Gleb Natapov wrote on 2013-03-22:
> On Fri, Mar 22, 2013 at 01:24:05PM +0800, Yang Zhang wrote:
>> From: Yang Zhang <[email protected]>
>>
>> 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 <[email protected]>
>> ---
>> 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?
>> + } else
>> + ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe, NULL);
>> +
>> + return ret;
>> }
>>
>> int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int
>> irq_source_id,
>> @@ -268,6 +299,11 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int
> irq, int irq_source_id,
>> ret = 1;
>> } else {
>> int edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG);
>> +
>> + if (rtc_irq_check(ioapic, irq)) {
>> + ret = 0; /* coalesced */
>> + goto out;
>> + }
>> ioapic->irr |= mask;
>> if ((edge && old_irr != ioapic->irr) ||
>> (!edge && !entry.fields.remote_irr))
>> @@ -275,6 +311,7 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int
>> irq,
> int irq_source_id,
>> else ret = 0; /* report coalesced interrupt
>> */ } +out:
>> trace_kvm_ioapic_set_irq(entry.bits, irq, ret == 0);
>> spin_unlock(&ioapic->lock);
>> @@ -302,6 +339,7 @@ static void __kvm_ioapic_update_eoi(struct kvm_vcpu
> *vcpu,
>> if (ent->fields.vector != vector)
>> continue;
>> + rtc_irq_ack_eoi(vcpu, &ioapic->rtc_status, i);
>> /*
>> * We are dropping lock while calling ack notifiers because ack
>> * notifier callbacks for assigned devices call into IOAPIC
>> --
>> 1.7.1
>
> --
> Gleb.
> --
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Best regards,
Yang
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