Merge branch kvm-arm64/vfio-normal-nc into kvmarm/next

* kvm-arm64/vfio-normal-nc:
  : Normal-NC support for vfio-pci @ stage-2, courtesy of Ankit Agrawal
  :
  : KVM's policy to date has been that any and all MMIO mapping at stage-2
  : is treated as Device-nGnRE. This is primarily done due to concerns of
  : the guest triggering uncontainable failures in the system if they manage
  : to tickle the device / memory system the wrong way, though this is
  : unnecessarily restrictive for devices that can be reasoned as 'safe'.
  :
  : Unsurprisingly, the Device-* mapping can really hurt the performance of
  : assigned devices that can handle Gathering, and can be an outright
  : correctness issue if the guest driver does unaligned accesses.
  :
  : Rather than opening the floodgates to the full ecosystem of devices that
  : can be exposed to VMs, take the conservative approach and allow PCI
  : devices to be mapped as Normal-NC since it has been determined to be
  : 'safe'.
  vfio: Convey kvm that the vfio-pci device is wc safe
  KVM: arm64: Set io memory s2 pte as normalnc for vfio pci device
  mm: Introduce new flag to indicate wc safe
  KVM: arm64: Introduce new flag for non-cacheable IO memory

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>