1. A method of mapping platform configuration registers (PCRs) of a TRUSTED PLATFORM MODULE (TPM) or virtual TRUSTED PLATFORM MODULE (vTPM) instance into the register space of a child vTPM, said method comprising: receiving a request to read a state of a Platform Configuration Register (PCR) of the child vTPM; requesting from a parent of the child vTPM the value of the PCR in response to determining that the PCR is mapped to the parent TPM, the parent TPM comprising one of a TPM or a vTPM; requesting from the child vTPM the value of the PCR in response to determining that the PCR is not mapped to the parent TPM; and returning the value of the PCR in response to the receiving.