Openstack以qcow2为镜像创建实例，实例的CPU类型自动分配为EYPC，
但是查看计算节点CPU类型为Inter，
因此在nova配置中设置计算节点的cpu_mode

[libvirt]
virt_type=kvm
cpu_mode=host-model

以下引入Openstack官网的配置信息描述：

virt_type = kvm    

(StrOpt) Libvirt domain type 
(valid options are: kvm, lxc, qemu, uml, xen and parallels)

cpu_mode = None    

(StrOpt) Set to "host-model" to clone the host CPU feature flags;
to "host-passthrough" to use the host CPU model exactly; 
to "custom" to use a named CPU model; 
to "none" to not set any CPU model. 
If virt_type="kvm|qemu", it will default to "host-model", 
otherwise it will default to "none"

cpu_model = None

(StrOpt) Set to a named libvirt CPU model 
(see names listed in /usr/share/libvirt/cpu_map.xml). 
Only has effect if cpu_mode="custom" and virt_type="kvm|qemu"