Re: [Qemu-devel] [PATCH v2 1/6] s390x/vfio: ap: Finding the AP bridge

[Pierre Morel <pmorel@linux.ibm.com>]

On 29/11/2018 21:30, Tony Krowiak wrote:
> On 11/22/18 11:35 AM, Pierre Morel wrote:
>> In the case we will enter QEMU through interception of instructions,
>> we will need to retrieve the AP devices.
>> The base device is the AP bridge.
>>
>> Let us implement a way to retrieve the AP Bridge from qtree.
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>>   hw/s390x/ap-bridge.c         | 12 ++++++++++++
>>   include/hw/s390x/ap-bridge.h |  1 +
>>   2 files changed, 13 insertions(+)
>>
>> diff --git a/hw/s390x/ap-bridge.c b/hw/s390x/ap-bridge.c
>> index 3795d30..831ad5d 100644
>> --- a/hw/s390x/ap-bridge.c
>> +++ b/hw/s390x/ap-bridge.c
>> @@ -14,6 +14,18 @@
>>   #include "hw/s390x/ap-bridge.h"
>>   #include "cpu.h"
>> +DeviceState *s390_get_ap_bridge(void)
>> +{
>> +    static DeviceState *apb;
> 
> Since you are caching a reference to the bridge after
> retrieving it, why not make apb a global scope variable
> and initialize it in s390_init_ap() when the bridge is
> created. You can then declare it as an extern in the
> ap-bridge.h header file and you eliminate the need for
> this function. If you do make it a global var, I would
> name it ap_bridge;

We already had this discussion when implementing zPCI.
I use a similar solution as it was decided at that time.


Regards,
Pierre


-- 
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany