Re: [PATCH v3 1/7] HostIOMMUDevice: Store the VFIO/VDPA agent

["Cédric Le Goater" <clg@redhat.com>]

On 6/13/24 11:20 AM, Eric Auger wrote:
> Store the agent device (VFIO or VDPA) in the host IOMMU device.
> This will allow easy access to some of its resources.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> ---
>   include/sysemu/host_iommu_device.h | 1 +
>   hw/vfio/container.c                | 1 +
>   hw/vfio/iommufd.c                  | 2 ++
>   3 files changed, 4 insertions(+)
> 
> diff --git a/include/sysemu/host_iommu_device.h b/include/sysemu/host_iommu_device.h
> index a57873958b..3e5f058e7b 100644
> --- a/include/sysemu/host_iommu_device.h
> +++ b/include/sysemu/host_iommu_device.h
> @@ -34,6 +34,7 @@ struct HostIOMMUDevice {
>       Object parent_obj;
>   
>       char *name;
> +    void *agent; /* pointer to agent device, ie. VFIO or VDPA device */
>       HostIOMMUDeviceCaps caps;
>   };
>   
> diff --git a/hw/vfio/container.c b/hw/vfio/container.c
> index 26e6f7fb4f..b728b978a2 100644
> --- a/hw/vfio/container.c
> +++ b/hw/vfio/container.c
> @@ -1145,6 +1145,7 @@ static bool hiod_legacy_vfio_realize(HostIOMMUDevice *hiod, void *opaque,
>   
>       hiod->name = g_strdup(vdev->name);
>       hiod->caps.aw_bits = vfio_device_get_aw_bits(vdev);
> +    hiod->agent = opaque;
>   
>       return true;
>   }
> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
> index 409ed3dcc9..dbdae1adbb 100644
> --- a/hw/vfio/iommufd.c
> +++ b/hw/vfio/iommufd.c
> @@ -631,6 +631,8 @@ static bool hiod_iommufd_vfio_realize(HostIOMMUDevice *hiod, void *opaque,
>           struct iommu_hw_info_vtd vtd;
>       } data;
>   
> +    hiod->agent = opaque;
> +

This opaque pointer could be assigned in vfio_attach_device().

Talking of which, why are we passing a 'VFIODevice *' parameter to
HostIOMMUDeviceClass::realize ? I don't see a good reason

I think a 'VFIOContainerBase *' would be more appropriate since
'HostIOMMUDevice' represents a device on the host which is common
to all VFIO devices.
  
In that case, HostIOMMUDevice::agent wouldn't need to be opaque
anymore. It could  simply be a 'VFIOContainerBase *' and
hiod_legacy_vfio_get_iova_ranges() in patch 3 would grab the
'iova_ranges' from the 'VFIOContainerBase *' directly.

This means some rework :

* vfio_device_get_aw_bits() would use a  'VFIOContainerBase *' instead.
* HostIOMMUDevice::name would be removed. This is just for error messages.
* hiod_iommufd_vfio_realize() would use VFIOIOMMUFDContainer::be.

That said, I think we need the QOMification changes first.

Thanks,

C.




>       if (!iommufd_backend_get_device_info(vdev->iommufd, vdev->devid,
>                                            &type, &data, sizeof(data), errp)) {
>           return false;