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vhost: add a helper for force stopping a device

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This adds an ability to skip GET_VRING_BASE during device stop entirely,
and thus the expensive drain operation that this call entails as well,
which may be useful during a non-graceful shutdown in case the guest
operating system hangs or refuses to react to a previously requested
ACPI shutdown for whatever reason.

Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
Message-Id: <20250609212547.2859224-3-d-tatianin@yandex-team.ru>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Daniil Tatianin
2025-07-14 09:16:40 -04:00
committed by Michael S. Tsirkin
parent 260f826cf8
commit 2f527fff46
2 changed files with 54 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files
hw/virtio/vhost.c
+39 -13
View File
@@ -1354,25 +1354,30 @@ fail_alloc_desc:
return r;
}
int vhost_virtqueue_stop(struct vhost_dev *dev,
struct VirtIODevice *vdev,
struct vhost_virtqueue *vq,
unsigned idx)
static int do_vhost_virtqueue_stop(struct vhost_dev *dev,
struct VirtIODevice *vdev,
struct vhost_virtqueue *vq,
unsigned idx, bool force)
{
int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, idx);
struct vhost_vring_state state = {
.index = vhost_vq_index,
};
int r;
int r = 0;
if (virtio_queue_get_desc_addr(vdev, idx) == 0) {
/* Don't stop the virtqueue which might have not been started */
return 0;
}
r = dev->vhost_ops->vhost_get_vring_base(dev, &state);
if (r < 0) {
VHOST_OPS_DEBUG(r, "vhost VQ %u ring restore failed: %d", idx, r);
if (!force) {
r = dev->vhost_ops->vhost_get_vring_base(dev, &state);
if (r < 0) {
VHOST_OPS_DEBUG(r, "vhost VQ %u ring restore failed: %d", idx, r);
}
}
if (r < 0 || force) {
/* Connection to the backend is broken, so let's sync internal
* last avail idx to the device used idx.
*/
@@ -1401,6 +1406,14 @@ int vhost_virtqueue_stop(struct vhost_dev *dev,
return r;
}
int vhost_virtqueue_stop(struct vhost_dev *dev,
struct VirtIODevice *vdev,
struct vhost_virtqueue *vq,
unsigned idx)
{
return do_vhost_virtqueue_stop(dev, vdev, vq, idx, false);
}
static int vhost_virtqueue_set_busyloop_timeout(struct vhost_dev *dev,
int n, uint32_t timeout)
{
@@ -2119,7 +2132,8 @@ fail_features:
}
/* Host notifiers must be enabled at this point. */
int vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
static int do_vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev,
bool vrings, bool force)
{
int i;
int rc = 0;
@@ -2141,10 +2155,11 @@ int vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
vhost_dev_set_vring_enable(hdev, false);
}
for (i = 0; i < hdev->nvqs; ++i) {
rc |= vhost_virtqueue_stop(hdev,
vdev,
hdev->vqs + i,
hdev->vq_index + i);
rc |= do_vhost_virtqueue_stop(hdev,
vdev,
hdev->vqs + i,
hdev->vq_index + i,
force);
}
if (hdev->vhost_ops->vhost_reset_status) {
hdev->vhost_ops->vhost_reset_status(hdev);
@@ -2164,6 +2179,17 @@ int vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
return rc;
}
int vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
{
return do_vhost_dev_stop(hdev, vdev, vrings, false);
}
int vhost_dev_force_stop(struct vhost_dev *hdev, VirtIODevice *vdev,
bool vrings)
{
return do_vhost_dev_stop(hdev, vdev, vrings, true);
}
int vhost_net_set_backend(struct vhost_dev *hdev,
struct vhost_vring_file *file)
{
include/hw/virtio/vhost.h
+15
View File
@@ -237,6 +237,21 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings);
*/
int vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings);
/**
* vhost_dev_force_stop() - force stop the vhost device
* @hdev: common vhost_dev structure
* @vdev: the VirtIODevice structure
* @vrings: true to have vrings disabled in this call
*
* Force stop the vhost device. After the device is stopped the notifiers
* can be disabled (@vhost_dev_disable_notifiers) and the device can
* be torn down (@vhost_dev_cleanup). Unlike @vhost_dev_stop, this doesn't
* attempt to flush in-flight backend requests by skipping GET_VRING_BASE
* entirely.
*/
int vhost_dev_force_stop(struct vhost_dev *hdev, VirtIODevice *vdev,
bool vrings);
/**
* DOC: vhost device configuration handling
*