Boxes is an application from the GNOME project that allows you to create and access virtual machines, running locally or remotely. It also allows you to connect to the display of a remote computer.
USE flags for gnome-extra/gnome-boxes Simple GNOME application to access remote or virtual systems
emerge --ask gnome-extra/gnome-boxes
Additionally, the user must be added to the kvm group:
usermod -a -G kvm <user>