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

[Avi Kivity <avi@redhat.com>]

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?

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