Re: [PATCH v6 07/18] fs/resctrl: Introduce resctrl_set_kmode_support() to register supported modes

[Moger, Babu]

Hi Reinette,

On 10/15/2026 9:40 AM, Reinette Chatre wrote:
> Hi Babu,
>
> On 10/1/26 8:10 AM, Babu Moger wrote:
> > The resctrl subsystem tracks kernel mode configuration. Architectures need
>
> resctrl tracks nothing at this point. This is preparatory work to enable resctrl
> to do so.

Yes. That is correct. Hope this looks ok.

Architectures may support different kernel modes that need to be
exposed to resctrl.

Add resctrl_set_kmode_support() to allow an architecture to register
its supported kernel modes. This is preparatory infrastructure for
future kernel mode support in resctrl.



> > to register the supported kernel modes.
> >
> > Add resctrl_set_kmode_support() so an architecture can register supported
> > kernel modes.
> >
> > Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> > ---
>
> ...
>
> > ---
> >   fs/resctrl/rdtgroup.c   |  6 ++++++
> >   include/linux/resctrl.h | 15 +++++++++++++++
> >   2 files changed, 21 insertions(+)
> >
> > diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> > index 7c39792be1fa..75b81d07a247 100644
> > --- a/fs/resctrl/rdtgroup.c
> > +++ b/fs/resctrl/rdtgroup.c
> > @@ -2320,6 +2320,12 @@ static void resctrl_kmode_init(void)
> >   	resctrl_kmode.mon = KMODE_ASSIGN;
> >   }
> >   
> > +void resctrl_set_kmode_support(enum resctrl_kernel_mode kmode)
> > +{
> > +	if (kmode < RESCTRL_NUM_KERNEL_MODES)
> > +		__set_bit(kmode, resctrl_kmode.kmode_sup);
> > +}
> > +
> >   void resctrl_file_fflags_init(const char *config, unsigned long fflags)
> >   {
> >   	struct rftype *rft;
> > diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> > index dcb0beb847b6..5553f6301bd4 100644
> > --- a/include/linux/resctrl.h
> > +++ b/include/linux/resctrl.h
> > @@ -752,6 +752,21 @@ enum resctrl_kernel_mode {
> >   
> >   #define RESCTRL_NUM_KERNEL_MODES (RESCTRL_KMODE_LAST + 1)
> >   
> > +/**
> > + * resctrl_set_kmode_support() - Register a supported kernel mode
> > + * @kmode:	Kernel mode supported by the architecture.
> > + *
> > + * RESCTRL_INHERIT_USER is registered by resctrl_kmode_init() and does
> > + * not need to be registered again.
> > + *
> > + * Architectures use this interface during resctrl initialization to
> > + * advertise supported kernel modes. Registration of a mode indicates
> > + * architectural support only. The final decision to expose and enable
> > + * a mode is made by resctrl based on system capabilities and
> > + * configuration.
>
> The last sentence is not clear to me. There is no filtering of any modes
> before it is exposed to user space. It is the architecture that sets the
> modes based on the "system capabilities", this is not something the filesystem
> decides?

Yes. Will remove last two lines.
Thanks
Babu