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/*
* 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"
/* 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 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);
EventNotifier *host_notifier;
int i;
virtio_queue_aio_detach_host_notifier(vs->ctrl_vq, s->ctx);
host_notifier = virtio_queue_get_host_notifier(vs->ctrl_vq);
/*
* Test and clear notifier after disabling event, in case poll callback
* didn't have time to run.
*/
virtio_queue_host_notifier_read(host_notifier);
virtio_queue_aio_detach_host_notifier(vs->event_vq, s->ctx);
host_notifier = virtio_queue_get_host_notifier(vs->event_vq);
virtio_queue_host_notifier_read(host_notifier);
for (i = 0; i < vs->conf.num_queues; i++) {
virtio_queue_aio_detach_host_notifier(vs->cmd_vqs[i], s->ctx);
host_notifier = virtio_queue_get_host_notifier(vs->cmd_vqs[i]);
virtio_queue_host_notifier_read(host_notifier);
}
}
/* 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();
/*
* These fields are visible to the IOThread so we rely on implicit barriers
* in aio_context_acquire() on the write side and aio_notify_accept() on
* the read side.
*/
s->dataplane_starting = false;
s->dataplane_started = true;
if (s->bus.drain_count == 0) {
aio_context_acquire(s->ctx);
virtio_queue_aio_attach_host_notifier(vs->ctrl_vq, s->ctx);
virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq, s->ctx);
for (i = 0; i < vs->conf.num_queues; i++) {
virtio_queue_aio_attach_host_notifier(vs->cmd_vqs[i], s->ctx);
}
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;
if (s->bus.drain_count == 0) {
aio_wait_bh_oneshot(s->ctx, virtio_scsi_dataplane_stop_bh, s);
}
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;
}
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