Virtual machines are increasingly important today because of their extensive use
in cloud computing. The performance of these systems is often limited by the fact
that a lot of relevant information is only known to the guests running in the virtual
machines and is opaque to the host. Paravirtualization, i.e., creating explicit communication
interfaces between the guests and the host, is the mayor technique used
today to overcome this limitation, but the evolution of these interfaces is limited
by the need of keeping them compatible with legacy guests. The purpose of this
thesis is to design and implement a mechanism to extend paravirtualization using
eBPF in order to allow the host to inject arbitrary code into the guest kernel, as
well as the application of this mechanism in order to improve the performance of
virtual machines.