x86/speculation: Clean up various Spectre related details

BugLink: https://bugs.launchpad.net/bugs/1791080

commit 21e433bd upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa@csail.mit.edu>
Reviewed-by: Matt Helsley (VMware) <matt.helsley@gmail.com>
Reviewed-by: Alexey Makhalov <amakhalov@vmware.com>
Reviewed-by: Bo Gan <ganb@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/x86/kernel/cpu/bugs.c

@@ -283,8 +283,7 @@ 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;
 
@@ -305,8 +304,7 @@ 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;
 	}
 
@@ -359,14 +357,14 @@ 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 :
@@ -386,7 +384,7 @@ static void __init spectre_v2_select_mitigation(void)
 	/* 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");
 
 		set_ibpb_supported();
 		if (ibpb_inuse)
@@ -395,14 +393,14 @@ static void __init spectre_v2_select_mitigation(void)
 
 	/* Initialize Indirect Branch Restricted Speculation if supported */
 	if (boot_cpu_has(X86_FEATURE_IBRS)) {
-		pr_info("Enabling Indirect Branch Restricted Speculation\n");
+		pr_info("Spectre v2 mitigation: Enabling Indirect Branch Restricted Speculation\n");
 
 		set_ibrs_supported();
 		if (ibrs_inuse)
 			sysctl_ibrs_enabled = 1;
         }
 
-	pr_info("Speculation control IBPB %s IBRS %s",
+	pr_info("Spectre v2 mitigation: Speculation control IBPB %s IBRS %s",
 	        ibpb_supported ? "supported" : "not-supported",
 	        ibrs_supported ? "supported" : "not-supported");
 
@@ -827,8 +825,7 @@ ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, c
 	return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V1);
 }
 
-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)
 {
 	return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V2);
 }