iommu: introduce page response function

hulk inclusion
category: feature
bugzilla: 14369
CVE: NA
-------------------

IO page faults can be handled outside IOMMU subsystem. For an example,
when nested translation is turned on and guest owns the
first level page tables, device page request can be forwared
to the guest for handling faults. As the page response returns
by the guest, IOMMU driver on the host need to process the
response which informs the device and completes the page request
transaction.

This patch introduces generic API function for page response
passing from the guest or other in-kernel users. The definitions of
the generic data is based on PCI ATS specification not limited to
any vendor.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lkml.org/lkml/2017/12/7/1725


Signed-off-by: Fang Lijun <fanglijun3@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>