KVM virtualization quick setup on Linux

Introduction

KVM (Kernel Virtual Machine) is a great implementation for virtualization in Linux on x86 architectures. It has both Intel and AMD virtualization extensions with :

• Kernel module : kvm.ko - core virtualization infrastructure
• Processor module : kvm-intel.ko or kvm-amd.ko
• Files can be located e.g.

$ ls -lh /lib/modules/3.5.0-17-generic/kernel/arch/x86/kvm/
total 936K
-rw-r--r-- 1 root root  95K Oct  9  2012 kvm-amd.ko
-rw-r--r-- 1 root root 195K Oct  9  2012 kvm-intel.ko
-rw-r--r-- 1 root root 642K Oct  9  2012 kvm.ko

 Kernel Version Check

• The KVM kernel component has been in Linux since 2.6.20
• Check your version :

$ uname -r

Hardware Virtualization Support

• A lot of hardware does not enable virtualization by default
• You can review the BIOS and check for any virtualization enable options
• Note : For Dell laptops (and potentially others) I have found you need to go into the BIOS and disable Trusted Execution
• From the OS we can review flags set on /proc/cpu

 $ egrep "flags.*:.*(svm|vmx)" /proc/cpuinfo

• If values are returned virtulaization is supported
• Flags of interest
• vmx — Intel VT-x, basic virtualization
• svm — AMD SVM, basic virtualization 

• Review of dmesg (kernel  message buffer) shows if kvm loaded e.g.

 $ dmesg | egrep kvm
[   25.601412] kvm: Nested Virtualization enabled

 

Package Requirements

 

qemu-kvm

• qemu-kmv (Quick EMUlator) : allows userspace programs to access virtulization components of supported CPU's
• As mention previously the kernel modules for KVM are included in mainline Linux
• qemu features
• Processor emulator (here x86)
• Emulated devices e.g. keyboard, mouse, NIC, graphics card, hard disk etc
• Generic devices connect emulated devices to the related host devices
• Machine descriptions of virtual machines
• Debugger
• User interface
• Hardware acceleration 

• Emulated and generic devices comprise its device models for I/O virtualization

libvirt-bin

• API that acts as a wrapper for qemu-kvm 
• Toolkit to interact and manage  a quemu-kvm hypervisor
• Features
• Mange VM's, virtual networks and storage
• Remote management with TLS and x509 certificates
• Its possible to use qemu-kvm without libvirtapi
• VM's created by qemu-kvm are not visible with the libvirt tools

bridge-utils

• Contains brctl program to create and manage bridge devices
• Required for configuring hosted VM ntwork

virt-goodies

• A collection of helpful virtualization related tools
• Tool to convert from VMWare images to kvm/libvirt e.g. vmware2libvirt
• A libvirt munin plugin

Installation

• The following installation is for Linux Mint but other Linux distributions will be similar
• Install :

$ sudo apt-get install qemu-kvm libvirt-bin bridge-utils virt-goodies

• This will also install 

kvm-ipxe qemu-common qemu-utils

Bridge Setup

• One option is to remove the Linux Mint 'network-manager' but in my case I did not want to remove this component
• Backup interfaces files

 $ sudo cp /etc/network/interfaces ~/tmp/interfaces.bak

• Update /etc/network/interfaces as follows

auto lo
iface lo inet loopback

iface eth0 inet manual

auto br0
iface br0 inet dhcp
        bridge_ports eth0
        bridge_maxwait 0

• Restart networking

$ sudo service networking restart

• Check networking with ifconfig (I have changed the MAC's) :

$ ifconfig br0
br0       Link encap:Ethernet  HWaddr 11:11:11:11:11:11 
          inet addr:192.168.0.197  Bcast:192.168.0.255                          Mask:255.255.255.0
          inet6 addr: fe80::21f:16ff:fe45:49eb/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:334 errors:0 dropped:0 overruns:0 frame:0
          TX packets:364 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:127873 (127.8 KB)  TX bytes:89251 (89.2 KB)

$ ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 11:11:11:11:11:00 
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:60003 errors:0 dropped:0 overruns:0 frame:0
          TX packets:47724 errors:0 dropped:0 overruns:0                          carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:45267129 (45.2 MB) TX bytes:11804118 (11.8 MB)

• Check bridge status

$ sudo brctl show
bridge name    bridge id        STP enabled    interfaces
br0        8000.001f164549eb    no        eth0

• Ping Google's DNS to test connectivity

$ ping  8.8.8.8

• Reboot machine to ensure connection is retained

GUI Management

• Install GUI

 $ sudo apt-get install -y virt-manager

• Check libvirtd group exists

$ cat /etc/group | grep -i libvirt
libvirtd:x:128:

•  Add your username to this group i.e. replace 'cwishaw'

$ sudo usermod -a -G libvirtd cwishaw

• Logout and back in again for group change to take effect 
• Open 'Virtual Machine manager from the Menu and following should appear

•  If it does not connect locally check libvirtd is running and if not restart

$ ps -ef | grep -i libvirtd
root      1622     1  0 14:35 ?        00:00:05 /usr/sbin/libvirtd -d
$ sudo /etc/init.d/libvirt-bin restart

  Change Default VM Location

• By default, libvirt stores images in the /var/lib/libvirt/images directory
• As the owner is root we would like to select our own dir
• Create directory

$ mkdir ~/KVMImages
$ virsh pool-edit default 

• Update <path> e.g.

<path>/home/cwishaw/KVMImages</path>

•  Restart libvirt

$ sudo /etc/init.d/libvirt-bin restart

• Open 'Virtual Machine manager select 'Edit -> Connection Details->Storage -> default'
• Location should be new folder e.g. /home/cwishaw/KVMImages

Custom Storage ISO Location

• Create directory

$ mkdir ~/ISOs

• Open 'Virtual Machine manager select 'Edit -> Connection Details->Storage -> +'
• Define new Storage Pool then select 'Next'

• Define 'Target Path' as new directory then select 'Finish'
• Disconnect then reconnect to GUI and new Storage Pool will appear 

 Create a VM

• Right Click on 'localhost (QEMU) and select 'New'
• The following screenshots show examples of setting up a new VM

Graphs

• There are some nice graph options that can be enabled in 'Virtual Machine Manager under 'Edit -> Preferences -> Stats

• Change view under 'View -> Graph'