On Fri, Mar 15, 2013 at 04:05:00PM +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 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 <[email protected]>
> ---
> 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.
> 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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