Linux.com - https://www.linux.com/news/linux-vs-meltdown-and-spectre-battle-continues-2
So, where are we with fixing the problems? Work is continuing, but the latest update of the stable Linux kernel, 4.14.2, has the current patches. Some people may experience boot problems with this release, but 4.14.13 will be out in a few days.
Patches have also been added to the 4.4 and 4.9 stable kernel trees. But, as Greg Kroah-Hartman added, “This backport is very different from the mainline version that is in 4.14 and 4.15, there are different bugs happening.” Still, he said, “Those are the minority at the moment, and should not stop you from upgrading.”