Re: [RFC 6/8] virtio-ccw: Lock ioeventfd state with VIRTIO_F_NOTIFICATION_DATA

From: Thomas Huth <thuth@redhat.com>
To: Jonah Palmer <jonah.palmer@oracle.com>, qemu-devel@nongnu.org
Cc: mst@redhat.com, jasowang@redhat.com, eperezma@redhat.com,
	si-wei.liu@oracle.com, boris.ostrovsky@oracle.com,
	raphael@enfabrica.net, kwolf@redhat.com, hreitz@redhat.com,
	pasic@linux.ibm.com, borntraeger@linux.ibm.com,
	farman@linux.ibm.com, richard.henderson@linaro.org,
	david@redhat.com, iii@linux.ibm.com, cohuck@redhat.com,
	pbonzini@redhat.com, fam@euphon.net, stefanha@redhat.com,
	qemu-block@nongnu.org, qemu-s390x@nongnu.org,
	virtio-fs@lists.linux.dev
Subject: Re: [RFC 6/8] virtio-ccw: Lock ioeventfd state with VIRTIO_F_NOTIFICATION_DATA
Date: Sat, 2 Mar 2024 16:35:08 +0100	[thread overview]
Message-ID: <356dff14-af44-403b-9a9c-b4ea9e156f19@redhat.com> (raw)
In-Reply-To: <20240301134330.4191007-7-jonah.palmer@oracle.com>

On 01/03/2024 14.43, Jonah Palmer wrote:
> Prevent ioeventfd from being enabled/disabled when a virtio-ccw device
> has negotiated the VIRTIO_F_NOTIFICATION_DATA transport feature.
> 
> Due to the ioeventfd not being able to carry the extra data associated
> with this feature, the ioeventfd should be left in a disabled state for
> emulated virtio-ccw devices using this feature.
> 
> Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
> ---
>   hw/s390x/virtio-ccw.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
> index b4676909dd..936ba78fda 100644
> --- a/hw/s390x/virtio-ccw.c
> +++ b/hw/s390x/virtio-ccw.c
> @@ -530,14 +530,16 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
>               if (ret) {
>                   break;
>               }
> -            if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> +            if (!(status & VIRTIO_CONFIG_S_DRIVER_OK) &&
> +                !virtio_vdev_has_feature(vdev, VIRTIO_F_NOTIFICATION_DATA)) {
>                   virtio_ccw_stop_ioeventfd(dev);
>               }
>               if (virtio_set_status(vdev, status) == 0) {
>                   if (vdev->status == 0) {
>                       virtio_ccw_reset_virtio(dev);
>                   }
> -                if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
> +                if ((status & VIRTIO_CONFIG_S_DRIVER_OK) &&
> +                    !virtio_vdev_has_feature(vdev, VIRTIO_F_NOTIFICATION_DATA)) {
>                       virtio_ccw_start_ioeventfd(dev);
>                   }
>                   sch->curr_status.scsw.count = ccw.count - sizeof(status);

Acked-by: Thomas Huth <thuth@redhat.com>