x86-urgent-2020-04-12

detection feature.

It addressed the case where a KVM guest triggers a split lock #AC and KVM
reinjects it into the guest which is not prepared to handle it.

Adds proper sanity checks which prevent the unconditional injection into
the guest and handles the #AC on the host side in the same way as user
space detections are handled. Depending on the detection mode it either
warns and disables detection for the task or kills the task if the mode is
set to fatal.