[3.11.y.z extended stable] Patch "intel_pstate: Set CPU number before accessing MSRs" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    intel_pstate: Set CPU number before accessing MSRs

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 0d4b0b86107dfc7e71f79731c6c3aab0cfc1e941 Mon Sep 17 00:00:00 2001
From: Vincent Minet <vincent at vincent-minet.net>
Date: Sat, 5 Jul 2014 01:51:33 +0200
Subject: [PATCH 15/41] intel_pstate: Set CPU number before accessing MSRs

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 at vincent-minet.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
[ luis: backported to 3.11:
  - moved cpu->cpu up, instead of intel_pstate_get_cpu_pstates() down ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/cpufreq/intel_pstate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index e52e5420033a..96a4c6e4d526 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -550,6 +550,7 @@ static int intel_pstate_init_cpu(unsigned int cpunum)

 	cpu = all_cpu_data[cpunum];

+	cpu->cpu = cpunum;
 	intel_pstate_get_cpu_pstates(cpu);
 	if (!cpu->pstate.current_pstate) {
 		all_cpu_data[cpunum] = NULL;
@@ -557,7 +558,6 @@ static int intel_pstate_init_cpu(unsigned int cpunum)
 		return -ENODATA;
 	}

-	cpu->cpu = cpunum;
 	cpu->pstate_policy =
 		(struct pstate_adjust_policy *)id->driver_data;
 	init_timer_deferrable(&cpu->timer);
--
1.9.1