In a cloud computing environment, a production server virtualization stack is minimized to present fewer security vulnerabilities to malicious software running within a guest virtual machine. The minimal virtualization stack includes support for those virtual devices necessary for the operation of a guest operating system, with the code base of those virtual devices further reduced. Further, a dedicated, isolated boot server provides functionality to securely boot a guest operating system. The boot server is isolated through use of an attestation protocol, by which the boot server presents a secret to a network switch to attest that the boot server is operating in a clean mode. The attestation protocol may further employ a secure co-processor to seal the secret, so that it is only accessible when the boot server is operating in the clean mode.