[Qemu-devel] [QEMU RFC PATCH v4 5/6] migration: migrate ccs_list in spapr state

[Jianjun Duan <duanj@linux.vnet.ibm.com>]

ccs_list in spapr state maintains the device tree related
information on the rtas side for hotplugged devices. In racing
situations between hotplug events and migration operation, a rtas
hotplug event could be migrated from the source guest to target
guest, or the source guest could have not yet finished fetching
the device tree when migration is started, the target will try
to finish fetching the device tree. By migrating ccs_list, the
target can fetch the device tree properly.

ccs_list is put in a subsection in the spapr state VMSD to make
sure migration across different versions is not broken.

Signed-off-by: Jianjun Duan <duanj@linux.vnet.ibm.com>
---
 hw/ppc/spapr.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 0636642..54a8af6 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1266,6 +1266,36 @@ static bool version_before_3(void *opaque, int version_id)
     return version_id < 3;
 }
 
+static bool spapr_ccs_list_needed(void *opaque)
+{
+    sPAPRMachineState *spapr = (sPAPRMachineState *)opaque;
+    return !QTAILQ_EMPTY(&spapr->ccs_list);
+}
+
+static const VMStateDescription vmstate_spapr_ccs = {
+    .name = "spaprconfigureconnectorstate",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(drc_index, sPAPRConfigureConnectorState),
+        VMSTATE_INT32(fdt_offset, sPAPRConfigureConnectorState),
+        VMSTATE_INT32(fdt_depth, sPAPRConfigureConnectorState),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+static const VMStateDescription vmstate_spapr_ccs_list = {
+    .name = "spaprccslist",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = spapr_ccs_list_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_QTAILQ_V(ccs_list, sPAPRMachineState, 1,
+                         vmstate_spapr_ccs, sPAPRConfigureConnectorState, next),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
 static const VMStateDescription vmstate_spapr = {
     .name = "spapr",
     .version_id = 3,
@@ -1281,6 +1311,10 @@ static const VMStateDescription vmstate_spapr = {
         VMSTATE_PPC_TIMEBASE_V(tb, sPAPRMachineState, 2),
         VMSTATE_END_OF_LIST()
     },
+    .subsections = (const VMStateDescription*[]) {
+        &vmstate_spapr_ccs_list,
+        NULL
+    }
 };
 
 static int htab_save_setup(QEMUFile *f, void *opaque)
-- 
1.9.1