Re: [PATCH v5] s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated

[Christian Borntraeger]

On 23.12.20 02:20, Tony Krowiak wrote:
> The vfio_ap device driver registers a group notifier with VFIO when the
> file descriptor for a VFIO mediated device for a KVM guest is opened to
> receive notification that the KVM pointer is set (VFIO_GROUP_NOTIFY_SET_KVM
> event). When the KVM pointer is set, the vfio_ap driver takes the
> following actions:
> 1. Stashes the KVM pointer in the vfio_ap_mdev struct that holds the state
>    of the mediated device.
> 2. Calls the kvm_get_kvm() function to increment its reference counter.
> 3. Sets the function pointer to the function that handles interception of
>    the instruction that enables/disables interrupt processing.
> 4. Sets the masks in the KVM guest's CRYCB to pass AP resources through to
>    the guest.
> 
> In order to avoid memory leaks, when the notifier is called to receive
> notification that the KVM pointer has been set to NULL, the vfio_ap device
> driver should reverse the actions taken when the KVM pointer was set.
> 
> Fixes: 258287c994de ("s390: vfio-ap: implement mediated device open callback")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
> Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>


Just to keep you up2date why this patch is still waiting in our queue. This triggered
a lockdep splat in the CI which we want to fix first.