Install KVM in RHEL7

Install KVM in RHEL7

By default, a RHEL 7 system doesn't come with a KVM or libvirt preinstalled. This can be installed in three ways:

Through the graphical setup during the system's setupVia a kickstart installationThrough a manual installation from the command line

To install a KVM, you will require at least 6 GB of free disk space, 2 GB of RAM, and an additional core or thread per guest.

Check whether your CPU supports a virtualization flag (such as SVM or VMX). Some hardware vendors disable this in the BIOS, so you may want to check your BIOS as well. Run the following command:

# grep -E 'svm|vmx' /proc/cpuinfo
flags    : ... svm ...
Check whether the hardware virtualization modules (such as kvm_intel and kvm) are loaded in the kernel using the following command:

# lsmod | grep kvm
kvm_intel             155648  0
kvm                      495616  1 kvm_intel

Manual installation
This way of installing a KVM is generally done once the base system is installed by some other means. 

Install the software needed to provide an environment to host virtualized guests with the following command:
# yum -y install qemu-kvm qemu-img libvirt

The installation of these packages will include quite a lot of dependencies.

Install additional utilities required to configure libvirt and install virtual machines by running this command:
# yum -y install virt-install libvirt-python python-virthost libvirt-client

By default, the libvirt daemon is marked to autostart on each boot. Check whether it is enabled by executing the following command:
# systemctl status libvirtd

libvirtd.service - Virtualization daemon
   Loaded: loaded (/usr/lib/systemd/system/libvirtd.service; enabled)
   Active: inactive
   Docs: man:libvirtd(8)
    http://libvirt.org

If for some reason this is not the case, mark it for autostart by executing the following:
# systemctl enable libvirtd
To manually stop/start/restart the libvirt daemon, this is what you'll need to execute:
# systemctl stop libvirtd
# systemctl start libvirtd
# systemctl restart libvirtd

Kickstart installation
Installing a KVM during kickstart offers you an easy way to automate the installation of KVM instances. 

Add the following package groups to your kickstarted file in the %packages section:
@virtualization-hypervisor
@virtualization-client
@virtualization-platform
@virtualization-tools
Start the installation of your host with this kickstart file.

Graphical setup during the system's setup
This is probably the least common way of installing a KVM. The only time I used this was during the course of writing this recipe. Here's how you can do this:

Boot from the RHEL 7 Installation media.
Complete all steps besides the Software selection step.
Go to Software Selection to complete the KVM software selection.
Select the Virtualization host radio button in Base Environment, and check the Virtualization Platform checkbox in Add-Ons for Selected Environment:
Finalize the installation.
On the Installation Summary screen, complete any other steps and click on Begin Installation.