[libvirt] xml config nested

How to configure libvirt, so qemu-kvm support nested virtualization, virtual machine installed operating system is windows_7_ultimate_sp1_x64_dvd_618537.iso, configure libvirt xml file is as follows: <cpu mode='custom' match='exact'> <model fallback='allow'>core2duo</model> <feature policy='require' name='vmx'/> </cpu> or <cpu mode='host-model'> <model fallback='allow'/> </cpu> or <cpu mode='host-passthrough'> <topology sockets='2' cores='2' threads='2'/> </cpu> We install libvirt in centos 7, qemu-kvm version is: [Root @ localhost libexec] # ./qemu-kvm --version QEMU emulator version 2.6.0 (qemu-kvm-ev-2.6.0-27.1.el7), Copyright (c) 2003-2008 Fabrice Bellard Above is the basic environment and libvirt configuration, but in this environment to install the internal implementation of the following windows7 virtual machine kernel interface calls are as follows: if (!FeatrueControlMsr.fields.enable_vmxon) { MyWriteFile(FileHanle, "Bios设置没有开启虚拟化\n", strlen("Bios设置没有开启虚拟化\n"), &ReturnLen); MyCloseFile(FileHanle); KdPrint(("Bios设置没有开启虚拟化")); return FALSE; } in conclusion: Through this kernel interface to determine the result is: Bios settings do not turn on virtualization How to solve this problem? Hope to get your help. thank you very much。