These pages are from other domains, so don't have any local PFN.
VM_PFNMAP is the closest concept Linux has to this.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The gntdev driver allows usermode to map granted pages from other
domains.  This is typically used to implement a Xen backend driver
in user mode.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Signed-off-by: NStefano Stabellini <Stefano.Stabellini@eu.citrix.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>