libnvdimm: allow a platform to force enable label support

Platforms like QEMU-KVM implement an NFIT table and label DSMs.
However, since that environment does not define an aliased
configuration, the labels are currently ignored and the kernel registers
a single full-sized pmem-namespace per region. Now that the kernel
supports sub-divisions of pmem regions the labels have a purpose.
Arrange for the labels to be honored when we find an existing / valid
namespace index block.

Cc: <qemu-devel@nongnu.org>
Cc: Haozhong Zhang <haozhong.zhang@intel.com>
Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/dimm.c

@@ -64,6 +64,8 @@ static int nvdimm_probe(struct device *dev)
 	nd_label_copy(ndd, to_next_namespace_index(ndd),
 			to_current_namespace_index(ndd));
 	rc = nd_label_reserve_dpa(ndd);
+	if (ndd->ns_current >= 0)
+		nvdimm_set_aliasing(dev);
 	nvdimm_bus_unlock(dev);
 
 	if (rc)

drivers/nvdimm/dimm_devs.c

@@ -184,6 +184,13 @@ int nvdimm_set_config_data(struct nvdimm_drvdata *ndd, size_t offset,
 	return rc;
 }
 
+void nvdimm_set_aliasing(struct device *dev)
+{
+	struct nvdimm *nvdimm = to_nvdimm(dev);
+
+	nvdimm->flags |= NDD_ALIASING;
+}
+
 static void nvdimm_release(struct device *dev)
 {
 	struct nvdimm *nvdimm = to_nvdimm(dev);

drivers/nvdimm/nd.h

@@ -238,6 +238,7 @@ int nvdimm_set_config_data(struct nvdimm_drvdata *ndd, size_t offset,
 		void *buf, size_t len);
 long nvdimm_clear_poison(struct device *dev, phys_addr_t phys,
 		unsigned int len);
+void nvdimm_set_aliasing(struct device *dev);
 struct nd_btt *to_nd_btt(struct device *dev);
 
 struct nd_gen_sb {