Re: [PATCH v2 8/9] qemu-kvm: Refresh MSI settings after vmload

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On 2011-04-27 17:09, Michael S. Tsirkin wrote:
> On Wed, Apr 27, 2011 at 04:39:53PM +0200, Jan Kiszka wrote:
>> On 2011-04-27 16:30, Michael S. Tsirkin wrote:
>>>>>> --- a/hw/pci.c
>>>>>> +++ b/hw/pci.c
>>>>>> @@ -34,6 +34,7 @@
>>>>>>  #include "device-assignment.h"
>>>>>>  #include "qemu-objects.h"
>>>>>>  #include "range.h"
>>>>>> +#include "msi.h"
>>>>>>  
>>>>>>  //#define DEBUG_PCI
>>>>>>  #ifdef DEBUG_PCI
>>>>>> @@ -342,6 +343,7 @@ static int get_pci_config_device(QEMUFile *f, void *pv, size_t size)
>>>>>>      memcpy(s->config, config, size);
>>>>>>  
>>>>>>      pci_update_mappings(s);
>>>>>> +    msi_post_load(s);
>>>>>
>>>>> Pls don't do this: I'm trying to keep just the core in
>>>>> pci.c and all capabilities in separate files.
>>>>> msix has msix_load, msi will just need one too,
>>>>> and let all devices call that.
>>>>>
>>>>
>>>> Preferred alternatives are...? Registering a vmstate for msi?
>>>>
>>>> Jan
>>>
>>> Add msi_load and call that from devices that need it.
>>> Like msix_load does now.
>>>
>>
>> msix_load/save are refactoring candidates IMHO. MSI-X has a real need
>> for storing additional state information, so it should register its own
>> subsection.
> 
> That's an implementation detail though, isn't it.
> 
>> I don't want to offload this burden to the devices also for
>> MSI.
>> From the devices' POV, why shouldn't msi_init suffice?
>>
>> Jan
> 
> One can also claim this about config writes:
>     pci_bridge_write_config(d, address, val, len);
>     pcie_cap_flr_write_config(d, address, val, len);
>     pcie_cap_slot_write_config(d, address, val, len);
>     msi_write_config(d, address, val, len);
>     pcie_aer_write_config(d, address, val, len);
> which arguably just duplicates the initialization sequence.
> 
> What I'm trying to do though is to keep it modular and
> keep module inter-dependencies to a minimum,
> so that pci is the core and msix depends on it
> but not the other way around.

I still don't see the bigger benefit in saving a single bidirectional
dependency at core level vs. saving additional callbacks at each and
every MSI user. The latter is also a source for bugs.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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