Introduces a kernel option that, when enabled, reduces the kernel window in a user address
space to just be Static Kernel Image and Microstate (SKIM), instead of the full kernel
address space. This isolates the important kernel data from the user preventing a
Meltdown style attack being able to violate secrecy. The kernel text and read only data,
i.e. anything that is static from boot, is not secret and can be allowed in the SKIM window
and potentially read by the user. Additionally to switch to and from the actual kernel
address space a small amount of state needs to also be in the SKIM window.
This is only an implementation for x86-64, although the same design is applicable to ia32
