What happens if there is a warrant or subpoena? Is there some kind of "backdoor" to enable the cloud provider to grant law enforcement/intelligence/etc access?

What happens if there is a warrant or subpoena? Is there some kind of "backdoor" to enable the cloud provider to grant law enforcement/intelligence/etc access? Or not? From what I understand, theoretically with something like AMD SEV it could be configured so no such "backdoor" exists. However, is it actually set up that way in practice?