On 4/7/25 13:19, Cédric Le Goater wrote:
On 2/19/25 09:22, Zhenzhong Duan wrote:
Currently we have realize() callback which is called before attachment.
But there are still some elements e.g., hwpt_id is not ready before
attachment. So we need a realize_late() callback to further initialize
them.
The relation between objects HostIOMMUDevice and VFIOIOMMU is starting
to look too complex for me.
I think it makes sense to realize HostIOMMUDevice after the device
is attached. Can't we move :
hiod = HOST_IOMMU_DEVICE(object_new(ops->hiod_typename));
vbasedev->hiod = hiod;
under ->attach_device() and also the call :
if (!vfio_device_hiod_realize(vbasedev, errp)) {
later in the ->attach_device() patch ?
hiod_legacy_vfio_realize() doesn't do much. We might need to rework
hiod_iommufd_vfio_realize() which queries the iommufd hw caps, later
used by intel-iommu.
The only dependency I see on the IOMMUFD HostIOMMUDevice when attaching
the device to the container is in iommufd_cdev_autodomains_get(). The
flags for IOMMU_HWPT_ALLOC depends on the HW capability of the IOMMFD
backend and we rely on hiod_iommufd_vfio_realize() to have done the
query on the iommufd kernel device before.
Since this is not a hot path, I don't think it is a problem to add
a redundant call to iommufd_backend_get_device_info() in
iommufd_cdev_autodomains_get() and avoid the IOMMUFD HostIOMMUDevice
dependency. With that we can move the HostIOMMUDevice creation and
realize sequence at the end of the device attach sequence.
I think this makes the code cleaner when it comes to using the
vbasedev->hiod pointer too.
Anyway, it is good time to cleanup our interfaces before adding more.
On that topic, I think
iommufd_cdev_attach_ioas_hwpt
iommufd_cdev_detach_ioas_hwpt
belong to IOMMUFD backend.
Thanks,
C.
