Comment 11 for bug 639712

I'm trying with 12.04 LTS KVM host and guest.

RHEL 6 documentation says: {{ Secure device assignment also requires interrupt remapping support. If a platform does not support interrupt remapping, device assignment will fail. To use device assignment without interrupt remapping support in a development environment, set the allow_unsafe_assigned_interrupts KVM module parameter to 1. }}

and I get in dmesg:

[ 5556.500176] kvm_iommu_map_guest: No interrupt remapping support, disallowing device assignment. Re-enble with "allow_unsafe_assigned_interrupts=1" module option.

Easy to create
/etc/modprobe.d/kvm.conf containing

options kvm allow_unsafe_assigned_interrupts=1

However, there is CVE-2011-1898 which this makes your system vulnerable to see:

https://bugzilla.redhat.com/show_bug.cgi?id=715555