nfit: skip region registration for incomplete control regions

BugLink: http://bugs.launchpad.net/bugs/1773233
commit 0731de476a37c33485af82d64041c9d193208df8 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Khalid Elmously <khalid.elmously@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 9151d6903b855a7d4deadf3fce0be56a16c5e824..fb80dbf80e4b793badfca089a11e3ad314ddb749 100644 (file)
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -2582,7 +2582,7 @@ 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",
@@ -2602,15 +2602,14 @@ 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;