releases/5.0.16/0023-s390-speculation-Support-mitigations-cmdline-option.patch

   1 From aa18d76c6cd803424e787d15d6af34d7339c8419 Mon Sep 17 00:00:00 2001
   2 From: Josh Poimboeuf <jpoimboe@redhat.com>
   3 Date: Fri, 12 Apr 2019 15:39:31 -0500
   4 Subject: [PATCH 23/27] s390/speculation: Support 'mitigations=' cmdline option
   5
   6 commit 0336e04a6520bdaefdb0769d2a70084fa52e81ed upstream
   7
   8 Configure s390 runtime CPU speculation bug mitigations in accordance
   9 with the 'mitigations=' cmdline option.  This affects Spectre v1 and
  10 Spectre v2.
  11
  12 The default behavior is unchanged.
  13
  14 Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
  15 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  16 Tested-by: Jiri Kosina <jkosina@suse.cz> (on x86)
  17 Reviewed-by: Jiri Kosina <jkosina@suse.cz>
  18 Cc: Borislav Petkov <bp@alien8.de>
  19 Cc: "H . Peter Anvin" <hpa@zytor.com>
  20 Cc: Andy Lutomirski <luto@kernel.org>
  21 Cc: Peter Zijlstra <peterz@infradead.org>
  22 Cc: Jiri Kosina <jikos@kernel.org>
  23 Cc: Waiman Long <longman@redhat.com>
  24 Cc: Andrea Arcangeli <aarcange@redhat.com>
  25 Cc: Jon Masters <jcm@redhat.com>
  26 Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
  27 Cc: Paul Mackerras <paulus@samba.org>
  28 Cc: Michael Ellerman <mpe@ellerman.id.au>
  29 Cc: linuxppc-dev@lists.ozlabs.org
  30 Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
  31 Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
  32 Cc: linux-s390@vger.kernel.org
  33 Cc: Catalin Marinas <catalin.marinas@arm.com>
  34 Cc: Will Deacon <will.deacon@arm.com>
  35 Cc: linux-arm-kernel@lists.infradead.org
  36 Cc: linux-arch@vger.kernel.org
  37 Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  38 Cc: Tyler Hicks <tyhicks@canonical.com>
  39 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  40 Cc: Randy Dunlap <rdunlap@infradead.org>
  41 Cc: Steven Price <steven.price@arm.com>
  42 Cc: Phil Auld <pauld@redhat.com>
  43 Link: https://lkml.kernel.org/r/e4a161805458a5ec88812aac0307ae3908a030fc.1555085500.git.jpoimboe@redhat.com
  44 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  45 ---
  46  Documentation/admin-guide/kernel-parameters.txt | 5 +++--
  47  arch/s390/kernel/nospec-branch.c                | 3 ++-
  48  2 files changed, 5 insertions(+), 3 deletions(-)
  49
  50 diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
  51 index ed9ec2ea362d..9aa3543a8723 100644
  52 --- a/Documentation/admin-guide/kernel-parameters.txt
  53 +++ b/Documentation/admin-guide/kernel-parameters.txt
  54 @@ -2540,7 +2540,7 @@
  55                         http://repo.or.cz/w/linux-2.6/mini2440.git
  56
  57         mitigations=
  58 -                       [X86,PPC] Control optional mitigations for CPU
  59 +                       [X86,PPC,S390] Control optional mitigations for CPU
  60                         vulnerabilities.  This is a set of curated,
  61                         arch-independent options, each of which is an
  62                         aggregation of existing arch-specific options.
  63 @@ -2551,7 +2551,8 @@
  64                                 expose users to several CPU vulnerabilities.
  65                                 Equivalent to: nopti [X86,PPC]
  66                                                nospectre_v1 [PPC]
  67 -                                              nospectre_v2 [X86,PPC]
  68 +                                              nobp=0 [S390]
  69 +                                              nospectre_v2 [X86,PPC,S390]
  70                                                spectre_v2_user=off [X86]
  71                                                spec_store_bypass_disable=off [X86,PPC]
  72                                                l1tf=off [X86]
  73 diff --git a/arch/s390/kernel/nospec-branch.c b/arch/s390/kernel/nospec-branch.c
  74 index bdddaae96559..649135cbedd5 100644
  75 --- a/arch/s390/kernel/nospec-branch.c
  76 +++ b/arch/s390/kernel/nospec-branch.c
  77 @@ -1,6 +1,7 @@
  78  // SPDX-License-Identifier: GPL-2.0
  79  #include <linux/module.h>
  80  #include <linux/device.h>
  81 +#include <linux/cpu.h>
  82  #include <asm/nospec-branch.h>
  83
  84  static int __init nobp_setup_early(char *str)
  85 @@ -58,7 +59,7 @@ early_param("nospectre_v2", nospectre_v2_setup_early);
  86
  87  void __init nospec_auto_detect(void)
  88  {
  89 -       if (test_facility(156)) {
  90 +       if (test_facility(156) || cpu_mitigations_off()) {
  91                 /*
  92                  * The machine supports etokens.
  93                  * Disable expolines and disable nobp.
  94 --
  95 2.21.0
  96