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Date:   Fri, 10 Jun 2022 16:37:54 +0100
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Subject: Re: [PATCH v3 3/4] scsi: core: Cap shost max_sectors according to DMA
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To:     Bart Van Assche <bvanassche@acm.org>,
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From:   John Garry <john.garry@huawei.com>
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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