linux-kernel - Re: [PATCH v7 21/24] x86/resctrl: Configure mbm_cntr

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Message-ID: <f1362aab-82e8-8995-fc27-1fdb8e95f799@amd.com>
Date: Fri, 27 Sep 2024 09:37:22 -0500
From: "Moger, Babu" <bmoger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>,
 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 v7 21/24] x86/resctrl: Configure mbm_cntr_assign mode if
 supported

Hi Reinette,

On 9/19/2024 12:43 PM, Reinette Chatre wrote:
> Hi Babu,
> 
> On 9/4/24 3:21 PM, Babu Moger wrote:
>> Configure mbm_cntr_assign on AMD.
>>
>> 'mbm_cntr_assign' mode in AMD is ABMC (Assignable Bandwidth Monitoring
>> Counters). When the ABMC is updated, it must be updated on all logical
>> processors in the resctrl domain.
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>> v7: Introduced resctrl_arch_mbm_cntr_assign_configure() to configure.
>>      Moved the default settings to rdt_get_mon_l3_config(). It should be
>>      done before the hotplug handler is called. It cannot be done at
>>      rdtgroup_init().
>>
>> v6: Keeping the default enablement in arch init code for now.
>>       This may need some discussion.
>>       Renamed resctrl_arch_configure_abmc to resctrl_arch_mbm_cntr_assign_configure.
>>
>> v5: New patch to enable ABMC by default.
>> ---
>>   arch/x86/kernel/cpu/resctrl/internal.h |  1 +
>>   arch/x86/kernel/cpu/resctrl/monitor.c  |  1 +
>>   arch/x86/kernel/cpu/resctrl/rdtgroup.c | 11 +++++++++++
>>   3 files changed, 13 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
>> index 9a65a13ccbe9..3250561f0187 100644
>> --- a/arch/x86/kernel/cpu/resctrl/internal.h
>> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
>> @@ -709,6 +709,7 @@ int rdtgroup_assign_cntr(struct rdt_resource *r, struct rdtgroup *rdtgrp,
>>   			 struct rdt_mon_domain *d, enum resctrl_event_id evtid);
>>   int rdtgroup_unassign_cntr(struct rdt_resource *r, struct rdtgroup *rdtgrp,
>>   			   struct rdt_mon_domain *d, enum resctrl_event_id evtid);
>> +void resctrl_arch_mbm_cntr_assign_configure(struct rdt_resource *r);
>>   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 09b1d8bb0aa0..314c0b297470 100644
>> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
>> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
>> @@ -1261,6 +1261,7 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
>>   			cpuid_count(0x80000020, 5, &eax, &ebx, &ecx, &edx);
>>   			r->mon.num_mbm_cntrs = (ebx & 0xFFFF) + 1;
>>   			resctrl_file_fflags_init("num_mbm_cntrs", RFTYPE_MON_INFO);
>> +			hw_res->mbm_cntr_assign_enabled = true;
> 
> This is a major change to require architecture to set whether this is the default mode.
> That seems fine but needs to be highlighted in the changelog and descriptions of this work.

Sure. Will add the text about this.

> 
>>   		}
>>   	}
>>   
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index 7a8ece12d7da..1054583bef9d 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -2726,6 +2726,13 @@ int resctrl_arch_mbm_cntr_assign_set(struct rdt_resource *r, bool enable)
>>   	return 0;
>>   }
>>   
>> +void resctrl_arch_mbm_cntr_assign_configure(struct rdt_resource *r)
> 
> How about resctrl_arch_mbm_cntr_assign_set_one() to match existing
> resctrl_arch_mbm_cntr_assign_set()?

Sure.

> 
>> +{
>> +	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
>> +
>> +	resctrl_abmc_set_one_amd(&hw_res->mbm_cntr_assign_enabled);
>> +}
>> +
>>   /*
>>    * We don't allow rdtgroup directories to be created anywhere
>>    * except the root directory. Thus when looking for the rdtgroup
>> @@ -4510,9 +4517,13 @@ int resctrl_online_mon_domain(struct rdt_resource *r, struct rdt_mon_domain *d)
>>   
>>   void resctrl_online_cpu(unsigned int cpu)
>>   {
>> +	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
>> +
>>   	mutex_lock(&rdtgroup_mutex);
>>   	/* The CPU is set in default rdtgroup after online. */
>>   	cpumask_set_cpu(cpu, &rdtgroup_default.cpu_mask);
>> +	if (r->mon.mbm_cntr_assignable)
> 
> Needs a r->mon_capable check?

Sure. Will add it.

> 
>> +		resctrl_arch_mbm_cntr_assign_configure(r);
>>   	mutex_unlock(&rdtgroup_mutex);
>>   }
>>   
> 
> Reinette
> 

Thanks
- Babu Moger