On 05/08/2017 06:45 PM, Dr. David Alan Gilbert wrote:
> * Halil Pasic (pa...@linux.vnet.ibm.com) wrote:
>> As a preparation for switching to a vmstate based migration let us
>> introduce vmstate entities (e.g. VMStateDescription) for the css entities
>> to be migrated. Alongside some comments explaining or indicating the not
>> migration of certain members are introduced too.
>>
>> No changes in behavior, we just added some dead code -- which should
>> rise to life soon.
>>
>> Signed-off-by: Halil Pasic <pa...@linux.vnet.ibm.com>
>> ---
>> hw/s390x/css.c | 276
>> +++++++++++++++++++++++++++++++++++++++++++++++++
>> include/hw/s390x/css.h | 10 +-
>> 2 files changed, 285 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/s390x/css.c b/hw/s390x/css.c
>> index c03bb20..2bda7d0 100644
>> --- a/hw/s390x/css.c
>> +++ b/hw/s390x/css.c
>> @@ -20,29 +20,231 @@
>> #include "hw/s390x/css.h"
>> #include "trace.h"
>> #include "hw/s390x/s390_flic.h"
>> +#include "hw/s390x/s390-virtio-ccw.h"
>>
[..]
>> +static int css_get_ind_addr(QEMUFile *f, void *pv, size_t size,
>> + VMStateField *field)
>> +{
>> + int32_t len;
>> + IndAddr **ind_addr = pv;
>> +
>> + len = qemu_get_be32(f);
>> + if (len != 0) {
>> + *ind_addr = get_indicator(qemu_get_be64(f), len);
>> + } else {
>> + qemu_get_be64(f);
>> + *ind_addr = NULL;
>> + }
>> + return 0;
>> +}
>> +
>> +static int css_put_ind_addr(QEMUFile *f, void *pv, size_t size,
>> + VMStateField *field, QJSON *vmdesc)
>> +{
>> + IndAddr *ind_addr = *(IndAddr **) pv;
>> +
>> + if (ind_addr != NULL) {
>> + qemu_put_be32(f, ind_addr->len);
>> + qemu_put_be64(f, ind_addr->addr);
>> + } else {
>> + qemu_put_be32(f, 0);
>> + qemu_put_be64(f, 0UL);
>> + }
>> + return 0;
>> +}
>> +
>> +const VMStateInfo vmstate_info_ind_addr = {
>> + .name = "s390_ind_addr",
>> + .get = css_get_ind_addr,
>> + .put = css_put_ind_addr
>> +};
>
> You should be able to avoid this .get/.put by using VMSTATE_WITH_TMP,
> declare a temporary struct something like:
> struct tmp_ind_addr {
> IndAddr *parent;
> uint32_t len;
> uint64_t addr;
> }
>
> and then your .get/.put routines turn into pre_save/post_load
> routines to just setup the len/addr.
>
I don't think this is going to work -- unfortunately! You can see below,
how this IndAddr* migration stuff is supposed to be used:
the client code just uses the VMSTATE_PTR_TO_IND_ADDR macro as a
field when describing state which needs and IndAddr* migrated.
The problem is, we do not know in what state will this field
be embedded, the pre_save/post_load called by put_tmp/get_tmp
is however copying the pointer to this state into the parent.
So instead of having a pointer to IndAddr* in those functions
and updating it accordingly, I would have to find the IndAddr*
in some arbitrary state (in our case VirtioCcwDevice) first,
and I lack information for that.
If it's hard to follow I can give you the patch I was debugging
to come to this conclusion. (By the way I ended up with 10
lines of code more than in this version, and although I think
it looks nicer, it's simpler only if one knows how WITH_TMP
works. My plan was to ask you which version do you like more
and go with that before I realized it ain't gonna work.)
>> diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
>> index f1f0d7f..6a451b2 100644
>> --- a/include/hw/s390x/css.h
[..]
>>
>> +extern const VMStateInfo vmstate_info_ind_addr;
>> +
>> +#define VMSTATE_PTR_TO_IND_ADDR(_f, _s) \
>> + VMSTATE_SINGLE(_f, _s, 1 , vmstate_info_ind_addr, IndAddr*)
>> +
>> IndAddr *get_indicator(hwaddr ind_addr, int len);
>> void release_indicator(AdapterInfo *adapter, IndAddr *indicator);
>> int map_indicator(AdapterInfo *adapter, IndAddr *indicator);
>> --
>> 2.10.2
>>
> --
> Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
>
Cheers,
Halil
