On Mon, Sep 19, 2011 at 05:30:27PM +0300, Avi Kivity wrote: > On 09/19/2011 04:54 PM, Marcelo Tosatti wrote: > >> >> > >> >> Yes, due to NMI-blocked-by-STI. A really touchy area. > >> >And we don't need the window exit notification then? I don't understand > >> >what nmi_in_progress is supposed to do here. > >> > >> We need the window notification in both cases. If we're recovering > >> from STI, then we don't need to collapse NMIs. If we're completing > >> an NMI handler, then we do need to collapse NMIs (since the queue > >> length is two, and we just completed one). > > > >I don't understand what is the point with nmi_in_progress, and the above > >hunk, either. Can't inject_nmi do: > > > >if (nmi_injected + atomic_read(nmi_pending)< 2) > > atomic_inc(nmi_pending) > > > >Instead of collapsing somewhere else? > > We could. It's not atomic though - two threads executing in > parallel could raise the value to three. Could do a cmpxchg loop > does an increment bounded to two. I guess this is a lot clearer, > thanks. > > >You'd also have to change > >nmi_injected handling in arch code so its value is not "hidden", in > >complete_interrupts(). > > Or maybe make raising nmi_injected not decrement nmi_pending. So: > > nmi_pending: total number of interrupts in queue > nmi_injected: of these, how many are currently being injected > > yes? Yes, at the expense of decrementing on subarch code (which is fine, apparently). -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
