Secure and efficient memory sharing for guests is disclosed. For example, a host has a host memory storing first and second guests whose memory access is managed by a hypervisor. A request to map an IOVA of the first guest to the second guest is received, where the IOVA is mapped to a GPA of the first guest, which is is mapped to an HPA of the host memory. The HPA is mapped to a second GPA of the second guest, where the hypervisor controls access permissions of the HPA. The second GPA is mapped in a second page table of the second guest to a GVA of the second guest, where a supervisor of the second guest controls access permissions of the second GPA. The hypervisor enables a program executing on the second guest to access contents of the HPA based on the access permissions of the HPA.