On 4/9/25 10:27, Duan, Zhenzhong wrote:
-----Original Message-----
From: Cédric Le Goater <c...@redhat.com>
Subject: Re: [PATCH rfcv2 03/20] HostIOMMUDevice: Introduce realize_late
callback
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.
Agree.
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.
Yes.
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.
OK, let me think about this further and write some patches to move .realize()
after .attach_device().
will be based on vfio-next.
I just updated the vfio-next branch with what should be in the next PR
for QEMU 10.1.
On that topic, I think
iommufd_cdev_attach_ioas_hwpt
iommufd_cdev_detach_ioas_hwpt
belong to IOMMUFD backend.
They are operation on VFIODevice, backends/iommufd.c are for operation on
IOMMUFDBackend,
Do we need to move iommufd_cdev_attach/detach_ioas_hwpt to backends/iommufd.c
which is VFIODevice agnostic?
My mistake. I was confused with
int iommufd = vbasedev->iommufd->fd
and thought we could simply replace 'VFIODevice *' parameter with a
'IOMMUFDBackend *be' parameter but this is not the case.
Thanks,
C.
