[078/200] powerpc/pseries: Only call start-cpu when a CPU is stopped

Greg KH
2010-07-01T21:15:59Z

2.6.34-stable review patch. If anyone has any objections, please let me know.

------------------

From: Michael Neuling <mikey@neuling.org>

commit aef40e87d866355ffd279ab21021de733242d0d5 upstream.

Currently we always call start-cpu irrespective of if the CPU is
stopped or not. Unfortunatley on POWER7, firmware seems to not like
start-cpu being called when a cpu already been started. This was not
the case on POWER6 and earlier.

This patch checks to see if the CPU is stopped or not via an
query-cpu-stopped-state call, and only calls start-cpu on CPUs which
are stopped.

This fixes a bug with kexec on POWER7 on PHYP where only the primary
thread would make it to the second kernel.

Reported-by: Ankita Garg <ankita@linux.vnet.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/powerpc/platforms/pseries/smp.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/arch/powerpc/platforms/pseries/smp.c
+++ b/arch/powerpc/platforms/pseries/smp.c
@@ -82,6 +82,12 @@ static inline int __devinit smp_startup_

pcpu = get_hard_smp_processor_id(lcpu);

+ /* Check to see if the CPU out of FW already for kexec */
+ if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
+ cpu_set(lcpu, of_spin_map);
+ return 1;
+ }
+
/* Fixup atomic count: it exited inside IRQ handler. */
task_thread_info(paca[lcpu].__current)->preempt_count = 0;