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>

diff --git a/hw/hyperv/hyperv.c b/hw/hyperv/hyperv.c
index 6c4a18dd0e2ab71c38acb93482901105cc040b2c..3ea54ba818b2813fc9d9b77e5412c0be94af12df 100644 (file)
--- 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;
+}

diff --git a/hw/hyperv/vmbus.c b/hw/hyperv/vmbus.c
index 380239af2c7ba8f55b8f35e5af13d4cb0491d005..f33afeeea27d4e46da64c991001bf356d51f2227 100644 (file)
--- 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"));
 }
 

diff --git a/include/hw/hyperv/hyperv.h b/include/hw/hyperv/hyperv.h
index 015c3524b1c2e19a77c501fe8e9a69799543a1ba..d717b4e13d40d3ee6f7351038538545c202f9210 100644 (file)
--- a/include/hw/hyperv/hyperv.h
+++ b/include/hw/hyperv/hyperv.h
@@ -139,4 +139,8 @@ typedef struct HvSynDbgMsg {
 } HvSynDbgMsg;
 typedef uint16_t (*HvSynDbgHandler)(void *context, HvSynDbgMsg *msg);
 void hyperv_set_syndbg_handler(HvSynDbgHandler handler, void *context);
+
+bool hyperv_are_vmbus_recommended_features_enabled(void);
+void hyperv_set_vmbus_recommended_features_enabled(void);
+
 #endif

diff --git a/target/i386/kvm/hyperv-stub.c b/target/i386/kvm/hyperv-stub.c
index 778ed782e6fc87a7e1ae46535039dbd3fb68d56b..3263dcf05d312636e46ae2769eef48bde4f56aa2 100644 (file)
--- a/target/i386/kvm/hyperv-stub.c
+++ b/target/i386/kvm/hyperv-stub.c
@@ -52,3 +52,7 @@ void hyperv_x86_synic_reset(X86CPU *cpu)
 void hyperv_x86_synic_update(X86CPU *cpu)
 {
 }
+
+void hyperv_x86_set_vmbus_recommended_features_enabled(void)
+{
+}

diff --git a/target/i386/kvm/hyperv.c b/target/i386/kvm/hyperv.c
index 6825c89af374ab7319a1bc10724068fffe16e306..f2a3fe650a186d8e02870338d0e251fd1f67a27a 100644 (file)
--- a/target/i386/kvm/hyperv.c
+++ b/target/i386/kvm/hyperv.c
@@ -149,3 +149,8 @@ int kvm_hv_handle_exit(X86CPU *cpu, struct kvm_hyperv_exit *exit)
         return -1;
     }
 }
+
+void hyperv_x86_set_vmbus_recommended_features_enabled(void)
+{
+    hyperv_set_vmbus_recommended_features_enabled();
+}

diff --git a/target/i386/kvm/hyperv.h b/target/i386/kvm/hyperv.h
index 67543296c3a4e12bc382ea2177bb609c72aac1cb..e3982c8f4dd1b5751454eeb1d90a3077144b85b1 100644 (file)
--- a/target/i386/kvm/hyperv.h
+++ b/target/i386/kvm/hyperv.h
@@ -26,4 +26,6 @@ int hyperv_x86_synic_add(X86CPU *cpu);
 void hyperv_x86_synic_reset(X86CPU *cpu);
 void hyperv_x86_synic_update(X86CPU *cpu);
 
+void hyperv_x86_set_vmbus_recommended_features_enabled(void);
+
 #endif

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 42970ab046fac152abdfbccb8fca226f6e90bca5..e68cbe92930291ea62d5ead4a557b0f69c0ec3e1 100644 (file)
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -1650,6 +1650,13 @@ static int hyperv_init_vcpu(X86CPU *cpu)
         }
     }
 
+    /* Skip SynIC and VP_INDEX since they are hard deps already */
+    if (hyperv_feat_enabled(cpu, HYPERV_FEAT_STIMER) &&
+        hyperv_feat_enabled(cpu, HYPERV_FEAT_VAPIC) &&
+        hyperv_feat_enabled(cpu, HYPERV_FEAT_RUNTIME)) {
+        hyperv_x86_set_vmbus_recommended_features_enabled();
+    }
+
     return 0;
 }