3 files changed, 372 insertions, 0 deletions

diff --git a/qemu/hw/block/dataplane/Makefile.objs b/qemu/hw/block/dataplane/Makefile.objs
new file mode 100644
index 000000000..e786f6642
--- /dev/null
+++ b/qemu/hw/block/dataplane/Makefile.objs
@@ -0,0 +1 @@
+obj-y += virtio-blk.o
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;
+}
diff --git a/qemu/hw/block/dataplane/virtio-blk.h b/qemu/hw/block/dataplane/virtio-blk.h
new file mode 100644
index 000000000..c88d40e72
--- /dev/null
+++ b/qemu/hw/block/dataplane/virtio-blk.h
@@ -0,0 +1,30 @@
+/*
+ * 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.
+ *
+ */
+
+#ifndef HW_DATAPLANE_VIRTIO_BLK_H
+#define HW_DATAPLANE_VIRTIO_BLK_H
+
+#include "hw/virtio/virtio.h"
+
+typedef struct VirtIOBlockDataPlane VirtIOBlockDataPlane;
+
+void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
+                                  VirtIOBlockDataPlane **dataplane,
+                                  Error **errp);
+void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s);
+void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s);
+void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s);
+void virtio_blk_data_plane_drain(VirtIOBlockDataPlane *s);
+
+#endif /* HW_DATAPLANE_VIRTIO_BLK_H */