Most of the callers of vfio_pin_pages() want "struct page *" and the
low-level mm code to pin pages returns a list of "struct page *" too.
So there's no gain in converting "struct page *" to PFN in between.

Replace the output parameter "phys_pfn" list with a "pages" list, to
simplify callers. This also allows us to replace the vfio_iommu_type1
implementation with a more efficient one.

And drop the pfn_valid check in the gvt code, as there is no need to
do such a check at a page-backed struct page pointer.

For now, also update vfio_iommu_type1 to fit this new parameter too.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NKirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: NJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: NKevin Tian <kevin.tian@intel.com>
Acked-by: NEric Farman <farman@linux.ibm.com>
Tested-by: NTerrence Xu <terrence.xu@intel.com>
Tested-by: NEric Farman <farman@linux.ibm.com>
Signed-off-by: NNicolin Chen <nicolinc@nvidia.com>
Link: https://lore.kernel.org/r/20220723020256.30081-11-nicolinc@nvidia.comSigned-off-by: NAlex Williamson <alex.williamson@redhat.com>