Re: [PATCH v3 03/10] iommu/sva: Manage process address spaces

[Lu Baolu <baolu.lu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

Hi Joerg,

On 09/25/2018 09:26 PM, Joerg Roedel wrote:
> On Tue, Sep 25, 2018 at 11:15:40AM +0800, Lu Baolu wrote:
>> This might be problematic for vt-d (and other possible arch's which use
>> PASID other than SVA). When vt-d iommu works in scalable mode, a PASID
>> might be allocated for:
>>
>> (1) SVA
>> (2) Device Assignable Interface (might be a mdev or directly managed
>>      within a device driver).
>> (3) SVA in VM guest
>> (4) Device Assignable Interface in VM guest
>>
>> So we can't expect that an io_mm pointer was associated with each PASID.
>> And this code might run into problem if the pasid is allocated for
>> usages other than SVA.
> 
> So all of these use-cases above should work in parallel on the same
> device, just with different PASIDs?

No. It's not required.

> Or is a device always using only one
> of the above modes at the same time?

A device might use one or multiple modes described above at the same
time.

Best regards,
Lu Baolu