Investigate hypervisor/guest/vm behaviour.

[cvonelm]

perf has a lot of options to control how it interacts with guest VMs below it and hypervisors above it.

Currently, lo2s is oblivious to the fact that virtualization exists.

It would be nice to know:

• What already works right now without any manual intervention
• What we could gain from making lo2s vm-aware
• What things are possible and what are almost certainly impossible (for example, I think that sample resolution for IPs in the hypervisor is going to be pretty hard, because we have to look up binaries in the hypervisor)

Something to keep in mind, and which started of this whole discussion is the existence of

PERF_CONTEXT_GUEST_{KERNEL, USER} and PERF_CONTEXT_HV callstack markers, which show you where in the callstack the guest/hypervisor begins.