On Fri, Dec 01, 2023, Nicolas Saenz Julienne wrote: > > To support this I think that we can add a userspace msr filter on the HV_X64_MSR_HYPERCALL, > > although I am not 100% sure if a userspace msr filter overrides the in-kernel msr handling. > > I thought about it at the time. It's not that simple though, we should > still let KVM set the hypercall bytecode, and other quirks like the Xen > one. Yeah, that Xen quirk is quite the killer. Can you provide pseudo-assembly for what the final page is supposed to look like? I'm struggling mightily to understand what this is actually trying to do.