Patent ID: 8793785

Claim:
A microprocessor, comprising: a model specific register (MSR), having an address; fuses, manufactured with a first predetermined value; a control register, wherein the microprocessor is adapted to initially load the first predetermined value from fuses into the control register, wherein the microprocessor is adapted to receive a second predetermined value into the control register from system software of a computer system comprising the microprocessor subsequent to initially loading the first predetermined value into the control register; and wherein the microprocessor is configured to prohibit access to the MSR by an instruction that provides a first password generated by encrypting a function of the first predetermined value and the MSR address with a secret key manufactured into the first instance of the microprocessor, and configured to enable access to the MSR by an instruction that provides a second password generated by encrypting the function of the second predetermined value and the MSR address with the secret key.