Re: [PATCH v1] vfio/common: Separate vfio-pci ranges

[Joao Martins <joao.m.martins@oracle.com>]

On 11/09/2023 10:48, Duan, Zhenzhong wrote:
>>>> +static bool vfio_section_is_vfio_pci(MemoryRegionSection *section,
>>>> +                                     VFIOContainer *container)
>>>> +{
>>>> +    VFIOPCIDevice *pcidev;
>>>> +    VFIODevice *vbasedev;
>>>> +    VFIOGroup *group;
>>>> +    Object *owner;
>>>> +
>>>> +    owner = memory_region_owner(section->mr);
>>>> +
>>>> +    QLIST_FOREACH(group, &container->group_list, container_next) {
>>>> +        QLIST_FOREACH(vbasedev, &group->device_list, next) {
>>>> +            if (vbasedev->type != VFIO_DEVICE_TYPE_PCI) {
>>>> +                continue;
>>>> +            }
>>>> +            pcidev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
>>>> +            if (OBJECT(pcidev) == owner) {
>>>> +                return true;
>>>> +            }
>>>> +        }
>>>> +    }
>>>> +
>>>> +    return false;
>>>> +}
>>>
>>> What about simplify it with memory_region_is_ram_device()?
>>> This way vdpa device could also be included.
>>>
>>
>> Note that the check is not interested in RAM (or any other kinda of memory like
>> VGA). That's covered in the 32-64 ranges. But rather in any PCI device RAM that
>> would fall in the 64-bit PCI hole. Would memory_region_is_ram_device() really
>> cover it? If so, I am all for the simplification.
> 
> Ram device is used not only by vfio pci bars but also host notifier of vdpa and vhost-user.

My only concern is whether this is all part of the pci-hole64 or not e.g. if we
expand to general memory_region_is_ram_device() would we go back to the initial
bug where we create an enourmous range. The latter that you mentioned should be
mainly virtio-net devices as presented to the guest (regardless of backend is
vdpa, or vhost-user) and perhaps they are all in the hole32 PCI hole?

	Joao