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

[Avi Kivity <avi@redhat.com>]

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.