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authorJosh Poimboeuf <[email protected]>2019-04-12 15:39:31 -0500
committerThomas Gleixner <[email protected]>2019-04-17 21:37:29 +0200
commit0336e04a6520bdaefdb0769d2a70084fa52e81ed (patch)
tree7ed49208b1df059ff9125e24240b698e66c6c705
parent782e69efb3dfed6e8360bc612e8c7827a901a8f9 (diff)
s390/speculation: Support 'mitigations=' cmdline option
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 protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Jiri Kosina <[email protected]> (on x86) Reviewed-by: Jiri Kosina <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: "H . Peter Anvin" <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Jiri Kosina <[email protected]> Cc: Waiman Long <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Jon Masters <[email protected]> Cc: Benjamin Herrenschmidt <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Michael Ellerman <[email protected]> Cc: [email protected] Cc: Martin Schwidefsky <[email protected]> Cc: Heiko Carstens <[email protected]> Cc: [email protected] Cc: Catalin Marinas <[email protected]> Cc: Will Deacon <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Greg Kroah-Hartman <[email protected]> Cc: Tyler Hicks <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Randy Dunlap <[email protected]> Cc: Steven Price <[email protected]> Cc: Phil Auld <[email protected]> Link: https://lkml.kernel.org/r/e4a161805458a5ec88812aac0307ae3908a030fc.1555085500.git.jpoimboe@redhat.com
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt5
-rw-r--r--arch/s390/kernel/nospec-branch.c3
2 files changed, 5 insertions, 3 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index ac7150a25a7a..1ae93872b79f 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2514,7 +2514,7 @@
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.
@@ -2525,7 +2525,8 @@
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.