patches/kernel/0015-x86-mm-Add-the-nopcid-boot-option-to-turn-off-PCID.patch

   1 From 95e4ae0f4ad738ff6ec8e44ab9fa5529d4369655 Mon Sep 17 00:00:00 2001
   2 From: Andy Lutomirski <luto@kernel.org>
   3 Date: Thu, 29 Jun 2017 08:53:20 -0700
   4 Subject: [PATCH 015/233] x86/mm: Add the 'nopcid' boot option to turn off PCID
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 CVE-2017-5754
  10
  11 The parameter is only present on x86_64 systems to save a few bytes,
  12 as PCID is always disabled on x86_32.
  13
  14 Signed-off-by: Andy Lutomirski <luto@kernel.org>
  15 Reviewed-by: Nadav Amit <nadav.amit@gmail.com>
  16 Reviewed-by: Borislav Petkov <bp@suse.de>
  17 Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
  18 Cc: Andrew Morton <akpm@linux-foundation.org>
  19 Cc: Arjan van de Ven <arjan@linux.intel.com>
  20 Cc: Borislav Petkov <bp@alien8.de>
  21 Cc: Dave Hansen <dave.hansen@intel.com>
  22 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  23 Cc: Mel Gorman <mgorman@suse.de>
  24 Cc: Peter Zijlstra <peterz@infradead.org>
  25 Cc: Rik van Riel <riel@redhat.com>
  26 Cc: linux-mm@kvack.org
  27 Link: http://lkml.kernel.org/r/8bbb2e65bcd249a5f18bfb8128b4689f08ac2b60.1498751203.git.luto@kernel.org
  28 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  29 (cherry picked from commit 0790c9aad84901ca1bdc14746175549c8b5da215)
  30 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  31 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  32 (cherry picked from commit 62d3a63645c17611fe8ccc0c5adc5e840d9cff7b)
  33 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  34 ---
  35  Documentation/admin-guide/kernel-parameters.txt |  2 ++
  36  arch/x86/kernel/cpu/common.c                    | 18 ++++++++++++++++++
  37  2 files changed, 20 insertions(+)
  38
  39 diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
  40 index 73fd6abac39b..3510e255ef4c 100644
  41 --- a/Documentation/admin-guide/kernel-parameters.txt
  42 +++ b/Documentation/admin-guide/kernel-parameters.txt
  43 @@ -2700,6 +2700,8 @@
  44         nopat           [X86] Disable PAT (page attribute table extension of
  45                         pagetables) support.
  46
  47 +       nopcid          [X86-64] Disable the PCID cpu feature.
  48 +
  49         norandmaps      Don't use address space randomization.  Equivalent to
  50                         echo 0 > /proc/sys/kernel/randomize_va_space
  51
  52 diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
  53 index c8b39870f33e..904485e7b230 100644
  54 --- a/arch/x86/kernel/cpu/common.c
  55 +++ b/arch/x86/kernel/cpu/common.c
  56 @@ -168,6 +168,24 @@ static int __init x86_mpx_setup(char *s)
  57  }
  58  __setup("nompx", x86_mpx_setup);
  59
  60 +#ifdef CONFIG_X86_64
  61 +static int __init x86_pcid_setup(char *s)
  62 +{
  63 +       /* require an exact match without trailing characters */
  64 +       if (strlen(s))
  65 +               return 0;
  66 +
  67 +       /* do not emit a message if the feature is not present */
  68 +       if (!boot_cpu_has(X86_FEATURE_PCID))
  69 +               return 1;
  70 +
  71 +       setup_clear_cpu_cap(X86_FEATURE_PCID);
  72 +       pr_info("nopcid: PCID feature disabled\n");
  73 +       return 1;
  74 +}
  75 +__setup("nopcid", x86_pcid_setup);
  76 +#endif
  77 +
  78  static int __init x86_noinvpcid_setup(char *s)
  79  {
  80         /* noinvpcid doesn't accept parameters */
  81 --
  82 2.14.2
  83