We have here R410 servers with Intel L5640 CPUs (Westmere microarchitecture).
L5640s support the new AES instructions, as well as the PCLMULQDQ instruction.
The BIOS version 1.4.7 displays a field ``Intel(R) AES-NI'', which is not modifiable, and says ``enabled''. Unfortunately the BIOS writer apparently misunderstood Intel's documentation, and instead of enabling the instructions, BIOS 1.4.7 invariably sets bis 0 and 1 of the MSR number 0x13c, which has the effect of _disabling_ the AES instructions.
The older BIOS version 1.3.9 plays no funny game with this MSR, and as a consequence, AES instructions do work when BIOS is downgraded to 1.3.9:
@dell: please fix your bios, and adjust your testing procedures. You might want to fix function aes_config in mp.rom, or maybe fix setup.ibl's data field at offset 0x14c32 (haven't figured out all the bits).
I have encountered a similar issue after updating the BIOS on a Poweredge M610 with Intel X6850 CPUs.
With BIOS 2.0.11, my GNU/Linux kernel detects and uses the AES-NI instructions.
With BIOS 2.1.15, the kernel no longer sees AES-NI and fails with error messages when trying to use it.
I have rolled back to the 2.0.11 BIOS and it all works again.
I have not tried any of the intermediate BIOS updates, but looking at the release notes on http://ftp.dell.com/bios/PEM610-020109BIOS.txt it was most likely introduced in BIOS 2.1.9
Similar to the original poster, the 2.1.15 BIOS shows the AES-NI as an unmodifiable option in the BIOS that is set to enabled.
This issue is apparently fixed in the latest BIOS http://ftp.dell.com/bios/PEM610-020209BIOS.TXT
"* Ensure BIOS has enabled processor AES-NI before booting to the operating system."