diff --git a/lib/hypervisor/hv_xen.py b/lib/hypervisor/hv_xen.py
index a563e9373d8f12ddbb6bc9c1957b722a524d1ddb..ba7b51138c25f8017aefa34a039587e3e0892558 100644
--- a/lib/hypervisor/hv_xen.py
+++ b/lib/hypervisor/hv_xen.py
@@ -356,6 +356,7 @@ class XenHypervisor(hv_base.BaseHypervisor):
     dom0_info = self.GetInstanceInfo(_DOM0_NAME)
     if dom0_info is not None:
       result["memory_dom0"] = dom0_info[2]
+      result["dom0_cpus"] = dom0_info[3]
 
     if not (xen_major is None or xen_minor is None):
       result[constants.HV_NODEINFO_KEY_VERSION] = (xen_major, xen_minor)