Re: [PATCH] KVM: No disable_irq for MSI/MSI-X interrupt on device assignment

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Sheng Yang wrote:
On Monday 04 May 2009 16:25:55 Avi Kivity wrote:
Sheng Yang wrote:
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).


 	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);
I don't have the spin_lock_irqrestore() here.  The patch applies, but
with fuzz.  Am I missing a patch?

Oh, it's Marcelo's patchset...

[patch 0/4] use smp_send_reschedule in vcpu_kick / assigned dev host intx race fix

Okay, I am working my queue in reverse order :)

But please note dependencies on other patches for me.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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