Kvm

KVM is a Linux-based full virtualization tool which utilizes the virutalization extensions available with several models of Intel and AMD processors.

Installation

Prerequisites

KVM will only work on systems with processors offer virtualization support. To find out if a system's processor supports virtualization you can look in /proc/cpuinfo for the vmx (Intel) or svm (AMD) flags. This command should do the trick:

egrep '(vmx|svm)' --color=always /proc/cpuinfo

NPG Systems With Virtualization Support

• Gluon
• Gourd
• Taro
• Tomato
• Pumpkin

Installing the Software

If you're using a RHEL system you need to enable the virtualization add-on entitlement to your RHEL license. You can install the packages via yum. This is the list of packages you will need:

libvirt-python
kvm
virt-manager
libvirt
kvm-qemu-img
kmod-kvm
kvm-tools
python-virtinst

Configuration

Start the libvirtd service, and configure it to start at boot.

chkconfig --level 345 libvirtd on
service libvirtd start

Network Bridging

KVM requires bridged networks to be configured manually. The configuration for RHEL 5 systems should look something like this:

/etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0
ONBOOT=yes
HWADDR=FF:FF:FF:FF:FF:FF
BRIDGE=br0

/etc/sysconfig/network-scripts/ifcfg-br0

ONBOOT=yes
TYPE=Bridge
DEVICE=br0
BOOTPROTO=static
IPADDR=10.0.0.2
NETMASK=255.0.0.0
NM_CONTROLLED=no
DELAY=0

Also, the system firewall should contain a rule that forwards traffic to the bridged interfaces. This will require virtual systems to maintain their own firewalls because it won't be filtered by the host:

-I FORWARD -m physdev --physdev-is-bridge -j ACCEPT

Managing Virtual Machines

The virt-manager tool provides a GUI for creating and managing VMs.

virt-manager can be used to view virtual machine details, add and remove virtual hardware, and access the system console.

CentOS booting in the virt-manager console