Patch "x86/Documentation: Add PTI description" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

x86/Documentation: Add PTI description

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-documentation-add-pti-description.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Dave Hansen <[email protected]>
Date: Fri, 5 Jan 2018 09:44:36 -0800
Subject: x86/Documentation: Add PTI description

From: Dave Hansen <[email protected]>

commit 01c9b17bf673b05bb401b76ec763e9730ccf1376 upstream.

Add some details about how PTI works, what some of the downsides are, and how to debug it when things go wrong.

Also document the kernel parameter: 'pti/nopti'.

---
 Documentation/admin-guide/kernel-parameters.txt |   21 +-
 Documentation/x86/pti.txt                       |  186 ++++++++++++++++++++++++
 2 files changed, 200 insertions(+), 7 deletions(-)

@@ -2685,8 +2685,6 @@
 			steal time is computed, but won't influence scheduler
 			behaviour
 
-	nopti		[X86-64] Disable kernel page table isolation
-
 	nolapic		[X86-32,APIC] Do not enable or use the local APIC.
 
 	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.

@@ -3255,11 +3253,20 @@
 	pt.		[PARIDE]
 			See Documentation/blockdev/paride.txt.
 
-	pti=		[X86_64]
-			Control user/kernel address space isolation:
-			on - enable
-			off - disable
-			auto - default setting
+	pti=		[X86_64] Control Page Table Isolation of user and
+			kernel address spaces.  Disabling this feature
+			removes hardening, but improves performance of
+			system calls and interrupts.
+
+			on   - unconditionally enable
+			off  - unconditionally disable
+			auto - kernel detects whether your CPU model is
+			       vulnerable to issues that PTI mitigates
+
+			Not specifying this option is equivalent to pti=auto.
+
+	nopti		[X86_64]
+			Equivalent to pti=off
 
 	pty.legacy_count=
 			[KNL] Number of legacy pty's. Overwrites compiled-in

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/x86-pti-unbreak-efi-old_memmap.patch queue-4.14/x86-documentation-add-pti-description.patch