Re: [PATCH v3 3/4] scsi: core: Cap shost max_sectors according to DMA optimum mapping limits

John Garry
2022-06-10T15:38:10Z

On 09/06/2022 21:34, Bart Van Assche wrote:
> On 6/9/22 10:54, John Garry wrote:
>> ok, but do you have a system where the UFS host controller is behind
>> an IOMMU? I had the impression that UFS controllers would be mostly
>> found in embedded systems and IOMMUs are not as common on there.
>
> Modern phones have an IOMMU. Below one can find an example from a Pixel
> 6 phone. The UFS storage controller is not controller by the IOMMU as
> far as I can see but I wouldn't be surprised if the security team would
> ask us one day to enable the IOMMU for the UFS controller.

OK, then unfortunately it seems that you have no method to test. I might
be able to test USB MSC but I am not even sure if I can even get DMA
mappings who length exceeds the IOVA rcache limit there.

Thanks,
John