I think most if not all cloud VMs dedicate a core to you. Well, there are some that share like the T series on AWS and I think other clouds have similar, but my bet is they can put in an extra "flush" between users to prevent cross tenant leakage.

Of course cross process leakage for a single tenant is an issue, in cloud or on prem, and folks will have to decide how much they trust the processes on their machine to not become evil...