x86/intel_rdt/mbm: Add mbm counter initialization

MBM counters are monotonically increasing counts representing the total
memory bytes at a particular time. In order to calculate total_bytes for
an rdtgroup, we store the value of the counter when we create an
rdtgroup or when a new domain comes online.

When the total_bytes(all memory controller bytes) or local_bytes(local
memory controller bytes) file in "mon_data" is read it shows the
total bytes for that rdtgroup since its creation. User can snapshot this
at different time intervals to obtain bytes/second.

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: vikas.shivappa@intel.com
Cc: ak@linux.intel.com
Cc: davidcc@google.com
Cc: reinette.chatre@intel.com
Link: http://lkml.kernel.org/r/1501017287-28083-28-git-send-email-vikas.shivappa@linux.intel.com

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index ea37b97..05088e3 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -1351,6 +1351,7 @@ static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
 	union mon_data_bits priv;
 	struct kernfs_node *kn;
 	struct mon_evt *mevt;
+	struct rmid_read rr;
 	char name[32];
 	int ret;
 
@@ -1381,6 +1382,9 @@ static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
 		ret = mon_addfile(kn, mevt->name, priv.priv);
 		if (ret)
 			goto out_destroy;
+
+		if (is_mbm_event(mevt->evtid))
+			mon_event_read(&rr, d, prgrp, mevt->evtid, true);
 	}
 	kernfs_activate(kn);
 	return 0;