Security sensitive workloads are often not virtualised because it opens them up to "What are the other virtual machines doing?". There've been a number of Xen

Security sensitive workloads are often not virtualised because it opens them up to "What are the other virtual machines doing?". There've been a number of Xen and KVM issues over the years, including a couple which may have resulted in a bad actor having access to the hypervisor (and thus, all its guests). Attacks like Rowhammer also play in this space.