Re: [PATCH v10 12/18] iommufd: Enforce PASID-compatible domain for RID

[Yi Liu <yi.l.liu@intel.com>]

On 2025/3/21 07:31, Jason Gunthorpe wrote:
> On Thu, Mar 20, 2025 at 03:23:15PM -0700, Nicolin Chen wrote:
> 
>>> +		attach = xa_load(&igroup->pasid_attach, IOMMU_NO_PASID);
>>> +		if (attach && attach->hwpt && !attach->hwpt->pasid_compat)
>>> +			return -EINVAL;
>>
>> Should we also make sure that RID hwpt is attached before storing
>> any PASID hwpt to a !IOMMU_NO_PASID slot in igroup->pasid_attach?
> 
> AFAIK, no.. If a driver cannot support the combination of blocked on
> RID and a paging on PASID then it should fail the attach.

I think this is by architecture, not need to really check what the
RID path is attached. right?

> smmuv3 has support for this so, and I'd expect the same of other
> drivers.

The VT-d scalable mode allows each PASID (includes the IOMMU_NO_PASID which
is used by the RID path) to be attached to different domains (blocked,
paging, identity, sva and nested). So I think intel iommu side should
support it as well.

-- 
Regards,
Yi Liu