Pull VFIO updates from Alex Williamson:
 - Nested IOMMU extension to type1 (Will Deacon)
 - Restore MSIx message before enabling (Gavin Shan)
 - Fix remove path locking (Alex Williamson)

* tag 'vfio-v3.18-rc1' of git://github.com/awilliam/linux-vfio:
  vfio-pci: Fix remove path locking
  drivers/vfio: Export vfio_spapr_iommu_eeh_ioctl() with GPL
  vfio/pci: Restore MSIx message prior to enabling
  PCI: Export MSI message relevant functions
  vfio/iommu_type1: add new VFIO_TYPE1_NESTING_IOMMU IOMMU type
  iommu: introduce domain attribute for nesting IOMMUs