Yeah, the blog post says they knew since June 2017, with that blog post being from July.
> This initial report did not contain any information about variant 3. We had discussed whether direct reads from kernel memory could work, but thought that it was unlikely. We later tested and reported variant 3 prior to the publication of Anders Fogh's work at https://cyber.wtf/2017/07/28/negative-result-reading-kernel-....
