Re: [PATCH v1 13/22] vfio: Add base container

[Eric Auger]

Hi Zhenzhong,
On 9/21/23 05:35, Duan, Zhenzhong wrote:
> Hi Eric,
>
>> -----Original Message-----
>> From: Eric Auger <eric.auger@redhat.com>
>> Sent: Thursday, September 21, 2023 1:31 AM
>> Subject: Re: [PATCH v1 13/22] vfio: Add base container
>>
>> Hi Zhenzhong,
>>
>> On 9/19/23 19:23, Cédric Le Goater wrote:
>>> On 8/30/23 12:37, Zhenzhong Duan wrote:
>>>> From: Yi Liu <yi.l.liu@intel.com>
>>>>
>>>> Abstract the VFIOContainer to be a base object. It is supposed to be
>>>> embedded by legacy VFIO container and later on, into the new iommufd
>>>> based container.
>>>>
>>>> The base container implements generic code such as code related to
>>>> memory_listener and address space management. The VFIOContainerOps
>>>> implements callbacks that depend on the kernel user space being used.
>>>>
>>>> 'common.c' and vfio device code only manipulates the base container with
>>>> wrapper functions that calls the functions defined in
>>>> VFIOContainerOpsClass.
>>>> Existing 'container.c' code is converted to implement the legacy
>>>> container
>>>> ops functions.
>>>>
>>>> Below is the base container. It's named as VFIOContainer, old
>>>> VFIOContainer
>>>> is replaced with VFIOLegacyContainer.
>>> Usualy, we introduce the new interface solely, port the current models
>>> on top of the new interface, wire the new models in the current
>>> implementation and remove the old implementation. Then, we can start
>>> adding extensions to support other implementations.
>>>
>>> spapr should be taken care of separatly following the principle above.
>>> With my PPC hat, I would not even read such a massive change, too risky
>>> for the subsystem. This path will need (much) further splitting to be
>>> understandable and acceptable.
>> We might split this patch by
>> 1) introducing VFIOLegacyContainer encapsulating the base VFIOContainer,
>> without using the ops in a first place:
>>  common.c would call vfio_container_* with harcoded legacy
>> implementation, ie. retrieving the legacy container with container_of.
>> 2) we would introduce the BE interface without using it.
>> 3) we would use the new BE interface
>>
>> Obviously this needs to be further tried out. If you wish I can try to
>> split it that way ... Please let me know
> Sure, thanks for your help, glad that I can cooperate with you to move
> this series forward.
> I just updated the branch which rebased to newest upstream for you to pick at 
> https://github.com/yiliu1765/qemu/tree/zhenzhong/iommufd_cdev_v1_rebased 

I have spent most of my day reshuffling this single patch into numerous
ones (16!). This should help the review.
I was short of time. This compiles, the end code should be identical to
the original one. Besides this deserves some additional review on your
end, commit msg tuning, ...

But at least it is a move forward. Feel free to incorporate that in your
next respin.

Please find that work on the following branch

https://github.com/eauger/qemu/tree/iommufd_cdev_v1_rebased_split

Thanks

Eric
>
> Thanks
> Zhenzhong