memory: Add Error** argument to the global_dirty_log routines

Now that the log_global*() handlers take an Error** parameter and
return a bool, do the same for memory_global_dirty_log_start() and
memory_global_dirty_log_stop(). The error is reported in the callers
for now and it will be propagated in the call stack in the next
changes.

To be noted a functional change in ram_init_bitmaps(), if the dirty
pages logger fails to start, there is no need to synchronize the dirty
pages bitmaps. colo_incoming_start_dirty_log() could be modified in a
similar way.

Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Paul Durrant <paul@xen.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hyman Huang <yong.huang@smartx.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Acked-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20240320064911.545001-12-clg@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

2 files changed, 32 insertions, 4 deletions

diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
index 1d2e85746f..d02d70b7b4 100644
--- a/migration/dirtyrate.c
+++ b/migration/dirtyrate.c
@@ -90,9 +90,15 @@ static int64_t do_calculate_dirtyrate(DirtyPageRecord dirty_pages,
 
 void global_dirty_log_change(unsigned int flag, bool start)
 {
+    Error *local_err = NULL;
+    bool ret;
+
     bql_lock();
     if (start) {
-        memory_global_dirty_log_start(flag);
+        ret = memory_global_dirty_log_start(flag, &local_err);
+        if (!ret) {
+            error_report_err(local_err);
+        }
     } else {
         memory_global_dirty_log_stop(flag);
     }
@@ -608,9 +614,12 @@ static void calculate_dirtyrate_dirty_bitmap(struct DirtyRateConfig config)
 {
     int64_t start_time;
     DirtyPageRecord dirty_pages;
+    Error *local_err = NULL;
 
     bql_lock();
-    memory_global_dirty_log_start(GLOBAL_DIRTY_DIRTY_RATE);
+    if (!memory_global_dirty_log_start(GLOBAL_DIRTY_DIRTY_RATE, &local_err)) {
+        error_report_err(local_err);
+    }
 
     /*
      * 1'round of log sync may return all 1 bits with
diff --git a/migration/ram.c b/migration/ram.c
index f0bd71438a..bade3e9281 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2862,18 +2862,32 @@ static void migration_bitmap_clear_discarded_pages(RAMState *rs)
 
 static void ram_init_bitmaps(RAMState *rs)
 {
+    Error *local_err = NULL;
+    bool ret = true;
+
     qemu_mutex_lock_ramlist();
 
     WITH_RCU_READ_LOCK_GUARD() {
         ram_list_init_bitmaps();
         /* We don't use dirty log with background snapshots */
         if (!migrate_background_snapshot()) {
-            memory_global_dirty_log_start(GLOBAL_DIRTY_MIGRATION);
+            ret = memory_global_dirty_log_start(GLOBAL_DIRTY_MIGRATION,
+                                                &local_err);
+            if (!ret) {
+                error_report_err(local_err);
+                goto out_unlock;
+            }
             migration_bitmap_sync_precopy(rs, false);
         }
     }
+out_unlock:
     qemu_mutex_unlock_ramlist();
 
+    if (!ret) {
+        ram_bitmaps_destroy();
+        return;
+    }
+
     /*
      * After an eventual first bitmap sync, fixup the initial bitmap
      * containing all 1s to exclude any discarded pages from migration.
@@ -3665,6 +3679,8 @@ int colo_init_ram_cache(void)
 void colo_incoming_start_dirty_log(void)
 {
     RAMBlock *block = NULL;
+    Error *local_err = NULL;
+
     /* For memory_global_dirty_log_start below. */
     bql_lock();
     qemu_mutex_lock_ramlist();
@@ -3676,7 +3692,10 @@ void colo_incoming_start_dirty_log(void)
             /* Discard this dirty bitmap record */
             bitmap_zero(block->bmap, block->max_length >> TARGET_PAGE_BITS);
         }
-        memory_global_dirty_log_start(GLOBAL_DIRTY_MIGRATION);
+        if (!memory_global_dirty_log_start(GLOBAL_DIRTY_MIGRATION,
+                                           &local_err)) {
+            error_report_err(local_err);
+        }
     }
     ram_state->migration_dirty_pages = 0;
     qemu_mutex_unlock_ramlist();