powerpc/powernv: Ignore smt-enabled on Power8 and later
Starting with POWER8, the subcore logic relies on all threads of a core
being booted so that they can participate in split mode switches. So on
those machines we ignore the smt_enabled_at_boot setting (smt-enabled on
the kernel command line).
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
[mpe: Update comment and change log to be more precise]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index 6c551a2..fc34025 100644
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -209,13 +209,27 @@
#endif /* CONFIG_HOTPLUG_CPU */
+static int pnv_cpu_bootable(unsigned int nr)
+{
+ /*
+ * Starting with POWER8, the subcore logic relies on all threads of a
+ * core being booted so that they can participate in split mode
+ * switches. So on those machines we ignore the smt_enabled_at_boot
+ * setting (smt-enabled on the kernel command line).
+ */
+ 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,
