Re: [PATCH v3 0/3] virtio DMA API core stuff

[Marcel Apfelbaum]

On 11/22/2015 05:54 PM, David Woodhouse wrote:
> On Sun, 2015-11-22 at 15:06 +0200, Marcel Apfelbaum wrote:
> > I tried to generate a DMAR table that excludes some devices from
> > IOMMU translation, however it does not help.
> >
> > The reason is, as far as I understand, that Linux kernel does
> > not allow any device being outside an IOMMU scope if the
> > iommu kernel option is activated.
> >
> > Does anybody know if it is "by design" or is simply an uncommon
> > configuration?
> > (some devices in an IOMMU scope, while others outside *any* IOMMU
> > scope)
>
> That's a kernel bug in the way it handles per-device DMA operations. Or
> more to the point, in the way it doesn't â the non-translated devices
> end up being pointed to the intel_dma_ops despite the fact they
> shouldn't be. I'm working on that...

Hi David,
Thank you for the fast response.

Sadly I am not familiar with the DMA/IOMMU code to contribute
with a sane idea, but I'll gladly test it.
If you lack the time and have an idea to share, I can give it a try though.

Thanks,
Marcel


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