This was fixed by commit 8f964525
upstream.  This alternate fix avoids the need for extensive backporting.

RHEL5 i386 guests register non 32-byte aligned addresses:

kvm-clock: cpu 1, msr 0:3018aa5, secondary cpu clock
kvm-clock: cpu 2, msr 0:301f8e9, secondary cpu clock
kvm-clock: cpu 3, msr 0:302672d, secondary cpu clock

Check for an address+len that would cross page boundary
instead.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
[dannf: backported to Debian's 2.6.32]
Signed-off-by: Willy Tarreau <w@1wt.eu>