Re: [RFC 2/3] iommu: Account for dma_mask and iommu aperture in IOVA reserved regions

[Auger Eric]

Hi Christoph,

On 9/29/20 8:03 AM, Christoph Hellwig wrote:
> On Mon, Sep 28, 2020 at 09:50:36PM +0200, Eric Auger wrote:
>> VFIO currently exposes the usable IOVA regions through the
>> VFIO_IOMMU_GET_INFO ioctl. However it fails to take into account
>> the dma_mask of the devices within the container. The top limit
>> currently is defined by the iommu aperture.
> 
> Can we take a step back here?  The dma_mask only has a meaning for
> the DMA API, and not the iommu API, it should have no relevance here.
> 
> More importantly if we are using vfio no dma_mask should be set to
> start with.

You will find more context in my reply to Alex.

Thanks

Eric
> 
>> +		if (geo.aperture_end < ULLONG_MAX && geo.aperture_end != geo.aperture_start) {
> 
> Please avoid pointlessly overlong lines.
>