Re: [Xen-devel] [PATCH 0 of 3] Deal with IOMMU faults in softirq context.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.12.11 at 19:34, Dario Faggioli <raistlin@xxxxxxxx> wrote:
> As already discussed here [1], dealing with IOMMU faults in interrupt
> context may cause nasty things to happen, up to being used as a form of
> DoS attack, e.g., by generating a "storm" of IOMMU faults that will
> livelock a pCPU.
> 
> To avoid this, IOMMU faults handling is being moved from interrupt to
> softirq context. Basically, the inerrupt handler of the IRQ originated
> by an IOMMU (page) fault will raise a softirq-tasklet which will then
> deal with the actual fault records by clearing the logs and re-enabling
> interrupts from the offending IOMMU(s). A single tasklet is being used
> even if there are more than just one IOMMU in the system, as the event
> should be rare enough.
> 
> The series introduces the described mechanism for both Intel VT-d and
> AMD-Vi, and has been tested on both platforms with an hacked DomU bnx2
> network driver which was generating I/O page faults upon request.

These look good to me (apart from a minor indentation issue in the
2nd patch), but we'd surely like to have an ack from the respective
maintainers. Also, despite the subject here, I suppose the series
consists of just two patches?

Thanks for doing this!

Jan


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