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Subject: [PATCH v7 03/12] x86/cpufeatures: Add Bandwidth Monitoring Event
 Configuration feature flag
From:   Babu Moger <babu.moger@amd.com>
To:     <corbet@lwn.net>, <reinette.chatre@intel.com>,
        <tglx@linutronix.de>, <mingo@redhat.com>, <bp@alien8.de>
CC:     <fenghua.yu@intel.com>, <dave.hansen@linux.intel.com>,
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        <james.morse@arm.com>, <linux-doc@vger.kernel.org>,
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Date:   Mon, 17 Oct 2022 17:26:25 -0500
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Newer AMD processors support the new feature Bandwidth Monitoring Event=0A=
Configuration (BMEC).=0A=
=0A=
The feature support is identified via CPUID Fn8000_0020_EBX_x0 (ECX=3D0).=
=0A=
Bits    Field Name    Description=0A=
3       EVT_CFG       Bandwidth Monitoring Event Configuration (BMEC)=0A=
=0A=
Currently, the bandwidth monitoring events mbm_total_bytes and=0A=
mbm_local_bytes are set to count all the total and local reads/writes=0A=
respectively. With the introduction of slow memory, the two counters=0A=
are not enough to count all the different types of memory events. With=0A=
the feature BMEC, the users have the option to configure=0A=
mbm_total_bytes and mbm_local_bytes to count the specific type of=0A=
events.=0A=
=0A=
Each BMEC event has a configuration MSR, QOS_EVT_CFG (0xc000_0400h +=0A=
EventID) which contains one field for each bandwidth type that can be=0A=
used to configure the bandwidth event to track any combination of=0A=
supported bandwidth types. The event will count requests from every=0A=
bandwidth type bit that is set in the corresponding configuration=0A=
register.=0A=
=0A=
Following are the types of events supported:=0A=
=0A=
=3D=3D=3D=3D    =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=0A=
Bits    Description=0A=
=3D=3D=3D=3D    =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=0A=
6       Dirty Victims from the QOS domain to all types of memory=0A=
5       Reads to slow memory in the non-local NUMA domain=0A=
4       Reads to slow memory in the local NUMA domain=0A=
3       Non-temporal writes to non-local NUMA domain=0A=
2       Non-temporal writes to local NUMA domain=0A=
1       Reads to memory in the non-local NUMA domain=0A=
0       Reads to memory in the local NUMA domain=0A=
=3D=3D=3D=3D    =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=0A=
=0A=
By default, the mbm_total_bytes configuration is set to 0x7F to count=0A=
all the event types and the mbm_local_bytes configuration is set to=0A=
0x15 to count all the local memory events.=0A=
=0A=
Feature description is available in the specification, "AMD64=0A=
Technology Platform Quality of Service Extensions, Revision: 1.03=0A=
Publication=0A=
=0A=
Link: https://www.amd.com/en/support/tech-docs/amd64-technology-platform-qu=
ality-service-extensions=0A=
Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D206537=0A=
Signed-off-by: Babu Moger <babu.moger@amd.com>=0A=
---=0A=
 arch/x86/include/asm/cpufeatures.h |    1 +=0A=
 arch/x86/kernel/cpu/cpuid-deps.c   |    1 +=0A=
 arch/x86/kernel/cpu/scattered.c    |    1 +=0A=
 3 files changed, 3 insertions(+)=0A=
=0A=
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpuf=
eatures.h=0A=
index 583b88bcc7e1..bf0fd022e80a 100644=0A=
--- a/arch/x86/include/asm/cpufeatures.h=0A=
+++ b/arch/x86/include/asm/cpufeatures.h=0A=
@@ -305,6 +305,7 @@=0A=
 #define X86_FEATURE_USE_IBPB_FW		(11*32+16) /* "" Use IBPB during runtime =
firmware calls */=0A=
 #define X86_FEATURE_RSB_VMEXIT_LITE	(11*32+17) /* "" Fill RSB on VM exit w=
hen EIBRS is enabled */=0A=
 #define X86_FEATURE_SMBA		(11*32+18) /* Slow Memory Bandwidth Allocation *=
/=0A=
+#define X86_FEATURE_BMEC		(11*32+19) /* AMD Bandwidth Monitoring Event Con=
figuration (BMEC) */=0A=
 =0A=
 /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */=
=0A=
 #define X86_FEATURE_AVX_VNNI		(12*32+ 4) /* AVX VNNI instructions */=0A=
diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-d=
eps.c=0A=
index c881bcafba7d..4555f9596ccf 100644=0A=
--- a/arch/x86/kernel/cpu/cpuid-deps.c=0A=
+++ b/arch/x86/kernel/cpu/cpuid-deps.c=0A=
@@ -68,6 +68,7 @@ static const struct cpuid_dep cpuid_deps[] =3D {=0A=
 	{ X86_FEATURE_CQM_OCCUP_LLC,		X86_FEATURE_CQM_LLC   },=0A=
 	{ X86_FEATURE_CQM_MBM_TOTAL,		X86_FEATURE_CQM_LLC   },=0A=
 	{ X86_FEATURE_CQM_MBM_LOCAL,		X86_FEATURE_CQM_LLC   },=0A=
+	{ X86_FEATURE_BMEC,			X86_FEATURE_CQM_LLC   },=0A=
 	{ X86_FEATURE_AVX512_BF16,		X86_FEATURE_AVX512VL  },=0A=
 	{ X86_FEATURE_AVX512_FP16,		X86_FEATURE_AVX512BW  },=0A=
 	{ X86_FEATURE_ENQCMD,			X86_FEATURE_XSAVES    },=0A=
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattere=
d.c=0A=
index 5a5f17ed69a2..67c4d24e06ef 100644=0A=
--- a/arch/x86/kernel/cpu/scattered.c=0A=
+++ b/arch/x86/kernel/cpu/scattered.c=0A=
@@ -45,6 +45,7 @@ static const struct cpuid_bit cpuid_bits[] =3D {=0A=
 	{ X86_FEATURE_PROC_FEEDBACK,    CPUID_EDX, 11, 0x80000007, 0 },=0A=
 	{ X86_FEATURE_MBA,		CPUID_EBX,  6, 0x80000008, 0 },=0A=
 	{ X86_FEATURE_SMBA,		CPUID_EBX,  2, 0x80000020, 0 },=0A=
+	{ X86_FEATURE_BMEC,		CPUID_EBX,  3, 0x80000020, 0 },=0A=
 	{ X86_FEATURE_PERFMON_V2,	CPUID_EAX,  0, 0x80000022, 0 },=0A=
 	{ X86_FEATURE_AMD_LBR_V2,	CPUID_EAX,  1, 0x80000022, 0 },=0A=
 	{ 0, 0, 0, 0, 0 }=0A=
=0A=