linux-kernel - RE: [PATCH v8 05/13] x86/resctrl: Detect and configure Slow Memory Bandwidth Allocation

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Message-ID: <MW3PR12MB45533D17ABC9024CA708CF40950C9@MW3PR12MB4553.namprd12.prod.outlook.com>
Date:   Wed, 23 Nov 2022 15:17:54 +0000
From:   "Moger, Babu" <Babu.Moger@....com>
To:     Reinette Chatre <reinette.chatre@...el.com>,
        "corbet@....net" <corbet@....net>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>
CC:     "fenghua.yu@...el.com" <fenghua.yu@...el.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "paulmck@...nel.org" <paulmck@...nel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
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Subject: RE: [PATCH v8 05/13] x86/resctrl: Detect and configure Slow Memory
 Bandwidth Allocation

[AMD Official Use Only - General]

Hi Reinette,

> -----Original Message-----
> From: Reinette Chatre <reinette.chatre@...el.com>
> Sent: Tuesday, November 22, 2022 6:13 PM
> To: Moger, Babu <Babu.Moger@....com>; corbet@....net;
> tglx@...utronix.de; mingo@...hat.com; bp@...en8.de
> Cc: fenghua.yu@...el.com; dave.hansen@...ux.intel.com; x86@...nel.org;
> hpa@...or.com; paulmck@...nel.org; akpm@...ux-foundation.org;
> quic_neeraju@...cinc.com; rdunlap@...radead.org;
> damien.lemoal@...nsource.wdc.com; songmuchun@...edance.com;
> peterz@...radead.org; jpoimboe@...nel.org; pbonzini@...hat.com;
> chang.seok.bae@...el.com; pawan.kumar.gupta@...ux.intel.com;
> jmattson@...gle.com; daniel.sneddon@...ux.intel.com; Das1, Sandipan
> <Sandipan.Das@....com>; tony.luck@...el.com; james.morse@....com;
> linux-doc@...r.kernel.org; linux-kernel@...r.kernel.org;
> bagasdotme@...il.com; eranian@...gle.com
> Subject: Re: [PATCH v8 05/13] x86/resctrl: Detect and configure Slow Memory
> Bandwidth Allocation
> 
> Hi Babu,
> 
> On 11/4/2022 1:00 PM, Babu Moger wrote:
> > The QoS slow memory configuration details are available via
> > CPUID_Fn80000020_EDX_x02. Detect the available details and initialize
> > the rest to defaults.
> >
> > Signed-off-by: Babu Moger <babu.moger@....com>
> > ---
> >  arch/x86/kernel/cpu/resctrl/core.c        |   36
> +++++++++++++++++++++++++++--
> >  arch/x86/kernel/cpu/resctrl/ctrlmondata.c |    2 +-
> >  arch/x86/kernel/cpu/resctrl/internal.h    |    1 +
> >  arch/x86/kernel/cpu/resctrl/rdtgroup.c    |    8 ++++--
> >  4 files changed, 41 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/x86/kernel/cpu/resctrl/core.c
> > b/arch/x86/kernel/cpu/resctrl/core.c
> > index e31c98e2fafc..6571d08e2b0d 100644
> > --- a/arch/x86/kernel/cpu/resctrl/core.c
> > +++ b/arch/x86/kernel/cpu/resctrl/core.c
> > @@ -162,6 +162,13 @@ bool is_mba_sc(struct rdt_resource *r)
> >  	if (!r)
> >  		return
> rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl.membw.mba_sc;
> >
> > +	/*
> > +	 * The software controller support is only applicable to MBA resource.
> > +	 * Make sure to check for resource type again.
> > +	 */
> 
> /again/d

Sure.

> 
> Not all callers of is_mba_sc() check if it is called for an MBA resource.
> 
> > +	if (r->rid != RDT_RESOURCE_MBA)
> > +		return false;
> > +
> >  	return r->membw.mba_sc;
> >  }
> >
> > @@ -225,9 +232,15 @@ static bool __rdt_get_mem_config_amd(struct
> rdt_resource *r)
> >  	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
> >  	union cpuid_0x10_3_eax eax;
> >  	union cpuid_0x10_x_edx edx;
> > -	u32 ebx, ecx;
> > +	u32 ebx, ecx, subleaf;
> >
> > -	cpuid_count(0x80000020, 1, &eax.full, &ebx, &ecx, &edx.full);
> > +	/*
> > +	 * Query CPUID_Fn80000020_EDX_x01 for MBA and
> > +	 * CPUID_Fn80000020_EDX_x02 for SMBA
> > +	 */
> > +	subleaf = (r->rid == RDT_RESOURCE_SMBA) ? 2 :  1;
> > +
> > +	cpuid_count(0x80000020, subleaf, &eax.full, &ebx, &ecx, &edx.full);
> >  	hw_res->num_closid = edx.split.cos_max + 1;
> >  	r->default_ctrl = MAX_MBA_BW_AMD;
> >
> > @@ -750,6 +763,19 @@ static __init bool get_mem_config(void)
> >  	return false;
> >  }
> >
> > +static __init bool get_slow_mem_config(void) {
> > +	struct rdt_hw_resource *hw_res =
> > +&rdt_resources_all[RDT_RESOURCE_SMBA];
> > +
> > +	if (!rdt_cpu_has(X86_FEATURE_SMBA))
> > +		return false;
> > +
> > +	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
> > +		return __rdt_get_mem_config_amd(&hw_res->r_resctrl);
> > +
> > +	return false;
> > +}
> > +
> >  static __init bool get_rdt_alloc_resources(void)  {
> >  	struct rdt_resource *r;
> > @@ -780,6 +806,9 @@ static __init bool get_rdt_alloc_resources(void)
> >  	if (get_mem_config())
> >  		ret = true;
> >
> > +	if (get_slow_mem_config())
> > +		ret = true;
> > +
> >  	return ret;
> >  }
> >
> > @@ -869,6 +898,9 @@ static __init void rdt_init_res_defs_amd(void)
> >  		} else if (r->rid == RDT_RESOURCE_MBA) {
> >  			hw_res->msr_base = MSR_IA32_MBA_BW_BASE;
> >  			hw_res->msr_update = mba_wrmsr_amd;
> > +		} else if (r->rid == RDT_RESOURCE_SMBA) {
> > +			hw_res->msr_base = MSR_IA32_SMBA_BW_BASE;
> > +			hw_res->msr_update = mba_wrmsr_amd;
> >  		}
> >  	}
> >  }
> 
> I mentioned earlier that this can be moved to init of rdt_resources_all[]. No
> strong preference, leaving here works also.

Sure. Will do.
Thanks
Babu
> 
> Reinette

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