Re: [PATCH 2/2] vfio/ccw: Don't initialize HOST_IOMMU_DEVICE with mdev

[Eric Farman <farman@linux.ibm.com>]

On Mon, 2024-07-22 at 15:07 +0800, Zhenzhong Duan wrote:
> mdevs aren't "physical" devices and when asking for backing IOMMU info,
> it fails the entire provisioning of the guest. Fix that by setting
> vbasedev->mdev true so skipping HostIOMMUDevice initialization in the
> presence of mdevs.

Hmm, picking the two commits that Cedric mentioned in his cover-letter reply [1] doesn't "fail the entire provisioning of the guest" for me.

Applying this patch on top of that causes the call from vfio_attach_device() to hiod_legacy_vfio_realize() to be skipped, which seems odd. What am I missing?

[1] https://lore.kernel.org/qemu-devel/4c9a184b-514c-4276-95ca-9ed86623b9a4@redhat.com/

> 
> Fixes: 930589520128 ("vfio/iommufd: Implement HostIOMMUDeviceClass::realize() handler")
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> ---
>  hw/vfio/ccw.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> index 1f8e1272c7..70934b01d5 100644
> --- a/hw/vfio/ccw.c
> +++ b/hw/vfio/ccw.c
> @@ -675,6 +675,9 @@ static void vfio_ccw_instance_init(Object *obj)
>      VFIOCCWDevice *vcdev = VFIO_CCW(obj);
>      VFIODevice *vbasedev = &vcdev->vdev;
>  
> +    /* CCW device is mdev type device */
> +    vbasedev->mdev = true;
> +
>      /*
>       * All vfio-ccw devices are believed to operate in a way compatible with
>       * discarding of memory in RAM blocks, ie. pages pinned in the host are