Nice writeup, very easy to read. This guy is a bonafide legend, the whole time, based on his writing style I thought it was someone new to the field explaining in detail because it was hard for him to get it as well, but I see his name at the end and recalled all the epic findings of his. Very humble/nice guy, even in person I hear (rare for well accomplished people in tech).

One thing I don't get though, if amd64 is affected, shouldn't the complementary instructions in X64/intel also be affected? Does intel move around RAT referenced values instead of just setting/unsetting the z-bit?