From: Stratos Karafotis <stratosk@semaphore.gr>
Date: Fri, 18 Jul 2014 15:37:24 +0000 (-0700)
Subject: cpufreq: intel_pstate: Disable interrupts during MSRs reading
X-Git-Tag: cleanup-for-v3.18~101^2~5^2~10
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4ab60c3f32c721e46217e762bcd3e55a8f659c04;p=pandora-kernel.git

cpufreq: intel_pstate: Disable interrupts during MSRs reading

According to Intel 64 and IA-32 Architectures SDM, Volume 3,
Chapter 14.2, "Software needs to exercise care to avoid delays
between the two RDMSRs (for example interrupts)".

So, disable interrupts during reading MSRs IA32_APERF and IA32_MPERF.
This should increase the accuracy of the calculations.

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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