Commit dd631697 authored by Li Zhijian's avatar Li Zhijian Committed by Juan Quintela
Browse files

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: default avatarLi Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: default avatarWen Congyang <wency@cn.fujitsu.com>
Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent 2ff64038

exec.c

+5 −0
Original line number Diff line number Diff line
@@ -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.

include/exec/exec-all.h

+3 −0
Original line number Diff line number Diff line
@@ -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

migration/ram.c

+28 −0
Original line number Diff line number Diff line
@@ -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();