when the scalable mode is enabled, there is no second level
page translation pointer in the context entry any more (for
DMA request without PASID). Instead, a new RID2PASID field
is introduced in the context entry. Software can choose any
PASID value to set RID2PASID and then setup the translation
in the corresponding PASID entry. Upon receiving a DMA request
without PASID, hardware will firstly look at this RID2PASID
field and then treat this request as a request with a pasid
value specified in RID2PASID field.

Though software is allowed to use any PASID for the RID2PASID,
we will always use the PASID 0 as a sort of design decision.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>