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

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Message-ID:
 <LV3PR12MB9265F32424F982EEAF542A9D94FCA@LV3PR12MB9265.namprd12.prod.outlook.com>
Date: Mon, 27 Oct 2025 13:59:44 +0000
From: "Kaplan, David" <David.Kaplan@....com>
To: Nikolay Borisov <nik.borisov@...e.com>, Thomas Gleixner
	<tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>, Peter Zijlstra
	<peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>, Pawan Gupta
	<pawan.kumar.gupta@...ux.intel.com>, Ingo Molnar <mingo@...hat.com>, Dave
 Hansen <dave.hansen@...ux.intel.com>, "x86@...nel.org" <x86@...nel.org>, "H .
 Peter Anvin" <hpa@...or.com>
CC: Alexander Graf <graf@...zon.com>, Boris Ostrovsky
	<boris.ostrovsky@...cle.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [RFC PATCH 53/56] drivers/cpu: Re-patch mitigations through sysfs

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Nikolay Borisov <nik.borisov@...e.com>
> Sent: Monday, October 27, 2025 7:25 AM
> To: Kaplan, David <David.Kaplan@....com>; Thomas Gleixner
> <tglx@...utronix.de>; Borislav Petkov <bp@...en8.de>; Peter Zijlstra
> <peterz@...radead.org>; Josh Poimboeuf <jpoimboe@...nel.org>; Pawan Gupta
> <pawan.kumar.gupta@...ux.intel.com>; Ingo Molnar <mingo@...hat.com>; Dave
> Hansen <dave.hansen@...ux.intel.com>; x86@...nel.org; H . Peter Anvin
> <hpa@...or.com>
> Cc: Alexander Graf <graf@...zon.com>; Boris Ostrovsky
> <boris.ostrovsky@...cle.com>; linux-kernel@...r.kernel.org
> Subject: Re: [RFC PATCH 53/56] drivers/cpu: Re-patch mitigations through sysfs
>
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
>
>
> 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@....com>
> > ---
> >   .../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