature_gnt_persistent);
919 xenbus_dev_fatal(dev, err, "writing %s/feature-persistent",
924 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
925 (unsigned long long)vbd_sz(&be->blkif->vbd));
927 xenbus_dev_fatal(dev, err, "writing %s/sectors",
932 /* FIXME: use a typename instead */
933 err = xenbus_printf(xbt, dev->nodename, "info", "%u",
934 be->blkif->vbd.type |
935 (be->blkif->vbd.readonly ? VDISK_READONLY : 0));
937 xenbus_dev_fatal(dev, err, "writing %s/info",
941 err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
943 bdev_logical_block_size(be->blkif->vbd.bdev));
945 xenbus_dev_fatal(dev, err, "writing %s/sector-size",
949 err = xenbus_printf(xbt, dev->nodename, "physical-sector-size", "%u",
950 bdev_physical_block_size(be->blkif->vbd.bdev));
952 xenbus_dev_error(dev, err, "writing %s/physical-sector-size",
955 err = xenbus_transaction_end(xbt, 0);
959 xenbus_dev_fatal(dev, err, "ending transaction");
961 err = xenbus_switch_state(dev, XenbusStateConnected);
963 xenbus_dev_fatal(dev, err, "%s: switching to Connected state",
968 xenbus_transaction_end(xbt, 1);
972 * Each ring may have multi pages, depends on "ring-page-order".
974 static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
976 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
977 struct pending_req *req, *n;
979 struct xen_blkif *blkif = ring->blkif;
980 struct xenbus_device *dev = blkif->be->dev;
981 unsigned int nr_grefs, evtchn;
983 err = xenbus_scanf(XBT_NIL, dir, "event-channel", "%u",
987 xenbus_dev_fatal(dev, err, "reading %s/event-channel", dir);
991 nr_grefs = blkif->nr_ring_pages;
993 if (unlikely(!nr_grefs)) {
998 for (i = 0; i < nr_grefs; i++) {
999 char ring_ref_name[RINGREF_NAME_LEN];
1001 if (blkif->multi_ref)
1002 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1005 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref");
1008 err = xenbus_scanf(XBT_NIL, dir, ring_ref_name,
1009 "%u", &ring_ref[i]);
1013 xenbus_dev_fatal(dev, err, "reading %s/%s",
1014 dir, ring_ref_name);
1020 for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
1021 req = kzalloc(sizeof(*req), GFP_KERNEL);
1024 list_add_tail(&req->free_list, &ring->pending_free);
1025 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
1026 req->segments[j] = kzalloc(sizeof(*req->segments[0]), GFP_KERNEL);
1027 if (!req->segments[j])
1030 for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
1031 req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]),
1033 if (!req->indirect_pages[j])
1038 /* Map the shared frame, irq etc. */
1039 err = xen_blkif_map(ring, ring_ref, nr_grefs, evtchn);
1041 xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn);
1048 list_for_each_entry_safe(req, n, &ring->pending_free, free_list) {
1049 list_del(&req->free_list);
1050 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
1051 if (!req->segments[j])
1053 kfree(req->segments[j]);
1055 for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
1056 if (!req->indirect_pages[j])
1058 kfree(req->indirect_pages[j]);
1065 static int connect_ring(struct backend_info *be)
1067 struct xenbus_device *dev = be->dev;
1068 struct xen_blkif *blkif = be->blkif;
1069 char protocol[64] = "";
1073 const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */
1074 unsigned int requested_num_queues = 0;
1075 unsigned int ring_page_order;
1077 pr_debug("%s %s\n", __func__, dev->otherend);
1079 blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
1080 err = xenbus_scanf(XBT_NIL, dev->otherend, "protocol",
1083 strcpy(protocol, "unspecified, assuming default");
1084 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
1085 blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
1086 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
1087 blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
1088 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
1089 blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
1091 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
1094 if (blkif->vbd.feature_gnt_persistent)
1095 blkif->vbd.feature_gnt_persistent =
1096 xenbus_read_unsigned(dev->otherend,
1097 "feature-persistent", 0);
1099 blkif->vbd.overflow_max_grants = 0;
1102 * Read the number of hardware queues from frontend.
1104 requested_num_queues = xenbus_read_unsigned(dev->otherend,
1105 "multi-queue-num-queues",
1107 if (requested_num_queues > xenblk_max_queues
1108 || requested_num_queues == 0) {
1109 /* Buggy or malicious guest. */
1110 xenbus_dev_fatal(dev, err,
1111 "guest requested %u queues, exceeding the maximum of %u.",
1112 requested_num_queues, xenblk_max_queues);
1115 blkif->nr_rings = requested_num_queues;
1116 if (xen_blkif_alloc_rings(blkif))
1119 pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename,
1120 blkif->nr_rings, blkif->blk_protocol, protocol,
1121 blkif->vbd.feature_gnt_persistent ? "persistent grants" : "");
1123 err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u",
1126 blkif->nr_ring_pages = 1;
1127 blkif->multi_ref = false;
1128 } else if (ring_page_order <= xen_blkif_max_ring_order) {
1129 blkif->nr_ring_pages = 1 << ring_page_order;
1130 blkif->multi_ref = true;
1133 xenbus_dev_fatal(dev, err,
1134 "requested ring page order %d exceed max:%d",
1136 xen_blkif_max_ring_order);
1140 if (blkif->nr_rings == 1)
1141 return read_per_ring_refs(&blkif->rings[0], dev->otherend);
1143 xspathsize = strlen(dev->otherend) + xenstore_path_ext_size;
1144 xspath = kmalloc(xspathsize, GFP_KERNEL);
1146 xenbus_dev_fatal(dev, -ENOMEM, "reading ring references");
1150 for (i = 0; i < blkif->nr_rings; i++) {
1151 memset(xspath, 0, xspathsize);
1152 snprintf(xspath, xspathsize, "%s/queue-%u", dev->otherend, i);
1153 err = read_per_ring_refs(&blkif->rings[i], xspath);
1164 static const struct xenbus_device_id xen_blkbk_ids[] = {
1169 static struct xenbus_driver xen_blkbk_driver = {
1170 .ids = xen_blkbk_ids,
1171 .probe = xen_blkbk_probe,
1172 .remove = xen_blkbk_remove,
1173 .otherend_changed = frontend_changed,
1174 .allow_rebind = true,
1175 .reclaim_memory = reclaim_memory,
1178 int xen_blkif_xenbus_init(void)
1180 return xenbus_register_backend(&xen_blkbk_driver);
1183 void xen_blkif_xenbus_fini(void)
1185 xenbus_unregister_driver(&xen_blkbk_driver);