https://www.theverge.com/2018/1/11/16880922/amd-spectre-firmware-updates-ryzen-epyc

AMD’s initial response to the Meltdown and Spectre CPU flaws made it clear “there is a near zero risk to AMD processors.” That zero risk doesn’t mean zero impact, as we’re starting to discover today. “We have defined additional steps through a combination of processor microcode updates and OS patches that we will make available to AMD customers and partners to further mitigate the threat,” says Mark Papermaster, AMD’s chief technology officer.

AMD is making firmware updates available for Ryzen and EPYC owners this week, and the company is planning to update older processors “over the coming weeks.” Like Intel, these firmware updates will be provided to PC makers, and it will be up to suppliers to ensure customers receive these. AMD isn’t saying whether there will be any performance impacts from applying these firmware updates, nor whether servers using EPYC processors will be greatly impacted or not.