qemu-patch-raspberry4/hw/scsi/virtio-scsi-dataplane.c
Paolo Bonzini 83d768b564 virtio: set ISR on dataplane notifications
Dataplane has been omitting forever the step of setting ISR when
an interrupt is raised.  This caused little breakage, because the
specification actually says that ISR may not be updated in MSI mode.

Some versions of the Windows drivers however didn't clear MSI mode
correctly, and proceeded using polling mode (using ISR, not the used
ring index!) for crashdump and hibernation.  If it were just crashdump
and hibernation it would not be a big deal, but recent releases of
Windows do not really shut down, but rather log out and hibernate to
make the next startup faster.  Hence, this manifested as a more serious
hang during shutdown with e.g. Windows 8.1 and virtio-win 1.8.0 RPMs.
Newer versions fixed this, while older versions do not use MSI at all.

The failure has always been there for virtio dataplane, but it became
visible after commits 9ffe337 ("virtio-blk: always use dataplane path
if ioeventfd is active", 2016-10-30) and ad07cd6 ("virtio-scsi: always
use dataplane path if ioeventfd is active", 2016-10-30) made virtio-blk
and virtio-scsi always use the dataplane code under KVM.  The good news
therefore is that it was not a bug in the patches---they were doing
exactly what they were meant for, i.e. shake out remaining dataplane bugs.

The fix is not hard, so it's worth arranging for the broken drivers.
The virtio_should_notify+event_notifier_set pair that is common to
virtio-blk and virtio-scsi dataplane is replaced with a new public
function virtio_notify_irqfd that also sets ISR.  The irqfd emulation
code now need not set ISR anymore, so virtio_irq is removed.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Farhan Ali <alifm@linux.vnet.ibm.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2016-11-18 17:29:25 +02:00

211 lines
6.1 KiB
C

/*
* 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 "block/scsi.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 void virtio_scsi_data_plane_handle_cmd(VirtIODevice *vdev,
VirtQueue *vq)
{
VirtIOSCSI *s = (VirtIOSCSI *)vdev;
assert(s->ctx && s->dataplane_started);
virtio_scsi_handle_cmd_vq(s, vq);
}
static void virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev,
VirtQueue *vq)
{
VirtIOSCSI *s = VIRTIO_SCSI(vdev);
assert(s->ctx && s->dataplane_started);
virtio_scsi_handle_ctrl_vq(s, vq);
}
static void virtio_scsi_data_plane_handle_event(VirtIODevice *vdev,
VirtQueue *vq)
{
VirtIOSCSI *s = VIRTIO_SCSI(vdev);
assert(s->ctx && s->dataplane_started);
virtio_scsi_handle_event_vq(s, vq);
}
static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
void (*fn)(VirtIODevice *vdev, VirtQueue *vq))
{
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;
}
virtio_queue_aio_set_host_notifier_handler(vq, s->ctx, fn);
return 0;
}
/* assumes s->ctx held */
static void virtio_scsi_clear_aio(VirtIOSCSI *s)
{
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;
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) {
fprintf(stderr, "virtio-scsi: Failed to set guest notifiers (%d), "
"ensure -enable-kvm is set\n", rc);
goto fail_guest_notifiers;
}
aio_context_acquire(s->ctx);
rc = virtio_scsi_vring_init(s, vs->ctrl_vq, 0,
virtio_scsi_data_plane_handle_ctrl);
if (rc) {
goto fail_vrings;
}
rc = virtio_scsi_vring_init(s, vs->event_vq, 1,
virtio_scsi_data_plane_handle_event);
if (rc) {
goto fail_vrings;
}
for (i = 0; i < vs->conf.num_queues; i++) {
rc = virtio_scsi_vring_init(s, vs->cmd_vqs[i], i + 2,
virtio_scsi_data_plane_handle_cmd);
if (rc) {
goto fail_vrings;
}
}
s->dataplane_starting = false;
s->dataplane_started = true;
aio_context_release(s->ctx);
return 0;
fail_vrings:
virtio_scsi_clear_aio(s);
aio_context_release(s->ctx);
for (i = 0; i < vs->conf.num_queues + 2; i++) {
virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
}
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);
virtio_scsi_clear_aio(s);
aio_context_release(s->ctx);
blk_drain_all(); /* ensure there are no in-flight requests */
for (i = 0; i < vs->conf.num_queues + 2; i++) {
virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
}
/* 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;
}