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Date: Wed, 23 Nov 2022 23:06:08 +0000
From: "Moger, Babu" <Babu.Moger@....com>
To: "Yu, Fenghua" <fenghua.yu@...el.com>,
"corbet@....net" <corbet@....net>,
"Chatre, Reinette" <reinette.chatre@...el.com>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"mingo@...hat.com" <mingo@...hat.com>,
"bp@...en8.de" <bp@...en8.de>
CC: "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>,
"quic_neeraju@...cinc.com" <quic_neeraju@...cinc.com>,
"rdunlap@...radead.org" <rdunlap@...radead.org>,
"damien.lemoal@...nsource.wdc.com" <damien.lemoal@...nsource.wdc.com>,
"songmuchun@...edance.com" <songmuchun@...edance.com>,
"peterz@...radead.org" <peterz@...radead.org>,
"jpoimboe@...nel.org" <jpoimboe@...nel.org>,
"pbonzini@...hat.com" <pbonzini@...hat.com>,
"Bae, Chang Seok" <chang.seok.bae@...el.com>,
"pawan.kumar.gupta@...ux.intel.com"
<pawan.kumar.gupta@...ux.intel.com>,
"jmattson@...gle.com" <jmattson@...gle.com>,
"daniel.sneddon@...ux.intel.com" <daniel.sneddon@...ux.intel.com>,
"Das1, Sandipan" <Sandipan.Das@....com>,
"Luck, Tony" <tony.luck@...el.com>,
"james.morse@....com" <james.morse@....com>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"bagasdotme@...il.com" <bagasdotme@...il.com>,
"Eranian, Stephane" <eranian@...gle.com>
Subject: RE: [PATCH v8 03/13] x86/cpufeatures: Add Bandwidth Monitoring Event
Configuration feature flag
[AMD Official Use Only - General]
Hi Fenghua,
> -----Original Message-----
> From: Yu, Fenghua <fenghua.yu@...el.com>
> Sent: Wednesday, November 23, 2022 12:17 PM
> To: Moger, Babu <Babu.Moger@....com>; corbet@....net; Chatre, Reinette
> <reinette.chatre@...el.com>; tglx@...utronix.de; mingo@...hat.com;
> bp@...en8.de
> Cc: 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; Bae, Chang Seok <chang.seok.bae@...el.com>;
> pawan.kumar.gupta@...ux.intel.com; jmattson@...gle.com;
> daniel.sneddon@...ux.intel.com; Das1, Sandipan <Sandipan.Das@....com>;
> Luck, Tony <tony.luck@...el.com>; james.morse@....com; linux-
> doc@...r.kernel.org; linux-kernel@...r.kernel.org; bagasdotme@...il.com;
> Eranian, Stephane <eranian@...gle.com>
> Subject: RE: [PATCH v8 03/13] x86/cpufeatures: Add Bandwidth Monitoring
> Event Configuration feature flag
>
> Hi, Babu,
>
> > Newer AMD processors support the new feature Bandwidth Monitoring
> > Event Configuration (BMEC).
> >
> > The feature support is identified via CPUID Fn8000_0020_EBX_x0 (ECX=0).
> > Bits Field Name Description
> > 3 EVT_CFG Bandwidth Monitoring Event Configuration (BMEC)
> >
> > Currently, the bandwidth monitoring events mbm_total_bytes and
> > mbm_local_bytes are set to count all the total and local reads/writes
> > respectively. With the introduction of slow memory, the two counters
> > are not enough to count all the different types of memory events. With
> > the feature BMEC, the users have the option to configure
> > mbm_total_bytes and mbm_local_bytes to count the specific type of events.
> >
> > Each BMEC event has a configuration MSR, QOS_EVT_CFG (0xc000_0400h +
> > EventID) which contains one field for each bandwidth type that can be
> > used to configure the bandwidth event to track any combination of
> > supported bandwidth types. The event will count requests from every
> > bandwidth type bit that is set in the corresponding configuration register.
> >
> > Following are the types of events supported:
> >
> > ==== ========================================================
> > Bits Description
> > ==== ========================================================
> > 6 Dirty Victims from the QOS domain to all types of memory
> > 5 Reads to slow memory in the non-local NUMA domain
> > 4 Reads to slow memory in the local NUMA domain
> > 3 Non-temporal writes to non-local NUMA domain
> > 2 Non-temporal writes to local NUMA domain
> > 1 Reads to memory in the non-local NUMA domain
> > 0 Reads to memory in the local NUMA domain
> > ==== ========================================================
> >
> > By default, the mbm_total_bytes configuration is set to 0x7F to count
> > all the event types and the mbm_local_bytes configuration is set to
> > 0x15 to count all the local memory events.
