On Fri, Mar 22, 2013 at 08:51:47AM +0000, Zhang, Yang Z wrote: > Gleb Natapov wrote on 2013-03-22: > > On Fri, Mar 22, 2013 at 08:37:22AM +0000, Zhang, Yang Z wrote: > >> Gleb Natapov wrote on 2013-03-22: > >>> On Fri, Mar 22, 2013 at 08:25:21AM +0000, Zhang, Yang Z wrote: > >>>> Gleb Natapov wrote on 2013-03-22: > >>>>> On Fri, Mar 22, 2013 at 08:05:27AM +0000, Zhang, Yang Z wrote: > >>>>>> Gleb Natapov wrote on 2013-03-22: > >>>>>>> On Fri, Mar 22, 2013 at 01:24:05PM +0800, Yang Zhang wrote: > >>>>>>>> From: Yang Zhang <yang.z.zhang@xxxxxxxxx> > >>>>>>>> > >>>>>>>> Current interrupt coalescing logci which only used by RTC has > >>>>>>>> conflict with Posted Interrupt. This patch introduces a new > >>>>>>>> mechinism to use eoi to track interrupt: When delivering an > >>>>>>>> interrupt to vcpu, the pending_eoi set to number of vcpu that > >>>>>>>> received the interrupt. And decrease it when each vcpu writing > >>>>>>>> eoi. No subsequent RTC interrupt can deliver to vcpu until all > >>>>>>>> vcpus write eoi. > >>>>>>>> > >>>>>>>> Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx> > >>>>>>>> --- > >>>>>>>> virt/kvm/ioapic.c | 40 > >>>>>>>> +++++++++++++++++++++++++++++++++++++++- 1 files changed, 39 > >>>>>>>> insertions(+), 1 deletions(-) > >>>>>>>> diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c > >>>>>>>> index c991e58..df16daf 100644 > >>>>>>>> --- a/virt/kvm/ioapic.c > >>>>>>>> +++ b/virt/kvm/ioapic.c > >>>>>>>> @@ -114,6 +114,29 @@ static void rtc_irq_restore(struct kvm_ioapic > >>>>> *ioapic) > >>>>>>>> ioapic->rtc_status.pending_eoi = pending_eoi; > >>>>>>>> } > >>>>>>>> +static void rtc_irq_ack_eoi(struct kvm_vcpu *vcpu, > >>>>>>>> + struct rtc_status *rtc_status, int irq) > >>>>>>>> +{ > >>>>>>>> + if (irq != RTC_GSI) > >>>>>>>> + return; > >>>>>>>> + > >>>>>>>> + if (test_and_clear_bit(vcpu->vcpu_id, rtc_status->dest_map)) > >>>>>>>> + --rtc_status->pending_eoi; > >>>>>>>> + > >>>>>>>> + WARN_ON(rtc_status->pending_eoi < 0); > >>>>>>>> +} > >>>>>>>> + > >>>>>>>> +static bool rtc_irq_check(struct kvm_ioapic *ioapic, int irq) > >>>>>>>> +{ > >>>>>>>> + if (irq != RTC_GSI) > >>>>>>>> + return false; > >>>>>>>> + > >>>>>>>> + if (ioapic->rtc_status.pending_eoi > 0) > >>>>>>>> + return true; /* coalesced */ > >>>>>>>> + > >>>>>>>> + return false; > >>>>>>>> +} > >>>>>>>> + > >>>>>>>> static int ioapic_service(struct kvm_ioapic *ioapic, unsigned int idx) > >>>>>>>> { > >>>>>>>> union kvm_ioapic_redirect_entry *pent; > >>>>>>>> @@ -229,6 +252,7 @@ static int ioapic_deliver(struct kvm_ioapic > > *ioapic, > >>> int > >>>>>>> irq) > >>>>>>>> { > >>>>>>>> union kvm_ioapic_redirect_entry *entry = &ioapic->redirtbl[irq]; > >>>>>>>> struct kvm_lapic_irq irqe; > >>>>>>>> + int ret; > >>>>>>>> > >>>>>>>> ioapic_debug("dest=%x dest_mode=%x delivery_mode=%x " > >>>>>>>> "vector=%x trig_mode=%x\n", > >>>>>>>> @@ -244,7 +268,14 @@ static int ioapic_deliver(struct kvm_ioapic > > *ioapic, > >>>>> int > >>>>>>> irq) > >>>>>>>> irqe.level = 1; > >>>>>>>> irqe.shorthand = 0; > >>>>>>>> - return kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe, > >>>>>>>> NULL); + if (irq == RTC_GSI) { + ret = > >>>>>>>> kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe, > >>>>>>>> + ioapic->rtc_status.dest_map); > >>>>>>>> + ioapic->rtc_status.pending_eoi = ret; > >>>>>>> We should track status only if IRQ_STATUS ioctl was used to inject an > >>>>>>> interrupt. > >>>>>> We already know RTC will use IRQ_STATUS ioctl. Why check it again? > >>>>>> > >>>>> QEMU does. QEMU is not the only userspace. > >>>> And this will break other userspace. > >>>> > >>> How? > >> If other userspace has the reinjection logic for RTC, but it not uses IRQ_STATUS, > > then it cannot get the right coalescing info. If it also use IRQ_STATUS to get > > coalescing info, then we don't need the IRQ_STATUS check. > >> > > If userspace does not care about irq status it does not use IRQ_STATUS > > ioctl and we should not go extra mile to provide one. Not everyone cares > > about running Windows as a guest. > I see your point. But if no windows guest running, RTC is hardly used by other guests and the overheard can be ignore. > Anyone can use RTC is Linux guest. Don't know about others. -- Gleb. -- 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