High-performance reconfigurable computers (HPRCs) are parallel computers but with added FPGA chips. Examples of such systems are the Cray XT5h and Cray XD1, the SRC-7 and SRC-6, and the SGI Altix/RASC. The execution of parallel applications on HPRCs mainly follows the single-program multiple-data (SPMD) model, which is largely the case in traditional high-performance computers (HPCs). In addition, the prevailing usage of FPGAs in such systems has been as co-processors. The overall system resources, however, are often underutilized because of the asymmetric distribution of the reconfigurable processors relative to the conventional processors. This asymmetry is often a challenge for using the SPMD programming model on these systems. In this work, we propose a resource virtualization solution based on partial run-time reconfiguration (PRTR). This technique will allow sharing the reconfigurable processors among the underutilized processors. We will present our virtualization infrastructure augmented with an analytical investigation. We will verify our proposed concepts with experimental implementations using the Cray XD1 as a testbed. It will be shown that this approach is quite promising and will allow full exploitation of the system resources with fair sharing of the reconfigurable processors among the microprocessors. Our approach is general and can be applied to any of the available HPRC systems.