Ok, here's a patch that also makes -kernel-kqemu behave (with the
previous patch it would abort with a "triple fault").

Due to the way kqemu sets up the mmu there should never be a GP fault
in the mem access operations, so it would normally indicate some
breakage and kqemu correctly aborts. However I looked it up in the
amd64 specs and there can be a GP fault in a memory access when the
sign extend bits ([63:52]) of the address are not in "canonical form"
(for instance 0xff00000000000000 is not in canonical form). This patch
will make such a GPF be reported to qemu. The patch only affects the
x86-64 on x86-64 case.