Hi Alex, January 9, 2025 at 2:57 PM, "Alex Bennée" wrote: > Julian Ganz <neither@nut.email> writes: > > diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h > > index 9c67374b7e..f998a465e5 100644 > > --- a/include/qemu/qemu-plugin.h > > +++ b/include/qemu/qemu-plugin.h > > @@ -273,6 +273,21 @@ QEMU_PLUGIN_API > > void qemu_plugin_register_vcpu_resume_cb(qemu_plugin_id_t id, > > qemu_plugin_vcpu_simple_cb_t cb); > > > > +/** > > + * qemu_plugin_register_vcpu_discon_cb() - register a discontinuity > > callback > > + * @id: plugin ID > > + * @cb: callback function > > + * > > + * The @cb function is called every time a vCPU receives a discontinuity > > event > > + * of the specified type(s), after the vCPU was prepared to handle the > > event. > > + * Preparation usually entails updating the PC to some interrupt handler > > or trap > > + * vector entry. > > > The "usually" here is a bit of a weasel word. We should be clear what > the contract is with the plugin. Can we say the PC will be updated to > the next instruction that will execute after the callback?
The contract is indeed clear: the PC will always be updated to the instruction that will be executed next, at least if we don't have a second discontinuity (e.g. jump to an unmapped page). The "usually" refers to the discontinuity itself: in the case of host calls, we don't observe a "jump" and the next instruction executed will just be the instruction following the call. I could have phrased this better, and will make this more clear in the next update. Regards, Julian
