Guest not working in KVM mode but does in TCG mode

Qemu: 1.5.0 (Debian 1.5.0+dfsg-3ubuntu5)
Host: Ubuntu 13.10 x86_64 (Intel Core i7-950)
Guest: FreeBSD 9.2 RELEASE x86_64

As initially reported here: https://www.redhat.com/archives/libvirt-users/2013-November/msg00066.html
I was told that this is a bug in Qemu.

Basically this command works:
qemu-system-x86_64 -hda images/FreeBSD-9.2-RELEASE-amd64.img

But this one doesn't:
qemu-system-x86_64 -machine accel=kvm -hda images/FreeBSD-9.2-RELEASE-amd64.img

FreeBSD is stuck after the bootloader:
Booting...
CPU doesn't support long mode