US 7,275,136 Bl *Sep. 25, 2007
In a computer system with a non-segmented, region-based memory architecture, such as Intel IA-64 systems, two or more sub-systems share a resource, such as a virtual-tophysical address mapping and need to have overlapping regions of the virtual address space for accessing different physical addresses. Virtual addresses include a portion that is used to identify which region the issuing sub-system wants to access. For example, the region-identifying portion of virtual addresses may select a region register whose contents point to a virtual-to-physical address mapping for the corresponding region. To protect a second sub-system S2 from a first SI, whenever the SI issues an address in a region occupied by S2, the region for the S2 is changed. This allows SI to issue its addresses without change. In a preferred embodiment of the invention, S2 is a virtual machine monitor (VMM) and SI is a virtual machine running on the VMM.
11 Claims, 6 Drawing Sheets