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vhost: return failure if stop virtqueue failed in vhost_dev_stop

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This patch captures the error of vhost_virtqueue_stop() in vhost_dev_stop()
and returns the error upward.

Specifically, if QEMU is disconnected from the vhost backend, some actions
in vhost_dev_stop() will fail, such as sending vhost-user messages to the
backend (GET_VRING_BASE, SET_VRING_ENABLE) and vhost_reset_status.

Considering that both set_vring_enable and vhost_reset_status require setting
the specific virtio feature bit, we can capture vhost_virtqueue_stop()'s
error to indicate that QEMU has lost connection with the backend.

This patch is the pre patch for 'vhost-user: return failure if backend crashes
when live migration', which makes the live migration aware of the loss of
connection with the vhost-user backend and aborts the live migration.

Signed-off-by: Haoqian He <haoqian.he@smartx.com>
Message-Id: <20250416024729.3289157-3-haoqian.he@smartx.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Haoqian He 2025-04-15 22:47:27 -04:00 • committed by Michael S. Tsirkin
parent e0f300b36d
commit 5a317017b8
2 changed files with 18 additions and 13 deletions
Download patch file Download diff file Expand all files Collapse all files

11
hw/virtio/vhost.c
View file

@ -1367,7 +1367,7 @@ fail_alloc_desc:
return r; return r;
} }
void vhost_virtqueue_stop(struct vhost_dev *dev, int vhost_virtqueue_stop(struct vhost_dev *dev,
struct VirtIODevice *vdev, struct VirtIODevice *vdev,
struct vhost_virtqueue *vq, struct vhost_virtqueue *vq,
unsigned idx) unsigned idx)
@ -1380,7 +1380,7 @@ void vhost_virtqueue_stop(struct vhost_dev *dev,
if (virtio_queue_get_desc_addr(vdev, idx) == 0) { if (virtio_queue_get_desc_addr(vdev, idx) == 0) {
/* Don't stop the virtqueue which might have not been started */ /* Don't stop the virtqueue which might have not been started */
return; return 0;
} }
r = dev->vhost_ops->vhost_get_vring_base(dev, &state); r = dev->vhost_ops->vhost_get_vring_base(dev, &state);
@ -1411,6 +1411,7 @@ void vhost_virtqueue_stop(struct vhost_dev *dev,
0, virtio_queue_get_avail_size(vdev, idx)); 0, virtio_queue_get_avail_size(vdev, idx));
vhost_memory_unmap(dev, vq->desc, virtio_queue_get_desc_size(vdev, idx), vhost_memory_unmap(dev, vq->desc, virtio_queue_get_desc_size(vdev, idx),
0, virtio_queue_get_desc_size(vdev, idx)); 0, virtio_queue_get_desc_size(vdev, idx));
return r;
} }
static int vhost_virtqueue_set_busyloop_timeout(struct vhost_dev *dev, static int vhost_virtqueue_set_busyloop_timeout(struct vhost_dev *dev,
@ -2135,9 +2136,10 @@ fail_features:
} }
/* Host notifiers must be enabled at this point. */ /* Host notifiers must be enabled at this point. */
void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings) int vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
{ {
int i; int i;
int rc = 0;
/* should only be called after backend is connected */ /* should only be called after backend is connected */
assert(hdev->vhost_ops); assert(hdev->vhost_ops);
@ -2156,7 +2158,7 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
vhost_dev_set_vring_enable(hdev, false); vhost_dev_set_vring_enable(hdev, false);
} }
for (i = 0; i < hdev->nvqs; ++i) { for (i = 0; i < hdev->nvqs; ++i) {
vhost_virtqueue_stop(hdev, rc |= vhost_virtqueue_stop(hdev,
vdev, vdev,
hdev->vqs + i, hdev->vqs + i,
hdev->vq_index + i); hdev->vq_index + i);
@ -2176,6 +2178,7 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
hdev->started = false; hdev->started = false;
vdev->vhost_started = false; vdev->vhost_started = false;
hdev->vdev = NULL; hdev->vdev = NULL;
return rc;
} }
int vhost_net_set_backend(struct vhost_dev *hdev, int vhost_net_set_backend(struct vhost_dev *hdev,

6
include/hw/virtio/vhost.h
View file

@ -232,8 +232,10 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings);
* Stop the vhost device. After the device is stopped the notifiers * Stop the vhost device. After the device is stopped the notifiers
* can be disabled (@vhost_dev_disable_notifiers) and the device can * can be disabled (@vhost_dev_disable_notifiers) and the device can
* be torn down (@vhost_dev_cleanup). * be torn down (@vhost_dev_cleanup).
*
* Return: 0 on success, != 0 on error when stopping dev.
*/ */
void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings); int vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings);
/** /**
* DOC: vhost device configuration handling * DOC: vhost device configuration handling
@ -333,7 +335,7 @@ int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write);
int vhost_virtqueue_start(struct vhost_dev *dev, struct VirtIODevice *vdev, int vhost_virtqueue_start(struct vhost_dev *dev, struct VirtIODevice *vdev,
struct vhost_virtqueue *vq, unsigned idx); struct vhost_virtqueue *vq, unsigned idx);
void vhost_virtqueue_stop(struct vhost_dev *dev, struct VirtIODevice *vdev, int vhost_virtqueue_stop(struct vhost_dev *dev, struct VirtIODevice *vdev,
struct vhost_virtqueue *vq, unsigned idx); struct vhost_virtqueue *vq, unsigned idx);
void vhost_dev_reset_inflight(struct vhost_inflight *inflight); void vhost_dev_reset_inflight(struct vhost_inflight *inflight);