I have 2 HP Blade c7000 enclosures approx half full of HP Blades all AMD (g1s to g7s) as well as many other rack mounted servers. I don't run any hyper-thread cores in my environment.
My understanding is that AMD cores are real cores and need to be licensed as such. If you use HT cores you may have to license them (I don't know). I personally multi-box multiple copies of the same game client on my HP Envy 17 3D which has in i7 with 4 real cores & 4 HT cores & I try to never run my clients on HTs (the MB software allows me to skip the HTs). I definitely see a difference in frame rates and performance if I forget to configure to not use HT cores... If I wouldn't do it to myself I wouldn't do it to my users either... That being said Oracle may count HT cores as real cores for licensing so I wouldn't pin them for that reason alone if they do.
Thanks for reply. In Intel HT technology is situation quite clear
(how is described in http://www.oracle.com/technetwork/server-storage/vm/ovm-hardpart-168217.pdf),
no need any licences for HT cores. But AMD technology is quite different: some parts of processors
are common, some not (see http://de.wikipedia.org/wiki/AMD_Bulldozer),
and, however, in licensy politics is impossible to find any logic :) . In licensy documentation which I found
isn't noticed this AMD technology, so I have the same opinion like you (all cores must be licensed),
but I'm not sure.