>> + if ( rsp.flags & VM_EVENT_FLAG_SET_REGISTERS ) > >> + vm_event_set_registers(v, &rsp); > >> + > >> if ( rsp.flags & VM_EVENT_FLAG_TOGGLE_SINGLESTEP ) > >> vm_event_toggle_singlestep(d, v); > > > > What meaning has setting both flags and EFLAGS.TF in the new > > register values? > > That's a good question. I'm not sure how that would affect an attached > debugger type scenario. > > I'm also unsure of what a good solution to this issue would be. I could > make the flags exclusive, but that would prevent, for example, setting > EAX and singlestepping, which should not be a problem. I could also > remove the eflags assignment from vm_event_set_registers() (maybe > replace it with a comment). > > Tamas, do you need eflags set? What do you think? Again, I'm happy with > just setting EIP, what scenarios are you interested in? > > Being able to set registers this way and enabling MTF in one-shot I think offers good flexibility and performance for vm_event applications. I don't see any reason why these options should be exclusive. Furthermore, I don't see why we would treat EFLAGS.TF any different then the others. If the vm_event application decides to flip both the in-guest TF and the external MTF, why prevent that? While I don't see an immediate use-case for this, I also don't see why it would be problematic either.
Tamas
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