2 * Dedicated thread for virtio-blk I/O processing
4 * Copyright 2012 IBM, Corp.
5 * Copyright 2012 Red Hat, Inc. and/or its affiliates
8 * Stefan Hajnoczi <stefanha@redhat.com>
10 * This work is licensed under the terms of the GNU GPL, version 2 or later.
11 * See the COPYING file in the top-level directory.
15 #include "qemu/osdep.h"
16 #include "qapi/error.h"
19 #include "qemu/thread.h"
20 #include "qemu/error-report.h"
21 #include "hw/virtio/virtio-access.h"
22 #include "sysemu/block-backend.h"
23 #include "hw/virtio/virtio-blk.h"
24 #include "virtio-blk.h"
25 #include "block/aio.h"
26 #include "hw/virtio/virtio-bus.h"
27 #include "qom/object_interfaces.h"
29 struct VirtIOBlockDataPlane {
36 VirtQueue *vq; /* virtqueue vring */
37 EventNotifier *guest_notifier; /* irq */
38 QEMUBH *bh; /* bh for guest notification */
40 Notifier insert_notifier, remove_notifier;
42 /* Note that these EventNotifiers are assigned by value. This is
43 * fine as long as you do not call event_notifier_cleanup on them
44 * (because you don't own the file descriptor or handle; you just
50 /* Operation blocker on BDS */
54 /* Raise an interrupt to signal guest, if necessary */
55 void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s)
57 qemu_bh_schedule(s->bh);
60 static void notify_guest_bh(void *opaque)
62 VirtIOBlockDataPlane *s = opaque;
64 if (!virtio_should_notify(s->vdev, s->vq)) {
68 event_notifier_set(s->guest_notifier);
71 static void data_plane_set_up_op_blockers(VirtIOBlockDataPlane *s)
74 error_setg(&s->blocker, "block device is in use by data plane");
75 blk_op_block_all(s->conf->conf.blk, s->blocker);
76 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_RESIZE, s->blocker);
77 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_DRIVE_DEL, s->blocker);
78 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_BACKUP_SOURCE, s->blocker);
79 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_CHANGE, s->blocker);
80 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_COMMIT_SOURCE, s->blocker);
81 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_COMMIT_TARGET, s->blocker);
82 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_EJECT, s->blocker);
83 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_EXTERNAL_SNAPSHOT,
85 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT,
87 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE,
89 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_MIRROR_SOURCE, s->blocker);
90 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_STREAM, s->blocker);
91 blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_REPLACE, s->blocker);
94 static void data_plane_remove_op_blockers(VirtIOBlockDataPlane *s)
97 blk_op_unblock_all(s->conf->conf.blk, s->blocker);
98 error_free(s->blocker);
103 static void data_plane_blk_insert_notifier(Notifier *n, void *data)
105 VirtIOBlockDataPlane *s = container_of(n, VirtIOBlockDataPlane,
107 assert(s->conf->conf.blk == data);
108 data_plane_set_up_op_blockers(s);
111 static void data_plane_blk_remove_notifier(Notifier *n, void *data)
113 VirtIOBlockDataPlane *s = container_of(n, VirtIOBlockDataPlane,
115 assert(s->conf->conf.blk == data);
116 data_plane_remove_op_blockers(s);
119 /* Context: QEMU global mutex held */
120 void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
121 VirtIOBlockDataPlane **dataplane,
124 VirtIOBlockDataPlane *s;
125 BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
126 VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
130 if (!conf->iothread) {
134 /* Don't try if transport does not support notifiers. */
135 if (!k->set_guest_notifiers || !k->set_host_notifier) {
137 "device is incompatible with dataplane "
138 "(transport does not support notifiers)");
142 /* If dataplane is (re-)enabled while the guest is running there could be
143 * block jobs that can conflict.
145 if (blk_op_is_blocked(conf->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
146 error_prepend(errp, "cannot start dataplane thread: ");
150 s = g_new0(VirtIOBlockDataPlane, 1);
154 if (conf->iothread) {
155 s->iothread = conf->iothread;
156 object_ref(OBJECT(s->iothread));
158 s->ctx = iothread_get_aio_context(s->iothread);
159 s->bh = aio_bh_new(s->ctx, notify_guest_bh, s);
161 s->insert_notifier.notify = data_plane_blk_insert_notifier;
162 s->remove_notifier.notify = data_plane_blk_remove_notifier;
163 blk_add_insert_bs_notifier(conf->conf.blk, &s->insert_notifier);
164 blk_add_remove_bs_notifier(conf->conf.blk, &s->remove_notifier);
166 data_plane_set_up_op_blockers(s);
171 /* Context: QEMU global mutex held */
172 void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
178 virtio_blk_data_plane_stop(s);
179 data_plane_remove_op_blockers(s);
180 notifier_remove(&s->insert_notifier);
181 notifier_remove(&s->remove_notifier);
182 qemu_bh_delete(s->bh);
183 object_unref(OBJECT(s->iothread));
187 static void virtio_blk_data_plane_handle_output(VirtIODevice *vdev,
190 VirtIOBlock *s = (VirtIOBlock *)vdev;
192 assert(s->dataplane);
193 assert(s->dataplane_started);
195 virtio_blk_handle_vq(s, vq);
198 /* Context: QEMU global mutex held */
199 void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
201 BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
202 VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
203 VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
206 if (vblk->dataplane_started || s->starting) {
211 s->vq = virtio_get_queue(s->vdev, 0);
213 /* Set up guest notifier (irq) */
214 r = k->set_guest_notifiers(qbus->parent, 1, true);
216 fprintf(stderr, "virtio-blk failed to set guest notifier (%d), "
217 "ensure -enable-kvm is set\n", r);
218 goto fail_guest_notifiers;
220 s->guest_notifier = virtio_queue_get_guest_notifier(s->vq);
222 /* Set up virtqueue notify */
223 r = k->set_host_notifier(qbus->parent, 0, true);
225 fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
226 goto fail_host_notifier;
230 vblk->dataplane_started = true;
231 trace_virtio_blk_data_plane_start(s);
233 blk_set_aio_context(s->conf->conf.blk, s->ctx);
235 /* Kick right away to begin processing requests already in vring */
236 event_notifier_set(virtio_queue_get_host_notifier(s->vq));
238 /* Get this show started by hooking up our callbacks */
239 aio_context_acquire(s->ctx);
240 virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx,
241 virtio_blk_data_plane_handle_output);
242 aio_context_release(s->ctx);
246 k->set_guest_notifiers(qbus->parent, 1, false);
247 fail_guest_notifiers:
248 vblk->dataplane_disabled = true;
250 vblk->dataplane_started = true;
253 /* Context: QEMU global mutex held */
254 void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
256 BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
257 VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
258 VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
260 if (!vblk->dataplane_started || s->stopping) {
264 /* Better luck next time. */
265 if (vblk->dataplane_disabled) {
266 vblk->dataplane_disabled = false;
267 vblk->dataplane_started = false;
271 trace_virtio_blk_data_plane_stop(s);
273 aio_context_acquire(s->ctx);
275 /* Stop notifications for new requests from guest */
276 virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, NULL);
278 /* Drain and switch bs back to the QEMU main loop */
279 blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());
281 aio_context_release(s->ctx);
283 k->set_host_notifier(qbus->parent, 0, false);
285 /* Clean up guest notifier (irq) */
286 k->set_guest_notifiers(qbus->parent, 1, false);
288 vblk->dataplane_started = false;