AMD admit that their CPUs are vulnerable to both variants of Spectre but they think that patches, OS plus microcode, will fix the vulnerability:As far as I'm aware, there is no real fix for Spectre variants 1 and 2 - only restrictions that hopefully make their exploitation more unlikely. A real fix requires a design change to both Intel and AMD CPUs (variant 1 only in the latter case). The fix for Meltdown is the real performance killer and I just hope that it isn't also applied to AMD CPUs that aren't susceptible.
https://www.amd.com/en/corporate/speculative-execution