linux-kernel - Re: [PATCH v4 11/19] x86/resctrl: Introduce mbm_total_cfg and mbm_local

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Message-ID: <48e0d78c-5ed8-4b93-8f12-3ce3fd74116c@intel.com>
Date: Thu, 13 Jun 2024 18:43:28 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <babu.moger@....com>, <corbet@....net>, <fenghua.yu@...el.com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>
CC: <x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
	<rdunlap@...radead.org>, <tj@...nel.org>, <peterz@...radead.org>,
	<yanjiewtw@...il.com>, <kim.phillips@....com>, <lukas.bulwahn@...il.com>,
	<seanjc@...gle.com>, <jmattson@...gle.com>, <leitao@...ian.org>,
	<jpoimboe@...nel.org>, <rick.p.edgecombe@...el.com>,
	<kirill.shutemov@...ux.intel.com>, <jithu.joseph@...el.com>,
	<kai.huang@...el.com>, <kan.liang@...ux.intel.com>,
	<daniel.sneddon@...ux.intel.com>, <pbonzini@...hat.com>,
	<sandipan.das@....com>, <ilpo.jarvinen@...ux.intel.com>,
	<peternewman@...gle.com>, <maciej.wieczor-retman@...el.com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<eranian@...gle.com>, <james.morse@....com>
Subject: Re: [PATCH v4 11/19] x86/resctrl: Introduce mbm_total_cfg and
 mbm_local_cfg

Hi Babu,

On 5/24/24 5:23 AM, 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,
> so it can be used for counter assignment.
> 
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---
> 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 |  5 +++++
>   arch/x86/kernel/cpu/resctrl/monitor.c  | 21 +++++++++++++++++++++
>   3 files changed, 28 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index ec93f6a50308..856c46d12177 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -542,6 +542,8 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r)
>   		return;
>   	}
>   
> +	arch_domain_mbm_evt_config(hw_dom);
> +
>   	list_add_tail_rcu(&d->list, add_pos);
>   
>   	err = resctrl_online_domain(r, d);
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 5e7e76cd512f..60a1ca0a11a7 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -373,6 +373,8 @@ struct arch_mbm_state {
>    * @ctrl_val:	array of cache or mem ctrl values (indexed by CLOSID)
>    * @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.
>    */
> @@ -381,6 +383,8 @@ struct rdt_hw_domain {
>   	u32				*ctrl_val;
>   	struct arch_mbm_state		*arch_mbm_total;
>   	struct arch_mbm_state		*arch_mbm_local;
> +	u32				mbm_total_cfg;
> +	u32				mbm_local_cfg;
>   };

Similar to the abmc_enabled member of rdt_hw_resource, these new
members of rdt_hw_domain are architecture specific and should never be
touched directly by resctrl fs code, for example, from mbm_config_show().

>   
>   static inline struct rdt_hw_domain *resctrl_to_arch_dom(struct rdt_domain *r)
> @@ -622,6 +626,7 @@ void __check_limbo(struct rdt_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 arch_domain_mbm_evt_config(struct rdt_hw_domain *hw_dom);
>   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 b1d002e5e93d..ab0f4bb49bd9 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -1093,6 +1093,27 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
>   	return 0;
>   }
>   
> +void arch_domain_mbm_evt_config(struct rdt_hw_domain *hw_dom)
> +{
> +	u64 msrval;
> +
> +	/*
> +	 * Read the configuration registers QOS_EVT_CFG_n, where <n> is
> +	 * the BMEC event number (EvtID).
> +	 * 0 for evtid == QOS_L3_MBM_TOTAL_EVENT_ID
> +	 * 1 for evtid == QOS_L3_MBM_LOCAL_EVENT_ID

This is what mon_event_config_index_get() is for, no?

> +	 */
> +	if (mbm_total_event.configurable) {
> +		rdmsrl(MSR_IA32_EVT_CFG_BASE, msrval);
> +		hw_dom->mbm_total_cfg = msrval & MAX_EVT_CONFIG_BITS;
> +	}
> +
> +	if (mbm_local_event.configurable) {
> +		rdmsrl(MSR_IA32_EVT_CFG_BASE + 1, msrval);
> +		hw_dom->mbm_local_cfg = msrval & MAX_EVT_CONFIG_BITS;
> +	}
> +}
> +
>   void __exit rdt_put_mon_l3_config(void)
>   {
>   	dom_data_exit();

Reinette