kvm的nested嵌套

关键点是
modprobe kvm_intel nested=1
使用qemu的时候 cpu透传设置 -cpu host
或者libvert的virsh命令的xml设置
<cpu mode='host-passthrough'></cpu>

###############################
kvm嵌套是只相同cpu的嵌套，64位编程32位的不行

在kvm启动的vm上启动kvm建立vm的vm

在没有vm启动的情况下操作
lsmod|grep kvm
如果什么都没有说明没有加载kvm模块
cat /sys/module/kvm_intel/parameters/nested
No such file or directory

不加nest启动内核模块

modprobe kvm
modprobe kvm_intel

cat /sys/module/kvm_intel/parameters/nested
N

nested并没有打开

设置内核模块的nest

rmmod kvm_intel
modprobe kvm_intel nested=1


cat /sys/module/kvm_intel/parameters/nested 
Y

当显示Y的时候才确实设置成功

测试：
libvirt建立vm的时候
配置文件加

<cpu mode='host-passthrough'>
</cpu>

透传cpu

建立的vm里面测试使用
/usr/libexec/qemu-kvm已经可以建vm成功
普通的qemu建立vm

/usr/libexec/qemu-kvm -kernel bzImage -drive file=hda.qcow2,if=ide,cache=none -append "console=ttyS0 root=/dev/sda rw rdinit=/sbin/init notsc=1"  -boot order=dc,menu=on -net nic,vlan=0,macaddr=52:54:00:12:34:22,model=e1000,addr=08 -net tap,name=haha,ifname=tap1,script=no,downscript=no -vnc 0.0.0.0:1 -monitor stdio

[root@jslinux test_migration]# 
lsmod|grep kvm
kvm_intel             162153  0 
kvm                   525409  1 kvm_intel
[root@jslinux test_migration]# 

##############################
附录：
完整的jslinux.xml文件为

<domain type='kvm'>  
  <name>jslinux</name>  
  <uuid>d16d7501-9b0d-f26e-f52a-77a81225242e</uuid>  
  <memory unit='KiB'>33554432</memory>  
  <currentMemory unit='KiB'>33554432</currentMemory>  
  <vcpu placement='static'>16</vcpu>  
  <cpu mode='host-passthrough'>
  </cpu>
  <os>  
    <type arch='x86_64' machine='pc'>hvm</type>  
    <boot dev='hd'/>  
     <bootmenu enable='yes'/>  
  </os>  
  <features>  
    <acpi/>  
    <apic/>  
    <pae/>  
  </features>  
  <clock offset='utc'/>  
  <on_poweroff>destroy</on_poweroff>  
  <on_reboot>restart</on_reboot>  
  <on_crash>restart</on_crash>  
  <devices>  
    <emulator>/usr/libexec/qemu-kvm</emulator>  
    <disk type='file' device='disk'>  
      <driver name='qemu' type='qcow2' cache='none'/>  
      <source file='/home/hao/jslinux.img'/>  
      <target dev='vda' bus='virtio'/>  
    </disk>  
    <disk type='file' device='cdrom'>  
      <driver name='qemu' type='raw'/>  
      <source file='/home/CentOS-7-x86_64-DVD-1503-01.iso'/>  
      <target dev='hdc' bus='ide'/>  
      <readonly/>  
      <address type='drive' controller='0' bus='1' target='0' unit='0'/>  
    </disk>  
    <controller type='usb' index='0'>  
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>  
    </controller>  
    <controller type='ide' index='0'>  
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>  
    </controller>  
    <interface type='bridge'>  
      <mac address='50:52:11:aa:12:35'/>  
      <source bridge='br0'/>  
      <model type='virtio'/>  
    </interface>  
    <serial type='pty'>  
      <target port='0'/>  
    </serial>  
    <console type='pty'>  
      <target type='serial' port='0'/>  
    </console>  
    <input type='mouse' bus='ps2'/>  
    <graphics type='vnc' port='5918' autoport='no' listen='0.0.0.0'>  
      <listen type='address' address='0.0.0.0'/>  
    </graphics>  
    <sound model='ich6'>  
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>  
    </sound>  
    <video>  
      <model type='cirrus' vram='9216' heads='1'/>  
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>  
    </video>  
    <memballoon model='virtio'>  
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>  
    </memballoon>  
  </devices>  
</domain> 

virsh start jslinux
启动的mv里面也可以使用kvm