Li Zhijian <lizhij...@cn.fujitsu.com> wrote:
> 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 <lizhij...@cn.fujitsu.com>
> Signed-off-by: Wen Congyang <we...@cn.fujitsu.com>
Just curious, how are you testing this?
because you need a way of doing the hot-plug "kind of" atomically on
both source and destination, no?
> ---
> exec.c | 7 ++++++-
> include/exec/exec-all.h | 1 +
> migration/ram.c | 16 ++++++++++++++++
> 3 files changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/exec.c b/exec.c
> index f7883d2..04d5c05 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1401,6 +1401,11 @@ 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.
> @@ -1435,7 +1440,7 @@ static ram_addr_t ram_block_add(RAMBlock *new_block,
> Error **errp)
> ram_list.dirty_memory[i] =
> bitmap_zero_extend(ram_list.dirty_memory[i],
> old_ram_size, new_ram_size);
> - }
> + }
Whitespace noise
> }
> cpu_physical_memory_set_dirty_range(new_block->offset,
> new_block->used_length,
> diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
> index 2573e8c..dd9be44 100644
> --- a/include/exec/exec-all.h
> +++ b/include/exec/exec-all.h
> @@ -385,4 +385,5 @@ static inline bool cpu_can_do_io(CPUState *cpu)
> return cpu->can_do_io != 0;
> }
>
> +void migration_bitmap_extend(ram_addr_t old, ram_addr_t new);
> #endif
> diff --git a/migration/ram.c b/migration/ram.c
> index 4754aa9..70dd8da 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -1063,6 +1063,22 @@ 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)
> +{
> + qemu_mutex_lock(&migration_bitmap_mutex);
> + if (migration_bitmap) {
> + unsigned long *old_bitmap = migration_bitmap, *bitmap;
> + bitmap = bitmap_new(new);
> + bitmap_set(bitmap, old, new - old);
> + memcpy(bitmap, old_bitmap,
> + BITS_TO_LONGS(old) * sizeof(unsigned long));
Shouldn't the last two sentences be reversed? memcpy could "potentially"
overwrote part of the bits setted on bitmap_set. (notice the
potentially part, my guess is that we never get a bitmap that is not
word aligned, but well ....)
My understanding of the rest look right.
Later, Juan.
