x86/intel_rdt: Re-enable pseudo-lock measurements

Commit 4a7a54a55e72 ("x86/intel_rdt: Disable PMU access") disabled
measurements of pseudo-locked regions because of incorrect usage
of the performance monitoring hardware.

Cache pseudo-locking measurements are now done correctly with the
in-kernel perf API and its use can be re-enabled at this time.

The adjustment to the in-kernel perf API also separated the L2 and L3
measurements that can be triggered separately from user space. The
re-enabling of the measurements is thus not a simple revert of the
original disable in order to accommodate the additional parameter
possible.

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: peterz@infradead.org
Cc: acme@kernel.org
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/bfb9fc31692e0c62d9ca39062e55eceb6a0635b5.1537377064.git.reinette.chatre@intel.com

arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c

@@ -1236,7 +1236,7 @@ static ssize_t pseudo_lock_measure_trigger(struct file *file,
 	buf[buf_size] = '\0';
 	ret = kstrtoint(buf, 10, &sel);
 	if (ret == 0) {
-		if (sel != 1)
+		if (sel != 1 && sel != 2 && sel != 3)
 			return -EINVAL;
 		ret = debugfs_file_get(file->f_path.dentry);
 		if (ret)