releases/4.14.21/x86-speculation-clean-up-various-spectre-related-details.patch

   1 From 21e433bdb95bdf3aa48226fd3d33af608437f293 Mon Sep 17 00:00:00 2001
   2 From: Ingo Molnar <mingo@kernel.org>
   3 Date: Tue, 13 Feb 2018 09:03:08 +0100
   4 Subject: x86/speculation: Clean up various Spectre related details
   5
   6 From: Ingo Molnar <mingo@kernel.org>
   7
   8 commit 21e433bdb95bdf3aa48226fd3d33af608437f293 upstream.
   9
  10 Harmonize all the Spectre messages so that a:
  11
  12     dmesg | grep -i spectre
  13
  14 ... gives us most Spectre related kernel boot messages.
  15
  16 Also fix a few other details:
  17
  18  - clarify a comment about firmware speculation control
  19
  20  - s/KPTI/PTI
  21
  22  - remove various line-breaks that made the code uglier
  23
  24 Acked-by: David Woodhouse <dwmw@amazon.co.uk>
  25 Cc: Andy Lutomirski <luto@kernel.org>
  26 Cc: Arjan van de Ven <arjan@linux.intel.com>
  27 Cc: Borislav Petkov <bp@alien8.de>
  28 Cc: Dan Williams <dan.j.williams@intel.com>
  29 Cc: Dave Hansen <dave.hansen@linux.intel.com>
  30 Cc: David Woodhouse <dwmw2@infradead.org>
  31 Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  32 Cc: Josh Poimboeuf <jpoimboe@redhat.com>
  33 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  34 Cc: Peter Zijlstra <peterz@infradead.org>
  35 Cc: Thomas Gleixner <tglx@linutronix.de>
  36 Cc: linux-kernel@vger.kernel.org
  37 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  38 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  39
  40 ---
  41  arch/x86/kernel/cpu/bugs.c |   28 +++++++++++-----------------
  42  1 file changed, 11 insertions(+), 17 deletions(-)
  43
  44 --- a/arch/x86/kernel/cpu/bugs.c
  45 +++ b/arch/x86/kernel/cpu/bugs.c
  46 @@ -162,8 +162,7 @@ static enum spectre_v2_mitigation_cmd __
  47         if (cmdline_find_option_bool(boot_command_line, "nospectre_v2"))
  48                 return SPECTRE_V2_CMD_NONE;
  49         else {
  50 -               ret = cmdline_find_option(boot_command_line, "spectre_v2", arg,
  51 -                                         sizeof(arg));
  52 +               ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
  53                 if (ret < 0)
  54                         return SPECTRE_V2_CMD_AUTO;
  55
  56 @@ -175,8 +174,7 @@ static enum spectre_v2_mitigation_cmd __
  57                 }
  58
  59                 if (i >= ARRAY_SIZE(mitigation_options)) {
  60 -                       pr_err("unknown option (%s). Switching to AUTO select\n",
  61 -                              mitigation_options[i].option);
  62 +                       pr_err("unknown option (%s). Switching to AUTO select\n", mitigation_options[i].option);
  63                         return SPECTRE_V2_CMD_AUTO;
  64                 }
  65         }
  66 @@ -185,8 +183,7 @@ static enum spectre_v2_mitigation_cmd __
  67              cmd == SPECTRE_V2_CMD_RETPOLINE_AMD ||
  68              cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC) &&
  69             !IS_ENABLED(CONFIG_RETPOLINE)) {
  70 -               pr_err("%s selected but not compiled in. Switching to AUTO select\n",
  71 -                      mitigation_options[i].option);
  72 +               pr_err("%s selected but not compiled in. Switching to AUTO select\n", mitigation_options[i].option);
  73                 return SPECTRE_V2_CMD_AUTO;
  74         }
  75
  76 @@ -256,14 +253,14 @@ static void __init spectre_v2_select_mit
  77                         goto retpoline_auto;
  78                 break;
  79         }
  80 -       pr_err("kernel not compiled with retpoline; no mitigation available!");
  81 +       pr_err("Spectre mitigation: kernel not compiled with retpoline; no mitigation available!");
  82         return;
  83
  84  retpoline_auto:
  85         if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
  86         retpoline_amd:
  87                 if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
  88 -                       pr_err("LFENCE not serializing. Switching to generic retpoline\n");
  89 +                       pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n");
  90                         goto retpoline_generic;
  91                 }
  92                 mode = retp_compiler() ? SPECTRE_V2_RETPOLINE_AMD :
  93 @@ -281,7 +278,7 @@ retpoline_auto:
  94         pr_info("%s\n", spectre_v2_strings[mode]);
  95
  96         /*
  97 -        * If neither SMEP or KPTI are available, there is a risk of
  98 +        * If neither SMEP nor PTI are available, there is a risk of
  99          * hitting userspace addresses in the RSB after a context switch
 100          * from a shallow call stack to a deeper one. To prevent this fill
 101          * the entire RSB, even when using IBRS.
 102 @@ -295,21 +292,20 @@ retpoline_auto:
 103         if ((!boot_cpu_has(X86_FEATURE_PTI) &&
 104              !boot_cpu_has(X86_FEATURE_SMEP)) || is_skylake_era()) {
 105                 setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
 106 -               pr_info("Filling RSB on context switch\n");
 107 +               pr_info("Spectre v2 mitigation: Filling RSB on context switch\n");
 108         }
 109
 110         /* Initialize Indirect Branch Prediction Barrier if supported */
 111         if (boot_cpu_has(X86_FEATURE_IBPB)) {
 112                 setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
 113 -               pr_info("Enabling Indirect Branch Prediction Barrier\n");
 114 +               pr_info("Spectre v2 mitigation: Enabling Indirect Branch Prediction Barrier\n");
 115         }
 116  }
 117
 118  #undef pr_fmt
 119
 120  #ifdef CONFIG_SYSFS
 121 -ssize_t cpu_show_meltdown(struct device *dev,
 122 -                         struct device_attribute *attr, char *buf)
 123 +ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
 124  {
 125         if (!boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
 126                 return sprintf(buf, "Not affected\n");
 127 @@ -318,16 +314,14 @@ ssize_t cpu_show_meltdown(struct device
 128         return sprintf(buf, "Vulnerable\n");
 129  }
 130
 131 -ssize_t cpu_show_spectre_v1(struct device *dev,
 132 -                           struct device_attribute *attr, char *buf)
 133 +ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
 134  {
 135         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1))
 136                 return sprintf(buf, "Not affected\n");
 137         return sprintf(buf, "Mitigation: __user pointer sanitization\n");
 138  }
 139
 140 -ssize_t cpu_show_spectre_v2(struct device *dev,
 141 -                           struct device_attribute *attr, char *buf)
 142 +ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
 143  {
 144         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
 145                 return sprintf(buf, "Not affected\n");