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Patch "x86/speculation: Clean up various Spectre related details" has been added to the 4.14-stable tree

PATCH [email protected] 1 participant 1 message Feb 20, 2018

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This is a note to let you know that I've just added the patch titled

x86/speculation: Clean up various Spectre related details

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-speculation-clean-up-various-spectre-related-details.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 21e433bdb95bdf3aa48226fd3d33af608437f293 Mon Sep 17 00:00:00 2001

From: Ingo Molnar <[email protected]>
Date: Tue, 13 Feb 2018 09:03:08 +0100
Subject: x86/speculation: Clean up various Spectre related details

From: Ingo Molnar <[email protected]>

commit 21e433bdb95bdf3aa48226fd3d33af608437f293 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

Cc Andy Lutomirski <[email protected]>
Cc Arjan van de Ven <[email protected]>
Cc Borislav Petkov <[email protected]>
Cc Dan Williams <[email protected]>
Cc Dave Hansen <[email protected]>
Cc David Woodhouse <[email protected]>
Cc Greg Kroah-Hartman <[email protected]>
Cc Josh Poimboeuf <[email protected]>
Cc Linus Torvalds <[email protected]>
Cc Peter Zijlstra <[email protected]>
Cc Thomas Gleixner <[email protected]>
---
 arch/x86/kernel/cpu/bugs.c |   28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)
arch/x86/kernel/cpu/bugs.c +11 -17
@@ -162,8 +162,7 @@ static enum spectre_v2_mitigation_cmd __
 	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 __
 		}
 
 		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 __
 	     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_mit
 			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
 	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");

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/x86-gpu-add-cfl-to-early-quirks.patch queue-4.14/kvm-nvmx-set-the-cpu_based_use_msr_bitmaps-if-we-have-a-valid-l02-msr-bitmap.patch queue-4.14/x86-nvmx-properly-set-spec_ctrl-and-pred_cmd-before-merging-msrs.patch queue-4.14/x86-speculation-update-speculation-control-microcode-blacklist.patch queue-4.14/x86-speculation-correct-speculation-control-microcode-blacklist-again.patch queue-4.14/x86-entry-64-clear-extra-registers-beyond-syscall-arguments-to-reduce-speculation-attack-surface.patch queue-4.14/kvm-x86-reduce-retpoline-performance-impact-in-slot_handle_level_range-by-always-inlining-iterator-helper-methods.patch queue-4.14/x86-mm-pti-fix-pti-comment-in-entry_syscall_64.patch queue-4.14/x86-speculation-clean-up-various-spectre-related-details.patch queue-4.14/x86-kexec-make-kexec-mostly-work-in-5-level-paging-mode.patch queue-4.14/revert-x86-speculation-simplify-indirect_branch_prediction_barrier.patch queue-4.14/x86-entry-64-compat-clear-registers-for-compat-syscalls-to-reduce-speculation-attack-surface.patch