On 03/05/2018 14:09, Alexander Shishkin wrote: >>> 1. Do we have an event in pt_ctx? >>> * No -> Set up the context for VMX. >>> * Yes -> 2. Is attr.exclude_guest set? >>> * No -> Guest trace goes to the host's buffer, do nothing. >>> * Yes -> Set up/switch the context for VMX. >> Can you explain this more clearly? > Let's see; in the intel_pt driver we have a per-cpu PT "context", from which > we can tell if there is a host event that wants to trace the guest. This > should provide enough information to make a decision whether we want to > context switch PT MSRs or not on the spot, instead of having a module > parameter. I still don't understand how the host event is useful... Paolo
