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SubjectRe: [PATCH 0/3] Fix virtio-blk issue with SWIOTLB
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On 2019/1/14 下午5:50, Christoph Hellwig wrote:
> On Mon, Jan 14, 2019 at 05:41:56PM +0800, Jason Wang wrote:
>> On 2019/1/11 下午5:15, Joerg Roedel wrote:
>>> On Fri, Jan 11, 2019 at 11:29:31AM +0800, Jason Wang wrote:
>>>> Just wonder if my understanding is correct IOMMU_PLATFORM must be set for
>>>> all virtio devices under AMD-SEV guests?
>>> Yes, that is correct. Emulated DMA can only happen on the SWIOTLB
>>> aperture, because that memory is not encrypted. The guest bounces the
>>> data then to its encrypted memory.
>>>
>>> Regards,
>>>
>>> Joerg
>>
>> Thanks, have you tested vhost-net in this case. I suspect it may not work
> Which brings me back to my pet pevee that we need to take actions
> that virtio uses the proper dma mapping API by default with quirks
> for legacy cases. The magic bypass it uses is just causing problems
> over problems.


Yes, I fully agree with you. This is probably an exact example of such
problem.

Thanks

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