Subject: Patch "[PATCH 23/27] s390/speculation: Support 'mitigations=' cmdline option" has been added to the 5.1-stable tree

From: <[email-masked]>
Date: Tue, 14 May 2019 19:06:20 +0200

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

    [PATCH 23/27] s390/speculation: Support 'mitigations=' cmdline option

to the 5.1-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:
     0023-s390-speculation-Support-mitigations-cmdline-option.patch
and it can be found in the queue-5.1 subdirectory.

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

>From e6d932f77faa0f3f1430f083f74792cd391b1ada Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <[email-masked]>
Date: Fri, 12 Apr 2019 15:39:31 -0500
Subject: [PATCH 23/27] s390/speculation: Support 'mitigations=' cmdline option

commit 0336e04a6520bdaefdb0769d2a70084fa52e81ed upstream

Configure s390 runtime CPU speculation bug mitigations in accordance
with the 'mitigations=' cmdline option.  This affects Spectre v1 and
Spectre v2.

The default behavior is unchanged.

Signed-off-by: Josh Poimboeuf <[email-masked]>
Signed-off-by: Thomas Gleixner <[email-masked]>
Tested-by: Jiri Kosina <[email-masked]> (on x86)
Reviewed-by: Jiri Kosina <[email-masked]>
Cc: Borislav Petkov <[email-masked]>
Cc: "H . Peter Anvin" <[email-masked]>
Cc: Andy Lutomirski <[email-masked]>
Cc: Peter Zijlstra <[email-masked]>
Cc: Jiri Kosina <[email-masked]>
Cc: Waiman Long <[email-masked]>
Cc: Andrea Arcangeli <[email-masked]>
Cc: Jon Masters <[email-masked]>
Cc: Benjamin Herrenschmidt <[email-masked]>
Cc: Paul Mackerras <[email-masked]>
Cc: Michael Ellerman <[email-masked]>
Cc: [email-masked]
Cc: Martin Schwidefsky <[email-masked]>
Cc: Heiko Carstens <[email-masked]>
Cc: [email-masked]
Cc: Catalin Marinas <[email-masked]>
Cc: Will Deacon <[email-masked]>
Cc: [email-masked]
Cc: [email-masked]
Cc: Greg Kroah-Hartman <[email-masked]>
Cc: Tyler Hicks <[email-masked]>
Cc: Linus Torvalds <[email-masked]>
Cc: Randy Dunlap <[email-masked]>
Cc: Steven Price <[email-masked]>
Cc: Phil Auld <[email-masked]>
Link: https://lkml.kernel.org/r/[email-masked]
Signed-off-by: Greg Kroah-Hartman <[email-masked]>
---
 Documentation/admin-guide/kernel-parameters.txt | 5 +++--
 arch/s390/kernel/nospec-branch.c                | 3 ++-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3294030d7f57..2bf137f97902 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2571,7 +2571,7 @@
 			http://repo.or.cz/w/linux-2.6/mini2440.git
 
 	mitigations=
-			[X86,PPC] Control optional mitigations for CPU
+			[X86,PPC,S390] Control optional mitigations for CPU
 			vulnerabilities.  This is a set of curated,
 			arch-independent options, each of which is an
 			aggregation of existing arch-specific options.
@@ -2582,7 +2582,8 @@
 				expose users to several CPU vulnerabilities.
 				Equivalent to: nopti [X86,PPC]
 					       nospectre_v1 [PPC]
-					       nospectre_v2 [X86,PPC]
+					       nobp=0 [S390]
+					       nospectre_v2 [X86,PPC,S390]
 					       spectre_v2_user=off [X86]
 					       spec_store_bypass_disable=off [X86,PPC]
 					       l1tf=off [X86]
diff --git a/arch/s390/kernel/nospec-branch.c b/arch/s390/kernel/nospec-branch.c
index bdddaae96559..649135cbedd5 100644
--- a/arch/s390/kernel/nospec-branch.c
+++ b/arch/s390/kernel/nospec-branch.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/module.h>
 #include <linux/device.h>
+#include <linux/cpu.h>
 #include <asm/nospec-branch.h>
 
 static int __init nobp_setup_early(char *str)
@@ -58,7 +59,7 @@ early_param("nospectre_v2", nospectre_v2_setup_early);
 
 void __init nospec_auto_detect(void)
 {
-	if (test_facility(156)) {
+	if (test_facility(156) || cpu_mitigations_off()) {
 		/*
 		 * The machine supports etokens.
 		 * Disable expolines and disable nobp.
-- 
2.21.0

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

queue-5.1/0019-x86-speculation-mds-Print-SMT-vulnerable-on-MSBDS-wi.patch
queue-5.1/0016-x86-speculation-Move-arch_smt_update-call-to-after-m.patch
queue-5.1/0024-x86-speculation-mds-Add-mitigations-support-for-MDS.patch
queue-5.1/0021-x86-speculation-Support-mitigations-cmdline-option.patch
queue-5.1/0022-powerpc-speculation-Support-mitigations-cmdline-opti.patch
queue-5.1/0020-cpu-speculation-Add-mitigations-cmdline-option.patch
queue-5.1/0023-s390-speculation-Support-mitigations-cmdline-option.patch
queue-5.1/0015-x86-speculation-mds-Add-mds-full-nosmt-cmdline-optio.patch
queue-5.1/0027-x86-speculation-mds-Fix-documentation-typo.patch
queue-5.1/0017-x86-speculation-mds-Add-SMT-warning-message.patch
queue-5.1/0018-x86-speculation-mds-Fix-comment.patch

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