An update that protects against the Spectre version 1 attack was already available. To protect computers against Spectre version 2, both an update for the operating system as a microcode update for the CPU is required.
Microsoft has now released Spectre updates for AMD systems running Windows 10 Fall Creators Update. The updates will be automatically downloaded and installed on relevant systems. AMD has released microcode updates for processors from 2011 (Bulldozer) and later. Users should be able to find the respective updates on the website of their main board manufacturer.
Initially the Windows patches for AMD computers caused issues for users with specific hardware, after which Microsoft decided to temporarily put the distribution of the updates on hold.
AMD powered systems don’t need to install updates for the Meltdown attack because AMD processors are not vulnerable to that attack.