Disabling CPU vulnerabilities workarounds

From: Artem S. Tashkinov
Date: Thu Aug 23 2018 - 12:33:51 EST

Hello LKML,

As time goes by more and more fixes of Intel/AMD/ARM CPUs vulnerabilities are added to the Linux kernel without a simple way to disable them all in one fell swoop.

Disabling is a good option for strictly confined environments where no 3d party untrusted code is ever to be run, e.g. a rendering farm, a supercomputer, or even a home server which runs Samba/SSH server and nothing else.

I wonder if someone could wrote a patch which implemented the following two options for the kernel:

* A boot option option which allows to disable most runtime protections/workarounds/fixes (as far as I understand some of them can't be reverted since they are compiled in or use certain GCC flags), e.g. let's call it "insecure" or "insecurecpumode".

* A compile-time CONFIG_ option which disables all these fixes _permanently_ without a way to turn them later back on during runtime.

Right now linux/Documentation/admin-guide/kernel-parameters.txt is a mess of various things which take ages to sift through and there's zero understanding whether you've found everything and correctly disabled it.

Best regards,