diff options
author | 2015-08-28 09:58:54 +0800 | |
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committer | 2015-09-01 12:44:00 +0800 | |
commit | e44e3482bdb4d0ebde2d8b41830ac2cdb07948fb (patch) | |
tree | 66b09f592c55df2878107a468a91d21506104d3f /qemu/hw/block/dataplane/virtio-blk.c | |
parent | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (diff) |
Add qemu 2.4.0
Change-Id: Ic99cbad4b61f8b127b7dc74d04576c0bcbaaf4f5
Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>
Diffstat (limited to 'qemu/hw/block/dataplane/virtio-blk.c')
-rw-r--r-- | qemu/hw/block/dataplane/virtio-blk.c | 341 |
1 files changed, 341 insertions, 0 deletions
diff --git a/qemu/hw/block/dataplane/virtio-blk.c b/qemu/hw/block/dataplane/virtio-blk.c new file mode 100644 index 000000000..6106e4615 --- /dev/null +++ b/qemu/hw/block/dataplane/virtio-blk.c @@ -0,0 +1,341 @@ +/* + * Dedicated thread for virtio-blk I/O processing + * + * Copyright 2012 IBM, Corp. + * Copyright 2012 Red Hat, Inc. and/or its affiliates + * + * Authors: + * Stefan Hajnoczi <stefanha@redhat.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + * + */ + +#include "trace.h" +#include "qemu/iov.h" +#include "qemu/thread.h" +#include "qemu/error-report.h" +#include "hw/virtio/virtio-access.h" +#include "hw/virtio/dataplane/vring.h" +#include "hw/virtio/dataplane/vring-accessors.h" +#include "sysemu/block-backend.h" +#include "hw/virtio/virtio-blk.h" +#include "virtio-blk.h" +#include "block/aio.h" +#include "hw/virtio/virtio-bus.h" +#include "qom/object_interfaces.h" + +struct VirtIOBlockDataPlane { + bool started; + bool starting; + bool stopping; + bool disabled; + + VirtIOBlkConf *conf; + + VirtIODevice *vdev; + Vring vring; /* virtqueue vring */ + EventNotifier *guest_notifier; /* irq */ + QEMUBH *bh; /* bh for guest notification */ + + /* Note that these EventNotifiers are assigned by value. This is + * fine as long as you do not call event_notifier_cleanup on them + * (because you don't own the file descriptor or handle; you just + * use it). + */ + IOThread *iothread; + IOThread internal_iothread_obj; + AioContext *ctx; + EventNotifier host_notifier; /* doorbell */ + + /* Operation blocker on BDS */ + Error *blocker; + void (*saved_complete_request)(struct VirtIOBlockReq *req, + unsigned char status); +}; + +/* Raise an interrupt to signal guest, if necessary */ +static void notify_guest(VirtIOBlockDataPlane *s) +{ + if (!vring_should_notify(s->vdev, &s->vring)) { + return; + } + + event_notifier_set(s->guest_notifier); +} + +static void notify_guest_bh(void *opaque) +{ + VirtIOBlockDataPlane *s = opaque; + + notify_guest(s); +} + +static void complete_request_vring(VirtIOBlockReq *req, unsigned char status) +{ + VirtIOBlockDataPlane *s = req->dev->dataplane; + stb_p(&req->in->status, status); + + vring_push(s->vdev, &req->dev->dataplane->vring, &req->elem, req->in_len); + + /* Suppress notification to guest by BH and its scheduled + * flag because requests are completed as a batch after io + * plug & unplug is introduced, and the BH can still be + * executed in dataplane aio context even after it is + * stopped, so needn't worry about notification loss with BH. + */ + qemu_bh_schedule(s->bh); +} + +static void handle_notify(EventNotifier *e) +{ + VirtIOBlockDataPlane *s = container_of(e, VirtIOBlockDataPlane, + host_notifier); + VirtIOBlock *vblk = VIRTIO_BLK(s->vdev); + + event_notifier_test_and_clear(&s->host_notifier); + blk_io_plug(s->conf->conf.blk); + for (;;) { + MultiReqBuffer mrb = {}; + int ret; + + /* Disable guest->host notifies to avoid unnecessary vmexits */ + vring_disable_notification(s->vdev, &s->vring); + + for (;;) { + VirtIOBlockReq *req = virtio_blk_alloc_request(vblk); + + ret = vring_pop(s->vdev, &s->vring, &req->elem); + if (ret < 0) { + virtio_blk_free_request(req); + break; /* no more requests */ + } + + trace_virtio_blk_data_plane_process_request(s, req->elem.out_num, + req->elem.in_num, + req->elem.index); + + virtio_blk_handle_request(req, &mrb); + } + + if (mrb.num_reqs) { + virtio_blk_submit_multireq(s->conf->conf.blk, &mrb); + } + + if (likely(ret == -EAGAIN)) { /* vring emptied */ + /* Re-enable guest->host notifies and stop processing the vring. + * But if the guest has snuck in more descriptors, keep processing. + */ + if (vring_enable_notification(s->vdev, &s->vring)) { + break; + } + } else { /* fatal error */ + break; + } + } + blk_io_unplug(s->conf->conf.blk); +} + +/* Context: QEMU global mutex held */ +void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf, + VirtIOBlockDataPlane **dataplane, + Error **errp) +{ + VirtIOBlockDataPlane *s; + Error *local_err = NULL; + BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev))); + VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus); + + *dataplane = NULL; + + if (!conf->data_plane && !conf->iothread) { + return; + } + + /* Don't try if transport does not support notifiers. */ + if (!k->set_guest_notifiers || !k->set_host_notifier) { + error_setg(errp, + "device is incompatible with x-data-plane " + "(transport does not support notifiers)"); + return; + } + + /* If dataplane is (re-)enabled while the guest is running there could be + * block jobs that can conflict. + */ + if (blk_op_is_blocked(conf->conf.blk, BLOCK_OP_TYPE_DATAPLANE, + &local_err)) { + error_setg(errp, "cannot start dataplane thread: %s", + error_get_pretty(local_err)); + error_free(local_err); + return; + } + + s = g_new0(VirtIOBlockDataPlane, 1); + s->vdev = vdev; + s->conf = conf; + + if (conf->iothread) { + s->iothread = conf->iothread; + object_ref(OBJECT(s->iothread)); + } else { + /* Create per-device IOThread if none specified. This is for + * x-data-plane option compatibility. If x-data-plane is removed we + * can drop this. + */ + object_initialize(&s->internal_iothread_obj, + sizeof(s->internal_iothread_obj), + TYPE_IOTHREAD); + user_creatable_complete(OBJECT(&s->internal_iothread_obj), &error_abort); + s->iothread = &s->internal_iothread_obj; + } + s->ctx = iothread_get_aio_context(s->iothread); + s->bh = aio_bh_new(s->ctx, notify_guest_bh, s); + + error_setg(&s->blocker, "block device is in use by data plane"); + blk_op_block_all(conf->conf.blk, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_RESIZE, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_DRIVE_DEL, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_BACKUP_SOURCE, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_CHANGE, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_COMMIT_SOURCE, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_COMMIT_TARGET, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_EJECT, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_EXTERNAL_SNAPSHOT, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE, + s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_MIRROR, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_STREAM, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_REPLACE, s->blocker); + + *dataplane = s; +} + +/* Context: QEMU global mutex held */ +void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s) +{ + if (!s) { + return; + } + + virtio_blk_data_plane_stop(s); + blk_op_unblock_all(s->conf->conf.blk, s->blocker); + error_free(s->blocker); + qemu_bh_delete(s->bh); + object_unref(OBJECT(s->iothread)); + g_free(s); +} + +/* Context: QEMU global mutex held */ +void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) +{ + BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev))); + VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus); + VirtIOBlock *vblk = VIRTIO_BLK(s->vdev); + VirtQueue *vq; + int r; + + if (s->started || s->disabled) { + return; + } + + if (s->starting) { + return; + } + + s->starting = true; + + vq = virtio_get_queue(s->vdev, 0); + if (!vring_setup(&s->vring, s->vdev, 0)) { + goto fail_vring; + } + + /* Set up guest notifier (irq) */ + r = k->set_guest_notifiers(qbus->parent, 1, true); + if (r != 0) { + fprintf(stderr, "virtio-blk failed to set guest notifier (%d), " + "ensure -enable-kvm is set\n", r); + goto fail_guest_notifiers; + } + s->guest_notifier = virtio_queue_get_guest_notifier(vq); + + /* Set up virtqueue notify */ + r = k->set_host_notifier(qbus->parent, 0, true); + if (r != 0) { + fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r); + goto fail_host_notifier; + } + s->host_notifier = *virtio_queue_get_host_notifier(vq); + + s->saved_complete_request = vblk->complete_request; + vblk->complete_request = complete_request_vring; + + s->starting = false; + s->started = true; + trace_virtio_blk_data_plane_start(s); + + blk_set_aio_context(s->conf->conf.blk, s->ctx); + + /* Kick right away to begin processing requests already in vring */ + event_notifier_set(virtio_queue_get_host_notifier(vq)); + + /* Get this show started by hooking up our callbacks */ + aio_context_acquire(s->ctx); + aio_set_event_notifier(s->ctx, &s->host_notifier, handle_notify); + aio_context_release(s->ctx); + return; + + fail_host_notifier: + k->set_guest_notifiers(qbus->parent, 1, false); + fail_guest_notifiers: + vring_teardown(&s->vring, s->vdev, 0); + s->disabled = true; + fail_vring: + s->starting = false; +} + +/* Context: QEMU global mutex held */ +void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s) +{ + BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev))); + VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus); + VirtIOBlock *vblk = VIRTIO_BLK(s->vdev); + + + /* Better luck next time. */ + if (s->disabled) { + s->disabled = false; + return; + } + if (!s->started || s->stopping) { + return; + } + s->stopping = true; + vblk->complete_request = s->saved_complete_request; + trace_virtio_blk_data_plane_stop(s); + + aio_context_acquire(s->ctx); + + /* Stop notifications for new requests from guest */ + aio_set_event_notifier(s->ctx, &s->host_notifier, NULL); + + /* Drain and switch bs back to the QEMU main loop */ + blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context()); + + aio_context_release(s->ctx); + + /* Sync vring state back to virtqueue so that non-dataplane request + * processing can continue when we disable the host notifier below. + */ + vring_teardown(&s->vring, s->vdev, 0); + + k->set_host_notifier(qbus->parent, 0, false); + + /* Clean up guest notifier (irq) */ + k->set_guest_notifiers(qbus->parent, 1, false); + + s->started = false; + s->stopping = false; +} |