diff options
| -rw-r--r-- | migration/ram.c | 51 |
1 files changed, 45 insertions, 6 deletions
diff --git a/migration/ram.c b/migration/ram.c index 4053ca1..c703176 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -237,7 +237,14 @@ typedef struct PageSearchStatus PageSearchStatus; static struct BitmapRcu { struct rcu_head rcu; + /* Main migration bitmap */ unsigned long *bmap; + /* bitmap of pages that haven't been sent even once + * only maintained and used in postcopy at the moment + * where it's used to send the dirtymap at the start + * of the postcopy phase + */ + unsigned long *unsentmap; } *migration_bitmap_rcu; struct CompressParam { @@ -531,10 +538,18 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data, return 1; } -/* Called with rcu_read_lock() to protect migration_bitmap */ +/* Called with rcu_read_lock() to protect migration_bitmap + * rb: The RAMBlock to search for dirty pages in + * start: Start address (typically so we can continue from previous page) + * ram_addr_abs: Pointer into which to store the address of the dirty page + * within the global ram_addr space + * + * Returns: byte offset within memory region of the start of a dirty page + */ static inline ram_addr_t migration_bitmap_find_and_reset_dirty(RAMBlock *rb, - ram_addr_t start) + ram_addr_t start, + ram_addr_t *ram_addr_abs) { unsigned long base = rb->offset >> TARGET_PAGE_BITS; unsigned long nr = base + (start >> TARGET_PAGE_BITS); @@ -555,6 +570,7 @@ ram_addr_t migration_bitmap_find_and_reset_dirty(RAMBlock *rb, clear_bit(next, bitmap); migration_dirty_pages--; } + *ram_addr_abs = next << TARGET_PAGE_BITS; return (next - base) << TARGET_PAGE_BITS; } @@ -953,10 +969,11 @@ static int ram_save_compressed_page(QEMUFile *f, RAMBlock *block, * @*again: Set to false if the search has scanned the whole of RAM */ static bool find_dirty_block(QEMUFile *f, PageSearchStatus *pss, - bool *again) + bool *again, ram_addr_t *ram_addr_abs) { pss->offset = migration_bitmap_find_and_reset_dirty(pss->block, - pss->offset); + pss->offset, + ram_addr_abs); if (pss->complete_round && pss->block == last_seen_block && pss->offset >= last_offset) { /* @@ -1014,6 +1031,8 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage, PageSearchStatus pss; int pages = 0; bool again, found; + ram_addr_t dirty_ram_abs; /* Address of the start of the dirty page in + ram_addr_t space */ pss.block = last_seen_block; pss.offset = last_offset; @@ -1024,7 +1043,7 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage, } do { - found = find_dirty_block(f, &pss, &again); + found = find_dirty_block(f, &pss, &again, &dirty_ram_abs); if (found) { if (compression_switch && migrate_use_compression()) { @@ -1038,7 +1057,14 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage, /* if page is unmodified, continue to the next */ if (pages > 0) { + unsigned long *unsentmap; + + unsentmap = atomic_rcu_read(&migration_bitmap_rcu)->unsentmap; last_sent_block = pss.block; + if (unsentmap) { + clear_bit(dirty_ram_abs >> TARGET_PAGE_BITS, unsentmap); + } + } } } while (!pages && again); @@ -1097,6 +1123,7 @@ void free_xbzrle_decoded_buf(void) static void migration_bitmap_free(struct BitmapRcu *bmap) { g_free(bmap->bmap); + g_free(bmap->unsentmap); g_free(bmap); } @@ -1153,6 +1180,13 @@ void migration_bitmap_extend(ram_addr_t old, ram_addr_t new) qemu_mutex_lock(&migration_bitmap_mutex); bitmap_copy(bitmap->bmap, old_bitmap->bmap, old); bitmap_set(bitmap->bmap, old, new - old); + + /* We don't have a way to safely extend the sentmap + * with RCU; so mark it as missing, entry to postcopy + * will fail. + */ + bitmap->unsentmap = NULL; + atomic_rcu_set(&migration_bitmap_rcu, bitmap); qemu_mutex_unlock(&migration_bitmap_mutex); migration_dirty_pages += new - old; @@ -1253,10 +1287,15 @@ static int ram_save_setup(QEMUFile *f, void *opaque) reset_ram_globals(); ram_bitmap_pages = last_ram_offset() >> TARGET_PAGE_BITS; - migration_bitmap_rcu = g_new(struct BitmapRcu, 1); + migration_bitmap_rcu = g_new0(struct BitmapRcu, 1); migration_bitmap_rcu->bmap = bitmap_new(ram_bitmap_pages); bitmap_set(migration_bitmap_rcu->bmap, 0, ram_bitmap_pages); + if (migrate_postcopy_ram()) { + migration_bitmap_rcu->unsentmap = bitmap_new(ram_bitmap_pages); + bitmap_set(migration_bitmap_rcu->unsentmap, 0, ram_bitmap_pages); + } + /* * Count the total number of pages used by ram blocks not including any * gaps due to alignment or unplugs. |