Re: [Xen-devel] [PATCH 3/5] xen/arm: Don't reinject the IRQ if it's already in LRs

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 25 Jun 2013, Julien Grall wrote:
> On 06/25/2013 05:36 PM, Stefano Stabellini wrote:
> 
> > On Tue, 25 Jun 2013, Julien Grall wrote:
> >> On 06/25/2013 02:24 PM, Stefano Stabellini wrote:
> >>
> >>> On Tue, 25 Jun 2013, Julien Grall wrote:
> >>>> From: Julien Grall <julien.grall@xxxxxxxxxx>
> >>>>
> >>>> When an IRQ, marked as IRQS_ONESHOT, is injected Linux will:
> >>>>   - Disable the IRQ
> >>>>   - Call the interrupt handler
> >>>>   - Conditionnally enable the IRQ
> >>>>   - EOI the IRQ
> >>>>
> >>>> When Linux will re-enable the IRQ, Xen will inject again the IRQ because 
> >>>> it's
> >>>> still inflight. Therefore, LRs will contains duplicated IRQs and Xen will
> >>>> EOI it twice if it's a physical IRQ.
> >>>>
> >>>> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> >>>> ---
> >>>>  xen/arch/arm/gic.c        |   27 +++++++++++++++++++++++++++
> >>>>  xen/arch/arm/vgic.c       |    3 ++-
> >>>>  xen/include/asm-arm/gic.h |    3 +++
> >>>>  3 files changed, 32 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
> >>>> index 21575df..bf05716 100644
> >>>> --- a/xen/arch/arm/gic.c
> >>>> +++ b/xen/arch/arm/gic.c
> >>>> @@ -570,6 +570,33 @@ int __init setup_dt_irq(const struct dt_irq *irq, 
> >>>> struct irqaction *new)
> >>>>      return rc;
> >>>>  }
> >>>>  
> >>>> +/* Check if an IRQ was already injected to the current VCPU */
> >>>> +bool_t gic_irq_injected(unsigned int irq)
> >>>
> >>> Can you rename it to something more specific, like gic_irq_inlr?
> >>>
> >>>> +{
> >>>> +    bool_t found = 0;
> >>>> +    int i = 0;
> >>>> +    unsigned int virq;
> >>>> +
> >>>> +    spin_lock_irq(&gic.lock);
> >>>> +
> >>>> +    while ( (i = find_next_bit((unsigned long *)&this_cpu(lr_mask),
> >>>> +                               nr_lrs, i)) < nr_lrs )
> >>>> +    {
> >>>> +        virq = GICH[GICH_LR + i] & GICH_LR_VIRTUAL_MASK;
> >>>> +
> >>>> +        if ( virq == irq )
> >>>> +        {
> >>>> +            found = 1;
> >>>> +            break;
> >>>> +        }
> >>>> +        i++;
> >>>> +    }
> >>>
> >>> Instead of reading back all the GICH_LR registers, can't just just read
> >>> the ones that have a corresponding bit set in lr_mask?
> >>
> >> It's already the case, I use find_next_bit to find the next used LRs.
> >>
> >>> Also you should be able to avoid having to read the GICH_LR registers by
> >>> simply checking if the irq is in the lr_queue list: if an irq is in
> >>> inflight but not in lr_queue, it means that it is in one of the LRs.
> >>
> >>
> >> No. When a disabled IRQ is injected to the VCPU, Xen puts it in inflight
> >> but not in lr_queue. We don't have a way to know whether the IRQ is
> >> really in LRs or not.
> > 
> > I think it's time we introduce a "status" member in struct irq_desc, so
> 
> Do you mean struct irq_pending?

Yes, sorry I meant struct irq_pending

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel