linux-kernel - Re: [patch V2 1/2] sysfs/cpu: Add vulnerability folder

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Message-ID: <20180107221438.GS21689@char.us.oracle.com>
Date:   Sun, 7 Jan 2018 17:14:38 -0500
From:   Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...uxfoundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Dave Hansen <dave.hansen@...el.com>,
        Will Deacon <will.deacon@....com>
Subject: Re: [patch V2 1/2] sysfs/cpu: Add vulnerability folder

On Sun, Jan 07, 2018 at 10:48:00PM +0100, Thomas Gleixner wrote:
> 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@...utronix.de>
> ---
>  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
> @@ -373,3 +373,19 @@ Contact:	Linux kernel mailing list <linu
>  Description:	information about CPUs heterogeneity.
>  
>  		cpu_capacity: capacity of cpu#.
> +
> +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

s/Januar/January/

and with that
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

Thank you!
> +#ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
> +
> +ssize_t __weak cpu_show_meltdown(struct device *dev,
> +				 struct device_attribute *attr, char *buf)
> +{
> +	return sprintf(buf, "Not affected\n");
> +}
> +
> +ssize_t __weak cpu_show_spectre_v1(struct device *dev,
> +				   struct device_attribute *attr, char *buf)
> +{
> +	return sprintf(buf, "Not affected\n");
> +}
> +
> +ssize_t __weak cpu_show_spectre_v2(struct device *dev,
> +				   struct device_attribute *attr, char *buf)
> +{
> +	return sprintf(buf, "Not affected\n");
> +}
> +
> +static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
> +static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
> +static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
> +
> +static struct attribute *cpu_root_vulnerabilities_attrs[] = {
> +	&dev_attr_meltdown.attr,
> +	&dev_attr_spectre_v1.attr,
> +	&dev_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_subsys.dev_root->kobj,
> +			       &cpu_root_vulnerabilities_group))
> +		pr_err("Unable to register CPU vulnerabilities\n");
> +}
> +
> +#else
> +static inline void cpu_register_vulnerabilities(void) { }
> +#endif
> +
>  void __init cpu_dev_init(void)
>  {
>  	if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
>  		panic("Failed to register CPU subsystem");
>  
>  	cpu_dev_register_generic();
> +	cpu_register_vulnerabilities();
>  }
> --- a/include/linux/cpu.h
> +++ b/include/linux/cpu.h
> @@ -47,6 +47,13 @@ extern void cpu_remove_dev_attr(struct d
>  extern int cpu_add_dev_attr_group(struct attribute_group *attrs);
>  extern void cpu_remove_dev_attr_group(struct attribute_group *attrs);
>  
> +extern ssize_t cpu_show_meltdown(struct device *dev,
> +				 struct device_attribute *attr, char *buf);
> +extern ssize_t cpu_show_spectre_v1(struct device *dev,
> +				   struct device_attribute *attr, char *buf);
> +extern ssize_t cpu_show_spectre_v2(struct device *dev,
> +				   struct device_attribute *attr, char *buf);
> +
>  extern __printf(4, 5)
>  struct device *cpu_device_create(struct device *parent, void *drvdata,
>  				 const struct attribute_group **groups,
> 
>