From dd63169766abd2b8dc33f4451dac5e778458a47c Mon Sep 17 00:00:00 2001 From: Li Zhijian Date: Thu, 2 Jul 2015 20:18:06 +0800 Subject: [PATCH] migration: extend migration_bitmap Prevously, if we hotplug a device(e.g. device_add e1000) during migration is processing in source side, qemu will add a new ram block but migration_bitmap is not extended. In this case, migration_bitmap will overflow and lead qemu abort unexpectedly. Signed-off-by: Li Zhijian Signed-off-by: Wen Congyang Signed-off-by: Juan Quintela --- exec.c | 5 +++++ include/exec/exec-all.h | 3 +++ migration/ram.c | 28 ++++++++++++++++++++++++++++ 3 files changed, 36 insertions(+) diff --git a/exec.c b/exec.c index 251dc79e10..b7f7f9818f 100644 --- a/exec.c +++ b/exec.c @@ -1414,6 +1414,11 @@ static ram_addr_t ram_block_add(RAMBlock *new_block, Error **errp) } } + new_ram_size = MAX(old_ram_size, + (new_block->offset + new_block->max_length) >> TARGET_PAGE_BITS); + if (new_ram_size > old_ram_size) { + migration_bitmap_extend(old_ram_size, new_ram_size); + } /* Keep the list sorted from biggest to smallest block. Unlike QTAILQ, * QLIST (which has an RCU-friendly variant) does not have insertion at * tail, so save the last element in last_block. diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index d678114cb2..2e74760ade 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -365,4 +365,7 @@ static inline bool cpu_can_do_io(CPUState *cpu) return cpu->can_do_io != 0; } +#if !defined(CONFIG_USER_ONLY) +void migration_bitmap_extend(ram_addr_t old, ram_addr_t new); +#endif #endif diff --git a/migration/ram.c b/migration/ram.c index 9c0bcfefc8..c696814196 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -222,6 +222,7 @@ static RAMBlock *last_seen_block; static RAMBlock *last_sent_block; static ram_addr_t last_offset; static unsigned long *migration_bitmap; +static QemuMutex migration_bitmap_mutex; static uint64_t migration_dirty_pages; static uint32_t last_version; static bool ram_bulk_stage; @@ -569,11 +570,13 @@ static void migration_bitmap_sync(void) trace_migration_bitmap_sync_start(); address_space_sync_dirty_bitmap(&address_space_memory); + qemu_mutex_lock(&migration_bitmap_mutex); rcu_read_lock(); QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { migration_bitmap_sync_range(block->mr->ram_addr, block->used_length); } rcu_read_unlock(); + qemu_mutex_unlock(&migration_bitmap_mutex); trace_migration_bitmap_sync_end(migration_dirty_pages - num_dirty_pages_init); @@ -1062,6 +1065,30 @@ static void reset_ram_globals(void) #define MAX_WAIT 50 /* ms, half buffered_file limit */ +void migration_bitmap_extend(ram_addr_t old, ram_addr_t new) +{ + /* called in qemu main thread, so there is + * no writing race against this migration_bitmap + */ + if (migration_bitmap) { + unsigned long *old_bitmap = migration_bitmap, *bitmap; + bitmap = bitmap_new(new); + + /* prevent migration_bitmap content from being set bit + * by migration_bitmap_sync_range() at the same time. + * it is safe to migration if migration_bitmap is cleared bit + * at the same time. + */ + qemu_mutex_lock(&migration_bitmap_mutex); + bitmap_copy(bitmap, old_bitmap, old); + bitmap_set(bitmap, old, new - old); + atomic_rcu_set(&migration_bitmap, bitmap); + qemu_mutex_unlock(&migration_bitmap_mutex); + migration_dirty_pages += new - old; + synchronize_rcu(); + g_free(old_bitmap); + } +} /* Each of ram_save_setup, ram_save_iterate and ram_save_complete has * long-running RCU critical section. When rcu-reclaims in the code @@ -1078,6 +1105,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque) dirty_rate_high_cnt = 0; bitmap_sync_count = 0; migration_bitmap_sync_init(); + qemu_mutex_init(&migration_bitmap_mutex); if (migrate_use_xbzrle()) { XBZRLE_cache_lock(); -- 2.11.0