virt_whp: coconut-svsm self test with 2 procs hangs on ipi test

[chris-oo]

Running coconut-svsm built with hyper-v support, the ipi self tests seem to hang. I suspect that something is broken with our start vp hypercall handling since openhcl does not use it in vtl2.

build the svsm with make test-in-hyperv and run with something like:

cargo run --target x86_64-pc-windows-msvc -- --hv --vtl2 --igvm ~/svsm/bin/coconut-test-hyperv.igvm --com3 console --com1 none --igvm-vtl2-relocation-type disable --late-map-vtl0-policy off --processors 2

[chris-oo]

probably we're missing some active_vtl check in hypercall handling, because from inspect it looks like we started VTL0, but not VTL2:

    vtl2: {
        activity: {
            interrupt_shadow: false,
            mp_state: "halted",
 
    vtl0: {
        activity: {
            interrupt_shadow: false,
            mp_state: "running",

[chris-oo]

actually on second glance, the vp start seems to work but then sending an ipi isn't? will need more debugging.