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));
}
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))
+ /* Clear irr to accept subsequent RTC interrupt */
+ vcpu->kvm->arch.vioapic->irr &= ~(1 << 8);
+ }
+}
+
+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);
+
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
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