Re: [PATCH v2 2/2] s390/vfio-ap: reverse group notifier actions when KVM pointer invalidated

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Dec 11, 2020 at 05:22:11PM -0500, 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.
> 
> When the notifier is called to make notification that the KVM pointer has
> been set to NULL, the driver should reverse the actions taken when the
> KVM pointer was set as well as unplugging the AP devices passed through
> to the KVM guest.
> 
> Fixes: 258287c994de ("s390: vfio-ap: implement mediated device open callback")
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> ---
>  drivers/s390/crypto/vfio_ap_ops.c | 40 ++++++++++++++++++-------------
>  1 file changed, 24 insertions(+), 16 deletions(-)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>