Implement the SpeculationBarrier with implementations consisting of
fence instruction which provides finer-grain memory orderings.
Perform Data Barrier in RiscV: fence rw,rw
Perform Instruction Barrier in RiscV: fence.i; fence r,r
More detail is in Appendix A: RVWMO Explanatory Material in
https://github.com/riscv/riscv-isa-manual
This API is first introduced in the below commits for IA32 and x64
d9f1cac51be83d841fdc
and below the commit for ARM and AArch64 implementation
c0959b4426
This commit is to add the RiscV64 implementation which will be used by
variable service under Variable/RuntimeDxe
Cc: Andrei Warkentin <andrei.warkentin@intel.com>
Cc: Evan Chai <evan.chai@intel.com>
Cc: Sunil V L <sunilvl@ventanamicro.com>
Cc: Tuan Phan <tphan@ventanamicro.com>
Signed-off-by: Yong Li <yong.li@intel.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Yong Li