Re: [PATCH 06/12] hw/xen: add get_frontend_path() method to XenDeviceClass

[Paul Durrant <xadimgnik@gmail.com>]

On 16/10/2023 16:19, David Woodhouse wrote:
> From: David Woodhouse <dwmw@amazon.co.uk>
> 
> The primary Xen console is special. The guest's side is set up for it by
> the toolstack automatically and not by the standard PV init sequence.
> 
> Accordingly, its *frontend* doesn't appear in …/device/console/0 either;
> instead it appears under …/console in the guest's XenStore node.
> 
> To allow the Xen console driver to override the frontend path for the
> primary console, add a method to the XenDeviceClass which can be used
> instead of the standard xen_device_get_frontend_path()
> 
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
>   hw/xen/xen-bus.c         | 10 +++++++++-
>   include/hw/xen/xen-bus.h |  2 ++
>   2 files changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c
> index ece8ec40cd..cc524ed92c 100644
> --- a/hw/xen/xen-bus.c
> +++ b/hw/xen/xen-bus.c
> @@ -711,8 +711,16 @@ static void xen_device_frontend_create(XenDevice *xendev, Error **errp)
>   {
>       ERRP_GUARD();
>       XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
> +    XenDeviceClass *xendev_class = XEN_DEVICE_GET_CLASS(xendev);
>   
> -    xendev->frontend_path = xen_device_get_frontend_path(xendev);
> +    if (xendev_class->get_frontend_path) {
> +        xendev->frontend_path = xendev_class->get_frontend_path(xendev, errp);
> +        if (!xendev->frontend_path) {
> +            return;

I think you need to update errp here to note that you are failing to 
create the frontend.

   Paul