Does this, like SGX, require signing by AMD itself?

This is a major letdown for SGX adoption, making it essentially useless for anyone but maybe niche markets trying to protect IP on cloud services.

If a master key COULD be loaded by the OS early at boot time (and cannot be replaced until CPU reset), it would be incredibly useful to create software-based TPM services that provide trusted isolation where needed.

It seems as if intel/amd are doing this 'just because die space is cheap, and why not try "ip-protection-as-a-service"' instead of a truly generic solution.