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Subject[PATCH 5.7 106/265] x86/resctrl: Support CPUID enumeration of MBM counter width
Date
From: Reinette Chatre <reinette.chatre@intel.com>

[ Upstream commit f3d44f18b0662327c42128b9d3604489bdb6e36f ]

The original Memory Bandwidth Monitoring (MBM) architectural
definition defines counters of up to 62 bits in the
IA32_QM_CTR MSR while the first-generation MBM implementation
uses statically defined 24 bit counters.

Expand the MBM CPUID enumeration properties to include the MBM
counter width. The previously undefined EAX output register contains,
in bits [7:0], the MBM counter width encoded as an offset from
24 bits. Enumerating this property is only specified for Intel
CPUs.

Suggested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/afa3af2f753f6bc301fb743bc8944e749cb24afa.1588715690.git.reinette.chatre@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/include/asm/processor.h | 3 ++-
arch/x86/kernel/cpu/resctrl/core.c | 5 +++++
2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 3bcf27caf6c9f..c4e8fd709cf67 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -113,9 +113,10 @@ struct cpuinfo_x86 {
/* in KB - valid for CPUS which support this call: */
unsigned int x86_cache_size;
int x86_cache_alignment; /* In bytes */
- /* Cache QoS architectural values: */
+ /* Cache QoS architectural values, valid only on the BSP: */
int x86_cache_max_rmid; /* max index */
int x86_cache_occ_scale; /* scale to bytes */
+ int x86_cache_mbm_width_offset;
int x86_power;
unsigned long loops_per_jiffy;
/* cpuid returned max cores value: */
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 49599733fa94d..d242e864726c0 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -963,6 +963,7 @@ void resctrl_cpu_detect(struct cpuinfo_x86 *c)
if (!cpu_has(c, X86_FEATURE_CQM_LLC)) {
c->x86_cache_max_rmid = -1;
c->x86_cache_occ_scale = -1;
+ c->x86_cache_mbm_width_offset = -1;
return;
}

@@ -979,6 +980,10 @@ void resctrl_cpu_detect(struct cpuinfo_x86 *c)

c->x86_cache_max_rmid = ecx;
c->x86_cache_occ_scale = ebx;
+ if (c->x86_vendor == X86_VENDOR_INTEL)
+ c->x86_cache_mbm_width_offset = eax & 0xff;
+ else
+ c->x86_cache_mbm_width_offset = -1;
}
}

--
2.25.1
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