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authorJosh Poimboeuf <jpoimboe@redhat.com>2019-04-12 15:39:31 -0500
committerThomas Gleixner <tglx@linutronix.de>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 <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Jiri Kosina <jkosina@suse.cz> (on x86) Reviewed-by: Jiri Kosina <jkosina@suse.cz> Cc: Borislav Petkov <bp@alien8.de> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jiri Kosina <jikos@kernel.org> Cc: Waiman Long <longman@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Jon Masters <jcm@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: linuxppc-dev@lists.ozlabs.org Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: linux-s390@vger.kernel.org Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-arch@vger.kernel.org Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Tyler Hicks <tyhicks@canonical.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Steven Price <steven.price@arm.com> Cc: Phil Auld <pauld@redhat.com> 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.