1. A computer-implemented method, comprising: under the control of one or more computer systems configured with executable instructions, instantiating a virtual machine managed by a hypervisor by at least loading obfuscated memory associated with the virtual machine into memory of a host computer system; receiving at the hypervisor a page fault corresponding to an attempt, by the virtual machine, to access at least one memory page stored in obfuscated memory and at least partially referenced in a page table; transmitting a command to a memory obfuscation service, the command causing the memory obfuscation service to un-obfuscate the at least one memory page and load the un-obfuscated at least one memory page into a virtual cache associated with the virtual machine; updating the page table to include information corresponding to the un-obfuscated at least one memory page and the virtual cache; and providing the virtual machine with access to the un-obfuscated at least one memory page.