patches/kernel/0278-x86-idle-Disable-IBRS-when-offlining-cpu-and-re-enab.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Tim Chen <tim.c.chen@linux.intel.com>
   3 Date: Wed, 15 Nov 2017 12:24:19 -0800
   4 Subject: [PATCH] x86/idle: Disable IBRS when offlining cpu and re-enable on
   5  wakeup
   6 MIME-Version: 1.0
   7 Content-Type: text/plain; charset=UTF-8
   8 Content-Transfer-Encoding: 8bit
   9
  10 CVE-2017-5753
  11 CVE-2017-5715
  12
  13 Clear IBRS when cpu is offlined and set it when brining it back online.
  14
  15 Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
  16 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  17 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  18 (cherry picked from commit 9bcf662c1690880b2464fe99d0f58dce53c0d89f)
  19 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  20 ---
  21  arch/x86/kernel/smpboot.c | 7 +++++++
  22  1 file changed, 7 insertions(+)
  23
  24 diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
  25 index 398e8324fea4..a652bff7add4 100644
  26 --- a/arch/x86/kernel/smpboot.c
  27 +++ b/arch/x86/kernel/smpboot.c
  28 @@ -77,6 +77,7 @@
  29  #include <asm/i8259.h>
  30  #include <asm/realmode.h>
  31  #include <asm/misc.h>
  32 +#include <asm/microcode.h>
  33
  34  /* Number of siblings per CPU package */
  35  int smp_num_siblings = 1;
  36 @@ -1692,9 +1693,15 @@ void native_play_dead(void)
  37         play_dead_common();
  38         tboot_shutdown(TB_SHUTDOWN_WFS);
  39
  40 +       if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
  41 +               native_wrmsrl(MSR_IA32_SPEC_CTRL, 0);
  42 +
  43         mwait_play_dead();      /* Only returns on failure */
  44         if (cpuidle_play_dead())
  45                 hlt_play_dead();
  46 +
  47 +       if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
  48 +               native_wrmsrl(MSR_IA32_SPEC_CTRL, FEATURE_ENABLE_IBRS);
  49  }
  50
  51  #else /* ... !CONFIG_HOTPLUG_CPU */
  52 --
  53 2.14.2
  54