Hi Guys!
I just created my first virtual installation using KVM in Ubuntu and installed an OS guest, The issue I am having is When I switch to fullscreen mode, the display is not fully resized to cover the entire available screen of the monitor.
There is black space left on both sides of the display in full screen.

I am using the virt-manager graphical tool to boot into the guest OS. I cant figure out how to have this OS completely go full screen.

I will appreciate all advice, thank you.

The guest needs correct graphics driver to handle the [virtual] graphics card. For instance, VirtualBox ships with drivers for most used operating systems.

Thank you for the reply, I am familiar with virtualbox guest extension package. It works good for the Oracle client, but I am in the Linux Kernel Virtual Machine so the oracle packages probably wont work for me. The reason I decided to go with KVM is because it is built in the Linux Kernel so I thought I would have better performance than VirtualBox, but it is so unfamiliar to me that I am having issues managing it.

If you use qxl graphics You need the spice drivers:

http://www.spice-space.org/download.html

Windows guest -> spice guest tools package - this contains more than the video drivers, it has every kvm-specific driver, including virtio networking, serial and virtio storage + vdagent service (latter is needed for clipboard sharing and dynamic resolution switching).

For USB passthrough: Note that USB redirection has 2 modes - one that you use the host redirection(usb device plugged in the host) and the other is via spice redirection where the USB is plugged in the computer that runs the spice viewer (this works on viewers running ONLY on Linux), which can be connected through ssh redirection from a remote location (i used usb redirection through vpn and worked just fine). You can use this redirection method using a viewer directly on the host too, but if you disconnect the viewer (or crashes), the USB device will be disconnected.

Linux guest -> all drivers are in the kernel (a reasonably new kernel 3 or newer is recommended), for guest X you need xserver-xorg-video-qxl package (this is the Debian package name, every distro has to have something similar).