>-----Original Message-----
>From: Nicolin Chen <nicol...@nvidia.com>
>Subject: Re: [PATCH v2 2/4] vfio/iommufd: Add properties and handlers to
>TYPE_HOST_IOMMU_DEVICE_IOMMUFD
>
>On Fri, May 30, 2025 at 05:35:10PM +0800, Zhenzhong Duan wrote:
>> Enhance HostIOMMUDeviceIOMMUFD object with 3 new members, specific
>> to the iommufd BE + 2 new class functions.
>>
>> IOMMUFD BE includes IOMMUFD handle, devid and hwpt_id. IOMMUFD handle
>> and devid are used to allocate/free ioas and hwpt. hwpt_id is used to
>> re-attach IOMMUFD backed device to its default VFIO sub-system created
>> hwpt, i.e., when vIOMMU is disabled by guest. These properties are
>> initialized in hiod::realize() after attachment.
>>
>> 2 new class functions are [at|de]tach_hwpt(). They are used to
>> attach/detach hwpt. VFIO and VDPA can have different implementions,
>> so implementation will be in sub-class instead of HostIOMMUDeviceIOMMUFD,
>> e.g., in HostIOMMUDeviceIOMMUFDVFIO.
>
>You mean HostIOMMUDeviceVFIO and HostIOMMUDeviceVDPA?
HostIOMMUDeviceIOMMUFDVFIO and HostIOMMUDeviceIOMMUFDVDPA.
>
>I wonder what are the difference between their implementations.
They have different way to transform HOST_IOMMU_DEVICE(idev)->agent.
See host_iommu_device_iommufd_vfio_attach_hwpt()
>
>Main reason for asking this is that we have alloc_hwpt (and will
>have alloc_viommu soon) too, and should that/those be a part of
>the Class op(s) too?
I think vIOMMU could call alloc_viommu and alloc_hwpt directly,
they are common IOMMUFD interface no matter VFIO or VDPA backend device.
>
>> @@ -833,6 +834,11 @@ static bool
>hiod_iommufd_vfio_realize(HostIOMMUDevice *hiod, void *opaque,
>> caps->type = type;
>> caps->hw_caps = hw_caps;
>>
>> + idev = HOST_IOMMU_DEVICE_IOMMUFD(hiod);
>> + idev->iommufd = vdev->iommufd;
>> + idev->devid = vdev->devid;
>> + idev->hwpt_id = vdev->hwpt->hwpt_id;
>
>Since it's the default hwpt that VFIO contain allocated, perhaps
>it's better to call it default_hwpt_id, indicating that won't be
>changed by further HWPT attachment.
hiod_iommufd_vfio_realize() is called only once, no one will change
idev->hwpt_id.
Thanks
Zhenzhong
