Re: [PATCH linux-next] iommu: add iommu for s390 platform

[Joerg Roedel]

Hi Frank,

On Tue, Oct 21, 2014 at 01:57:25PM +0200, Frank Blaschka wrote:
> Add a basic iommu for the s390 platform. The code is pretty simple
> since on s390 each PCI device has its own virtual io address space
> starting at the same vio address.

Are there any limitations on IOVA address space for the devices or can
be really any system physical address mapped starting from 0 to 2^64?

> For this a domain could hold only one pci device.

This bothers me, as it is not compatible with the IOMMU-API. I looked a
little bit into how the mappings are created, and it seems there is a
per-device dma_table.

Is there any reason a dma_table can't be per IOMMU domain and assigned
to multiple devices at the same time?

Otherwise the code looks quite simple and straight forward.


	Joerg


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