This is a note to let you know that I've just added the patch titled
intel_pstate: Set CPU number before accessing MSRs
to the 3.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
intel_pstate-set-cpu-number-before-accessing-msrs.patch
and it can be found in the queue-3.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 179e8471673ce0249cd4ecda796008f7757e5bad Mon Sep 17 00:00:00 2001
From: Vincent Minet <vincent@xxxxxxxxxxxxxxxxx>
Date: Sat, 5 Jul 2014 01:51:33 +0200
Subject: intel_pstate: Set CPU number before accessing MSRs
From: Vincent Minet <vincent@xxxxxxxxxxxxxxxxx>
commit 179e8471673ce0249cd4ecda796008f7757e5bad upstream.
Ensure that cpu->cpu is set before writing MSR_IA32_PERF_CTL during CPU
initialization. Otherwise only cpu0 has its P-state set and all other
cores are left with their values unchanged.
In most cases, this is not too serious because the P-states will be set
correctly when the timer function is run. But when the default governor
is set to performance, the per-CPU current_pstate stays the same forever
and no attempts are made to write the MSRs again.
Signed-off-by: Vincent Minet <vincent@xxxxxxxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/cpufreq/intel_pstate.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -709,9 +709,8 @@ static int intel_pstate_init_cpu(unsigne
cpu = all_cpu_data[cpunum];
- intel_pstate_get_cpu_pstates(cpu);
-
cpu->cpu = cpunum;
+ intel_pstate_get_cpu_pstates(cpu);
init_timer_deferrable(&cpu->timer);
cpu->timer.function = intel_pstate_timer_func;
Patches currently in stable-queue which might be from vincent@xxxxxxxxxxxxxxxxx are
queue-3.15/intel_pstate-set-cpu-number-before-accessing-msrs.patch
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