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x86/intel_rdt: Turn off most RDT features on Skylake

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Errata list is included in this document:
https://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/6th-gen-x-series-spec-update.pdf
with more details in:
https://www.intel.com/content/www/us/en/processors/xeon/scalable/xeon-scalable-spec-update.html

But the tl;dr summary (using tags from first of the documents) is:
SKZ4  MBM does not accurately track write bandwidth
SKZ17 CMT counters may not count accurately
SKZ18 CAT may not restrict cacheline allocation under certain conditions
SKZ19 MBM counters may undercount

Disable all these features on Skylake models. Users who understand the
errata may re-enable using boot command line options.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: Fenghua" <fenghua.yu@intel.com>
Cc: Ravi V" <ravi.v.shankar@intel.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>
Cc: "Stephane Eranian" <eranian@google.com>
Cc: "Andi Kleen" <ak@linux.intel.com>
Cc: "David Carrillo-Cisneros" <davidcc@google.com>
Cc: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Link: http://lkml.kernel.org/r/3aea0a3bae219062c812668bd9b7b8f1a25003ba.1503512900.git.tony.luck@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Tony Luck 2017-08-24 09:26:52 -07:00 committed by Thomas Gleixner
parent 1d9807fc64
commit d56593eb5e
1 changed files with 3 additions and 0 deletions
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3
arch/x86/kernel/cpu/intel_rdt.c
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@ -769,6 +769,9 @@ static __init void rdt_quirks(void)
if (!rdt_options[RDT_FLAG_L3_CAT].force_off)
cache_alloc_hsw_probe();
break;
case INTEL_FAM6_SKYLAKE_X:
if (boot_cpu_data.x86_mask <= 4)
set_rdt_options("!cmt,!mbmtotal,!mbmlocal,!l3cat");
}
}