nvdimm: set non-volatile on the memory region

qemu-system-x86_64 -machine pc,nvdimm -m 2G,slots=4,maxmem=16G -enable-kvm -monitor stdio -object memory-backend-file,id=mem1,share=on,mem-path=/tmp/foo,size=1G -device nvdimm,id=nvdimm1,memdev=mem1

HMP info mtree command reflects the flag with "nv-" prefix on memory type:

(qemu) info mtree
0000000100000000-000000013fffffff (prio 0, nv-i/o): alias nvdimm-memory @/objects/mem1 0000000000000000-000000003fffffff

(qemu) info mtree -f
0000000100000000-000000013fffffff (prio 0, nv-ram): /objects/mem1

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20181003114454.5662-3-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/mem/nvdimm.c

@@ -116,6 +116,7 @@ static void nvdimm_prepare_memory_region(NVDIMMDevice *nvdimm, Error **errp)
     nvdimm->nvdimm_mr = g_new(MemoryRegion, 1);
     memory_region_init_alias(nvdimm->nvdimm_mr, OBJECT(dimm),
                              "nvdimm-memory", mr, 0, pmem_size);
+    memory_region_set_nonvolatile(nvdimm->nvdimm_mr, true);
     nvdimm->nvdimm_mr->align = align;
 }