Re: [PATCH v3] s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated

[Tony Krowiak]

On 12/14/20 12:07 PM, Greg KH wrote:
> On Mon, Dec 14, 2020 at 11:56:17AM -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.
> > 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")
> > Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> > ---
> >   drivers/s390/crypto/vfio_ap_ops.c | 29 ++++++++++++++++++++---------
> >   1 file changed, 20 insertions(+), 9 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>

I read the document on the correct way to submit patches for inclusion in
the stable kernel. I apologize for my ignorance, but I don't see the
problem. Can you help me out here? Does a patch that fixes a memory leak
not qualify or is it something else?