feat(downfall): add downfall checks

[PandiPanda69]

Attempt to add the downfall checks with an update of the Intel db (feat issue #465).

Tested in different contexts and do work properly in these contexts:

• Not vulnerable hardware (Atom, AMD, Xeon D-1540, ...)
• Vulnerable hardware with no kernel upgrade & no microcode upgrade
• Vulnerable hardware with kernel upgrade (and sysfs support)
• Vulnerable hardware with kernel upgrade and microcode patched
• Vulnerable hardware with microcode patched but old kernel

Review & feedbacks welcomed :)

[speed47]

Thanks! Added a commit on top of yours, and rearranged some of your code to stick with the code style and expected output.

We're still missing:

• BSD support
• offline mode checking for Linux
• checking whether kernel has indeed disabled AVX on an affected CPU with no microcode update, in live mode, when --no-sysfs is specified

It's still not 100% clear whether no-longer Intel supported CPUs that have AVX are affected or not. The script will currently deem those as safe, as it seems to be what the kernel does. This may change in the next few days when more data is available.

[speed47]

Can you test it?

[speed47]

Thanks a bunch!