On Wed, 8 Nov 2017 13:14:01 +0100 Michael Mueller <mimu@xxxxxxxxxxxxxxxxxx> wrote: > On 08.11.17 12:09, Cornelia Huck wrote: > > On Wed, 8 Nov 2017 12:04:22 +0100 > > Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote: > > > >> On 11/08/2017 10:19 AM, Cornelia Huck wrote: > >>> On Wed, 8 Nov 2017 09:41:43 +0100 > >>> Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote: > >>> > >>>> From: Michael Mueller <mimu@xxxxxxxxxxxxxxxxxx> > >>>> > >>>> There is a chance to delete not yet delivered I/O interrupts if an > >>>> exploiter uses the subsystem identification word 0x0000 while > >>>> processing a KVM_DEV_FLIC_CLEAR_IO_IRQ ioctl. -EINVAL will be returned > >>>> now instead in that case. > >>>> > >>>> Classic interrupts will always have bit 0x10000 set in the schid while > >>>> adapter interrupts have a zero schid. The clear_io_irq interface is > >>>> only useful for classic interrupts (as adapter interrupts belong to > >>>> many devices). Let's make this interface more strict and forbid a schid > >>>> of 0. > >>> I'm wondering: Is there any possible use case to clear adapter > >>> interrupts? This interface was introduced to handle the case where a > >>> CRW was made pending for a subchannel (which implies any pending > >>> interrupt needs to be cleared.) > >> The problem with clearing adapter interrupts is that is actually a summary > >> interrupt for every potential device. So I somewhat consider an adapter interrupt > >> pending when the summary indicator went from 0 to 1. So I dont think clearing > >> a single one makes not much sense. (And this interface would be wrong for > >> that I think) > > Yes, this interface would be problematic. I'm not sure what's supposed > > to happen with crws vs. pending adapter interrupts, though. > They will be delivered based on ISC priority and the traditional first > when both have the same class. I'm just wondering what is supposed to happen when all devices associated with a summary indicator go away. The OS will hopefully deregister the indicator if needed; the hypervisor might still set the indicator and trigger an adapter interrupt before that happens (and hopefully the OS can deal with that.) Likely we don't have a problem, but I'm curious if there is anything architected for the cases where real hardware exists (like qdio). > > > >> The only use cases I can imagine for clearing adapter interrupts (e.g. reset) > >> is already covered by KVM_DEV_FLIC_CLEAR_IRQS > >> > >>> Alas, I cannot check the adapter interrupt question myself, as the > >>> public doc is lacking :( But qdio as another adapter interrupt user > >>> comes to mind (not that we support it in qemu, but still...) -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
