I've had this discussion several times - unfortunately Oracle doesn't recognise BIOS disabling of cores as a valid means of "hard partitioning". I know it sounds nuts 
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The only way to sub-divide a physical x86 server, when not an Oracle engineered system, is to:
* use Oracle VM Server and pin VMs to cores (even to just to have 1 VM and leave lots of cores idle),
* use Solaris x86 and use capped containers/zones.
VMware can say what they like but at the end of the day the customer receives the licence audit from Oracle LMS, not VMware. I'd love to hear if anyone has had a written agreement with Oracle to recognise BIOS disabling on other vendors' hardware though.