x86/speculation: Clean up various Spectre related details

Harmonize all the Spectre messages so that a:

    dmesg | grep -i spectre

... gives us most Spectre related kernel boot messages.

Also fix a few other details:

 - clarify a comment about firmware speculation control

 - s/KPTI/PTI

 - remove various line-breaks that made the code uglier

Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 11 insertions, 17 deletions

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 61152aa53377..4acf16a76d1e 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -162,8 +162,7 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
         if (cmdline_find_option_bool(boot_command_line, "nospectre_v2"))
                 return SPECTRE_V2_CMD_NONE;
         else {
-                ret = cmdline_find_option(boot_command_line, "spectre_v2", arg,
-                                          sizeof(arg));
+                ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
                 if (ret < 0)
                         return SPECTRE_V2_CMD_AUTO;
 
@@ -175,8 +174,7 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
                 }
 
                 if (i >= ARRAY_SIZE(mitigation_options)) {
-                        pr_err("unknown option (%s). Switching to AUTO select\n",
-                               mitigation_options[i].option);
+                        pr_err("unknown option (%s). Switching to AUTO select\n", mitigation_options[i].option);
                         return SPECTRE_V2_CMD_AUTO;
                 }
         }
@@ -185,8 +183,7 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
              cmd == SPECTRE_V2_CMD_RETPOLINE_AMD ||
              cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC) &&
             !IS_ENABLED(CONFIG_RETPOLINE)) {
-                pr_err("%s selected but not compiled in. Switching to AUTO select\n",
-                       mitigation_options[i].option);
+                pr_err("%s selected but not compiled in. Switching to AUTO select\n", mitigation_options[i].option);
                 return SPECTRE_V2_CMD_AUTO;
         }
 
@@ -256,14 +253,14 @@ static void __init spectre_v2_select_mitigation(void)
                         goto retpoline_auto;
                 break;
         }
-        pr_err("kernel not compiled with retpoline; no mitigation available!");
+        pr_err("Spectre mitigation: kernel not compiled with retpoline; no mitigation available!");
         return;
 
 retpoline_auto:
         if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
         retpoline_amd:
                 if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
-                        pr_err("LFENCE not serializing. Switching to generic retpoline\n");
+                        pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n");
                         goto retpoline_generic;
                 }
                 mode = retp_compiler() ? SPECTRE_V2_RETPOLINE_AMD :
@@ -281,7 +278,7 @@ retpoline_auto:
         pr_info("%s\n", spectre_v2_strings[mode]);
 
         /*
-         * If neither SMEP or KPTI are available, there is a risk of
+         * If neither SMEP nor PTI are available, there is a risk of
          * hitting userspace addresses in the RSB after a context switch
          * from a shallow call stack to a deeper one. To prevent this fill
          * the entire RSB, even when using IBRS.
@@ -295,21 +292,20 @@ retpoline_auto:
         if ((!boot_cpu_has(X86_FEATURE_PTI) &&
              !boot_cpu_has(X86_FEATURE_SMEP)) || is_skylake_era()) {
                 setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
-                pr_info("Filling RSB on context switch\n");
+                pr_info("Spectre v2 mitigation: Filling RSB on context switch\n");
         }
 
         /* Initialize Indirect Branch Prediction Barrier if supported */
         if (boot_cpu_has(X86_FEATURE_IBPB)) {
                 setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
-                pr_info("Enabling Indirect Branch Prediction Barrier\n");
+                pr_info("Spectre v2 mitigation: Enabling Indirect Branch Prediction Barrier\n");
         }
 }
 
 #undef pr_fmt
 
 #ifdef CONFIG_SYSFS
-ssize_t cpu_show_meltdown(struct device *dev,
-                          struct device_attribute *attr, char *buf)
+ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
 {
         if (!boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
                 return sprintf(buf, "Not affected\n");
@@ -318,16 +314,14 @@ ssize_t cpu_show_meltdown(struct device *dev,
         return sprintf(buf, "Vulnerable\n");
 }
 
-ssize_t cpu_show_spectre_v1(struct device *dev,
-                            struct device_attribute *attr, char *buf)
+ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
 {
         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1))
                 return sprintf(buf, "Not affected\n");
         return sprintf(buf, "Mitigation: __user pointer sanitization\n");
 }
 
-ssize_t cpu_show_spectre_v2(struct device *dev,
-                            struct device_attribute *attr, char *buf)
+ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
 {
         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
                 return sprintf(buf, "Not affected\n");