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, 12 insertions, 0 deletions

diff --git a/hw/hyperv/hyperv.c b/hw/hyperv/hyperv.c
index 6c4a18dd0e..3ea54ba818 100644
--- a/hw/hyperv/hyperv.c
+++ b/hw/hyperv/hyperv.c
@@ -951,3 +951,15 @@ uint64_t hyperv_syndbg_query_options(void)
 
     return msg.u.query_options.options;
 }
+
+static bool vmbus_recommended_features_enabled;
+
+bool hyperv_are_vmbus_recommended_features_enabled(void)
+{
+    return vmbus_recommended_features_enabled;
+}
+
+void hyperv_set_vmbus_recommended_features_enabled(void)
+{
+    vmbus_recommended_features_enabled = true;
+}