Commit 3a38429 ("spapr: Add a "no HPT" encoding to HTAB migration stream")
allows to migrate an empty HPT, but doesn't mark correctly the
end of the migration stream.

The end condition (value returned by htab_save_iterate() and
 htab_save_complete()) should be 1, whereas in 3a38429 they
return 0.

The problem can be reproduced with QEMU monitor command "savevm":
the command never stops and the disk image grows without limit.

Fixes: 3a38429748aa4f74abaecf16c4c087e8a325e12a
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 hw/ppc/spapr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 970093e..fa01511 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1827,7 +1827,7 @@ static int htab_save_iterate(QEMUFile *f, void *opaque)
     /* Iteration header */
     if (!spapr->htab_shift) {
         qemu_put_be32(f, -1);
-        return 0;
+        return 1;
     } else {
         qemu_put_be32(f, 0);
     }
@@ -1866,7 +1866,7 @@ static int htab_save_complete(QEMUFile *f, void *opaque)
     /* Iteration header */
     if (!spapr->htab_shift) {
         qemu_put_be32(f, -1);
-        return 0;
+        return 1;
     } else {
         qemu_put_be32(f, 0);
     }
-- 
2.9.4

On 18.07.2017 10:05, Laurent Vivier wrote:
> Commit 3a38429 ("spapr: Add a "no HPT" encoding to HTAB migration stream")
> allows to migrate an empty HPT, but doesn't mark correctly the
> end of the migration stream.
> 
> The end condition (value returned by htab_save_iterate() and
>  htab_save_complete()) should be 1, whereas in 3a38429 they
> return 0.
> 
> The problem can be reproduced with QEMU monitor command "savevm":
> the command never stops and the disk image grows without limit.
> 
> Fixes: 3a38429748aa4f74abaecf16c4c087e8a325e12a
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  hw/ppc/spapr.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 970093e..fa01511 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1827,7 +1827,7 @@ static int htab_save_iterate(QEMUFile *f, void *opaque)
>      /* Iteration header */
>      if (!spapr->htab_shift) {
>          qemu_put_be32(f, -1);
> -        return 0;
> +        return 1;
>      } else {
>          qemu_put_be32(f, 0);
>      }
> @@ -1866,7 +1866,7 @@ static int htab_save_complete(QEMUFile *f, void *opaque)
>      /* Iteration header */
>      if (!spapr->htab_shift) {
>          qemu_put_be32(f, -1);
> -        return 0;
> +        return 1;
>      } else {
>          qemu_put_be32(f, 0);
>      }
> 

I think you only need to change htab_save_iterate(), but not
htab_save_complete(), don't you? "1" does not seem to have any real
meaning for the *save_complete functions, as far as I can see.

 Thomas

On 18/07/2017 11:33, Thomas Huth wrote:
> On 18.07.2017 10:05, Laurent Vivier wrote:
>> Commit 3a38429 ("spapr: Add a "no HPT" encoding to HTAB migration stream")
>> allows to migrate an empty HPT, but doesn't mark correctly the
>> end of the migration stream.
>>
>> The end condition (value returned by htab_save_iterate() and
>>  htab_save_complete()) should be 1, whereas in 3a38429 they
>> return 0.
>>
>> The problem can be reproduced with QEMU monitor command "savevm":
>> the command never stops and the disk image grows without limit.
>>
>> Fixes: 3a38429748aa4f74abaecf16c4c087e8a325e12a
>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
>> ---
>>  hw/ppc/spapr.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index 970093e..fa01511 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -1827,7 +1827,7 @@ static int htab_save_iterate(QEMUFile *f, void *opaque)
>>      /* Iteration header */
>>      if (!spapr->htab_shift) {
>>          qemu_put_be32(f, -1);
>> -        return 0;
>> +        return 1;
>>      } else {
>>          qemu_put_be32(f, 0);
>>      }
>> @@ -1866,7 +1866,7 @@ static int htab_save_complete(QEMUFile *f, void *opaque)
>>      /* Iteration header */
>>      if (!spapr->htab_shift) {
>>          qemu_put_be32(f, -1);
>> -        return 0;
>> +        return 1;
>>      } else {
>>          qemu_put_be32(f, 0);
>>      }
>>
> 
> I think you only need to change htab_save_iterate(), but not
> htab_save_complete(), don't you? "1" does not seem to have any real
> meaning for the *save_complete functions, as far as I can see.

Yes, you're right, htab_save_complete() always returns 0 or an error (< 0).

I update the patch.

Thanks,
Laurent