Method for sharing memory of virtual machine and computer system using the same

A computer system, adapted to execute at least one virtual machine, and the computer system comprising:

• a memory unit, comprising a plurality of physical memory pages;
• a processing unit, coupled to the memory unit;
• and
• a memory control unit, coupled to the processing unit and the memory unit, wherein the memory control unit obtains a memory map corresponding to the at least one virtual machine, the memory map stores usage states of a plurality of memory pages of the corresponding virtual machine, the memory control unit marks unused memory pages on the at least one virtual machine as a plurality of first free pages according to the memory map corresponding to the at least one virtual machine, and shares the first free pages in the at least one virtual machine.