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

From	David Woodhouse <dwmw2@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 0/3] virtio DMA API core stuff
Date	2015-11-22 17:00 +0100
Message-ID	<qxFdx-5OZ-19@gated-at.bofh.it> (permalink)
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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 — 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...

-- 
dwmw2

Thread

Re: [PATCH v3 0/3] virtio DMA API core stuff Marcel Apfelbaum <marcel.apfelbaum@gmail.com> - 2015-11-22 14:10 +0100
  Re: [PATCH v3 0/3] virtio DMA API core stuff David Woodhouse <dwmw2@infradead.org> - 2015-11-22 17:00 +0100
    Re: [PATCH v3 0/3] virtio DMA API core stuff Marcel Apfelbaum <marcel@redhat.com> - 2015-11-22 18:10 +0100
    Re: [PATCH v3 0/3] virtio DMA API core stuff "Michael S. Tsirkin" <mst@redhat.com> - 2015-11-22 23:20 +0100

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