[PATCH v1 1/7] xen-block: Do not write frontend nodes

[Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

The PV backend running in other than Dom0 domain (non toolstack domain)
is not allowed to write frontend nodes. The more, the backend does not
need to do that at all, this is purely toolstack/xl devd business.

I do not know for what reason the backend does that here, this is not really
needed, probably it is just a leftover and all xen_device_frontend_printf()
instances should go away completely.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com>
---
 hw/block/xen-block.c | 11 +++++++----
 hw/xen/xen-bus.c     |  2 +-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c
index a07cd7eb5d..dc4d477c22 100644
--- a/hw/block/xen-block.c
+++ b/hw/block/xen-block.c
@@ -221,6 +221,7 @@ static void xen_block_realize(XenDevice *xendev, Error **errp)
     XenBlockVdev *vdev = &blockdev->props.vdev;
     BlockConf *conf = &blockdev->props.conf;
     BlockBackend *blk = conf->blk;
+    XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
 
     if (vdev->type == XEN_BLOCK_VDEV_TYPE_INVALID) {
         error_setg(errp, "vdev property not set");
@@ -280,10 +281,12 @@ static void xen_block_realize(XenDevice *xendev, Error **errp)
 
     xen_device_backend_printf(xendev, "info", "%u", blockdev->info);
 
-    xen_device_frontend_printf(xendev, "virtual-device", "%lu",
-                               vdev->number);
-    xen_device_frontend_printf(xendev, "device-type", "%s",
-                               blockdev->device_type);
+    if (xenbus->backend_id == 0) {
+        xen_device_frontend_printf(xendev, "virtual-device", "%lu",
+                                   vdev->number);
+        xen_device_frontend_printf(xendev, "device-type", "%s",
+                                   blockdev->device_type);
+    }
 
     xen_device_backend_printf(xendev, "sector-size", "%u",
                               conf->logical_block_size);
diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c
index ece8ec40cd..06d5192aca 100644
--- a/hw/xen/xen-bus.c
+++ b/hw/xen/xen-bus.c
@@ -1048,7 +1048,7 @@ static void xen_device_realize(DeviceState *dev, Error **errp)
     xen_device_backend_set_online(xendev, true);
     xen_device_backend_set_state(xendev, XenbusStateInitWait);
 
-    if (!xen_device_frontend_exists(xendev)) {
+    if (!xen_device_frontend_exists(xendev) && xenbus->backend_id == 0) {
         xen_device_frontend_printf(xendev, "backend", "%s",
                                    xendev->backend_path);
         xen_device_frontend_printf(xendev, "backend-id", "%u",
-- 
2.42.0