nfit: fix multi-interface dimm handling, acpi6.1 compatibility

ACPI 6.1 clarified that multi-interface dimms require multiple control
region entries (DCRs) per dimm.  Previously we were assuming that a
control region is only present when block-data-windows are present.
This implementation was done with an eye to be compatibility with the
looser ACPI 6.0 interpretation of this table.

1/ When coalescing the memory device (MEMDEV) tables for a single dimm,
coalesce on device_handle rather than control region index.

2/ Whenever we disocver a control region with non-zero block windows
re-scan for block-data-window (BDW) entries.

We may need to revisit this if a DIMM ever implements a format interface
outside of blk or pmem, but that is not on the foreseeable horizon.

Cc: <stable@vger.kernel.org>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

drivers/acpi/nfit.c

@@ -469,37 +469,16 @@ static void nfit_mem_find_spa_bdw(struct acpi_nfit_desc *acpi_desc,
 	nfit_mem->bdw = NULL;
 }
 
-static int nfit_mem_add(struct acpi_nfit_desc *acpi_desc,
+static void nfit_mem_init_bdw(struct acpi_nfit_desc *acpi_desc,
 		struct nfit_mem *nfit_mem, struct acpi_nfit_system_address *spa)
 {
 	u16 dcr = __to_nfit_memdev(nfit_mem)->region_index;
 	struct nfit_memdev *nfit_memdev;
 	struct nfit_flush *nfit_flush;
-	struct nfit_dcr *nfit_dcr;
 	struct nfit_bdw *nfit_bdw;
 	struct nfit_idt *nfit_idt;
 	u16 idt_idx, range_index;
 
-	list_for_each_entry(nfit_dcr, &acpi_desc->dcrs, list) {
-		if (nfit_dcr->dcr->region_index != dcr)
-			continue;
-		nfit_mem->dcr = nfit_dcr->dcr;
-		break;
-	}
-
-	if (!nfit_mem->dcr) {
-		dev_dbg(acpi_desc->dev, "SPA %d missing:%s%s\n",
-				spa->range_index, __to_nfit_memdev(nfit_mem)
-				? "" : " MEMDEV", nfit_mem->dcr ? "" : " DCR");
-		return -ENODEV;
-	}
-
-	/*
-	 * We've found enough to create an nvdimm, optionally
-	 * find an associated BDW
-	 */
-	list_add(&nfit_mem->list, &acpi_desc->dimms);
-
 	list_for_each_entry(nfit_bdw, &acpi_desc->bdws, list) {
 		if (nfit_bdw->bdw->region_index != dcr)
 			continue;
@@ -508,12 +487,12 @@ static int nfit_mem_add(struct acpi_nfit_desc *acpi_desc,
 	}
 
 	if (!nfit_mem->bdw)
-		return 0;
+		return;
 
 	nfit_mem_find_spa_bdw(acpi_desc, nfit_mem);
 
 	if (!nfit_mem->spa_bdw)
-		return 0;
+		return;
 
 	range_index = nfit_mem->spa_bdw->range_index;
 	list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list) {
@@ -538,8 +517,6 @@ static int nfit_mem_add(struct acpi_nfit_desc *acpi_desc,
 		}
 		break;
 	}
-
-	return 0;
 }
 
 static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
@@ -548,7 +525,6 @@ static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
 	struct nfit_mem *nfit_mem, *found;
 	struct nfit_memdev *nfit_memdev;
 	int type = nfit_spa_type(spa);
-	u16 dcr;
 
 	switch (type) {
 	case NFIT_SPA_DCR:
@@ -559,14 +535,18 @@ static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
 	}
 
 	list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list) {
-		int rc;
+		struct nfit_dcr *nfit_dcr;
+		u32 device_handle;
+		u16 dcr;
 
 		if (nfit_memdev->memdev->range_index != spa->range_index)
 			continue;
 		found = NULL;
 		dcr = nfit_memdev->memdev->region_index;
+		device_handle = nfit_memdev->memdev->device_handle;
 		list_for_each_entry(nfit_mem, &acpi_desc->dimms, list)
-			if (__to_nfit_memdev(nfit_mem)->region_index == dcr) {
+			if (__to_nfit_memdev(nfit_mem)->device_handle
+					== device_handle) {
 				found = nfit_mem;
 				break;
 			}
@@ -579,6 +559,31 @@ static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
 			if (!nfit_mem)
 				return -ENOMEM;
 			INIT_LIST_HEAD(&nfit_mem->list);
+			list_add(&nfit_mem->list, &acpi_desc->dimms);
+		}
+
+		list_for_each_entry(nfit_dcr, &acpi_desc->dcrs, list) {
+			if (nfit_dcr->dcr->region_index != dcr)
+				continue;
+			/*
+			 * Record the control region for the dimm.  For
+			 * the ACPI 6.1 case, where there are separate
+			 * control regions for the pmem vs blk
+			 * interfaces, be sure to record the extended
+			 * blk details.
+			 */
+			if (!nfit_mem->dcr)
+				nfit_mem->dcr = nfit_dcr->dcr;
+			else if (nfit_mem->dcr->windows == 0
+					&& nfit_dcr->dcr->windows)
+				nfit_mem->dcr = nfit_dcr->dcr;
+			break;
+		}
+
+		if (dcr && !nfit_mem->dcr) {
+			dev_err(acpi_desc->dev, "SPA %d missing DCR %d\n",
+					spa->range_index, dcr);
+			return -ENODEV;
 		}
 
 		if (type == NFIT_SPA_DCR) {
@@ -595,6 +600,7 @@ static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
 				nfit_mem->idt_dcr = nfit_idt->idt;
 				break;
 			}
+			nfit_mem_init_bdw(acpi_desc, nfit_mem, spa);
 		} else {
 			/*
 			 * A single dimm may belong to multiple SPA-PM
@@ -603,13 +609,6 @@ static int nfit_mem_dcr_init(struct acpi_nfit_desc *acpi_desc,
 			 */
 			nfit_mem->memdev_pmem = nfit_memdev->memdev;
 		}
-
-		if (found)
-			continue;
-
-		rc = nfit_mem_add(acpi_desc, nfit_mem, spa);
-		if (rc)
-			return rc;
 	}
 
 	return 0;