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

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/[email protected]
Fixes: b7b3c01 ("mm/memremap_pages: support multiple ranges per invocation")
Signed-off-by: Pankaj Gupta <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: pagupta

mm/memremap.c

@@ -335,6 +335,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
 			WARN(1, "File system DAX not supported\n");
 			return ERR_PTR(-EINVAL);
 		}
+		params.pgprot = pgprot_decrypted(params.pgprot);
 		break;
 	case MEMORY_DEVICE_GENERIC:
 		break;