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

From Marcel Apfelbaum <marcel@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH v3 0/3] virtio DMA API core stuff
Date 2015-11-22 18:10 +0100
Message-ID <qxGjg-6O6-7@gated-at.bofh.it> (permalink)
References (8 earlier) <qoY5J-2tW-27@gated-at.bofh.it> <qsvy9-7nD-15@gated-at.bofh.it> <qswNA-86y-21@gated-at.bofh.it> <qxCyZ-4di-7@gated-at.bofh.it> <qxFdx-5OZ-19@gated-at.bofh.it>
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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 — 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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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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