Re: [Ksummit-discuss] [CORE TOPIC] Device error handling / reporting / isolation

[Daniel Vetter <daniel.vetter@ffwll.ch>]

On Mon, May 12, 2014 at 5:07 PM, Joerg Roedel <joro@8bytes.org> wrote:
> On Mon, May 12, 2014 at 12:43:09AM +0200, Daniel Vetter wrote:
>> So I think having some iommu storm handling (like we have for
>> interrupts in general and a lot of other things) would go a long way
>> towards the goal of enabling iommus everywhere.
>
> Right, the developer use-case needs also be taken into account. We could
> easily ignore a device after it did something wrong to get rid of
> io-page-fault or interupt storms. But we also need a way to tell the
> kernel to unignore the device later :)

A disable/enable cycle of the pci bus master setting should be a good
enough signal? Presuming you can say for sure which devices is doing
the offending dma transactions ofc ... Or maybe we should just be
optimists and re-enable the IOMMU if _any_ child device gets
re-enabled (or bus master re-enabled for pci) in the hopes that the
developers just reloaded the driver. Worst case the storm handling
will kick in again shortly.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch