linux-kernel - [PATCH 3.2 047/104] x86/cpu: Implement CPU vulnerabilites sysfs functions

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Message-ID: <lsq.1520823814.610579380@decadent.org.uk>
Date:   Mon, 12 Mar 2018 03:03:34 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Will Deacon" <will.deacon@....com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "David Woodhouse" <dwmw@...zon.co.uk>,
        "Linus Torvalds" <torvalds@...uxfoundation.org>,
        "Dave Hansen" <dave.hansen@...el.com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>,
        "Borislav Petkov" <bp@...en8.de>
Subject: [PATCH 3.2 047/104] x86/cpu: Implement CPU vulnerabilites sysfs
 functions

3.2.101-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Gleixner <tglx@...utronix.de>

commit 61dc0f555b5c761cdafb0ba5bd41ecf22d68a4c4 upstream.

Implement the CPU vulnerabilty show functions for meltdown, spectre_v1 and
spectre_v2.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Will Deacon <will.deacon@....com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Linus Torvalds <torvalds@...uxfoundation.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: David Woodhouse <dwmw@...zon.co.uk>
Link: https://lkml.kernel.org/r/20180107214913.177414879@linutronix.de
[bwh: Backported to 3.2:
 - Meltdown mitigation feature flag is KAISER
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/Kconfig           |  1 +
 arch/x86/kernel/cpu/bugs.c | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -75,6 +75,7 @@ config X86
 	select HAVE_BPF_JIT if (X86_64 && NET)
 	select CLKEVT_I8253
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
+	select GENERIC_CPU_VULNERABILITIES
 	select ARCH_SUPPORTS_ATOMIC_RMW
 
 config INSTRUCTION_DECODER
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -9,6 +9,7 @@
  */
 #include <linux/init.h>
 #include <linux/utsname.h>
+#include <linux/cpu.h>
 #include <asm/bugs.h>
 #include <asm/processor.h>
 #include <asm/processor-flags.h>
@@ -202,3 +203,31 @@ void __init check_bugs(void)
 		set_memory_4k((unsigned long)__va(0), 1);
 #endif
 }
+
+#ifdef CONFIG_SYSFS
+ssize_t cpu_show_meltdown(struct sysdev_class *dev,
+			  struct sysdev_class_attribute *attr, char *buf)
+{
+	if (!boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
+		return sprintf(buf, "Not affected\n");
+	if (boot_cpu_has(X86_FEATURE_KAISER))
+		return sprintf(buf, "Mitigation: PTI\n");
+	return sprintf(buf, "Vulnerable\n");
+}
+
+ssize_t cpu_show_spectre_v1(struct sysdev_class *dev,
+			    struct sysdev_class_attribute *attr, char *buf)
+{
+	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1))
+		return sprintf(buf, "Not affected\n");
+	return sprintf(buf, "Vulnerable\n");
+}
+
+ssize_t cpu_show_spectre_v2(struct sysdev_class *dev,
+			    struct sysdev_class_attribute *attr, char *buf)
+{
+	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
+		return sprintf(buf, "Not affected\n");
+	return sprintf(buf, "Vulnerable\n");
+}
+#endif