[PATCH stable-4.9] Documentation: Document arm64 kpti control

[Florian Fainelli]

From: Jeremy Linton <jeremy.linton@xxxxxxx>

commit de19055564c8f8f9d366f8db3395836da0b2176c upstream

For a while Arm64 has been capable of force enabling
or disabling the kpti mitigations. Lets make sure the
documentation reflects that.

Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>
Signed-off-by: Jonathan Corbet <corbet@xxxxxxx>
[florian: patch the correct file]
Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
---
 Documentation/kernel-parameters.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1bc12619bedd..b2d2f4539a3f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1965,6 +1965,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			kmemcheck=2 (one-shot mode)
 			Default: 2 (one-shot mode)
 
+	kpti=		[ARM64] Control page table isolation of user
+			and kernel address spaces.
+			Default: enabled on cores which need mitigation.
+			0: force disabled
+			1: force enabled
+
 	kstack=N	[X86] Print N words from the kernel stack
 			in oops dumps.
 
-- 
2.17.1