It wasn't publicly acknowledged but people figured it out already. Take a look at https://news.ycombinator.com/item?id=16046636 (both the article and the comments) for example. This wasn't going to stay secret much longer.
That post is a couple days after the 28 Dec AMD commit, though. Curious if it was _already_ discussed since that would mean no way what AMD said is how people figured it out.
my123 does point out that the author of the speculative execution blog post is first in the KAISER paper's acknowledgments, and looks like the paper was presented at a July conference, so that's an earlier clue out in public, for what it's worth.
