Re: [PATCH v5 10/20] x86/resctrl: Introduce mbm_total_cfg and mbm_local_cfg

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

Hi Reinette,

On 7/12/24 17:08, Reinette Chatre wrote:
> Hi Babu,
> 
> On 7/3/24 2:48 PM, Babu Moger wrote:
>> If the BMEC (Bandwidth Monitoring Event Configuration) feature is
>> supported, the bandwidth events can be configured to track specific
>> events. The event configuration is domain specific. ABMC (Assignable
>> Bandwidth Monitoring Counters) feature needs event configuration
>> information to assign hardware counter to an RMID. Event configurations
>> are not stored in resctrl but instead always read from or written to
>> hardware directly when prompted by user space.
>>
>> Read the event configuration from the hardware during the domain
>> initialization. Save the configuration information in the rdt_hw_domain,
> 
> rdt_hw_domain -> rdt_hw_mon_domain

Sure.

> 
>> so it can be used for counter assignment.
>>
>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>> ---
>> v5: Exported mon_event_config_index_get.
>>      Renamed arch_domain_mbm_evt_config to resctrl_arch_mbm_evt_config.
>>
>> v4: Read the configuration information from the hardware to initialize.
>>      Added few commit messages.
>>      Fixed the tab spaces.
>>
>> v3: Minor changes related to rebase in mbm_config_write_domain.
>>
>> v2: No changes.
>> ---
>>   arch/x86/kernel/cpu/resctrl/core.c     |  2 ++
>>   arch/x86/kernel/cpu/resctrl/internal.h |  6 ++++++
>>   arch/x86/kernel/cpu/resctrl/monitor.c  | 22 ++++++++++++++++++++++
>>   arch/x86/kernel/cpu/resctrl/rdtgroup.c |  2 +-
>>   4 files changed, 31 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/core.c
>> b/arch/x86/kernel/cpu/resctrl/core.c
>> index ff5cb693b396..6265ef8b610f 100644
>> --- a/arch/x86/kernel/cpu/resctrl/core.c
>> +++ b/arch/x86/kernel/cpu/resctrl/core.c
>> @@ -619,6 +619,8 @@ static void domain_add_cpu_mon(int cpu, struct
>> rdt_resource *r)
>>         arch_mon_domain_online(r, d);
>>   +    resctrl_arch_mbm_evt_config(hw_dom);
>> +
> 
> This does not look to be an arch call called by the fs code so special
> naming does not seem to be required? If it _was_ an arch callback then

Yes. Correct.

> it cannot take a HW resource as parameter since the fs code does not have
> access to that.
> 
> 
>>       if (arch_domain_mbm_alloc(r->mon.num_rmid, hw_dom)) {
>>           mon_domain_free(hw_dom);
>>           return;
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h
>> b/arch/x86/kernel/cpu/resctrl/internal.h
>> index 0ce9797f80fe..4cb1a5d014a3 100644
>> --- a/arch/x86/kernel/cpu/resctrl/internal.h
>> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
>> @@ -401,6 +401,8 @@ struct rdt_hw_ctrl_domain {
>>    * @d_resctrl:    Properties exposed to the resctrl file system
>>    * @arch_mbm_total:    arch private state for MBM total bandwidth
>>    * @arch_mbm_local:    arch private state for MBM local bandwidth
>> + * @mbm_total_cfg:    MBM total bandwidth configuration
>> + * @mbm_local_cfg:    MBM local bandwidth configuration
>>    *
>>    * Members of this structure are accessed via helpers that provide
>> abstraction.
>>    */
>> @@ -408,6 +410,8 @@ struct rdt_hw_mon_domain {
>>       struct rdt_mon_domain        d_resctrl;
>>       struct arch_mbm_state        *arch_mbm_total;
>>       struct arch_mbm_state        *arch_mbm_local;
>> +    u32                mbm_total_cfg;
>> +    u32                mbm_local_cfg;
>>   };
>>     static inline struct rdt_hw_ctrl_domain
>> *resctrl_to_arch_ctrl_dom(struct rdt_ctrl_domain *r)
>> @@ -662,6 +666,8 @@ void __check_limbo(struct rdt_mon_domain *d, bool
>> force_free);
>>   void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
>>   void __init resctrl_file_fflags_init(const char *config,
>>                        unsigned long fflags);
>> +void resctrl_arch_mbm_evt_config(struct rdt_hw_mon_domain *hw_dom);
>> +unsigned int mon_event_config_index_get(u32 evtid);
>>   void rdt_staged_configs_clear(void);
>>   bool closid_allocated(unsigned int closid);
>>   int resctrl_find_cleanest_closid(void);
>> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c
>> b/arch/x86/kernel/cpu/resctrl/monitor.c
>> index 7a93a6d2b2de..b96b0a8bd7d3 100644
>> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
>> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
>> @@ -1256,6 +1256,28 @@ int __init rdt_get_mon_l3_config(struct
>> rdt_resource *r)
>>       return 0;
>>   }
>>   +void resctrl_arch_mbm_evt_config(struct rdt_hw_mon_domain *hw_dom)
> 
> A function is expected to have a verb in its name and the verb here seems
> to be
> "config", which does not seem appropriate and creates confusion with
> resctrl_arch_event_config_set(). How about resctrl_arch_mbm_evt_config_init()
> with proper initializer of the config values to also cover case when
> events are
> not configurable (INVALID_CONFIG_VALUE introduced in next patch?) ?

Sorry. I am not clear on this comment. Can you please elaborate?

> 
>> +{
>> +    unsigned int index;
>> +    u64 msrval;
>> +
>> +    /*
>> +     * Read the configuration registers QOS_EVT_CFG_n, where <n> is
>> +     * the BMEC event number (EvtID).
>> +     */
>> +    if (mbm_total_event.configurable) {
>> +        index = mon_event_config_index_get(QOS_L3_MBM_TOTAL_EVENT_ID);
>> +        rdmsrl(MSR_IA32_EVT_CFG_BASE + index, msrval);
>> +        hw_dom->mbm_total_cfg = msrval & MAX_EVT_CONFIG_BITS;
>> +    }
>> +
>> +    if (mbm_local_event.configurable) {
>> +        index = mon_event_config_index_get(QOS_L3_MBM_LOCAL_EVENT_ID);
>> +        rdmsrl(MSR_IA32_EVT_CFG_BASE + index, msrval);
>> +        hw_dom->mbm_local_cfg = msrval & MAX_EVT_CONFIG_BITS;
>> +    }
>> +}
>> +
>>   void __exit rdt_put_mon_l3_config(void)
>>   {
>>       dom_data_exit();
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index b3d3fa048f15..b2b751741dd8 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -1606,7 +1606,7 @@ struct mon_config_info {
>>    *         1 for evtid == QOS_L3_MBM_LOCAL_EVENT_ID
>>    *         INVALID_CONFIG_INDEX for invalid evtid
>>    */
>> -static inline unsigned int mon_event_config_index_get(u32 evtid)
>> +unsigned int mon_event_config_index_get(u32 evtid)
>>   {
>>       switch (evtid) {
>>       case QOS_L3_MBM_TOTAL_EVENT_ID:
> 
> Reinette
> 

-- 
Thanks
Babu Moger