Pull arm swiotlb support from Christoph Hellwig:
 "This fixes a cascade of regressions that originally started with the
  addition of the ia64 port, but only got fatal once we removed most
  uses of block layer bounce buffering in Linux 4.18.

  The reason is that while the original i386/PAE code that was the first
  architecture that supported > 4GB of memory without an iommu decided
  to leave bounce buffering to the subsystems, which in those days just
  mean block and networking as no one else consumed arbitrary userspace
  memory.

  Later with ia64, x86_64 and other ports we assumed that either an
  iommu or something that fakes it up ("software IOTLB" in beautiful
  Intel speak) is present and that subsystems can rely on that for
  dealing with addressing limitations in devices. Except that the ARM
  LPAE scheme that added larger physical address to 32-bit ARM did not
  follow that scheme and thus only worked by chance and only for block
  and networking I/O directly to highmem.

  Long story, short fix - add swiotlb support to arm when build for LPAE
  platforms, which actuallys turns out to be pretty trivial with the
  modern dma-direct / swiotlb code to fix the Linux 4.18-ish regression"

* tag 'arm-swiotlb-5.3' of git://git.infradead.org/users/hch/dma-mapping:
  arm: use swiotlb for bounce buffering on LPAE configs
  dma-mapping: check pfn validity in dma_common_{mmap,get_sgtable}