On Wed, May 20, 2009 at 08:15:55AM -0400, Gregory Haskins wrote: > Marcelo Tosatti wrote: > > Switch irq injection/acking to irq_lock, and change PIO/MMIO paths > > so that the device search is protected by kvm->lock, but not the > > read/write callbacks (which is responsability of the device). > > > > Fix for http://article.gmane.org/gmane.comp.emulators.kvm.devel/32286. > > > > Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx> > > > > Index: kvm/arch/x86/kvm/i8254.c > > =================================================================== > > --- kvm.orig/arch/x86/kvm/i8254.c > > +++ kvm/arch/x86/kvm/i8254.c > > @@ -634,10 +634,10 @@ static void __inject_pit_timer_intr(stru > > struct kvm_vcpu *vcpu; > > int i; > > > > - mutex_lock(&kvm->lock); > > + mutex_lock(&kvm->irq_lock); > > > > There would be advantages to having irq_lock be > interrupt/nonpreempt-friendly design, such as s/mutex/spinlock. For > instance, irqfd could inject the interrupt directly without deferring to > a workqueue. I'm not sure if this is possible/easy, but its something > to consider. It is possible to convert to a spinlock (and required to switch bus->devs[] to be protected by RCU as discussed). Now if its worth to make it interrupt safe depends on how bad disabling interrupts on the non-interrupt-disabled paths is. I've seen kvm_set_irq relatively high in profiling yesterday, BTW, but this is just hand-waving.. -- 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
