[Qemu-devel] [PATCH v2 18/43] Allow savevm handlers to state whether they could go into postcopy

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

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

Use that to split the qemu_savevm_state_pending counts into postcopiable
and non-postcopiable amounts

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 arch_init.c                 |  7 +++++++
 include/migration/vmstate.h |  2 +-
 include/sysemu/sysemu.h     |  4 +++-
 migration.c                 |  9 ++++++++-
 savevm.c                    | 23 +++++++++++++++++++----
 5 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index a3c468e..aeeaf37 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -1190,6 +1190,12 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
     return ret;
 }
 
+/* RAM's always up for postcopying */
+static bool ram_can_postcopy(void *opaque)
+{
+    return true;
+}
+
 static SaveVMHandlers savevm_ram_handlers = {
     .save_live_setup = ram_save_setup,
     .save_live_iterate = ram_save_iterate,
@@ -1197,6 +1203,7 @@ static SaveVMHandlers savevm_ram_handlers = {
     .save_live_pending = ram_save_pending,
     .load_state = ram_load,
     .cancel = ram_migration_cancel,
+    .can_postcopy = ram_can_postcopy,
 };
 
 void ram_mig_init(void)
diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 9a001bd..4991935 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -54,7 +54,7 @@ typedef struct SaveVMHandlers {
     /* This runs outside the iothread lock!  */
     int (*save_live_setup)(QEMUFile *f, void *opaque);
     uint64_t (*save_live_pending)(QEMUFile *f, void *opaque, uint64_t max_size);
-
+    bool (*can_postcopy)(void *opaque);
     LoadStateHandler *load_state;
 } SaveVMHandlers;
 
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index abf0d63..dc53580 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -109,7 +109,9 @@ void qemu_savevm_state_begin(QEMUFile *f,
 int qemu_savevm_state_iterate(QEMUFile *f);
 void qemu_savevm_state_complete(QEMUFile *f);
 void qemu_savevm_state_cancel(void);
-uint64_t qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size);
+void qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size,
+                               uint64_t *res_non_postcopiable,
+                               uint64_t *res_postcopiable);
 void qemu_savevm_command_send(QEMUFile *f, enum qemu_vm_cmd command,
                               uint16_t len, uint8_t *data);
 void qemu_savevm_send_reqack(QEMUFile *f, uint32_t value);
diff --git a/migration.c b/migration.c
index 500de77..ee923e2 100644
--- a/migration.c
+++ b/migration.c
@@ -831,8 +831,15 @@ static void *migration_thread(void *opaque)
         uint64_t pending_size;
 
         if (!qemu_file_rate_limit(s->file)) {
-            pending_size = qemu_savevm_state_pending(s->file, max_size);
+            uint64_t pend_post, pend_nonpost;
+            DPRINTF("iterate\n");
+            qemu_savevm_state_pending(s->file, max_size, &pend_nonpost,
+                                      &pend_post);
+            pending_size = pend_nonpost + pend_post;
             trace_migrate_pending(pending_size, max_size);
+            DPRINTF("pending size %" PRIu64 " max %" PRIu64 " (post=%" PRIu64
+                    " nonpost=%" PRIu64 ")\n",
+                    pending_size, max_size, pend_post, pend_nonpost);
             if (pending_size && pending_size >= max_size) {
                 qemu_savevm_state_iterate(s->file);
             } else {
diff --git a/savevm.c b/savevm.c
index 809bd04..412bf9d 100644
--- a/savevm.c
+++ b/savevm.c
@@ -903,10 +903,18 @@ void qemu_savevm_state_complete(QEMUFile *f)
     qemu_fflush(f);
 }
 
-uint64_t qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size)
+/* Give an estimate of the amount left to be transferred,
+ * the result is split into the amount for units that can and
+ * for units that can't do postcopy.
+ */
+void qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size,
+                               uint64_t *res_non_postcopiable,
+                               uint64_t *res_postcopiable)
 {
     SaveStateEntry *se;
-    uint64_t ret = 0;
+    uint64_t res_nonpc = 0;
+    uint64_t res_pc = 0;
+    uint64_t tmp;
 
     QTAILQ_FOREACH(se, &savevm_handlers, entry) {
         if (!se->ops || !se->ops->save_live_pending) {
@@ -917,9 +925,16 @@ uint64_t qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size)
                 continue;
             }
         }
-        ret += se->ops->save_live_pending(f, se->opaque, max_size);
+        tmp = se->ops->save_live_pending(f, se->opaque, max_size);
+
+        if (se->ops->can_postcopy(se->opaque)) {
+            res_pc += tmp;
+        } else {
+            res_nonpc += tmp;
+        }
     }
-    return ret;
+    *res_non_postcopiable = res_nonpc;
+    *res_postcopiable = res_pc;
 }
 
 void qemu_savevm_state_cancel(void)
-- 
1.9.3