Jan Kiszka wrote: >> In some cases misbehaving NMIs are worse than no NMIs. For example, a >> software watchdog may use NMIs to monitor a system. But if the guest >> spins with interrupts disabled, the irq window will never open, and NMIs >> will never be delivered, so the watchdog will deliver a false negative. >> >> > > I fail to see the regression. Currently that watchdog would _always_ > deliver false positives and pull the trigger immediately (in fact, this > is precisely the situation we face @work with some special board > emulation where we have to provide an NMI-based watchdog). > >
Linux checks whether nmi works and enables it only if it does (I think -- not sure). So for Linux, there would be a regression. > Moreover, only the second and succeeding NMIs under the same > interrupts-disabled window need to get lost: Along with injecting the > first NMI we could request the IRQ window unconditionally, using it to > reset the virtual NMI-blocked state. > But the interrupt window would never open. Consider a spin_lock() executing with interrupts disabled, on a spin lock that is already locked by the current cpu. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
