Looking for which hardware is affected, I only found a statement form AMD [0] tldr, Ryzen CPUs are fine

> "AMD is aware of an issue with some older generation processors following installation of a Microsoft security update that was published over the weekend. AMD and Microsoft have been working on an update to resolve the issue and expect it to begin rolling out again for these impacted shortly."

[0] http://www.techradar.com/news/meltdown-and-spectre-windows-p...