[PATCH] powerpc/powernv: force all CPUs to be bootable

[Greg Kurz]

The subcore logic needs all the CPUs declared in the DT to be bootable,
otherwise the kernel hangs at boot time. Since subcore support starts
with POWER8, we can keep the current behaviour for older CPUs.

Signed-off-by: Greg Kurz <gkurz at linux.vnet.ibm.com>
---

Since smt-enabled is still needed by Freescale, the choice was made to fix
powernv only. I could test that smt-enabled is still honored on POWER7 and
ignored on POWER8, as expected.

 arch/powerpc/platforms/powernv/smp.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index b716f66..5b6e002 100644
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -198,13 +198,24 @@ static void pnv_smp_cpu_kill_self(void)
 
 #endif /* CONFIG_HOTPLUG_CPU */
 
+static int pnv_cpu_bootable(unsigned int nr)
+{
+	/* Starting with POWER8, all CPUs need to be booted to avoid hangs
+	 * during subcore init.
+	 */
+	if (cpu_has_feature(CPU_FTR_ARCH_207S))
+		return 1;
+
+	return smp_generic_cpu_bootable(nr);
+}
+
 static struct smp_ops_t pnv_smp_ops = {
 	.message_pass	= smp_muxed_ipi_message_pass,
 	.cause_ipi	= NULL,	/* Filled at runtime by xics_smp_probe() */
 	.probe		= xics_smp_probe,
 	.kick_cpu	= pnv_smp_kick_cpu,
 	.setup_cpu	= pnv_smp_setup_cpu,
-	.cpu_bootable	= smp_generic_cpu_bootable,
+	.cpu_bootable	= pnv_cpu_bootable,
 #ifdef CONFIG_HOTPLUG_CPU
 	.cpu_disable	= pnv_smp_cpu_disable,
 	.cpu_die	= generic_cpu_die,