[PATCH v9 15/17] x86/split_lock: Add documentation for split lock detection interface

[Fenghua Yu]

It is useful for development and debugging to document the new debugfs
interface /sys/kernel/debug/x86/split_lock_detect.

A new debugfs documentation is created to describe the split lock detection
interface. In the future, more entries may be added in the documentation to
describe other interfaces under /sys/kernel/debug/x86 directory.

Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
---
 Documentation/ABI/testing/debugfs-x86 | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 Documentation/ABI/testing/debugfs-x86

diff --git a/Documentation/ABI/testing/debugfs-x86 b/Documentation/ABI/testing/debugfs-x86
new file mode 100644
index 000000000000..17a1e9ed6712
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-x86
@@ -0,0 +1,21 @@
+What:		/sys/kernel/debugfs/x86/split_lock_detect
+Date:		May 2019
+Contact:	Linux kernel mailing list <linux-kernel@xxxxxxxxxxxxxxx>
+Description:	(RW) Control split lock detection on Intel Tremont and
+		future CPUs
+
+		Reads return split lock detection status:
+			0: disabled
+			1: enabled
+
+		Writes enable or disable split lock detection:
+			The first character is one of 'Nn0' or [oO][fF] for off
+			disables the feature.
+			The first character is one of 'Yy1' or [oO][nN] for on
+			enables the feature.
+
+		Please note the interface only shows or controls global setting.
+		During run time, split lock detection on one CPU may be
+		disabled if split lock operation in kernel code happens on
+		the CPU. The interface doesn't show or control split lock
+		detection on individual CPU.
-- 
2.19.1