Gleb Natapov wrote on 2013-03-17:
> On Fri, Mar 15, 2013 at 04:05:00PM +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 need_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>
>> ---
>> arch/x86/kvm/lapic.c | 2 +- arch/x86/kvm/lapic.h | 1 +
>> virt/kvm/ioapic.c | 105
>> ++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed,
>> 107 insertions(+), 1 deletions(-)
>> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
>> index ad97f1f..bf2d208 100644
>> --- a/arch/x86/kvm/lapic.c
>> +++ b/arch/x86/kvm/lapic.c
>> @@ -89,7 +89,7 @@ static inline int apic_test_and_clear_vector(int vec, void
> *bitmap)
>> return test_and_clear_bit(VEC_POS(vec), (bitmap) + REG_POS(vec));
>> }
>> -static inline int apic_test_vector(int vec, void *bitmap)
>> +int apic_test_vector(int vec, void *bitmap)
>> {
>> return test_bit(VEC_POS(vec), (bitmap) + REG_POS(vec));
>> }
> That's too low level to call from IOAPIC. Put kvm_apic_pending_eoi()
> here instead.
>
>> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index
>> 3a0f9d8..02da8b8 100644 --- a/arch/x86/kvm/lapic.h +++
>> b/arch/x86/kvm/lapic.h @@ -84,6 +84,7 @@ static inline bool
>> kvm_hv_vapic_assist_page_enabled(struct kvm_vcpu *vcpu)
>>
>> int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data);
>> void kvm_lapic_init(void);
>> +int apic_test_vector(int vec, void *bitmap);
>>
>> static inline u32 kvm_apic_get_reg(struct kvm_lapic *apic, int reg_off)
>> {
>> diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
>> index 2c6235c..46cb8ed 100644
>> --- a/virt/kvm/ioapic.c
>> +++ b/virt/kvm/ioapic.c
>> @@ -103,12 +103,110 @@ static void rtc_register_notifier(struct kvm_ioapic
> *ioapic)
>> kvm_register_irq_ack_notifier(ioapic->kvm,
>> &ioapic->rtc_status.irq_ack_notifier);
>> }
>> + +static void rtc_irq_reset(struct kvm_ioapic *ioapic) +{
>> + ioapic->rtc_status.need_eoi = 0;
>> + bitmap_zero(ioapic->rtc_status.vcpu_map, KVM_MAX_VCPUS); +} + +static
>> void rtc_irq_restore(struct kvm_ioapic *ioapic) +{ + struct kvm_vcpu
>> *vcpu; + struct kvm_lapic *apic; + int vector, i, need_eoi = 0, rtc_pin
>> = 8; + + vector = ioapic->redirtbl[rtc_pin].fields.vector;
>> + kvm_for_each_vcpu(i, vcpu, ioapic->kvm) { + apic = vcpu->arch.apic;
>> + if (apic_test_vector(vector, apic->regs + APIC_ISR) || +
>> apic_test_vector(vector, apic->regs + APIC_IRR)) { + need_eoi++;
>> + set_bit(vcpu->vcpu_id, ioapic->rtc_status.vcpu_map); + } + }
>> + ioapic->rtc_status.need_eoi = need_eoi; +} + +static void
>> rtc_irq_update(struct kvm_ioapic *ioapic, + struct kvm_lapic_irq
>> *irqe, int irq) +{ + int weight; + + if (irq != 8) + return; +
>> + rtc_irq_reset(ioapic); + + kvm_get_dest_vcpu(ioapic->kvm, irqe,
>> ioapic->rtc_status.vcpu_map); + if
>> (likely(!bitmap_empty(ioapic->rtc_status.vcpu_map, KVM_MAX_VCPUS))) {
>> + if (irqe->delivery_mode == APIC_DM_LOWEST)
>> + ioapic->rtc_status.need_eoi = 1; + else { + weight =
>> bitmap_weight(ioapic->rtc_status.vcpu_map,
>> + sizeof(ioapic->rtc_status.vcpu_map));
>> + ioapic->rtc_status.need_eoi = weight; + } + } +} + +static void
>> rtc_irq_ack_eoi(struct kvm_vcpu *vcpu, + struct rtc_status
>> *rtc_status, int irq) +{ + if (irq != 8) + return; + + if
>> (test_and_clear_bit(vcpu->vcpu_id, rtc_status->vcpu_map)) { + if
>> (!(--rtc_status->need_eoi))
> WARN_ON(need_eoi < 0)?
