Re: [PATCH 2/2] iommu/sva: Remove mm parameter from SVA bind API

Lu Baolu
2021-04-15T05:43:12Z

Hi Jason,

On 4/14/21 7:26 PM, Jason Gunthorpe wrote:
> On Wed, Apr 14, 2021 at 02:22:09PM +0800, Lu Baolu wrote:
>
>> I still worry about supervisor pasid allocation.
>>
>> If we use iommu_sva_alloc_pasid() to allocate a supervisor pasid, which
>> mm should the pasid be set? I've ever thought about passing &init_mm to
>> iommu_sva_alloc_pasid(). But if you add "mm != current->mm", this seems
>> not to work. Or do you prefer a separated interface for supervisor pasid
>> allocation/free?
>
> Without a mm_struct it is not SVA, so don't use SVA APIs for whatever
> a 'supervisor pasid' is

The supervisor PASID has its mm_struct. The only difference is that the
device will set priv=1 in its DMA transactions with the PASID.

Best regards,
baolu