Messages in this thread Patch in this message | | | Date | Fri, 25 Aug 2017 13:04:48 -0700 | From | tip-bot for Tony Luck <> | Subject | [tip:x86/cache] x86/intel_rdt: Turn off most RDT features on Skylake |
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Commit-ID: d56593eb5eda8f593db92927059697bbf89bc4b3 Gitweb: http://git.kernel.org/tip/d56593eb5eda8f593db92927059697bbf89bc4b3 Author: Tony Luck <tony.luck@intel.com> AuthorDate: Thu, 24 Aug 2017 09:26:52 -0700 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Fri, 25 Aug 2017 22:00:45 +0200
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 | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c index b641622..cd5fc61 100644 --- a/arch/x86/kernel/cpu/intel_rdt.c +++ b/arch/x86/kernel/cpu/intel_rdt.c @@ -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"); } }
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