> >
> > Feature description is available in the specification, "AMD64
> > Technology Platform Quality of Service Extensions, Revision: 1.03
> > Publication
> >
> > Link:
> > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.
> > amd.com%2Fen%2Fsupport%2Ftech-docs%2Famd64-technology-
> &data=05%7C0
> >
> 1%7Cbabu.moger%40amd.com%7C50e1807651fd4513648908dacd7efac0%7C3
> dd8961f
> >
> e4884e608e11a82d994e183d%7C0%7C0%7C638048242504277761%7CUnknow
> n%7CTWFp
> >
> bGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6
> Mn
> >
> 0%3D%7C3000%7C%7C%7C&sdata=5lpXbZkZ78mJ1d9PnLf7WmRT5vPogfs
> 5HaZLz76
> > x04I%3D&reserved=0
> > platform-quality-service-extensions
> > Link:
> > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugz
> >
> illa.kernel.org%2Fshow_bug.cgi%3Fid%3D206537&data=05%7C01%7Cbab
> u.m
> >
> oger%40amd.com%7C50e1807651fd4513648908dacd7efac0%7C3dd8961fe488
> 4e608e
> >
> 11a82d994e183d%7C0%7C0%7C638048242504277761%7CUnknown%7CTWFpb
> GZsb3d8ey
> >
> JWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7
> C300
> >
> 0%7C%7C%7C&sdata=2CjPpzCT4JeA9VPNZIW7zxyL22xpEm2FoXQlhAz5OK
> o%3D&am
> > p;reserved=0
> > Signed-off-by: Babu Moger <babu.moger@....com>
> > ---
> > arch/x86/include/asm/cpufeatures.h | 1 +
> > arch/x86/kernel/cpu/cpuid-deps.c | 1 +
> > arch/x86/kernel/cpu/scattered.c | 1 +
> > 3 files changed, 3 insertions(+)
> >
> > diff --git a/arch/x86/include/asm/cpufeatures.h
> > b/arch/x86/include/asm/cpufeatures.h
> > index d68b4c9c181d..6732ca0117be 100644
> > --- a/arch/x86/include/asm/cpufeatures.h
> > +++ b/arch/x86/include/asm/cpufeatures.h
> > @@ -306,6 +306,7 @@
> > #define X86_FEATURE_RSB_VMEXIT_LITE (11*32+17) /* "" Fill RSB on
> VM
> > exit when EIBRS is enabled */
> > #define X86_FEATURE_CALL_DEPTH (11*32+18) /* "" Call depth
> > tracking for RSB stuffing */
> > #define X86_FEATURE_SMBA (11*32+19) /* Slow Memory
> > Bandwidth Allocation */
> > +#define X86_FEATURE_BMEC (11*32+20) /* AMD
> Bandwidth
> > Monitoring Event Configuration (BMEC) */
> >
> > /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */
> > #define X86_FEATURE_AVX_VNNI (12*32+ 4) /* AVX VNNI
> > instructions */
> > diff --git a/arch/x86/kernel/cpu/cpuid-deps.c
> > b/arch/x86/kernel/cpu/cpuid- deps.c index c881bcafba7d..4555f9596ccf
> > 100644
> > --- a/arch/x86/kernel/cpu/cpuid-deps.c
> > +++ b/arch/x86/kernel/cpu/cpuid-deps.c
> > @@ -68,6 +68,7 @@ static const struct cpuid_dep cpuid_deps[] = {
> > { X86_FEATURE_CQM_OCCUP_LLC,
> > X86_FEATURE_CQM_LLC },
> > { X86_FEATURE_CQM_MBM_TOTAL,
> > X86_FEATURE_CQM_LLC },
> > { X86_FEATURE_CQM_MBM_LOCAL,
> > X86_FEATURE_CQM_LLC },
> > + { X86_FEATURE_BMEC, X86_FEATURE_CQM_LLC },
>
> Shouldn't X86_FEATURE_BMEC really depend on
> X86_FEATURE_CQM_MBM_LOCAL and _TOTAL?
>
> CQM_MBM_LOCAL and/or _TOTAL can be disabled but CQM_LLC can still be
> enabled. In this case, BMEC shouldn't be enabled, right? But with this patch,
> BMEC will be enabled but it won't work well as CQM_MBM_TOTAL/_LOCAL
> are not enabled.
Yes. You are right.
>
> You may remove the above line and add these two lines:
>
> + { X86_FEATURE_BMEC,
> X86_FEATURE_CQM_MBM_TOTAL },
> + { X86_FEATURE_BMEC,
> X86_FEATURE_CQM_MBM_LOCAL },
>
Sure. Will add these lines.
Thanks
Babu
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