Comment 9 for bug 1494602

Managed to verify that switching between pc-i440fx-trusty and -utopic will cause the svm flag to be dropped (as long as it is not forcefully enabled in the libvirt config).

And my special failure seems to be caused by another oddness in qemu: while a Opteron_G4 is too recent and I would have to disable things, the Opteron_G3 which normally gets picked as a base is far too old. (the G4 is based on 62xx but G3 is based on 23xx, while I got a 61xx). The better match for my case seems "phenom" which at least sets the right cpuid_level and xlevel.