diff mbox

[v8,7/7] KVM: Use eoi to track RTC interrupt delivery status

Message ID 1365430669-31126-8-git-send-email-yang.z.zhang@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Zhang, Yang Z April 8, 2013, 2:17 p.m. UTC 
From: Yang Zhang <yang.z.zhang@Intel.com>

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>
---
 virt/kvm/ioapic.c |   41 ++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 40 insertions(+), 1 deletions(-)

Comments

Gleb Natapov April 9, 2013, 7:06 a.m. UTC | #1 
On Mon, Apr 08, 2013 at 10:17:49PM +0800, Yang Zhang wrote:
> From: Yang Zhang <yang.z.zhang@Intel.com>
> 
> 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>
> ---
>  virt/kvm/ioapic.c |   41 ++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 40 insertions(+), 1 deletions(-)
> 
> diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
> index 8d1f662..197ef97 100644
> --- a/virt/kvm/ioapic.c
> +++ b/virt/kvm/ioapic.c
> @@ -149,6 +149,29 @@ static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic)
>  	    __rtc_irq_eoi_tracking_restore_one(vcpu, vector);
>  }
>  
> +static void rtc_irq_ack_eoi(struct kvm_ioapic *ioapic, struct kvm_vcpu *vcpu,
> +			int irq)
rtc_irq_eoi() drop ack. We sometimes call EOI ack, but putting ack and
eoi in the name is to much.

> +{
> +	if (irq != RTC_GSI)
> +		return;
> +
Lets move the check to the caller:
 if (i == RTC_GSI)
    rtc_irq_eoi()

> +	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(struct kvm_ioapic *ioapic, int irq, bool line_status)
rtc_irq_check_coalesced()

> +{
> +	if (irq != RTC_GSI || !line_status)
> +		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,
>  		bool line_status)
>  {
> @@ -262,6 +285,7 @@ static int ioapic_deliver(struct kvm_ioapic *ioapic, int irq, bool line_status)
>  {
>  	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",
> @@ -277,7 +301,15 @@ static int ioapic_deliver(struct kvm_ioapic *ioapic, int irq, bool line_status)
>  	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,
> @@ -301,6 +333,11 @@ 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, line_status)) {
> +			ret = 0; /* coalesced */
> +			goto out;
> +		}
>  		ioapic->irr |= mask;
>  		if ((edge && old_irr != ioapic->irr) ||
>  		    (!edge && !entry.fields.remote_irr))
> @@ -308,6 +345,7 @@ 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);
>  
> @@ -335,6 +373,7 @@ static void __kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu,
>  		if (ent->fields.vector != vector)
>  			continue;
>  
> +		rtc_irq_ack_eoi(ioapic, vcpu, 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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diff mbox

Patch

diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 8d1f662..197ef97 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -149,6 +149,29 @@  static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic)
 	    __rtc_irq_eoi_tracking_restore_one(vcpu, vector);
 }
 
+static void rtc_irq_ack_eoi(struct kvm_ioapic *ioapic, struct kvm_vcpu *vcpu,
+			int irq)
+{
+	if (irq != RTC_GSI)
+		return;
+
+	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(struct kvm_ioapic *ioapic, int irq, bool line_status)
+{
+	if (irq != RTC_GSI || !line_status)
+		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,
 		bool line_status)
 {
@@ -262,6 +285,7 @@  static int ioapic_deliver(struct kvm_ioapic *ioapic, int irq, bool line_status)
 {
 	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",
@@ -277,7 +301,15 @@  static int ioapic_deliver(struct kvm_ioapic *ioapic, int irq, bool line_status)
 	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,
@@ -301,6 +333,11 @@  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, line_status)) {
+			ret = 0; /* coalesced */
+			goto out;
+		}
 		ioapic->irr |= mask;
 		if ((edge && old_irr != ioapic->irr) ||
 		    (!edge && !entry.fields.remote_irr))
@@ -308,6 +345,7 @@  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);
 
@@ -335,6 +373,7 @@  static void __kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu,
 		if (ent->fields.vector != vector)
 			continue;
 
+		rtc_irq_ack_eoi(ioapic, vcpu, i);
 		/*
 		 * We are dropping lock while calling ack notifiers because ack
 		 * notifier callbacks for assigned devices call into IOAPIC