vmbus: Print a warning when enabled without the recommended set of features

Some Windows versions crash at boot or fail to enable the VMBus device if
they don't see the expected set of Hyper-V features (enlightenments).

Since this provides poor user experience let's warn user if the VMBus
device is enabled without the recommended set of Hyper-V features.

The recommended set is the minimum set of Hyper-V features required to make
the VMBus device work properly in Windows Server versions 2016, 2019 and
2022.

Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/hw/hyperv/vmbus.c b/hw/hyperv/vmbus.c
index 380239af2c..f33afeeea2 100644
--- a/hw/hyperv/vmbus.c
+++ b/hw/hyperv/vmbus.c
@@ -2631,6 +2631,12 @@ static void vmbus_bridge_realize(DeviceState *dev, Error **errp)
         return;
     }
 
+    if (!hyperv_are_vmbus_recommended_features_enabled()) {
+        warn_report("VMBus enabled without the recommended set of Hyper-V features: "
+                    "hv-stimer, hv-vapic and hv-runtime. "
+                    "Some Windows versions might not boot or enable the VMBus device");
+    }
+
     bridge->bus = VMBUS(qbus_new(TYPE_VMBUS, dev, "vmbus"));
 }