[ Upstream commit ac55c768 ]

This has become necessary with chips that support more than 43-bits
of physical addressing.

Based almost entirely upon a patch by Bob Picco.
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Bob Picco <bob.picco@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>