From 48cdd8287f47a3cdad5b9273a5ef81bf605f7826 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Tue, 13 Mar 2012 20:06:57 -0400
Subject: xen/cpufreq: Disable the cpu frequency scaling drivers from loading.

By using the functionality provided by "[CPUFREQ]: provide
disable_cpuidle() function to disable the API."

Under the Xen hypervisor we do not want the initial domain to exercise
the cpufreq scaling drivers. This is b/c the Xen hypervisor is
in charge of doing this as well and we can end up with both the
Linux kernel and the hypervisor trying to change the P-states
leading to weird performance issues.

Acked-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[v2: Fix compile error spotted by Benjamin Schweikert <b.schweikert@googlemail.com>]
---
 arch/x86/xen/setup.c | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'arch')

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 12366238d07d..1ba8dff26753 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -10,6 +10,7 @@
 #include <linux/pm.h>
 #include <linux/memblock.h>
 #include <linux/cpuidle.h>
+#include <linux/cpufreq.h>
 
 #include <asm/elf.h>
 #include <asm/vdso.h>
@@ -420,6 +421,7 @@ void __init xen_arch_setup(void)
 	boot_cpu_data.hlt_works_ok = 1;
 #endif
 	disable_cpuidle();
+	disable_cpufreq();
 	WARN_ON(set_pm_idle_to_default());
 	fiddle_vdso();
 }
-- 
cgit v1.2.3


From 106b44388d8f76373149c4ea144f717b6d4d9a6d Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Wed, 21 Mar 2012 13:03:45 -0400
Subject: xen/smp: Fix bringup bug in AP code.

The CPU hotplug code has now a callback to help bring up the CPU.
Without the call we end up getting:

 BUG: soft lockup - CPU#0 stuck for 29s! [migration/0:6]
Modules linked in:
CPU ] Pid: 6, comm: migration/0 Not tainted 3.3.0upstream-01180-ged378a5 #1 Dell Inc. PowerEdge T105 /0RR825
RIP: e030:[<ffffffff810d3b8b>]  [<ffffffff810d3b8b>] stop_machine_cpu_stop+0x7b/0xf0
RSP: e02b:ffff8800ceaabdb0  EFLAGS: 00000293
.. snip..
Call Trace:
 [<ffffffff810d3b10>] ? stop_one_cpu_nowait+0x50/0x50
 [<ffffffff810d3841>] cpu_stopper_thread+0xf1/0x1c0
 [<ffffffff815a9776>] ? __schedule+0x3c6/0x760
 [<ffffffff815aa749>] ? _raw_spin_unlock_irqrestore+0x19/0x30
 [<ffffffff810d3750>] ? res_counter_charge+0x150/0x150
 [<ffffffff8108dc76>] kthread+0x96/0xa0
 [<ffffffff815b27e4>] kernel_thread_helper+0x4/0x10
 [<ffffffff815aacbc>] ? retint_restore_ar

Thix fixes it.

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 arch/x86/xen/smp.c | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'arch')

diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 449f86897db3..240def438dc3 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -75,8 +75,14 @@ static void __cpuinit cpu_bringup(void)
 
 	xen_setup_cpu_clockevents();
 
+	notify_cpu_starting(cpu);
+
+	ipi_call_lock();
 	set_cpu_online(cpu, true);
+	ipi_call_unlock();
+
 	this_cpu_write(cpu_state, CPU_ONLINE);
+
 	wmb();
 
 	/* We can take interrupts now: we're officially "up". */
-- 
cgit v1.2.3