[PATCH v4 08/21] migration/colo: Use ram_block_discard_disable()

[David Hildenbrand <david@xxxxxxxxxx>]

COLO will copy all memory in a RAM block, disable discarding of RAM.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx>
Tested-by: Lukas Straub <lukasstraub2@xxxxxx>
Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Cc: Hailiang Zhang <zhang.zhanghailiang@xxxxxxxxxx>
Cc: Juan Quintela <quintela@xxxxxxxxxx>
Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 include/migration/colo.h |  2 +-
 migration/migration.c    |  8 +++++++-
 migration/savevm.c       | 11 +++++++++--
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/include/migration/colo.h b/include/migration/colo.h
index 1636e6f907..768e1f04c3 100644
--- a/include/migration/colo.h
+++ b/include/migration/colo.h
@@ -25,7 +25,7 @@ void migrate_start_colo_process(MigrationState *s);
 bool migration_in_colo_state(void);
 
 /* loadvm */
-void migration_incoming_enable_colo(void);
+int migration_incoming_enable_colo(void);
 void migration_incoming_disable_colo(void);
 bool migration_incoming_colo_enabled(void);
 void *colo_process_incoming_thread(void *opaque);
diff --git a/migration/migration.c b/migration/migration.c
index 14856cc930..0f6799f5d2 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -338,12 +338,18 @@ bool migration_incoming_colo_enabled(void)
 
 void migration_incoming_disable_colo(void)
 {
+    ram_block_discard_disable(false);
     migration_colo_enabled = false;
 }
 
-void migration_incoming_enable_colo(void)
+int migration_incoming_enable_colo(void)
 {
+    if (ram_block_discard_disable(true)) {
+        error_report("COLO: cannot disable RAM discard");
+        return -EBUSY;
+    }
     migration_colo_enabled = true;
+    return 0;
 }
 
 void migrate_add_address(SocketAddress *address)
diff --git a/migration/savevm.c b/migration/savevm.c
index c00a6807d9..19b4f9600d 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2111,8 +2111,15 @@ static int loadvm_handle_recv_bitmap(MigrationIncomingState *mis,
 
 static int loadvm_process_enable_colo(MigrationIncomingState *mis)
 {
-    migration_incoming_enable_colo();
-    return colo_init_ram_cache();
+    int ret = migration_incoming_enable_colo();
+
+    if (!ret) {
+        ret = colo_init_ram_cache();
+        if (ret) {
+            migration_incoming_disable_colo();
+        }
+    }
+    return ret;
 }
 
 /*
-- 
2.26.2