x86/resctrl: Correct MBM total and local values

Intel Memory Bandwidth Monitoring (MBM) counters may report system
memory bandwidth incorrectly on some Intel processors. The errata SKX99
for Skylake server, BDF102 for Broadwell server, and the correction
factor table are documented in Documentation/x86/resctrl.rst.

Intel MBM counters track metrics according to the assigned Resource
Monitor ID (RMID) for that logical core. The IA32_QM_CTR register
(MSR 0xC8E) used to report these metrics, may report incorrect system
bandwidth for certain RMID values.

Due to the errata, system memory bandwidth may not match what is
reported.

To work around the errata, correct MBM total and local readings using a
correction factor table. If rmid > rmid threshold, MBM total and local
values should be multiplied by the correction factor.

 [ bp: Mark mbm_cf_table[] __initdata. ]

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20201014004927.1839452-3-fenghua.yu@intel.com

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 80fa997fae60..6cb068fcf501 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -616,6 +616,7 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
 void mbm_setup_overflow_handler(struct rdt_domain *dom,
 				unsigned long delay_ms);
 void mbm_handle_overflow(struct work_struct *work);
+void __init intel_rdt_mbm_apply_quirk(void);
 bool is_mba_sc(struct rdt_resource *r);
 void setup_default_ctrlval(struct rdt_resource *r, u32 *dc, u32 *dm);
 u32 delay_bw_map(unsigned long bw, struct rdt_resource *r);