setup kvm nested virtualization guest

intel vt支持嵌套虚拟化，即在guest 里面继续使用虚拟化功能， xml配置文件如下

<domain type='kvm' id='205'>  <name>centos7.3</name>  <uuid>9e7ebbbf-8b9d-404a-a4dd-cda8152bd554</uuid>  <memory unit='KiB'>16049152</memory>  <currentMemory unit='KiB'>16048576</currentMemory>  <vcpu placement='static'>8</vcpu>  <resource>    <partition>/machine</partition>  </resource>  <os>    <type arch='x86_64' machine='pc-i440fx-rhel7.0.0'>hvm</type>    <boot dev='hd'/>  </os>  <features>    <acpi/>    <apic/>  </features>  <cpu mode='host-passthrough'>    <topology sockets='2' cores='4' threads='1'/>    <feature policy='require' name='pdpe1gb'/>    <feature policy='require' name='rdrand'/>    <feature policy='require' name='f16c'/>    <feature policy='require' name='osxsave'/>    <feature policy='require' name='dca'/>    <feature policy='require' name='pcid'/>    <feature policy='require' name='pdcm'/>    <feature policy='require' name='xtpr'/>    <feature policy='require' name='tm2'/>    <feature policy='require' name='est'/>    <feature policy='require' name='smx'/>    <feature policy='require' name='vmx'/>    <feature policy='require' name='ds_cpl'/>    <feature policy='require' name='monitor'/>    <feature policy='require' name='dtes64'/>    <feature policy='require' name='pbe'/>    <feature policy='require' name='tm'/>    <feature policy='require' name='ht'/>    <feature policy='require' name='ss'/>    <feature policy='require' name='acpi'/>    <feature policy='require' name='ds'/>    <feature policy='require' name='vme'/>  </cpu>  <clock offset='utc'>

    <timer name='rtc' tickpolicy='catchup'/>    <timer name='pit' tickpolicy='delay'/>    <timer name='hpet' present='no'/>  </clock>  <on_poweroff>destroy</on_poweroff>  <on_reboot>restart</on_reboot>  <on_crash>restart</on_crash>  <pm>    <suspend-to-mem enabled='no'/>    <suspend-to-disk enabled='no'/>  </pm>  <devices>    <emulator>/usr/libexec/qemu-kvm</emulator>    <disk type='file' device='disk'>      <driver name='qemu' type='qcow2'/>      <source file='/tmp/centos7.3.img'/>      <target dev='vda' bus='virtio'/>      <alias name='virtio-disk0'/>      <address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>    </disk>    <disk type='file' device='cdrom'>      <driver name='qemu' type='raw'/>      <source startupPolicy='optional'/>      <target dev='hda' bus='ide'/>      <readonly/>      <alias name='ide0-0-0'/>      <address type='drive' controller='0' bus='0' target='0' unit='0'/>    </disk>    <controller type='ide' index='0'>      <alias name='ide0'/>      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>    </controller>    <controller type='virtio-serial' index='0'>      <alias name='virtio-serial0'/>      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>    </controller>    <controller type='usb' index='0'>      <alias name='usb0'/>      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>    </controller>    <controller type='pci' index='0' model='pci-root'>      <alias name='pci.0'/>    </controller>    <interface type='bridge'>

     <mac address='52:54:25:8c:71:0d'/>      <source bridge='br_vm'/>      <target dev='vnet0'/>      <model type='virtio'/>      <alias name='net0'/>      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>    </interface>    <serial type='pty'>      <source path='/dev/pts/8'/>      <target port='0'/>      <alias name='serial0'/>    </serial>    <console type='pty' tty='/dev/pts/8'>      <source path='/dev/pts/8'/>      <target type='serial' port='0'/>      <alias name='serial0'/>    </console>    <input type='mouse' bus='ps2'/>    <graphics type='vnc' port='5900' autoport='yes' listen='0.0.0.0'>      <listen type='address' address='0.0.0.0'/>    </graphics>    <sound model='ich6'>      <alias name='sound0'/>      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>    </sound>    <video>      <model type='cirrus' vram='16384' heads='1' primary='yes'/>      <alias name='video0'/>      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>    </video>    <memballoon model='virtio'>      <alias name='balloon0'/>      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>    </memballoon>  </devices>  <seclabel type='none'/></domain>

参考：

http://www.rdoxenham.com/?p=275