Re: [PATCHv2 2 of 2] Move IOMMU faults handling into softirq for AMD-Vi.

[Dario Faggioli <raistlin@linux.it>]

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On Tue, 2012-01-17 at 11:17 +0000, Keir Fraser wrote: 
> > Dealing with interrupts from AMD-Vi IOMMU(s) is deferred to a softirq-tasklet,
> > raised by the actual IRQ handler. To avoid more interrupts being generated
> > (because of further faults), they must be masked in the IOMMU within the low
> > level IRQ handler and enabled back in the tasklet body. Notice that this may
> > cause the log to overflow, but none of the existing entry will be overwritten.
> > 
> > Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
> 
> This patch needs fixing to apply to xen-unstable tip. Please do that and
> resubmit.
> 
I see. I can easily rebase the patch but there are functional changes
involved, so I'd like to know what you think it's best to do first.

In particular, the clash is against Wei's patches introducing PPR. So
now the IOMMU interrupt handler checks both event log and ppr log.

Question is, should I move _BOTH_ these checks into softirq or just
defer event log processing, and leave ppr log handling in hard-irq
context? Quickly looking at the new specs, it seems to me that deferring
both should be fine, but I'd really appreciate your thoughts...

Wei, Jan, Tim?

Thanks and regards,
Dario

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-------------------------------------------------------------------
Dario Faggioli, http://retis.sssup.it/people/faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
PhD Candidate, ReTiS Lab, Scuola Superiore Sant'Anna, Pisa (Italy)



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