mm/memremap.c: map FS_DAX device memory as decrypted

mm/memremap.c: map FS_DAX device memory as decrypted

commit 867400af90f1f953ff9e10b1b87ecaf9369a7eb8 upstream.

virtio_pmem use devm_memremap_pages() to map the device memory.  By
default this memory is mapped as encrypted with SEV.  Guest reboot changes
the current encryption key and guest no longer properly decrypts the FSDAX
device meta data.

Mark the corresponding device memory region for FSDAX devices (mapped with
memremap_pages) as decrypted to retain the persistent memory property.

Link: https://lkml.kernel.org/r/20221102160728.3184016-1-pankaj.gupta@amd.com
Fixes: b7b3c01b19159 ("mm/memremap_pages: support multiple ranges per invocation")
Signed-off-by: Pankaj Gupta <pankaj.gupta@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>