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migration: always initial RAMBlock.bmap to 1 for new migration 

Reproduce the problem:
migrate
migrate_cancel
migrate

Error happen for memory migration

The reason as follows:
1. qemu start, ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] all set to
   1 by a series of cpu_physical_memory_set_dirty_range
2. migration start:ram_init_bitmaps
   - memory_global_dirty_log_start: begin log diry
   - memory_global_dirty_log_sync: sync dirty bitmap to
     ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION]
   - migration_bitmap_sync_range: sync ram_list.
     dirty_memory[DIRTY_MEMORY_MIGRATION] to RAMBlock.bmap
     and ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] is set to zero
3. migration data...
4. migrate_cancel, will stop log dirty
5. migration start:ram_init_bitmaps
   - memory_global_dirty_log_start: begin log diry
   - memory_global_dirty_log_sync: sync dirty bitmap to
     ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION]
   - migration_bitmap_sync_range: sync ram_list.
     dirty_memory[DIRTY_MEMORY_MIGRATION] to RAMBlock.bmap
     and ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] is set to zero

   Here RAMBlock.bmap only have new logged dirty pages, don't contain
   the whole guest pages.

Signed-off-by: Ivan Ren <ivanren@tencent.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <1563115879-2715-1-git-send-email-ivanren@tencent.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Ivan Ren 2019-07-14 22:51:19 +08:00 committed by Juan Quintela
parent 40277ca807
commit 40c4d4a835
1 changed files with 8 additions and 7 deletions
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15
migration/ram.c
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@ -3213,11 +3213,11 @@ static int ram_state_init(RAMState **rsp)
QSIMPLEQ_INIT(&(*rsp)->src_page_requests);
/*
* Count the total number of pages used by ram blocks not including any
* gaps due to alignment or unplugs.
* This must match with the initial values of dirty bitmap.
* Currently we initialize the dirty bitmap to all zeros so
* here the total dirty page count is zero.
*/
(*rsp)->migration_dirty_pages = 0;
(*rsp)->migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS;
ram_state_reset(*rsp);
return 0;
@ -3249,12 +3249,13 @@ static void ram_list_init_bitmaps(void)
* The initial dirty bitmap for migration must be set with all
* ones to make sure we'll migrate every guest RAM page to
* destination.
* Here we didn't set RAMBlock.bmap simply because it is already
* set in ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] in
* ram_block_add, and that's where we'll sync the dirty bitmaps.
* Here setting RAMBlock.bmap would be fine too but not necessary.
* Here we set RAMBlock.bmap all to 1 because when rebegin a
* new migration after a failed migration, ram_list.
* dirty_memory[DIRTY_MEMORY_MIGRATION] don't include the whole
* guest memory.
*/
block->bmap = bitmap_new(pages);
bitmap_set(block->bmap, 0, pages);
block->clear_bmap_shift = shift;
block->clear_bmap = bitmap_new(clear_bmap_size(pages, shift));
if (migrate_postcopy_ram()) {