Xen devel - Jul 2008 - [PATCH] Patchset to protect guest ROM areas from R/W access.

This is a set of patches to protect guest ROM areas by making them actually
be read-only.

xen_handle_p2m_type_ro.patch:
   This makes writes to pages with p2m_ram_ro stop falling through to the
device model, and instead writes get logged but discarded.

xen_hvmop_set_mem_type.patch:
   This adds a new command, "set_mem_type" to the hvmop hypercall
which
allows marking ram page ranges as ro, rw, or mmio_dm.

ioemu_xen_platform.patch
   This adds functionality to the xen platform device to enable a guest to
set/unset the RO state of ROM. A guest can enable
   or disable RW access to the ROM range ( 0xc0000-0xfffff ) by writing to
the lowermost io port of the xen platform device. This
   port now provides access to a flags register, which currently only has
one flag bit, namely bit 0, to set/clear write access to the ROM range.
   This patch should apply to both the old ioemu tree or the new
upstream-merged git tree.

xen_firmware_make_ROM_ro.patch
   This adds changes to hvmloader and rombios to make use of the above
platform_device functionality to write-protect ROM areas. This is somewhat
ugly, but unfortunately the virtual bios has grown to rely on being able to
self-modify. At a later stage, I''m going to try to remove any
self-modifying
bits on the rombios and move any such post-load modifications into
hvmloader, so that hvmloader can handle the ROM locking, which would be
cleaner.

Signed-off-by: Trolle Selander <trolle.selander@eu.citrix.com>






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New approach to the firmware part, as per Keir''s suggestions.

Signed-off-by: Trolle Selander <trolle.selander@eu.citrix.com>



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