3.2.101-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx> Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: David Woodhouse <dwmw@xxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20180107214913.096657732@xxxxxxxxxxxxx [bwh: Backported to 3.2: CPU device class is a sysdev_class, not a normal device class] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- Documentation/ABI/testing/sysfs-devices-system-cpu | 16 ++++++++ drivers/base/Kconfig | 3 ++ drivers/base/cpu.c | 48 ++++++++++++++++++++++ include/linux/cpu.h | 7 ++++ 4 files changed, 74 insertions(+) --- 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@xxxxxxxxxxxxxxx> +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 --- 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 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -247,6 +247,53 @@ struct sys_device *get_cpu_sysdev(unsign } 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; } --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -36,6 +36,13 @@ extern void cpu_remove_sysdev_attr_group 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);