[PATCH v3 14/28] hw/xen: add get_frontend_path() method to XenDeviceClass

David Woodhouse
2023-10-25T14:51:13Z

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 | 11 ++++++++++-
include/hw/xen/xen-bus.h | 2 ++
2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c
index ece8ec40cd..12ff782005 100644
--- a/hw/xen/xen-bus.c
+++ b/hw/xen/xen-bus.c
@@ -711,8 +711,17 @@ 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) {
+ error_prepend(errp, "failed to create frontend: ");
+ return;
+ }
+ } else {
+ xendev->frontend_path = xen_device_get_frontend_path(xendev);
+ }

/*
* The frontend area may have already been created by a legacy
diff --git a/include/hw/xen/xen-bus.h b/include/hw/xen/xen-bus.h
index f435898164..eb440880b5 100644
--- a/include/hw/xen/xen-bus.h
+++ b/include/hw/xen/xen-bus.h
@@ -33,6 +33,7 @@ struct XenDevice {
};
typedef struct XenDevice XenDevice;

+typedef char *(*XenDeviceGetFrontendPath)(XenDevice *xendev, Error **errp);
typedef char *(*XenDeviceGetName)(XenDevice *xendev, Error **errp);
typedef void (*XenDeviceRealize)(XenDevice *xendev, Error **errp);
typedef void (*XenDeviceFrontendChanged)(XenDevice *xendev,
@@ -46,6 +47,7 @@ struct XenDeviceClass {
/*< public >*/
const char *backend;
const char *device;
+ XenDeviceGetFrontendPath get_frontend_path;
XenDeviceGetName get_name;
XenDeviceRealize realize;
XenDeviceFrontendChanged frontend_changed;
--
2.40.1