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SubjectRe: [patch V2 1/2] sysfs/cpu: Add vulnerability folder
On Mon, 8 Jan 2018, Dominik Brodowski wrote:
> 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"

We do that in the same way as we did with BUG_INSECURE (now MELTDOWN). Err
out on the safe side and get the exceptions in place when people are
confident about them. It's not going to take long I assume.

Thanks,

tglx


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