Re: [PATCH v2 03/25] vhost: rework vhost_virtqueue_init()

[Raphael Norwitz <raphael.s.norwitz@gmail.com>]

Reviewed-by: Raphael Norwitz <raphael.s.norwitz@gmail.com>


On Thu, Oct 16, 2025 at 7:48 AM Vladimir Sementsov-Ogievskiy
<vsementsov@yandex-team.ru> wrote:
>
> We are going to split vhost_dev_init() so that the first part will do
> early initialization of QEMU structures, but don't communicate with
> backend, and the second part will do backend communication. We need
> this for future support for backend-transfer migration support for
> vhost-user-blk (backend will not be available in the early
> initialization point).
>
> With this commit, let's split vhost_virtqueue_init(). The whole function
> is mostly about configuring the backend, so this logic will be postponed

nit: "until the backend becomes"

> until backend become available. The only thing to keep in early
> initialization is attaching vhost_dev structure. Let's simply move it to
> vhost_dev_init().
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> ---
>  hw/virtio/vhost.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 551d1687fc..1998663461 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -1500,9 +1500,9 @@ static void vhost_virtqueue_error_notifier(EventNotifier *n)
>      }
>  }
>
> -static int vhost_virtqueue_init(struct vhost_dev *dev,
> -                                struct vhost_virtqueue *vq, int n)
> +static int vhost_virtqueue_connect(struct vhost_virtqueue *vq, int n)
>  {
> +    struct vhost_dev *dev = vq->dev;
>      int vhost_vq_index = dev->vhost_ops->vhost_get_vq_index(dev, n);
>      struct vhost_vring_file file = {
>          .index = vhost_vq_index,
> @@ -1519,8 +1519,6 @@ static int vhost_virtqueue_init(struct vhost_dev *dev,
>          goto fail_call;
>      }
>
> -    vq->dev = dev;
> -
>      if (dev->vhost_ops->vhost_set_vring_err) {
>          r = event_notifier_init(&vq->error_notifier, 0);
>          if (r < 0) {
> @@ -1629,6 +1627,10 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
>      hdev->migration_blocker = NULL;
>      hdev->busyloop_timeout = busyloop_timeout;
>
> +    for (i = 0; i < hdev->nvqs; ++i) {
> +        hdev->vqs[i].dev = hdev;
> +    }
> +
>      r = vhost_set_backend_type(hdev, backend_type);
>      assert(r >= 0);
>
> @@ -1680,7 +1682,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
>      }
>
>      for (i = 0; i < hdev->nvqs; ++i, ++n_initialized_vqs) {
> -        r = vhost_virtqueue_init(hdev, hdev->vqs + i, hdev->vq_index + i);
> +        r = vhost_virtqueue_connect(hdev->vqs + i, hdev->vq_index + i);
>          if (r < 0) {
>              error_setg_errno(errp, -r, "Failed to initialize virtqueue %d", i);
>              goto fail;
> --
> 2.48.1
>
>