It's not just hard to do, it's impossible. For a cloud provider anyway. Given that your software has to be capable of executing Bitcoin transactions itself, a

It's not just hard to do, it's impossible. For a cloud provider anyway. Given that your software has to be capable of executing Bitcoin transactions itself, and the VM manager sits at a higher level and controls allocation and access to your VM's memory (to isolate it from other VMs), you are at the very least trusting that (1) when your cloud provider says they are using VMware or whatever standard software they aren't lying, and (2) that VMware itself is securely designed to limit its own access (and access of its own operators) to the underlying VMs. If you don't want to trust your hosting provider with anything, you have to own the hardware.