Re: [Xen-devel] [PATCH] x86/IO-APIC: don't create pIRQ mapping from masked RTE

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.08.15 at 16:58, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 21/08/15 09:41, Jan Beulich wrote:
>> In the course of this I also found that the respective message isn't
>> really useful without also printing the pre-existing mapping. And I
>> noticed that map_domain_pirq() allowed IRQ0 to get through, despite us
>> never allowing and domain to control that interrupt.
> 
> s/and/a/ ? (I can't quite parse the original statement)

Ouch - "a" was meant.

> Also, doesn't irq_access_permitted() catch the irq0 case?

It should, yes, but ...

>> --- a/xen/arch/x86/irq.c
>> +++ b/xen/arch/x86/irq.c
>> @@ -1906,7 +1906,7 @@ int map_domain_pirq(
>>      if ( !irq_access_permitted(current->domain, irq))
>>          return -EPERM;
> 
> I would be tempted to put a comment here stating that irq0 is definitely
> a xen-reserved irq.  Otherwise, it is odd to have the mismatch between
> pirq and irq.

Such a "mismatch" was already there (albeit I wouldn't call it a
mismatch, since from an abstract pov the two number spaces are
entirely distinct), specifically ...

>> -    if ( pirq < 0 || pirq >= d->nr_pirqs || irq < 0 || irq >= nr_irqs )
>> +    if ( pirq < 0 || pirq >= d->nr_pirqs || irq <= 0 || irq >= nr_irqs )
>>      {
>>          dprintk(XENLOG_G_ERR, "dom%d: invalid pirq %d or irq %d\n",
>>                  d->domain_id, pirq, irq);
>> @@ -1919,8 +1919,9 @@ int map_domain_pirq(
>>      if ( (old_irq > 0 && (old_irq != irq) ) ||
>>           (old_pirq && (old_pirq != pirq)) )

... here.

Jan

>>      {
>> -        dprintk(XENLOG_G_WARNING, "dom%d: pirq %d or irq %d already 
>> mapped\n",
>> -                d->domain_id, pirq, irq);
>> +        dprintk(XENLOG_G_WARNING,
>> +                "dom%d: pirq %d or irq %d already mapped (%d,%d)\n",
>> +                d->domain_id, pirq, irq, old_pirq, old_irq);
>>          return 0;
>>      }
>>  



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