Re: [PATCH v2 1/1] s390/ipl: sync back loadparm

[David Hildenbrand <david@redhat.com>]

On 09.03.20 15:27, Halil Pasic wrote:
> On Mon, 9 Mar 2020 14:44:20 +0100
> David Hildenbrand <david@redhat.com> wrote:
> 
>> On 09.03.20 14:32, Halil Pasic wrote:
>>> We expose loadparm as a r/w machine property, but if loadparm is set by
>>> the guest via DIAG 308, we don't update the property. Having a
>>> disconnect between the guest view and the QEMU property is not nice in
>>> itself, but things get even worse for SCSI, where under certain
>>> circumstances (see 789b5a401b "s390: Ensure IPL from SCSI works as
>>> expected" for details) we call s390_gen_initial_iplb() on resets
>>> effectively overwriting the guest/user supplied loadparm with the stale
>>> value.
>>>
>>> Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
>>> Fixes: 7104bae9de ("hw/s390x: provide loadparm property for the machine")
>>> Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
>>> Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
>>> Reviewed-by: Viktor Mihajlovski <mihajlov@linux.ibm.com>
>>> Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com>
>>> ---
>>> v1 --> v2:
>>> * tweaked the Fixes tag (Connie)
>>> * s/mo/machine/ (David)
>>> * We decided to not abort if the setter fails. It is not clear where
>>>   do the validation logic come from in the first place. For now lets put
>>>   out a warning if things go wrong.
>>>   The warning we get looks something like:
>>>   qemu-system-s390x: warning: LOADPARM: invalid character '?' (ASCII 0x3f)
>>> * I keept the r-b's and the tested-by as the changes are minor. Please
>>>   shout at me if you object.
>>> ---
>>>  hw/s390x/ipl.c | 25 +++++++++++++++++++++++++
>>>  1 file changed, 25 insertions(+)
>>>
>>> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
>>> index 9c1ecd423c..8bd50de44c 100644
>>> --- a/hw/s390x/ipl.c
>>> +++ b/hw/s390x/ipl.c
>>> @@ -538,6 +538,30 @@ static bool is_virtio_scsi_device(IplParameterBlock *iplb)
>>>      return is_virtio_ccw_device_of_type(iplb, VIRTIO_ID_SCSI);
>>>  }
>>>  
>>> +static void update_machine_ipl_properties(IplParameterBlock *iplb)
>>> +{
>>> +    Object *machine = qdev_get_machine();
>>> +    Error *err = NULL;
>>> +
>>> +    /* Sync loadparm */
>>> +    if (iplb->flags & DIAG308_FLAGS_LP_VALID) {
>>> +        char ascii_loadparm[8];
>>> +        int i;
>>> +        uint8_t *ebcdic_loadparm = iplb->loadparm;
>>
>> Nit: move this to the top
> 
> Do you mean (reverse xmass tree)

Yep :)


-- 
Thanks,

David / dhildenb