Function _mm_encodekey256_u32 

pub unsafe fn _mm_encodekey256_u32(
    key_params: u32,
    key_lo: __m128i,
    key_hi: __m128i,
    handle: *mut u8,
) -> u32

Available on x86 and target feature kl only.

Wrap a 256-bit AES key into a 512-bit key handle and stores it in handle. Returns the control parameter used to create the IWKey.

• key_params[0]: If set, this key can only be used by the Kernel.
• key_params[1]: If set, this key can not be used to encrypt.
• key_params[2]: If set, this key can not be used to decrypt.
• key_params[31:3]: Reserved for future use, must be set to 0.

Note that these restrictions need hardware support, and the supported restrictions can be found by calling __cpuid(0x19) and checking the EAX[0:2] bits. Failing to follow these restrictions may result in a General Protection Exception.

Intel’s documentation