sysfs/cpu: Add vulnerability folder

commit 87590ce6e373d1a5401f6539f0c59ef92dd924a9 upstream.

As the meltdown/spectre problem affects several CPU architectures, it makes
sense to have common way to express whether a system is affected by a
particular vulnerability or not. If affected the way to express the
mitigation should be common as well.

Create /sys/devices/system/cpu/vulnerabilities folder and files for
meltdown, spectre_v1 and spectre_v2.

Allow architectures to override the show function.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lkml.kernel.org/r/20180107214913.096657732@linutronix.de
[bwh: Backported to 3.2: CPU device class is a sysdev_class, not a normal device
 class]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index e7be75b96e4bcae77caec52d3e00fa3d7d725204..83b82cc48c86ef748cab3735a33ed7825519b28d 100644 (file)
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -201,3 +201,19 @@ Description:       Disable L3 cache indices
                All AMD processors with L3 caches provide this functionality.
                For details, see BKDGs at
                http://developer.amd.com/documentation/guides/Pages/default.aspx
+
+What:          /sys/devices/system/cpu/vulnerabilities
+               /sys/devices/system/cpu/vulnerabilities/meltdown
+               /sys/devices/system/cpu/vulnerabilities/spectre_v1
+               /sys/devices/system/cpu/vulnerabilities/spectre_v2
+Date:          Januar 2018
+Contact:       Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:   Information about CPU vulnerabilities
+
+               The files are named after the code names of CPU
+               vulnerabilities. The output of those files reflects the
+               state of the CPUs in the system. Possible output values:
+
+               "Not affected"    CPU is not affected by the vulnerability
+               "Vulnerable"      CPU is affected and no mitigation in effect
+               "Mitigation: $M"  CPU is affetcted and mitigation $M is in effect

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 21cf46f45245e26851701cdf70e78008e3b18a3d..050b6c6a48f7d79d1906e6653674bf587402c636 100644 (file)
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -172,6 +172,9 @@ config SYS_HYPERVISOR
        bool
        default n
 
+config GENERIC_CPU_VULNERABILITIES
+       bool
+
 source "drivers/base/regmap/Kconfig"
 
 endmenu

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 251acea3d35986dc13f3b5f8423eb803d37508f4..8d82884da93a68f6e288460a266db845f15221f8 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -247,6 +247,53 @@ struct sys_device *get_cpu_sysdev(unsigned cpu)
 }
 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
 
+#ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
+
+ssize_t __weak cpu_show_meltdown(struct sysdev_class *class,
+                                struct sysdev_class_attribute *attr, char *buf)
+{
+       return sprintf(buf, "Not affected\n");
+}
+
+ssize_t __weak cpu_show_spectre_v1(struct sysdev_class *class,
+                                  struct sysdev_class_attribute *attr, char *buf)
+{
+       return sprintf(buf, "Not affected\n");
+}
+
+ssize_t __weak cpu_show_spectre_v2(struct sysdev_class *class,
+                                  struct sysdev_class_attribute *attr, char *buf)
+{
+       return sprintf(buf, "Not affected\n");
+}
+
+static SYSDEV_CLASS_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
+static SYSDEV_CLASS_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
+static SYSDEV_CLASS_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
+
+static struct attribute *cpu_root_vulnerabilities_attrs[] = {
+       &attr_meltdown.attr,
+       &attr_spectre_v1.attr,
+       &attr_spectre_v2.attr,
+       NULL
+};
+
+static const struct attribute_group cpu_root_vulnerabilities_group = {
+       .name  = "vulnerabilities",
+       .attrs = cpu_root_vulnerabilities_attrs,
+};
+
+static void __init cpu_register_vulnerabilities(void)
+{
+       if (sysfs_create_group(&cpu_sysdev_class.kset.kobj,
+                              &cpu_root_vulnerabilities_group))
+               pr_err("Unable to register CPU vulnerabilities\n");
+}
+
+#else
+static inline void cpu_register_vulnerabilities(void) { }
+#endif
+
 int __init cpu_dev_init(void)
 {
        int err;
@@ -256,6 +303,8 @@ int __init cpu_dev_init(void)
        if (!err)
                err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
 #endif
+       if (!err)
+               cpu_register_vulnerabilities();
 
        return err;
 }

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 21b1e9789a80ccf5c17e747b86ad820e4b0209ce..4583d615e90c6d36c8468527de8b7155f4427836 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -36,6 +36,13 @@ extern void cpu_remove_sysdev_attr_group(struct attribute_group *attrs);
 
 extern int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls);
 
+ssize_t cpu_show_meltdown(struct sysdev_class *class,
+                         struct sysdev_class_attribute *attr, char *buf);
+ssize_t cpu_show_spectre_v1(struct sysdev_class *class,
+                           struct sysdev_class_attribute *attr, char *buf);
+ssize_t cpu_show_spectre_v2(struct sysdev_class *class,
+                           struct sysdev_class_attribute *attr, char *buf);
+
 #ifdef CONFIG_HOTPLUG_CPU
 extern void unregister_cpu(struct cpu *cpu);
 extern ssize_t arch_cpu_probe(const char *, size_t);