Re: [Qemu-devel] [PATCH] kvm: fix kvm_set_migration_log() behavior

[Paolo Bonzini]

Il 18/02/2014 13:33, Vincent KHERBACHE ha scritto:
> diff --git a/kvm-all.c b/kvm-all.c
> index 2ca9143..f104f87 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -355,7 +355,7 @@ static int kvm_set_migration_log(int enable)
>  {
>      KVMState *s = kvm_state;
>      KVMSlot *mem;
> -    int i, err;
> +    int i, err = 0;
>
>      s->migration_log = enable;
>
> @@ -365,15 +365,9 @@ static int kvm_set_migration_log(int enable)
>          if (!mem->memory_size) {
>              continue;
>          }
> -        if (!!(mem->flags & KVM_MEM_LOG_DIRTY_PAGES) == enable) {
> -            continue;
> -        }
> -        err = kvm_set_user_memory_region(s, mem);
> -        if (err) {
> -            return err;
> -        }
> +        err = kvm_slot_dirty_pages_log_change(mem, (bool)enable);
>      }
> -    return 0;
> +    return err;
>  }

This patch is not correct, because it introduces another one: if dirty 
logging was enabled on the memory region (kvm_dirty_pages_log_change), 
it will be disabled after migration.

Can you explain better the problem?  I cannot see anything wrong in the 
code, though it is not the clearest.  Note that the effects of 
kvm_set_migration_log and kvm_dirty_pages_log_change should be logically 
ORed.

Paolo