Install KVM Hypervisor on CentOS 7

by Dheeraj Kumar · Published June 23, 2018 

KVM is an open source hardware virtualization software through which we can create and run multiple Linux based and windows based virtual machines simultaneously. KVM is known as Kernel based Virtual Machine because when we install KVM package then KVM module is loaded into the current kernel and turns our Linux machine into a hypervisor.

In this post first we will demonstrate how we can install KVM hypervisor on CentOS 7.x and RHEL 7.x and then we will try to install virtual machines.

Before proceeding KVM installation, let’s check whether your system’s CPU supports Hardware Virtualization.

Run the beneath command from the console.

[root@linuxtechi ~]# grep -E '(vmx|svm)' /proc/cpuinfo

We should get the word either vmx or svm in the output, otherwise CPU doesn’t support virtualization.

Step:1 Install KVM and its associate packages

Run the following yum command to install KVM and its associated packages.

[root@linuxtechi ~]# yum install qemu-kvm qemu-img virt-manager libvirt libvirt-python libvirt-client virt-install virt-viewer bridge-utils

Start and enable the libvirtd service

[root@linuxtechi ~]# systemctl start libvirtd
[root@linuxtechi ~]# systemctl enable libvirtd

Run the beneath command to check whether KVM module is loaded or not

[root@linuxtechi ~]# lsmod | grep kvm
kvm_intel             162153  0
kvm                   525409  1 kvm_intel
[root@linuxtechi ~]#

In Case you have Minimal CentOS 7 and RHEL 7 installation , then virt-manger will not start for that you need to install x-window package.

[root@linuxtechi ~]# yum install "@X Window System" xorg-x11-xauth xorg-x11-fonts-* xorg-x11-utils -y

Reboot the Server and then try to start virt manager.

Step:2 Start the Virt Manager

Virt Manager is a graphical tool through which we can install and manage virtual machines. To start the virt manager type the ‘virt-manager‘ command from the terminal.

[root@linuxtechi ~]# virt-manager

Step:3 Configure Bridge Interface

Before Start creating VMs , let’s first create the bridge interface. Bridge interface is required if you want to access virtual machines from outside of your hypervisor network.

[root@linuxtechi ~]# cd /etc/sysconfig/network-scripts/
[root@linuxtechi network-scripts]# cp ifcfg-eno49 ifcfg-br0
[root@linuxtechi network-scripts]#

Edit the Interface file and set followings:

[root@linuxtechi network-scripts]# vi ifcfg-eno49
TYPE=Ethernet
BOOTPROTO=static
DEVICE=eno49
ONBOOT=yes
BRIDGE=br0

Edit the Bridge file (ifcfg-br0) and set the followings:

[root@linuxtechi network-scripts]# vi ifcfg-br0
TYPE=Bridge
BOOTPROTO=static
DEVICE=br0
ONBOOT=yes
IPADDR=192.168.10.21
NETMASK=255.255.255.0
GATEWAY=192.168.10.1
DNS1=192.168.10.11

Replace the IP address and DNS server details as per your setup.

Restart the network Service to enable the bridge interface.

[root@linuxtechi ~]# systemctl restart network
[root@linuxtechi ~]#

Check the Bridge interface using below command :

[root@linuxtechi ~]# ip addr show br0

Step:4 Start Creating Virtual Machines.

Now Create Virtual Machine either from the command line using ‘virt-install‘ command or from GUI (virt-manager )

Let’s Create a virtual machine of “Windows Server 2012 R2” using virt-manager.

Start the “virt-manager”

Go to the File Option, click on “New Virtual Machine”

We will be using ISO file as installation media. In the next step Specify the path of ISO file.

Click on Forward.

Specify the Compute Resources : RAM and CPU as per your setup.

Click on Forward to proceed further.

Specify the storage Size of Virtual Machine, In my case I am using 25G.

In the Next step Specify the Name of Virtual Machine and select network as ‘ Bridge bro’

Click on Finish to start the installation.

Follow the screen instructions and complete the installation.

Creating a virtual Machine from Command Line:

Virtual Machines can be created from the console as well using ‘virt-install’ command. In the following example i going to virtual machine of Ubuntu 16.04 LTS.

[root@linuxtechi ~]# virt-install --name=Ubuntu-16-04 --file=/var/lib/libvirt/images/ubuntu16-04.dsk --file-size=20 --nonsparse --graphics spice --vcpus=2 --ram=2048 --cdrom=ubuntu-16.04-server-amd64.iso --network bridge=br0 --os-type=linux --os-variant=generic
Starting install...
Allocating 'ubuntu16-04.dsk'               | 20 GB 00:00:00
Creating domain...