spapr/xive: Fix migration of hot-plugged CPUs

The migration sequence of a guest using the XIVE exploitation mode
relies on the fact that the states of all devices are restored before
the machine is. This is not true for hot-plug devices such as CPUs
which state come after the machine. This breaks migration because the
thread interrupt context registers are not correctly set.

Fix migration of hotplugged CPUs by restoring their context in the
'post_load' handler of the XiveTCTX model.

Fixes: 277dd3d7712a ("spapr/xive: add migration support for KVM")
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20190813064853.29310-1-clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 20 insertions, 1 deletions

diff --git a/hw/intc/xive.c b/hw/intc/xive.c
index cf77bdb7d3..da148e9f6f 100644
--- a/hw/intc/xive.c
+++ b/hw/intc/xive.c
@@ -615,12 +615,31 @@ static int vmstate_xive_tctx_pre_save(void *opaque)
     return 0;
 }
 
+static int vmstate_xive_tctx_post_load(void *opaque, int version_id)
+{
+    Error *local_err = NULL;
+
+    if (kvm_irqchip_in_kernel()) {
+        /*
+         * Required for hotplugged CPU, for which the state comes
+         * after all states of the machine.
+         */
+        kvmppc_xive_cpu_set_state(XIVE_TCTX(opaque), &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
 static const VMStateDescription vmstate_xive_tctx = {
     .name = TYPE_XIVE_TCTX,
     .version_id = 1,
     .minimum_version_id = 1,
     .pre_save = vmstate_xive_tctx_pre_save,
-    .post_load = NULL, /* handled by the sPAPRxive model */
+    .post_load = vmstate_xive_tctx_post_load,
     .fields = (VMStateField[]) {
         VMSTATE_BUFFER(regs, XiveTCTX),
         VMSTATE_END_OF_LIST()