x86/intel_rdt: Introduce RDT resource group mode

At this time there are no constraints on how bitmasks represented by
schemata can be associated with closids represented by resource groups.  A
bitmask of one class of service can without any objections overlap with the
bitmask of another class of service.

The concept of "mode" is introduced in preparation for support of control
over whether cache regions can be shared between classes of service. At
this time the only mode reflects the current cache allocations where all
can potentially be shared.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: fenghua.yu@intel.com
Cc: tony.luck@intel.com
Cc: vikas.shivappa@linux.intel.com
Cc: gavin.hindman@intel.com
Cc: jithu.joseph@intel.com
Cc: dave.hansen@intel.com
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/87e88275597fbfa03ea9d41c1186bf012c831c01.1529706536.git.reinette.chatre@intel.com

arch/x86/kernel/cpu/intel_rdt.h

@@ -80,6 +80,22 @@ enum rdt_group_type {
 	RDT_NUM_GROUP,
 };
 
+/**
+ * enum rdtgrp_mode - Mode of a RDT resource group
+ * @RDT_MODE_SHAREABLE: This resource group allows sharing of its allocations
+ *
+ * The mode of a resource group enables control over the allowed overlap
+ * between allocations associated with different resource groups (classes
+ * of service). User is able to modify the mode of a resource group by
+ * writing to the "mode" resctrl file associated with the resource group.
+ */
+enum rdtgrp_mode {
+	RDT_MODE_SHAREABLE = 0,
+
+	/* Must be last */
+	RDT_NUM_MODES,
+};
+
 /**
  * struct mongroup - store mon group's data in resctrl fs.
  * @mon_data_kn		kernlfs node for the mon_data directory