>
>> + /* Clear irr to accept subsequent RTC interrupt */
>> + vcpu->kvm->arch.vioapic->irr &= ~(1 << 8);
> This is not needed if you do not set irr if irq is coalesced.
>
>> + }
>> +}
>> +
>> +static bool rtc_irq_check(struct kvm_ioapic *ioapic, int irq)
>> +{
>> + if (irq != 8)
>> + return false;
>> +
>> + if (ioapic->rtc_status.need_eoi > 0)
>> + return true; /* coalesced */
>> +
>> + return false;
>> +}
>> +
>> #else
>>
>> static void rtc_register_notifier(struct kvm_ioapic *ioapic)
>> {
>> return;
>> }
>> +
>> +static void rtc_irq_reset(struct kvm_ioapic *ioapic)
>> +{
>> + return;
>> +}
>> +
>> +static void rtc_irq_restore(struct kvm_ioapic *ioapic)
>> +{
>> + return;
>> +}
>> +
>> +static void rtc_irq_update(struct kvm_ioapic *ioapic,
>> + struct kvm_lapic_irq *irqe, int irq)
>> +{
>> + return;
>> +}
>> +
>> +static void rtc_irq_ack_eoi(struct kvm_vcpu *vcpu,
>> + struct rtc_status *rtc_status, int irq)
>> +{
>> + return;
>> +}
>> +
>> +static bool rtc_irq_check(struct kvm_ioapic *ioapic, int irq)
>> +{
>> + return false;
>> +}
>> #endif
>>
>> static int ioapic_service(struct kvm_ioapic *ioapic, unsigned int idx)
>> @@ -119,6 +217,8 @@ static int ioapic_service(struct kvm_ioapic *ioapic,
> unsigned int idx)
>> pent = &ioapic->redirtbl[idx];
>>
>> if (!pent->fields.mask) {
>> + if (rtc_irq_check(ioapic, idx))
>> + return 0; /* coalesced */
>> injected = ioapic_deliver(ioapic, idx);
>> if (injected && pent->fields.trig_mode == IOAPIC_LEVEL_TRIG)
>> pent->fields.remote_irr = 1;
>> @@ -241,6 +341,8 @@ static int ioapic_deliver(struct kvm_ioapic *ioapic, int
> irq)
>> irqe.level = 1;
>> irqe.shorthand = 0;
>> + rtc_irq_update(ioapic, &irqe, irq);
>> +
> Do it once when GSI is configured.
This function will set need_eoi to number of CPU received RTC interrupt. When GSI is configured, there is no real interrupt generated and if set need_eoi, no EOI will decrease it.
>> return kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe);
>> }
>> @@ -299,6 +401,7 @@ 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 @@
>> -452,6 +555,7 @@ void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
>> ioapic->ioregsel = 0; ioapic->irr = 0; ioapic->id = 0;
>> + rtc_irq_reset(ioapic); update_handled_vectors(ioapic); }
>> @@ -519,6 +623,7 @@ int kvm_set_ioapic(struct kvm *kvm, struct
> kvm_ioapic_state *state)
>> spin_lock(&ioapic->lock); memcpy(ioapic, state, sizeof(struct
>> kvm_ioapic_state)); update_handled_vectors(ioapic);
>> + rtc_irq_restore(ioapic); kvm_ioapic_make_eoibitmap_request(kvm);
>> spin_unlock(&ioapic->lock); return 0;
>> --
>> 1.7.1
>
> --
> Gleb.
> --
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Best regards,
Yang
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