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

[Reinette Chatre]

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

> so it can be used for counter assignment.
>
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---
> 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
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?) ?

> +{
> +	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