| From 4feab80ca8eef453dee018aecc877a5b1c4bc84d Mon Sep 17 00:00:00 2001 |
| From: Josh Poimboeuf <jpoimboe@redhat.com> |
| Date: Fri, 12 Apr 2019 15:39:31 -0500 |
| Subject: [PATCH 26/30] 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 <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 |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| 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 49aa191979c1..4f3efaaa46bd 100644 |
| --- a/Documentation/admin-guide/kernel-parameters.txt |
| +++ b/Documentation/admin-guide/kernel-parameters.txt |
| @@ -2503,7 +2503,7 @@ |
| 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. |
| @@ -2514,7 +2514,8 @@ |
| 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 |
| |