vhost_virtqueue_start() unmasks the call notifier by calling vhost_virtqueue_mask(), whose vhost_set_vring_call ioctl can fail (closed vhost-user socket, kernel ENOMEM, revoked guest_notifier fd) but whose void signature throws the error away. vhost_dev_start() then reports success while the backend has no valid call eventfd for that vq, leaving the guest with a working kick path but no virtqueue interrupts -- a half-up state harder to diagnose than a clean failure.
Make vhost_virtqueue_mask() return int and handle the error in the start path via the existing fail_vector unwind. Other callers reach the function through VirtioDeviceClass.guest_notifier_mask, whose void signature offers no upward error channel; they invoke it as a statement and remain source-compatible. Resolves a long-standing TODO at the unmask call. Signed-off-by: Bin Guo <[email protected]> --- hw/virtio/vhost.c | 12 +++++++++--- include/hw/virtio/vhost.h | 4 ++-- 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index b9dc4ed13b..42e2fc9952 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -1351,8 +1351,11 @@ int vhost_virtqueue_start(struct vhost_dev *dev, * will do it later. */ if (!vdev->use_guest_notifier_mask) { - /* TODO: check and handle errors. */ - vhost_virtqueue_mask(dev, vdev, idx, false); + r = vhost_virtqueue_mask(dev, vdev, idx, false); + if (r < 0) { + /* No call eventfd means no interrupts; bail out. */ + goto fail_vector; + } } if (k->query_guest_notifiers && @@ -1815,7 +1818,7 @@ bool vhost_virtqueue_pending(struct vhost_dev *hdev, int n) } /* Mask/unmask events from this vq. */ -void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n, +int vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n, bool mask) { struct VirtQueue *vvq = virtio_get_queue(vdev, n); @@ -1836,7 +1839,10 @@ void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n, r = hdev->vhost_ops->vhost_set_vring_call(hdev, &file); if (r < 0) { error_report("vhost_set_vring_call failed %d", -r); + return r; } + + return 0; } bool vhost_config_pending(struct vhost_dev *hdev) diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h index 89817bd848..96cc261822 100644 --- a/include/hw/virtio/vhost.h +++ b/include/hw/virtio/vhost.h @@ -317,8 +317,8 @@ bool vhost_virtqueue_pending(struct vhost_dev *hdev, int n); /* Mask/unmask events from this vq. */ -void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n, - bool mask); +int vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n, + bool mask); /** * vhost_get_features_ex() - sanitize the extended features set -- 2.50.1 (Apple Git-155)
