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

["Moger, Babu" <bmoger@amd.com>]

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@amd.com>
>> ---
> 
> ...
> 
>> ---
>>   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