x86/intel_rdt: Turn off most RDT features on Skylake
authorTony Luck <tony.luck@intel.com>
Thu, 24 Aug 2017 16:26:52 +0000 (09:26 -0700)
committerThomas Gleixner <tglx@linutronix.de>
Fri, 25 Aug 2017 20:00:45 +0000 (22:00 +0200)
commitd56593eb5eda8f593db92927059697bbf89bc4b3
treef833391c5bc62aa2c5a7e308914f907c782b8985
parent1d9807fc64c131a83a96917f2b2da1c9b00cf127
x86/intel_rdt: Turn off most RDT features on Skylake

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>
arch/x86/kernel/cpu/intel_rdt.c