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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Toshi Kani <toshi.kani@hpe.com>,
        Dan Williams <dan.j.williams@intel.com>
Subject: [PATCH 4.16 126/196] nfit: skip region registration for incomplete control regions
Date:   Sun, 22 Apr 2018 15:52:26 +0200
Message-Id: <20180422135110.768930335@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Williams <dan.j.williams@intel.com>

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>

---
 drivers/acpi/nfit/core.c |   13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -2583,7 +2583,7 @@ static int acpi_nfit_init_mapping(struct
 	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",
@@ -2603,15 +2603,14 @@ static int acpi_nfit_init_mapping(struct
 		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;