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Subject[PATCH 19/48] KVM: No disable_irq for MSI/MSI-X interrupt on device assignment
Date
From: Sheng Yang <sheng@linux.intel.com>

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: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
virt/kvm/kvm_main.c | 22 ++++++++--------------
1 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index dee321e..2d9bc43 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -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);

- disable_irq_nosync(irq);
- assigned_dev->host_irq_disabled = true;
+ 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
--
1.6.3.3


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