[Qemu-devel] [PULL 11/24] spapr/rtas: fix reboot of a a SMP TCG guest

[David Gibson <david@gibson.dropbear.id.au>]

From: Cédric Le Goater <clg@kaod.org>

Just like for hot unplug CPUs, when a guest is rebooted, the secondary
CPUs can be awaken by the decrementer and start entering SLOF at the
same time the boot CPU is.

To be safe, let's disable on the secondaries all the exceptions which
can cause an exit while the CPU is in power-saving mode.

Based on previous work from Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr_cpu_core.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 588f9b4571..1ea0e295dd 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -26,6 +26,7 @@ static void spapr_cpu_reset(void *opaque)
     PowerPCCPU *cpu = opaque;
     CPUState *cs = CPU(cpu);
     CPUPPCState *env = &cpu->env;
+    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
 
     cpu_reset(cs);
 
@@ -35,6 +36,13 @@ static void spapr_cpu_reset(void *opaque)
     cs->halted = 1;
 
     env->spr[SPR_HIOR] = 0;
+
+    /* Disable Power-saving mode Exit Cause exceptions for the CPU.
+     * This can cause issues when rebooting the guest if a secondary
+     * is awaken */
+    if (cs != first_cpu) {
+        env->spr[SPR_LPCR] &= ~pcc->lpcr_pm;
+    }
 }
 
 static void spapr_cpu_destroy(PowerPCCPU *cpu)
-- 
2.14.3