diff --git a/target/i386/kvm/hyperv-proto.h b/target/i386/kvm/hyperv-proto.h
index e30d64b4ad..5fbb385cc1 100644
--- a/target/i386/kvm/hyperv-proto.h
+++ b/target/i386/kvm/hyperv-proto.h
@@ -38,6 +38,12 @@
 #define HV_ACCESS_FREQUENCY_MSRS     (1u << 11)
 #define HV_ACCESS_REENLIGHTENMENTS_CONTROL  (1u << 13)
 
+/*
+ * HV_CPUID_FEATURES.EBX bits
+ */
+#define HV_POST_MESSAGES             (1u << 4)
+#define HV_SIGNAL_EVENTS             (1u << 5)
+
 /*
  * HV_CPUID_FEATURES.EDX bits
  */
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index eee1a6b46e..59ed8327ac 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -1346,6 +1346,12 @@ static int hyperv_fill_cpuids(CPUState *cs,
     /* Unconditionally required with any Hyper-V enlightenment */
     c->eax |= HV_HYPERCALL_AVAILABLE;
 
+    /* SynIC and Vmbus devices require messages/signals hypercalls */
+    if (hyperv_feat_enabled(cpu, HYPERV_FEAT_SYNIC) &&
+        !cpu->hyperv_synic_kvm_only) {
+        c->ebx |= HV_POST_MESSAGES | HV_SIGNAL_EVENTS;
+    }
+
     /* Not exposed by KVM but needed to make CPU hotplug in Windows work */
     c->edx |= HV_CPU_DYNAMIC_PARTITIONING_AVAILABLE;