The live migration of Virtual Machines (VMs) is a key technology in server virtualization solutions used to deploy Infrastructure-as-a-Service (IaaS) clouds. This process, on one hand, increases the elasticity, fault tolerance, and maintainability in the virtual environment. On the other hand, it increases the security challenges in cloud environments, especially when the migration is performed between different data centers. Secure live migration mechanisms are required to keep the security requirements of both cloud customers and providers satisfied. These mechanisms are known to increase the migration downtime of the VMs, which plays a significant role in the compliance to Service Level Agreements (SLAs). This paper discusses the main threats caused by live migration and the main approaches for securing the migration. The requirements of a comprehensive
Quality of Service (QoS)-aware secure live migration solution that keeps both security and QoS requirements satisfied are defined.