Re: [RFC v2 7/7] vhost: Route host->guest notification through shadow virtqueue

[Stefan Hajnoczi]

On Tue, Feb 09, 2021 at 04:37:57PM +0100, Eugenio Pérez wrote:
> @@ -40,6 +42,26 @@ static void vhost_handle_guest_kick(EventNotifier *n)
>      }
>  }
>  
> +/* Forward vhost notifications */
> +static void vhost_handle_call(EventNotifier *n)

The name vhost_shadow_vq_handle_call() expresses the purpose of the
function more clearly.

> @@ -75,8 +102,19 @@ bool vhost_shadow_vq_start_rcu(struct vhost_dev *dev,
>      /* Check for pending notifications from the guest */
>      vhost_handle_guest_kick(&svq->host_notifier);
>  
> +    r = dev->vhost_ops->vhost_set_vring_call(dev, &call_file);
> +    if (r != 0) {
> +        error_report("Couldn't set call fd: %s", strerror(errno));
> +        goto err_set_vring_call;
> +    }

This ignores notifier_is_masked and always unmasks.

> @@ -1608,6 +1607,10 @@ void vhost_virtqueue_mask(struct vhost_dev *hdev, 
> VirtIODevice *vdev, int n,
>      if (mask) {
>          assert(vdev->use_guest_notifier_mask);
>          file.fd = event_notifier_get_fd(&hdev->vqs[index].masked_notifier);
> +    } else if (hdev->sw_lm_enabled) {
> +        VhostShadowVirtqueue *svq = hdev->shadow_vqs[n];
> +        EventNotifier *e = vhost_shadow_vq_get_call_notifier(svq);
> +        file.fd = event_notifier_get_fd(e);
>      } else {
>          file.fd = 
> event_notifier_get_fd(virtio_queue_get_guest_notifier(vvq));
>      }

Maybe you can extend this function so it can be called unconditionally
from both vhost_shadow_vq_start_rcu() and vhost_shadow_vq_stop_rcu(). It
would be a single place that invokes vhost_set_vring_call().

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