nfit: skip region registration for incomplete control regions

Per the ACPI specification the only functional purpose for a DIMM
Control Region to be mapped into the system physical address space, from
an OSPM perspective, is to support block-apertures. However, there are
some BIOSen that publish DIMM Control Region SPA entries for pre-boot
environment consumption.  Undo the kernel policy of generating disabled
'ndblk' regions when this configuration is detected.

Cc: <stable@vger.kernel.org>
Fixes: 1f7df6f88b92 ("libnvdimm, nfit: regions (block-data-window...)")
Reviewed-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 39ad06143e78..4530d89044db 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -2578,7 +2578,7 @@ static int acpi_nfit_init_mapping(struct acpi_nfit_desc *acpi_desc,
         struct acpi_nfit_system_address *spa = nfit_spa->spa;
         struct nd_blk_region_desc *ndbr_desc;
         struct nfit_mem *nfit_mem;
-        int blk_valid = 0, rc;
+        int rc;
 
         if (!nvdimm) {
                 dev_err(acpi_desc->dev, "spa%d dimm: %#x not found\n",
@@ -2598,15 +2598,14 @@ static int acpi_nfit_init_mapping(struct acpi_nfit_desc *acpi_desc,
                 if (!nfit_mem || !nfit_mem->bdw) {
                         dev_dbg(acpi_desc->dev, "spa%d %s missing bdw\n",
                                         spa->range_index, nvdimm_name(nvdimm));
-                } else {
-                        mapping->size = nfit_mem->bdw->capacity;
-                        mapping->start = nfit_mem->bdw->start_address;
-                        ndr_desc->num_lanes = nfit_mem->bdw->windows;
-                        blk_valid = 1;
+                        break;
                 }
 
+                mapping->size = nfit_mem->bdw->capacity;
+                mapping->start = nfit_mem->bdw->start_address;
+                ndr_desc->num_lanes = nfit_mem->bdw->windows;
                 ndr_desc->mapping = mapping;
-                ndr_desc->num_mappings = blk_valid;
+                ndr_desc->num_mappings = 1;
                 ndbr_desc = to_blk_region_desc(ndr_desc);
                 ndbr_desc->enable = acpi_nfit_blk_region_enable;
                 ndbr_desc->do_io = acpi_desc->blk_do_io;