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.zh...@intel.com>
> >>>>
> >>>> 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.zh...@intel.com>
> >>>> ---
> >>>> 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?
--
Gleb.
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