Methods, systems, and machine readable medium for multi-thread safe system level modeling simulation (SLMS) of a target system on a host system. An example of a SLMS is a SYSTEMC simulation. During the SLMS, SLMS processes are executed in parallel via a plurality of threads. SLMS processes represent functional behaviors of components within the target system, such as functional behaviors of processor cores. Deferred execution may be used to defer execution of operations of SLMS processes that access a shared resource. Multi-thread safe direct memory interface (DMI) access may be used by a SLMS process to access a region of the memory in a multi-thread safe manner. Access to regions of the memory may also be guarded if they are at risk of being in a transient state when being accessed by more than one SLMS process.