Amazon patents memory sharing method for secure software handoffs

1. A method comprising: storing, in system memory, a set of page tables with mappings of virtual memory addresses to physical memory addresses associated with physical pages over multiple translation levels, wherein a first page table base address of a first software component points to a lowest level page table in the set of page tables, and a second page table base address of a second software component points to the lowest level page table in the set of page tables, wherein the lowest level page table is shared between the second software component and the first software component, the first software component having a higher execution privilege level than the second software component; determining that an ownership transfer of a physical page in the system memory from the first software component to the second software component is to be performed; performing a page table walk of the set of page tables to determine a mapping of a virtual memory address to a physical memory address associated with the physical page, each page table in the set of page tables comprising page table entries for a corresponding translation level; identifying a page table entry for a last translation level that corresponds to the physical page, the page table entry comprising a first ownership indicator bit to indicate ownership by the first software component and a second ownership indicator bit to indicate ownership by the second software component; determining that the physical page is owned by the first software component based on the first ownership indicator bit being enabled and the second ownership indicator bit being disabled in the page table entry; and performing the ownership transfer of the physical page from the first software component to the second software component by updating the page table entry to disable the first ownership indicator bit and to enable the second ownership indicator bit.