[Qemu-devel] [PATCH v6 28/47] Add qemu_savevm_state_complete_postcopy

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Add qemu_savevm_state_complete_postcopy to complement
qemu_savevm_state_complete_precopy together with a new
save_live_complete_postcopy method on devices.

The save_live_complete_precopy method is called on
all devices during a precopy migration, and all non-postcopy
devices during a postcopy migration at the transition.

The save_live_complete_postcopy method is called at
the end of postcopy for all postcopiable devices.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 arch_init.c                 |  1 +
 include/migration/vmstate.h |  1 +
 include/sysemu/sysemu.h     |  1 +
 savevm.c                    | 50 ++++++++++++++++++++++++++++++++++++++++++---
 4 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 977e98b..0a49ace 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -1275,6 +1275,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
 static SaveVMHandlers savevm_ram_handlers = {
     .save_live_setup = ram_save_setup,
     .save_live_iterate = ram_save_iterate,
+    .save_live_complete_postcopy = ram_save_complete,
     .save_live_complete_precopy = ram_save_complete,
     .save_live_pending = ram_save_pending,
     .load_state = ram_load,
diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 50efb09..06bed0a 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -40,6 +40,7 @@ typedef struct SaveVMHandlers {
     SaveStateHandler *save_state;
 
     void (*cancel)(void *opaque);
+    int (*save_live_complete_postcopy)(QEMUFile *f, void *opaque);
     int (*save_live_complete_precopy)(QEMUFile *f, void *opaque);
 
     /* This runs both outside and inside the iothread lock.  */
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index e45ef62..248f0d6 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -108,6 +108,7 @@ void qemu_savevm_state_begin(QEMUFile *f,
                              const MigrationParams *params);
 void qemu_savevm_state_header(QEMUFile *f);
 int qemu_savevm_state_iterate(QEMUFile *f);
+void qemu_savevm_state_complete_postcopy(QEMUFile *f);
 void qemu_savevm_state_complete_precopy(QEMUFile *f);
 void qemu_savevm_state_cancel(void);
 void qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size,
diff --git a/savevm.c b/savevm.c
index 23cc99e..c2d6241 100644
--- a/savevm.c
+++ b/savevm.c
@@ -866,7 +866,46 @@ int qemu_savevm_state_iterate(QEMUFile *f)
 static bool should_send_vmdesc(void)
 {
     MachineState *machine = MACHINE(qdev_get_machine());
-    return !machine->suppress_vmdesc;
+    bool in_postcopy = migration_postcopy_phase(migrate_get_current());
+    return !machine->suppress_vmdesc && !in_postcopy;
+}
+
+/*
+ * Calls the save_live_complete_postcopy methods
+ * causing the last few pages to be sent immediately and doing any associated
+ * cleanup.
+ * Note postcopy also calls qemu_savevm_state_complete_precopy to complete
+ * all the other devices, but that happens at the point we switch to postcopy.
+ */
+void qemu_savevm_state_complete_postcopy(QEMUFile *f)
+{
+    SaveStateEntry *se;
+    int ret;
+
+    QTAILQ_FOREACH(se, &savevm_handlers, entry) {
+        if (!se->ops || !se->ops->save_live_complete_postcopy) {
+            continue;
+        }
+        if (se->ops && se->ops->is_active) {
+            if (!se->ops->is_active(se->opaque)) {
+                continue;
+            }
+        }
+        trace_savevm_section_start(se->idstr, se->section_id);
+        /* Section type */
+        qemu_put_byte(f, QEMU_VM_SECTION_END);
+        qemu_put_be32(f, se->section_id);
+
+        ret = se->ops->save_live_complete_postcopy(f, se->opaque);
+        trace_savevm_section_end(se->idstr, se->section_id, ret);
+        if (ret < 0) {
+            qemu_file_set_error(f, ret);
+            return;
+        }
+    }
+
+    qemu_put_byte(f, QEMU_VM_EOF);
+    qemu_fflush(f);
 }
 
 void qemu_savevm_state_complete_precopy(QEMUFile *f)
@@ -875,13 +914,15 @@ void qemu_savevm_state_complete_precopy(QEMUFile *f)
     int vmdesc_len;
     SaveStateEntry *se;
     int ret;
+    bool in_postcopy = migration_postcopy_phase(migrate_get_current());
 
     trace_savevm_state_complete_precopy();
 
     cpu_synchronize_all_states();
 
     QTAILQ_FOREACH(se, &savevm_handlers, entry) {
-        if (!se->ops || !se->ops->save_live_complete_precopy) {
+        if (!se->ops || !se->ops->save_live_complete_precopy ||
+            (in_postcopy && se->ops->save_live_complete_postcopy)) {
             continue;
         }
         if (se->ops && se->ops->is_active) {
@@ -935,7 +976,10 @@ void qemu_savevm_state_complete_precopy(QEMUFile *f)
         trace_savevm_section_end(se->idstr, se->section_id, 0);
     }
 
-    qemu_put_byte(f, QEMU_VM_EOF);
+    if (!in_postcopy) {
+        /* Postcopy stream will still be going */
+        qemu_put_byte(f, QEMU_VM_EOF);
+    }
 
     json_end_array(vmdesc);
     qjson_finish(vmdesc);
-- 
2.1.0