卖萌的弱渣

I am stupid, I am hungry.

Build Nested KVM Virtualization

Platform

  • Dom0: Opensuse 13.1
  • Host/Guest Hypervisor: KVM
  • Guest OS: CentOS

Enable Nested in Host KVM

  1. Check if nested is enabled in host hypervisor
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cat /sys/module/kvm_intel/parameters/nested

if the result is Y. Nested virgualization in your host is open. Ohterwise you need to complete the followings

  1. `Modify /etc/default/grub

GRUB_CMDLINE_LINX = “kvm-intel.nested=1 ”

  1. Update grub
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grub2-mkconfig -o /boot/grub2/grub.cfg
  1. Reboot and check again

Install the guest Hypervisor

I use the raw disk as the VM partition

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virt-install --name=centos5.6 --os-variant=RHEL5 --ram=1024 --vcpus=1 --disk path=/dev/sda4,format=raw,bus=virtio --accelerate --cdrom /Your DVD / --vnc --vncport=5910 --vnclisten=0.0.0.0 --network bridge=br0,model=virtio --noautoconsole

Configure the Guest Hypervisor

  • Disable cache on guest disk In xml file, do
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<driver name='qemu' type='raw' cache='none'/>
  • Enable VMX in guest CPU In xml file, do
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<cpu match='exact'>
  <model>core2duo</model>
 <feature policy='require' name='vmx'/>
</cpu>
  • Check guest CPU feature in host In host OS
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ps -ef | grep qemu-kvm
  • Disable SELinux In SELinux
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SELINUX=permissive
  • Configure network
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service NetworkManager stop
chkconfig NetworkManager off
chkconfig network on
yum install bridge-utils

eth0:

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DEVICE=eth0
TYPE=Ethernet
ONBOOT=yes
NM_CONTROLLED=yes
BRIDGE=br0

br0

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DEVICE=br0
NM_CONTROLLED=yes
ONBOOT=yes
TYPE=Bridge
BOOTPROTO=dhcp

reboot your computer

  • Compile and Install QEMU
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./configure
make
make install
  • Install libvirt and management tool
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yum install libvirt-client virt-viewer guestfish libguestfs-tools virt-top libvrt python-virtinst
  • Launch libvirtd
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service libvirtd start
chkconfig libvirtd on
  • Check if libvirtd is turned on
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virsh list

Virsh Command

  • Launch a VM
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virsh start domain name
  • Undefine a VM
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virsh destroy domain name
virsh undefine domain name
  • Connect a VM
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virt-viewer -c qemu:///system  domain name
  • Delete a VM
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virsh destroy domain name
virsh undefine domain name
  • Add VCPU to a VM
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virsh shutdown domain Name
virsh edit domain name

do this

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edit <vcpu placement='static'>4</vcpu>
virsh create /etc/libvirt/qemu/yourconfig.xml
  • Solve the CPU incompatibility problems

In host, run virsh commands to check CPU compatibility.

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virsh  capabilities | virsh cpu-baseline /dev/stdin

Copy past the display in your VM XML file

For example

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<cpu match='exact'>
  <model>Penryn</model>
  <vendor>Intel</vendor>
  <feature policy='require' name='dca'/>
  <feature policy='require' name='xtpr'/>
  <feature policy='require' name='tm2'/>
  <feature policy='require' name='vmx'/>
  <feature policy='require' name='ds_cpl'/>
  <feature policy='require' name='monitor'/>
  <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>