Re: [Xen-devel] [PATCH v2 07/12] x86/IRQ: fix locking around vector management

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.05.19 at 15:48, <roger.pau@xxxxxxxxxx> wrote:
> On Wed, May 08, 2019 at 07:10:59AM -0600, Jan Beulich wrote:
>> --- a/xen/drivers/passthrough/vtd/iommu.c
>> +++ b/xen/drivers/passthrough/vtd/iommu.c
>> @@ -2134,11 +2134,16 @@ static void adjust_irq_affinity(struct a
>>      unsigned int node = rhsa ? pxm_to_node(rhsa->proximity_domain)
>>                               : NUMA_NO_NODE;
>>      const cpumask_t *cpumask = &cpu_online_map;
>> +    struct irq_desc *desc;
>>  
>>      if ( node < MAX_NUMNODES && node_online(node) &&
>>           cpumask_intersects(&node_to_cpumask(node), cpumask) )
>>          cpumask = &node_to_cpumask(node);
>> -    dma_msi_set_affinity(irq_to_desc(drhd->iommu->msi.irq), cpumask);
>> +
>> +    desc = irq_to_desc(drhd->iommu->msi.irq);
>> +    spin_lock_irq(&desc->lock);
> 
> I would use the irqsave/irqrestore variants here for extra safety.

Hmm, maybe. But I think we're in bigger trouble if IRQs indeed
ended up enabled at any of the two points where this function
gets called.

Jan



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