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Commit 968a6347 authored by Sheng Yang's avatar Sheng Yang Committed by Avi Kivity
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KVM: No disable_irq for MSI/MSI-X interrupt on device assignment 



Disable interrupt at interrupt handler and enable it when guest ack is for
the level triggered interrupt, to prevent reinjected interrupt. MSI/MSI-X don't
need it.

One possible problem is multiply same vector interrupt injected between irq
handler and scheduled work handler would be merged as one for MSI/MSI-X.
But AFAIK, the drivers handle it well.

The patch fixed the oplin card performance issue(MSI-X performance is half of
MSI/INTx).

Signed-off-by: default avatarSheng Yang <sheng@linux.intel.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 017cb99e

virt/kvm/kvm_main.c

+8 −14
Original line number Diff line number Diff line
@@ -120,7 +120,7 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work) 
{

	struct kvm_assigned_dev_kernel *assigned_dev;

	struct kvm *kvm;

	int irq, i;

	int i;



	assigned_dev = container_of(work, struct kvm_assigned_dev_kernel,

				    interrupt_work);
@@ -143,20 +143,10 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work) 
			kvm_set_irq(assigned_dev->kvm,

				    assigned_dev->irq_source_id,

				    guest_entries[i].vector, 1);

			irq = assigned_dev->host_msix_entries[i].vector;

			if (irq != 0)

				enable_irq(irq);

			assigned_dev->host_irq_disabled = false;

		}

	} else {

	} else

		kvm_set_irq(assigned_dev->kvm, assigned_dev->irq_source_id,

			    assigned_dev->guest_irq, 1);

		if (assigned_dev->irq_requested_type &

				KVM_DEV_IRQ_GUEST_MSI) {

			enable_irq(assigned_dev->host_irq);

			assigned_dev->host_irq_disabled = false;

		}

	}



	spin_unlock_irq(&assigned_dev->assigned_dev_lock);

	mutex_unlock(&assigned_dev->kvm->lock);
@@ -179,8 +169,10 @@ static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id) 


	schedule_work(&assigned_dev->interrupt_work);



	if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_GUEST_INTX) {

		disable_irq_nosync(irq);

		assigned_dev->host_irq_disabled = true;

	}



out:

	spin_unlock_irqrestore(&assigned_dev->assigned_dev_lock, flags);
@@ -417,6 +409,7 @@ static int assigned_device_enable_guest_msi(struct kvm *kvm, 
{

	dev->guest_irq = irq->guest_irq;

	dev->ack_notifier.gsi = -1;

	dev->host_irq_disabled = false;

	return 0;

}

#endif
@@ -427,6 +420,7 @@ static int assigned_device_enable_guest_msix(struct kvm *kvm, 
{

	dev->guest_irq = irq->guest_irq;

	dev->ack_notifier.gsi = -1;

	dev->host_irq_disabled = false;

	return 0;

}

#endif