[Qemu-devel] [PATCH v5 20/45] Modify savevm handlers for postcopy

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

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

Modify save_live_pending to return separate postcopiable and
non-postcopiable counts.

Add 'can_postcopy' to allow a device to state if it can postcopy

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 arch_init.c                 | 15 +++++++++++++--
 include/migration/vmstate.h | 10 ++++++++--
 include/sysemu/sysemu.h     |  4 +++-
 migration/block.c           |  7 +++++--
 migration/migration.c       |  9 +++++++--
 savevm.c                    | 21 +++++++++++++++++----
 trace-events                |  2 +-
 7 files changed, 54 insertions(+), 14 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index fe0df0d..7bc5fa6 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -997,7 +997,9 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
     return 0;
 }
 
-static uint64_t ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size)
+static void ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
+                             uint64_t *non_postcopiable_pending,
+                             uint64_t *postcopiable_pending)
 {
     uint64_t remaining_size;
 
@@ -1009,7 +1011,9 @@ static uint64_t ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size)
         qemu_mutex_unlock_iothread();
         remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE;
     }
-    return remaining_size;
+
+    *non_postcopiable_pending = 0;
+    *postcopiable_pending = remaining_size;
 }
 
 static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host)
@@ -1204,6 +1208,12 @@ 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,
@@ -1211,6 +1221,7 @@ 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 18da207..c9ec74a 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -54,8 +54,14 @@ 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);
-
+    /*
+     * postcopiable_pending must return 0 unless the can_postcopy
+     * handler returns true.
+     */
+    void (*save_live_pending)(QEMUFile *f, void *opaque, uint64_t max_size,
+                              uint64_t *non_postcopiable_pending,
+                              uint64_t *postcopiable_pending);
+    bool (*can_postcopy)(void *opaque);
     LoadStateHandler *load_state;
 } SaveVMHandlers;
 
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index e83bf80..5f518b3 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -111,7 +111,9 @@ void qemu_savevm_state_header(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_ping(QEMUFile *f, uint32_t value);
diff --git a/migration/block.c b/migration/block.c
index 0c76106..0f6f209 100644
--- a/migration/block.c
+++ b/migration/block.c
@@ -754,7 +754,9 @@ static int block_save_complete(QEMUFile *f, void *opaque)
     return 0;
 }
 
-static uint64_t block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size)
+static void block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
+                               uint64_t *non_postcopiable_pending,
+                               uint64_t *postcopiable_pending)
 {
     /* Estimate pending number of bytes to send */
     uint64_t pending;
@@ -773,7 +775,8 @@ static uint64_t block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size)
     qemu_mutex_unlock_iothread();
 
     DPRINTF("Enter save live pending  %" PRIu64 "\n", pending);
-    return pending;
+    *non_postcopiable_pending = pending;
+    *postcopiable_pending = 0;
 }
 
 static int block_load(QEMUFile *f, void *opaque, int version_id)
diff --git a/migration/migration.c b/migration/migration.c
index 2e6adca..a4fc7d7 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -868,8 +868,13 @@ 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);
-            trace_migrate_pending(pending_size, max_size);
+            uint64_t pend_post, pend_nonpost;
+
+            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,
+                                  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 df48ba8..e301a0a 100644
--- a/savevm.c
+++ b/savevm.c
@@ -944,10 +944,20 @@ 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 tmp_non_postcopiable, tmp_postcopiable;
+
+    *res_non_postcopiable = 0;
+    *res_postcopiable = 0;
+
 
     QTAILQ_FOREACH(se, &savevm_handlers, entry) {
         if (!se->ops || !se->ops->save_live_pending) {
@@ -958,9 +968,12 @@ uint64_t qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size)
                 continue;
             }
         }
-        ret += se->ops->save_live_pending(f, se->opaque, max_size);
+        se->ops->save_live_pending(f, se->opaque, max_size,
+                                   &tmp_non_postcopiable, &tmp_postcopiable);
+
+        *res_postcopiable += tmp_postcopiable;
+        *res_non_postcopiable += tmp_non_postcopiable;
     }
-    return ret;
 }
 
 void qemu_savevm_state_cancel(void)
diff --git a/trace-events b/trace-events
index cbf995c..83312b6 100644
--- a/trace-events
+++ b/trace-events
@@ -1400,7 +1400,7 @@ migrate_fd_cleanup(void) ""
 migrate_fd_cleanup_src_rp(void) ""
 migrate_fd_error(void) ""
 migrate_fd_cancel(void) ""
-migrate_pending(uint64_t size, uint64_t max) "pending size %" PRIu64 " max %" PRIu64
+migrate_pending(uint64_t size, uint64_t max, uint64_t post, uint64_t nonpost) "pending size %" PRIu64 " max %" PRIu64 " (post=%" PRIu64 " nonpost=%" PRIu64 ")"
 migrate_send_rp_message(int cmd, uint16_t len) "cmd=%d, len=%d"
 open_outgoing_return_path(void) ""
 open_outgoing_return_path_continue(void) ""
-- 
2.1.0