One of the more concerning details in the ongoing story of Spectre-related system patches has been how users would get said updates. Per Intel's announcement, distribution of the new CPU microcode is up to the whims of motherboard manufacturers, system integrators, and OEMs who may or may not find the time to push out updated firmware for motherboards many years old. Microsoft is stepping up to the plate to service potentially put-out customers.
The company has begun including microcode updates for Skylake systems on the Microsoft Update catalog, and says it will expand its offerings as Intel supplies further microcode patches for older CPUs. For now, the only updates that Microsoft is offering are for Skylake desktop and laptop processors. Hopefully the fixes that Intel is cooking up for older CPUs find their way to the Microsoft Update Catalog soon.
The current updates are only for Windows 10 version 1709—more widely known as the Fall Creators Update—and you won't get them through Windows Update. Instead, you'll have to head over to the Microsoft Update Catalog site to grab the packages. Note that you don't need to get the update if you've already flashed a fixed firmware for your motherboard.