Re: [PATCH v4 08/10] vhost: add vhost_dev_set_owner() / vhost_dev_reset_owner() helpers

[Stefano Garzarella <sgarzare@redhat.com>]

On Thu, Aug 20, 2026 at 02:39:53PM +0300, Andrey Drobyshev wrote:
>Wrap the set_owner/reset_owner backend ops in dev-level helpers, matching
>other vhost_dev_* wrappers, so device code can take or release ownership
>without reaching into vhost_ops directly.  vhost_dev_init() now uses
>vhost_dev_set_owner(). Both return -ENOSYS if the backend has no such op.
>
>No functional change.  These are used by the following vhost-vsock patch to
>hand a device between owners during CPR.
>
>Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
>---
> hw/virtio/vhost.c         | 20 +++++++++++++++++++-
> include/hw/virtio/vhost.h | 13 +++++++++++++
> 2 files changed, 32 insertions(+), 1 deletion(-)
>
>diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
>index 2bb9a23fee4..ea17bf01080 100644
>--- a/hw/virtio/vhost.c
>+++ b/hw/virtio/vhost.c
>@@ -1690,6 +1690,24 @@ int vhost_dev_init_backend(struct vhost_dev *hdev, void *opaque,
>     return 0;
> }
>
>+int vhost_dev_set_owner(struct vhost_dev *hdev)
>+{
>+    assert(hdev->vhost_ops);
>+    if (!hdev->vhost_ops->vhost_set_owner) {
>+        return -ENOSYS;
>+    }
>+    return hdev->vhost_ops->vhost_set_owner(hdev);
>+}
>+
>+int vhost_dev_reset_owner(struct vhost_dev *hdev)
>+{
>+    assert(hdev->vhost_ops);
>+    if (!hdev->vhost_ops->vhost_reset_owner) {
>+        return -ENOSYS;
>+    }
>+    return hdev->vhost_ops->vhost_reset_owner(hdev);
>+}
>+
> int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
>                    VhostBackendType backend_type, uint32_t busyloop_timeout,
>                    Error **errp)
>@@ -1707,7 +1725,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
>         goto fail;
>     }
>
>-    r = hdev->vhost_ops->vhost_set_owner(hdev);
>+    r = vhost_dev_set_owner(hdev);
>     if (r < 0) {
>         error_setg_errno(errp, -r, "vhost_set_owner failed");
>         goto fail;
>diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
>index 9b98d34dd04..44e65968d9b 100644
>--- a/include/hw/virtio/vhost.h
>+++ b/include/hw/virtio/vhost.h
>@@ -178,6 +178,19 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
> int vhost_dev_init_backend(struct vhost_dev *hdev, void *opaque,
>                            VhostBackendType backend_type, Error **errp);
>
>+/**
>+ * vhost_dev_set_owner() / vhost_dev_reset_owner() - take / release ownership

I'm not sure this is a common practice in kernel-doc format.
I think we should add 2 differnt blocks, one for each function.

Stefano

>+ * @hdev: the common vhost_dev structure
>+ *
>+ * Take (VHOST_SET_OWNER) or release (VHOST_RESET_OWNER) ownership of a
>+ * device that has already been set up.  Used to hand a device over during
>+ * CPR.  Returns -ENOSYS if the backend has no such op.
>+ *
>+ * Return: 0 on success, negative errno on failure.
>+ */
>+int vhost_dev_set_owner(struct vhost_dev *hdev);
>+int vhost_dev_reset_owner(struct vhost_dev *hdev);
>+
> /**
>  * vhost_dev_cleanup() - tear down and cleanup vhost interface
>  * @hdev: the common vhost_dev structure
>-- 
>2.47.1
>