aboutsummaryrefslogtreecommitdiffstats
path: root/hw/scsi/virtio-scsi-dataplane.c
diff options
context:
space:
mode:
Diffstat (limited to 'hw/scsi/virtio-scsi-dataplane.c')
-rw-r--r--hw/scsi/virtio-scsi-dataplane.c273
1 files changed, 273 insertions, 0 deletions
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
new file mode 100644
index 000000000..18eb824c9
--- /dev/null
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -0,0 +1,273 @@
+/*
+ * Virtio SCSI dataplane
+ *
+ * Copyright Red Hat, Inc. 2014
+ *
+ * Authors:
+ * Fam Zheng <famz@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 "qemu/osdep.h"
+#include "qapi/error.h"
+#include "hw/virtio/virtio-scsi.h"
+#include "qemu/error-report.h"
+#include "sysemu/block-backend.h"
+#include "hw/scsi/scsi.h"
+#include "scsi/constants.h"
+#include "hw/virtio/virtio-bus.h"
+#include "hw/virtio/virtio-access.h"
+
+/* Context: QEMU global mutex held */
+void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
+{
+ VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+ VirtIODevice *vdev = VIRTIO_DEVICE(s);
+ BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
+ VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+
+ if (vs->conf.iothread) {
+ if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
+ error_setg(errp,
+ "device is incompatible with iothread "
+ "(transport does not support notifiers)");
+ return;
+ }
+ if (!virtio_device_ioeventfd_enabled(vdev)) {
+ error_setg(errp, "ioeventfd is required for iothread");
+ return;
+ }
+ s->ctx = iothread_get_aio_context(vs->conf.iothread);
+ } else {
+ if (!virtio_device_ioeventfd_enabled(vdev)) {
+ return;
+ }
+ s->ctx = qemu_get_aio_context();
+ }
+}
+
+static bool virtio_scsi_data_plane_handle_cmd(VirtIODevice *vdev,
+ VirtQueue *vq)
+{
+ bool progress = false;
+ VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+
+ virtio_scsi_acquire(s);
+ if (!s->dataplane_fenced) {
+ assert(s->ctx && s->dataplane_started);
+ progress = virtio_scsi_handle_cmd_vq(s, vq);
+ }
+ virtio_scsi_release(s);
+ return progress;
+}
+
+static bool virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev,
+ VirtQueue *vq)
+{
+ bool progress = false;
+ VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+
+ virtio_scsi_acquire(s);
+ if (!s->dataplane_fenced) {
+ assert(s->ctx && s->dataplane_started);
+ progress = virtio_scsi_handle_ctrl_vq(s, vq);
+ }
+ virtio_scsi_release(s);
+ return progress;
+}
+
+static bool virtio_scsi_data_plane_handle_event(VirtIODevice *vdev,
+ VirtQueue *vq)
+{
+ bool progress = false;
+ VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+
+ virtio_scsi_acquire(s);
+ if (!s->dataplane_fenced) {
+ assert(s->ctx && s->dataplane_started);
+ progress = virtio_scsi_handle_event_vq(s, vq);
+ }
+ virtio_scsi_release(s);
+ return progress;
+}
+
+static int virtio_scsi_set_host_notifier(VirtIOSCSI *s, VirtQueue *vq, int n)
+{
+ BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
+ int rc;
+
+ /* Set up virtqueue notify */
+ rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), n, true);
+ if (rc != 0) {
+ fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
+ rc);
+ s->dataplane_fenced = true;
+ return rc;
+ }
+
+ return 0;
+}
+
+/* Context: BH in IOThread */
+static void virtio_scsi_dataplane_stop_bh(void *opaque)
+{
+ VirtIOSCSI *s = opaque;
+ VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+ int i;
+
+ virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx, NULL);
+ virtio_queue_aio_set_host_notifier_handler(vs->event_vq, s->ctx, NULL);
+ for (i = 0; i < vs->conf.num_queues; i++) {
+ virtio_queue_aio_set_host_notifier_handler(vs->cmd_vqs[i], s->ctx, NULL);
+ }
+}
+
+/* Context: QEMU global mutex held */
+int virtio_scsi_dataplane_start(VirtIODevice *vdev)
+{
+ int i;
+ int rc;
+ int vq_init_count = 0;
+ BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
+ VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+ VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
+ VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+
+ if (s->dataplane_started ||
+ s->dataplane_starting ||
+ s->dataplane_fenced) {
+ return 0;
+ }
+
+ s->dataplane_starting = true;
+
+ /* Set up guest notifier (irq) */
+ rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
+ if (rc != 0) {
+ error_report("virtio-scsi: Failed to set guest notifiers (%d), "
+ "ensure -accel kvm is set.", rc);
+ goto fail_guest_notifiers;
+ }
+
+ /*
+ * Batch all the host notifiers in a single transaction to avoid
+ * quadratic time complexity in address_space_update_ioeventfds().
