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SubjectRe: [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@linutronix.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
> +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.

Currently, your code sets X86_BUG_SPECTRE_V[12] unconditionally on x86
CPUs. However, to my understanding some CPUs which do not execute code
out-of-order aren't affected. As it is better to err on the safe side for
now, what about adding a disclaimer at the end of this sentence, such as:

", but may contain false positives"

Thanks,
Dominik

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