linux-kernel - Re: [PATCH v16 10/14] s390/zcrypt: driver callback to indicate resource in use

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Date:   Wed, 19 May 2021 14:58:54 +0300
From:   Julian Wiedmann <jwi@...ux.ibm.com>
To:     Tony Krowiak <akrowiak@...ux.ibm.com>, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     jjherne@...ux.ibm.com, freude@...ux.ibm.com,
        borntraeger@...ibm.com, cohuck@...hat.com, mjrosato@...ux.ibm.com,
        pasic@...ux.ibm.com, alex.williamson@...hat.com,
        kwankhede@...dia.com, fiuczy@...ux.ibm.com
Subject: Re: [PATCH v16 10/14] s390/zcrypt: driver callback to indicate
 resource in use

On 10.05.21 19:44, Tony Krowiak wrote:
> Introduces a new driver callback to prevent a root user from unbinding
> an AP queue from its device driver if the queue is in use. The callback
> will be invoked whenever a change to the AP bus's sysfs apmask or aqmask
> attributes would result in one or more AP queues being removed from its
> driver. If the callback responds in the affirmative for any driver
> queried, the change to the apmask or aqmask will be rejected with a device
> busy error.
> 
> For this patch, only non-default drivers will be queried. Currently,
> there is only one non-default driver, the vfio_ap device driver. The
> vfio_ap device driver facilitates pass-through of an AP queue to a
> guest. The idea here is that a guest may be administered by a different
> sysadmin than the host and we don't want AP resources to unexpectedly
> disappear from a guest's AP configuration (i.e., adapters and domains
> assigned to the matrix mdev). This will enforce the proper procedure for
> removing AP resources intended for guest usage which is to
> first unassign them from the matrix mdev, then unbind them from the
> vfio_ap device driver.
> 
> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
> Reviewed-by: Harald Freudenberger <freude@...ux.ibm.com>
> Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>
> ---
>  drivers/s390/crypto/ap_bus.c | 160 ++++++++++++++++++++++++++++++++---
>  drivers/s390/crypto/ap_bus.h |   4 +
>  2 files changed, 154 insertions(+), 10 deletions(-)
> 

This doesn't touch the zcrypt drivers, so I _think_ the subject should
rather be "s390/ap: driver callback to indicate resource in use". Harald?

Same for patch 13.