Re: [Qemu-devel] [PATCH v1 0/5][RFC] Refactoring of AIS support

[Christian Borntraeger]

On 11/06/2017 09:52 AM, Cornelia Huck wrote:
> On Mon, 30 Oct 2017 19:58:15 +0100
> Halil Pasic <address@hidden> wrote:
> 
>> On 10/30/2017 06:38 PM, Pierre Morel wrote:
>>> On 30/10/2017 18:08, Christian Borntraeger wrote:  
>>>>
>>>> On 10/30/2017 05:59 PM, Cornelia Huck wrote:  
>>>>> On Mon, 30 Oct 2017 14:48:23 +0100
>>>>> Christian Borntraeger <address@hidden> wrote:
>>>>>
>>>>>  
>>>>>> FWIW, I am testing a guest patch that enables zPCI without AIS. Its as 
>>>>>> simple as
>>>>>>
>>>>>>
>>>>>> diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
>>>>>> index 7b30af5..9b24836 100644
>>>>>> --- a/arch/s390/pci/pci.c
>>>>>> +++ b/arch/s390/pci/pci.c
>>>>>> @@ -953,7 +953,7 @@ static int __init pci_base_init(void)
>>>>>>          if (!s390_pci_probe)
>>>>>>                  return 0;
>>>>>>   -       if (!test_facility(69) || !test_facility(71) || 
>>>>>> !test_facility(72))
>>>>>> +       if (!test_facility(69) || !test_facility(71))
>>>>>>                  return 0;
>>>>>>            rc = zpci_debug_init();
>>>>>> diff --git a/arch/s390/pci/pci_insn.c b/arch/s390/pci/pci_insn.c
>>>>>> index ea34086..61f8c82 100644
>>>>>> --- a/arch/s390/pci/pci_insn.c
>>>>>> +++ b/arch/s390/pci/pci_insn.c
>>>>>> @@ -7,6 +7,7 @@
>>>>>>   #include <linux/export.h>
>>>>>>   #include <linux/errno.h>
>>>>>>   #include <linux/delay.h>
>>>>>> +#include <asm/facility.h>
>>>>>>   #include <asm/pci_insn.h>
>>>>>>   #include <asm/pci_debug.h>
>>>>>>   #include <asm/processor.h>
>>>>>> @@ -93,6 +94,8 @@ int zpci_refresh_trans(u64 fn, u64 addr, u64 range)
>>>>>>   /* Set Interruption Controls */
>>>>>>   void zpci_set_irq_ctrl(u16 ctl, char *unused, u8 isc)
>>>>>>   {
>>>>>> +       if (!test_facility(72))
>>>>>> +               return;
>>>>>>          asm volatile (
>>>>>>                  "       .insn   rsy,0xeb00000000d1,%[ctl],%[isc],%[u]\n"
>>>>>>                  : : [ctl] "d" (ctl), [isc] "d" (isc << 27), [u] "Q" 
>>>>>> (*unused));
>>>>>>  
>>>>>
>>>>> Sounds good. Presumably this makes the adapter interrupt handling work
>>>>> as for virtio (and qdio)? Is there any ais-less pci hardware out in the
>>>>> wild?  
>>
>> @Connie:
>> Do you have something in mind, or is curiosity the only reason for asking?
> 
> I just want to make sure we don't miss anything.
> 
>>
>>>>>  
>>>>
>>>> ais is z specific, not PCI specific. So PCI cards should not care as far 
>>>> as I can tell.
>>>>
>>>>  
>>>
>>> I bet Conny meant PCI hardware globaly, including zPCI adapters.
>>> I bet none but I will better ask Sebastian or Gerald if they know.
>>>   
>>
>> I side with Christian: it is a machine thing and not a card thing. So
>> the question is if there is a z machine which supports zpci but does
>> not support AIS. My guess is that such a machine was never produced.
> 
> That's exactly what I meant, and I would not expect such a machine to
> exist either.

That machine is called qemu 2.10 :-p



FWIW, I talked with Sebastian about that and he is fine with such a change. He
required some changes and I will work on such a patch.