[Qemu-devel] [PATCH v3 21/32] migration: setup ramstate for resume

[Peter Xu <peterx@redhat.com>]

After we updated the dirty bitmaps of ramblocks, we also need to update
the critical fields in RAMState to make sure it is ready for a resume.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/ram.c        | 37 ++++++++++++++++++++++++++++++++++++-
 migration/trace-events |  1 +
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/migration/ram.c b/migration/ram.c
index a7431a802e..79c52631b9 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2185,6 +2185,33 @@ static int ram_state_init(RAMState **rsp)
     return 0;
 }
 
+static void ram_state_resume_prepare(RAMState *rs)
+{
+    RAMBlock *block;
+    long pages = 0;
+
+    /*
+     * Postcopy is not using xbzrle/compression, so no need for that.
+     * Also, since source are already halted, we don't need to care
+     * about dirty page logging as well.
+     */
+
+    RAMBLOCK_FOREACH(block) {
+        pages += bitmap_count_one(block->bmap,
+                                  block->used_length >> TARGET_PAGE_BITS);
+    }
+
+    /* This may not be aligned with current bitmaps. Recalculate. */
+    rs->migration_dirty_pages = pages;
+
+    rs->last_seen_block = NULL;
+    rs->last_sent_block = NULL;
+    rs->last_page = 0;
+    rs->last_version = ram_list.version;
+
+    trace_ram_state_resume_prepare(pages);
+}
+
 /*
  * Each of ram_save_setup, ram_save_iterate and ram_save_complete has
  * long-running RCU critical section.  When rcu-reclaims in the code
@@ -3106,8 +3133,16 @@ out:
 static int ram_resume_prepare(MigrationState *s, void *opaque)
 {
     RAMState *rs = *(RAMState **)opaque;
+    int ret;
 
-    return ram_dirty_bitmap_sync_all(s, rs);
+    ret = ram_dirty_bitmap_sync_all(s, rs);
+    if (ret) {
+        return ret;
+    }
+
+    ram_state_resume_prepare(rs);
+
+    return 0;
 }
 
 static SaveVMHandlers savevm_ram_handlers = {
diff --git a/migration/trace-events b/migration/trace-events
index 804f18d492..98c2e4de58 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -88,6 +88,7 @@ ram_dirty_bitmap_reload_complete(char *str) "%s"
 ram_dirty_bitmap_sync_start(void) ""
 ram_dirty_bitmap_sync_wait(void) ""
 ram_dirty_bitmap_sync_complete(void) ""
+ram_state_resume_prepare(long v) "%ld"
 
 # migration/migration.c
 await_return_path_close_on_source_close(void) ""
-- 
2.13.5