1. One or more non-transitory computer-readable storage media having collectively stored thereon instructions that, when executed by one or more processors of a system, cause the system to: execute a hypervisor that controls interaction between one or more computer system instances and physical hardware of the one or more computer system instances, where the hypervisor is configured to expose at least two functions to the one or more computer system instances, the at least two functions containing at least: a first function of the at least two functions configured to cause the one or more cryptographic keys contained by the one or more computer system instances to be unavailable for inclusion in serialization data; and a second function of the at least two functions configured to restore the one or more cryptographic keys to the one or more computer system instances; determine that a serialization event will occur; cause the hypervisor to signal a particular computer system instance of the one or more computer system instances that a serialization event is scheduled to occur, thereby causing the particular computer system instance to perform one or more operations, as a result of calling the first function, prior to the serialization event such that one or more cryptographic keys contained in the particular computer system instance is made unavailable for inclusion in serialization data; and cause serialization of the particular computer system instance to be performed to generate the serialization data, the generated serialization data lacking the one or more cryptographic keys as a result of the one or more operations having been performed.