8fedf92a4e
New microcode update for Intel enables mitigation for SRBDS, which slows down RDSEED and related instructions. The update also provides a control to limit the mitigation to SGX enclaves, which should restore the speed of random generator by the cost of potential cross-core bufer sampling. See https://software.intel.com/security-software-guidance/insights/deep-dive-special-register-buffer-data-sampling GIve the user control over it. Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D25221