From: Nathan Fontenot nfont@linux.vnet.ibm.com
[ Upstream commit 85a88cabad57d26d826dd94ea34d3a785824d802 ]
When performing partition migrations all present CPUs must be online as all present CPUs must make the H_JOIN call as part of the migration process. Once all present CPUs make the H_JOIN call, one CPU is returned to make the rtas call to perform the migration to the destination system.
During testing of migration and changing the SMT state we have found instances where CPUs are offlined, as part of the SMT state change, before they make the H_JOIN call. This results in a hung system where every CPU is either in H_JOIN or offline.
To prevent this this patch disables CPU hotplug during the migration process.
Signed-off-by: Nathan Fontenot nfont@linux.vnet.ibm.com Reviewed-by: Tyrel Datwyler tyreld@linux.vnet.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/kernel/rtas.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 9e41a9de43235..95d1264ba7952 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -985,6 +985,7 @@ int rtas_ibm_suspend_me(u64 handle) goto out; }
+ cpu_hotplug_disable(); stop_topology_update();
/* Call function on all CPUs. One of us will make the @@ -999,6 +1000,7 @@ int rtas_ibm_suspend_me(u64 handle) printk(KERN_ERR "Error doing global join\n");
start_topology_update(); + cpu_hotplug_enable();
/* Take down CPUs not online prior to suspend */ cpuret = rtas_offline_cpus_mask(offline_mask);