RE: [RFC PATCH 53/56] drivers/cpu: Re-patch mitigations through sysfs

[Kaplan, David]

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Nikolay Borisov <nik.borisov@xxxxxxxx>
> Sent: Monday, October 27, 2025 7:25 AM
> To: Kaplan, David <David.Kaplan@xxxxxxx>; Thomas Gleixner
> <tglx@xxxxxxxxxxxxx>; Borislav Petkov <bp@xxxxxxxxx>; Peter Zijlstra
> <peterz@xxxxxxxxxxxxx>; Josh Poimboeuf <jpoimboe@xxxxxxxxxx>; Pawan Gupta
> <pawan.kumar.gupta@xxxxxxxxxxxxxxx>; Ingo Molnar <mingo@xxxxxxxxxx>; Dave
> Hansen <dave.hansen@xxxxxxxxxxxxxxx>; x86@xxxxxxxxxx; H . Peter Anvin
> <hpa@xxxxxxxxx>
> Cc: Alexander Graf <graf@xxxxxxxxxx>; Boris Ostrovsky
> <boris.ostrovsky@xxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [RFC PATCH 53/56] drivers/cpu: Re-patch mitigations through sysfs
>
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>
> On 10/13/25 17:34, David Kaplan wrote:
> > Create a new file at /sys/devices/system/cpu/mitigations that prints the
> > current set of mitigation options and can be written to in order to
> > re-select mitigations.
> >
> > Only options related to mitigations are handled, with the file initially
> > returning the relevant options from the command line.  When the file is
> > written, any existing selections are discarded and the new options are
> > evaluated.
> >
> > Signed-off-by: David Kaplan <david.kaplan@xxxxxxx>
> > ---
> >   .../ABI/testing/sysfs-devices-system-cpu      |   8 ++
> >   drivers/base/cpu.c                            | 113 ++++++++++++++++++
> >   include/linux/cpu.h                           |   3 +
> >   3 files changed, 124 insertions(+)
> >
>
> <snip>
>
> > +
> > +ssize_t cpu_show_mitigation_options(struct device *dev, struct device_attribute
> *attr, char *buf);
> > +ssize_t cpu_show_mitigation_options(struct device *dev, struct device_attribute
> *attr, char *buf)
>
> Make it static
>
> > +{
> > +     return sysfs_emit(buf, saved_opts);
> > +}
> > +
> > +ssize_t cpu_write_mitigation_options(struct device *dev,
> > +                             struct device_attribute *attr,
> > +                             const char *buf, size_t count);
> > +
> > +void __weak cpu_prepare_repatch_alternatives(void)
> > +{
> > +}
> > +
> > +void __weak cpu_update_alternatives(void)
> > +{
> > +}
> > +
> > +void __weak cpu_select_mitigations(void)
> > +{
> > +}
> > +
> > +ssize_t cpu_write_mitigation_options(struct device *dev,
> > +                             struct device_attribute *attr,
> > +                             const char *buf, size_t count)
> Ditto
>
> <snip>

Ack, thanks

--David Kaplan