commit c2eb6a383df9889759e5f4833634cb1f83a59d3c
author Andrew Scull <ascull@google.com> Thu Dec 13 16:54:24 2018 +0000
committer Andrew Scull <ascull@google.com> Tue Dec 18 10:39:46 2018 +0000
tree 753e7f48fc7ac43e7656de05c005e1f2dc304245
parent 35accfa081ff5e8c64c31b3ae3bf2cfec80ff4d1

Quit pretending that IPAs aren't identity mapped.

Information about memory sharing will be stored in the page table
entries rather than introducing a new data structure as that adds
complexity and new potential for memory management issues.

The information includes tracking whether memory is owned by a VM. If a
region of memory is borrowed by another, the memory can only be passed
back the the owner and this is checked by looking in the page table.
Identity mapping is needed so we know where to look in the table as,
otherwise, searching for a physical address is impractical.

Change-Id: I417376b3ecd31bc07518ac5c51b9fb7df2f4b3e1