Hi,

The first patch extend the configuration device with a guest write
capability. A callback is invoked when the buffer is full.

It's a bit odd to get completely different behavior when doing I/O to
the same port just because of the word size used in the IO. I'd rather
have two ports, one for control write or status read and another for
data read/write. Is two ports too much to ask on a PC?

The second patch uses the first one to add a new key for marking guest
pages read only. This patch was inspired due to discussion I saw on
KernelTrap:
http://kerneltrap.org/mailarchive/linux-kernel/2008/9/4/3191234