On 17/10/2018 15:21, Jean-Philippe Brucker wrote:
> Hi Jordan,
> 
> On 12/10/2018 15:32, Jordan Crouse wrote:
>> On Thu, Sep 20, 2018 at 06:00:46PM +0100, Jean-Philippe Brucker wrote:
>>> Provide an API for allocating PASIDs and populating them manually. To ease
>>> cleanup and factor allocation code, reuse the io_mm structure for private
>>> PASID. Private io_mm has a NULL mm_struct pointer, and cannot be bound to
>>> multiple devices. The mm_alloc() IOMMU op must now check if the mm
>>> argument is NULL, in which case it should allocate io_pgtables instead of
>>> binding to an mm.
>>>
>>> Signed-off-by: Jordan Crouse <[email protected]>
>>> Signed-off-by: Jean-Philippe Brucker <[email protected]>
>>> ---
>>> Sadly this probably won't be the final thing. The API in this patch is
>>> used like this:
>>>
>>>         iommu_sva_alloc_pasid(dev, &io_mm) -> PASID
>>>         iommu_sva_map(io_mm, ...)
>>>         iommu_sva_unmap(io_mm, ...)
>>>         iommu_sva_free_pasid(dev, io_mm)
>>>
>>> The proposed API for auxiliary domains is in an early stage but might
>>> replace this patch and could be used like this:
>>>
>>>         iommu_enable_aux_domain(dev)
>>>         d = iommu_domain_alloc()
>>>         iommu_attach_aux(dev, d)
>>>         iommu_aux_id(d) -> PASID
>>>         iommu_map(d, ...)
>>>         iommu_unmap(d, ...)
>>>         iommu_detach_aux(dev, d)
>>>         iommu_domain_free(d)
>>>
>>> The advantage being that the driver doesn't have to use a special
>>> version of map/unmap/etc.
>>
>> Hi Jean-Phillippe -
>>
>> Have you thought about this any more? I want to send out a
>> refresh for the per-context pagetables for arm-smmu so if we want to change
>> the underlying assumptions this would be a great time.
>>
>> For my part I'm okay with either model. In fact the second one is closer
>> to the original implementation that I sent out so I have a clear development
>> path in mind for either option depending on what the community decides.
> 
> We'll probably go with the second model. I'm trying to make the latest
> version work with SMMUv3
> (https://lwn.net/ml/linux-kernel/[email protected]/)
> and I'd like to send an RFC soon
> 
> Thanks,
> Jean
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Ugh. Please disregard this notice.

Thanks,
Jean
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