KVM: Use eoi to track RTC interrupt delivery status
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.zhang@Intel.com>
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index a49fcd5..97c67a5 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -147,6 +147,22 @@
__rtc_irq_eoi_tracking_restore_one(vcpu);
}
+static void rtc_irq_eoi(struct kvm_ioapic *ioapic, struct kvm_vcpu *vcpu)
+{
+ if (test_and_clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map))
+ --ioapic->rtc_status.pending_eoi;
+
+ WARN_ON(ioapic->rtc_status.pending_eoi < 0);
+}
+
+static bool rtc_irq_check_coalesced(struct kvm_ioapic *ioapic)
+{
+ if (ioapic->rtc_status.pending_eoi > 0)
+ return true; /* coalesced */
+
+ return false;
+}
+
static int ioapic_service(struct kvm_ioapic *ioapic, unsigned int idx,
bool line_status)
{
@@ -260,6 +276,7 @@
{
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",
@@ -275,7 +292,15 @@
irqe.level = 1;
irqe.shorthand = 0;
- return kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe, NULL);
+ if (irq == RTC_GSI && line_status) {
+ BUG_ON(ioapic->rtc_status.pending_eoi != 0);
+ ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe,
+ ioapic->rtc_status.dest_map);
+ ioapic->rtc_status.pending_eoi = ret;
+ } 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,
@@ -299,6 +324,12 @@
ret = 1;
} else {
int edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG);
+
+ if (irq == RTC_GSI && line_status &&
+ rtc_irq_check_coalesced(ioapic)) {
+ ret = 0; /* coalesced */
+ goto out;
+ }
ioapic->irr |= mask;
if ((edge && old_irr != ioapic->irr) ||
(!edge && !entry.fields.remote_irr))
@@ -306,6 +337,7 @@
else
ret = 0; /* report coalesced interrupt */
}
+out:
trace_kvm_ioapic_set_irq(entry.bits, irq, ret == 0);
spin_unlock(&ioapic->lock);
@@ -333,6 +365,8 @@
if (ent->fields.vector != vector)
continue;
+ if (i == RTC_GSI)
+ rtc_irq_eoi(ioapic, vcpu);
/*
* We are dropping lock while calling ack notifiers because ack
* notifier callbacks for assigned devices call into IOAPIC