+ */
+ memory_region_transaction_begin();
+
+ rc = virtio_scsi_set_host_notifier(s, vs->ctrl_vq, 0);
+ if (rc != 0) {
+ goto fail_host_notifiers;
+ }
+
+ vq_init_count++;
+ rc = virtio_scsi_set_host_notifier(s, vs->event_vq, 1);
+ if (rc != 0) {
+ goto fail_host_notifiers;
+ }
+
+ vq_init_count++;
+
+ for (i = 0; i < vs->conf.num_queues; i++) {
+ rc = virtio_scsi_set_host_notifier(s, vs->cmd_vqs[i], i + 2);
+ if (rc) {
+ goto fail_host_notifiers;
+ }
+ vq_init_count++;
+ }
+
+ memory_region_transaction_commit();
+
+ aio_context_acquire(s->ctx);
+ virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx,
+ virtio_scsi_data_plane_handle_ctrl);
+ virtio_queue_aio_set_host_notifier_handler(vs->event_vq, s->ctx,
+ virtio_scsi_data_plane_handle_event);
+
+ for (i = 0; i < vs->conf.num_queues; i++) {
+ virtio_queue_aio_set_host_notifier_handler(vs->cmd_vqs[i], s->ctx,
+ virtio_scsi_data_plane_handle_cmd);
+ }
+
+ s->dataplane_starting = false;
+ s->dataplane_started = true;
+ aio_context_release(s->ctx);
+ return 0;
+
+fail_host_notifiers:
+ for (i = 0; i < vq_init_count; i++) {
+ virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
+ }
+
+ /*
+ * The transaction expects the ioeventfds to be open when it
+ * commits. Do it now, before the cleanup loop.
+ */
+ memory_region_transaction_commit();
+
+ for (i = 0; i < vq_init_count; i++) {
+ virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
+ }
+ k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
+fail_guest_notifiers:
+ s->dataplane_fenced = true;
+ s->dataplane_starting = false;
+ s->dataplane_started = true;
+ return -ENOSYS;
+}
+
+/* Context: QEMU global mutex held */
+void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
+{
+ BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
+ VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+ VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
+ VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+ int i;
+
+ if (!s->dataplane_started || s->dataplane_stopping) {
+ return;
+ }
+
+ /* Better luck next time. */
+ if (s->dataplane_fenced) {
+ s->dataplane_fenced = false;
+ s->dataplane_started = false;
+ return;
+ }
+ s->dataplane_stopping = true;
+
+ aio_context_acquire(s->ctx);
+ aio_wait_bh_oneshot(s->ctx, virtio_scsi_dataplane_stop_bh, s);
+ aio_context_release(s->ctx);
+
+ blk_drain_all(); /* ensure there are no in-flight requests */
+
+ /*
+ * Batch all the host notifiers in a single transaction to avoid
+ * quadratic time complexity in address_space_update_ioeventfds().
+ */
+ memory_region_transaction_begin();
+
+ for (i = 0; i < vs->conf.num_queues + 2; i++) {
+ virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
+ }
+
+ /*
+ * The transaction expects the ioeventfds to be open when it
+ * commits. Do it now, before the cleanup loop.
+ */
+ memory_region_transaction_commit();
+
+ for (i = 0; i < vs->conf.num_queues + 2; i++) {
+ virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
+ }
+
+ /* Clean up guest notifier (irq) */
+ k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
+ s->dataplane_stopping = false;
+ s->dataplane_started = false;
+}