I have a similar FM2 motherboard, the FM2A85X Extreme6 paired with a AMD 5800-K processor and have just installed VMware ESXi 5.1 on it. The installation was flawless with the NIC being recognized immediately, no tweaks necessary. I do have SVM ,Secure Virtual Machine, enabled (it is by default) in the bios in the CPU section.
However currently, on the summary page of the vsphere client, The direct path I/O is not being recognized.
I have submitted the question to ASROCK support and am awaiting a response to see if I need to enable anything else to have it be recognized.
If you asking about it for Oracle/Sun Virtual box, ASROCK has posted a replay to what needs to changed to allow Virtual box to do this
" [Enable] [Secure Virtual Machine] option in the BIOS.
Please check the [Enable Nested Paging] box in Sun’s xVM virtual box software. "