Add admin documentation for "retbleed=stuff", based on commit
description and source code.
Fixes: d82a0345cf21 ("x86/retbleed: Add call depth tracking mitigation")
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: linux-doc@xxxxxxxxxxxxxxx
---
Documentation/admin-guide/kernel-parameters.txt | 8 ++++++++
1 file changed, 8 insertions(+)
diff -- a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5364,6 +5364,14 @@
when STIBP is not available. This is
the alternative for systems which do not
have STIBP.
+ stuff - Enables "stuffing" mode mitigation,
+ which uses return thunking and call depth
+ tracking. Only if effect if
+ CONFIG_CALL_DEPTH_TRACKING is set and
+ Spectre V2 mitigation mode is
+ "retpoline".
+ IBRS is fully secure mitigation but is
+ more costly (slower) than stuffing.
unret - Force enable untrained return thunks,
only effective on AMD f15h-f17h based
systems.
