v2: by Lionel
Fix memfd_create compilation issue
Fix pml4 address stored on 32 instead of 64bits
Return no buffer if first ppgtt page is not mapped
v3: Drop additional memfd_create() (Rafael)
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>