acpi, nfit: allow override of built-in bitmasks for nvdimm DSMs

As it is today, we can't enable or test new NVDIMM management functions
provided by new firmware and tools without changing the kernel.  We also
can't prevent documented DSM functions from being called in the case of
buggy firmware.  This patch provides a module parameter that overrides
the DSM function mask that is built into the kernel.

If the "disable_vendor_specific" module parameter is also used we ignore
the new parameter.
Signed-off-by: Linda Knippers <linda.knippers@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/acpi/nfit/core.c

@@ -51,6 +51,10 @@ module_param(disable_vendor_specific, bool, S_IRUGO);
 MODULE_PARM_DESC(disable_vendor_specific,
 		"Limit commands to the publicly specified set\n");
 
+static unsigned long override_dsm_mask;
+module_param(override_dsm_mask, ulong, S_IRUGO);
+MODULE_PARM_DESC(override_dsm_mask, "Bitmask of allowed NVDIMM DSM functions");
+
 LIST_HEAD(acpi_descs);
 DEFINE_MUTEX(acpi_desc_lock);
 
@@ -1402,7 +1406,9 @@ static int acpi_nfit_add_dimm(struct acpi_nfit_desc *acpi_desc,
 
 	/* limit the supported commands to those that are publicly documented */
 	nfit_mem->family = i;
-	if (nfit_mem->family == NVDIMM_FAMILY_INTEL) {
+	if (override_dsm_mask && !disable_vendor_specific)
+		dsm_mask = override_dsm_mask;
+	else if (nfit_mem->family == NVDIMM_FAMILY_INTEL) {
 		dsm_mask = 0x3fe;
 		if (disable_vendor_specific)
 			dsm_mask &= ~(1 << ND_CMD_VENDOR);