In outsourced computation, privacy of the computation itself is usually not important. You have your encrypted data in the cloud, and you want the cloud to perform a computation on it, on your behalf, so that you get no information about what computation was actually done?? That seems totally useless. Far more likely is that you know exactly what computation should be done on the encrypted data, and you want assurance that you received the correctly-computed output. This is a guarantee of integrity, not privacy.
Maybe you are thinking that the cloud has some kind of additional, secret input to the (agreed-upon) computation. In that case, the entire field of secure multi-party computation (SMPC) involves formalizations of what it means to "learn no more about the other guy's input than could be legitimately inferred from the output of the computation." Not all of SMPC involves settings that are suitable for outsourced cloud computing. But if you're just looking for formalizations of the requirements (i.e., security definitions), the SMPC literature will give you an idea of what they look like. It's hard to tell from your question whether you are interested in security definitions or constructions.