Comment 8 for bug 1581420

Right, I think I have v3 more or less but with the two hunks in guest_walk added (which I mentioned). It is a bit hard to compare patches as I had to refresh the quilt patch. On top of this I decided to pick the change that updates hvm_cpuid and the vMTRR code.
I kept this separate in case testing would blow up. Not done yet but so far looked promising.