Files copied from http://ayuda.com.au/pub/xen/grsecurity/patches/ 
linux-2.6.18.8-xen-3.1.0-grsec.bz2
v2.6.18.8-xen-3.1.2-grsecurity-2.1.9.patch.bz2
v2.6.20.20-xen-grsecurity-2.1.10-200704241759.patch.bz2

Files copied from http://download.ravencore.com/packages/source/kernel-xen-grsec/
grsecurity-2.1.9-xen-3.2.0.patch
kernel-xen-grsec-2.6.18.8-1.src.rpm
kernel-xen.spec


Please read the topic "Xen Paravirtualization + grsecurity working!" in the GR Security forum:
http://forums.grsecurity.net/viewtopic.php?f=1&t=1490&sid=8c7652ef01c0031d7061b3076722b41e

Notice for Gentoo users: 
v2.6.20.20-xen-grsecurity-2.1.10-200704241759.patch.bz2 patches cleanly over sys-kernel/xen-sources-2.6.20-r7 and seems to be stable.