Mandatory Access Control is really poorly supported by Cloud environments. Our paper proposes extensions of the OpenNebula Cloud in order to provide an advanced MAC protection of the virtual machines hosted by the different nodes of the Cloud. Thus, unique SELinx security labels are associated with the virtual machines and their ressources. The instanciations and migrations of the virtual machines maintain those unique security labels. Moreover, PIGA-Virt provides a unified way to control the information flows within a virtual machine but also between multiple virtual machines. SELinux controls the direct flows. PIGA-Virt adds advanced controls. Thus, a PIGA protection rule can control several direct and indirect flows. The benchmarks of PIGA-Virt show that our Trusted OpenNebula Cloud is efficient regarding the quality of the protection.