[tip: x86/splitlock] Documentation/admin-guide: Change doc for split_lock_detect parameter

[tip-bot2 for Fenghua Yu]

The following commit has been merged into the x86/splitlock branch of tip:

Commit-ID:     ebca17707e38f2050b188d837bd4646b29a1b0c2
Gitweb:        https://git.kernel.org/tip/ebca17707e38f2050b188d837bd4646b29a1b0c2
Author:        Fenghua Yu <fenghua.yu@xxxxxxxxx>
AuthorDate:    Mon, 22 Mar 2021 13:53:25 
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Sun, 28 Mar 2021 22:52:16 +02:00

Documentation/admin-guide: Change doc for split_lock_detect parameter

Since #DB for bus lock detect changes the split_lock_detect parameter,
update the documentation for the changes.

Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210322135325.682257-4-fenghua.yu@xxxxxxxxx

---
 Documentation/admin-guide/kernel-parameters.txt | 22 +++++++++++-----
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 0454572..aef927c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5100,27 +5100,37 @@
 	spia_peddr=
 
 	split_lock_detect=
-			[X86] Enable split lock detection
+			[X86] Enable split lock detection or bus lock detection
 
 			When enabled (and if hardware support is present), atomic
 			instructions that access data across cache line
-			boundaries will result in an alignment check exception.
+			boundaries will result in an alignment check exception
+			for split lock detection or a debug exception for
+			bus lock detection.
 
 			off	- not enabled
 
-			warn	- the kernel will emit rate limited warnings
+			warn	- the kernel will emit rate-limited warnings
 				  about applications triggering the #AC
-				  exception. This mode is the default on CPUs
-				  that supports split lock detection.
+				  exception or the #DB exception. This mode is
+				  the default on CPUs that support split lock
+				  detection or bus lock detection. Default
+				  behavior is by #AC if both features are
+				  enabled in hardware.
 
 			fatal	- the kernel will send SIGBUS to applications
-				  that trigger the #AC exception.
+				  that trigger the #AC exception or the #DB
+				  exception. Default behavior is by #AC if
+				  both features are enabled in hardware.
 
 			If an #AC exception is hit in the kernel or in
 			firmware (i.e. not while executing in user mode)
 			the kernel will oops in either "warn" or "fatal"
 			mode.
 
+			#DB exception for bus lock is triggered only when
+			CPL > 0.
+
 	srbds=		[X86,INTEL]
 			Control the Special Register Buffer Data Sampling
 			(SRBDS) mitigation.