Check out https://help.ubuntu.com/community/KVM for more updated and complete information on installing KVM on Ubuntu.

kvm is qemu plus some great kernel level stuff for VT enabled CPUs.

Some rough notes:-

== How to tell if you can use kvm ==
=== Intel CPU ===
{{{
 grep vmx /proc/cpuinfo
}}}

However, if you have an Intel CPU it's possible that your computer manufacturer may have turned off VT in the BIOS. See below for more info.

=== AMD CPU ===
{{{
 grep svm /proc/cpuinfo
}}}

On some Gigabyte motherboards it is turned off in the BIOS if you use "Load safe defaults" (GiBy M61SME-S2 nF405 RLVSM bios < F7)

If you see something you have it, if you don't you don't. 


== Install it ==

{{{
sudo apt-get install kvm qemu
}}}

== Load the modules ==

{{{
sudo modprobe kvm
}}}

=== Load Intel module ===

If you have an Intel CPU

{{{
sudo modprobe kvm-intel
}}}

'''Note''' if you get this when you load the module then it may mean VT is switched off in the BIOS.

{{{
$ sudo modprobe kvm-intel
FATAL: Error inserting kvm_intel (/lib/modules/2.6.20-15-generic/kernel/drivers/kvm/kvm-intel.ko): Operation not supported
}}}

Typing dmesg you may find the following at the end:-

{{{
 kvm: disabled by bios
}}}

 ||<rowbgcolor="#E5ECFF"> {{attachment:IconsPage/IconTip.png}} You might need to enable the virtualization setting in the BIOS. Each BIOS is different and it can be difficult to find (it may be in the "Advanced" section or under "CPU" or "Security"). You may also need to power shutdown for the changes to take effect (some bios will do this automatically).||

=== Load AMD module ===

If you have an AMD CPU

{{{
sudo modprobe kvm-amd
}}}

== Add yourself to the group ==

{{{
sudo addgroup `whoami` kvm
}}}

== Create a KVM disk image ==
This example makes a virtual disk that grows on the fly:
{{{
qemu-img create -f qcow2 virtualdisk.img 10G
}}}

== Start the emulator ==

For example:-

{{{
 kvm -hda virtualdisk.img -cdrom cdrom.iso -m 256 -net nic -net user -soundhw all
}}}

== Load the modules more permanently ==

Once you know it all works, edit /etc/modules and add the following two lines

{{{
kvm
kvm-intel
}}}
or 
{{{
kvm
kvm-amd
}}}