linux-kernel - Re: [PATCH v12 11/17] s390/vfio-ap: allow assignment of unavailable AP queues to mdev device

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Date:   Sun, 29 Nov 2020 02:17:17 +0100
From:   Halil Pasic <pasic@...ux.ibm.com>
To:     Tony Krowiak <akrowiak@...ux.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, freude@...ux.ibm.com, borntraeger@...ibm.com,
        cohuck@...hat.com, mjrosato@...ux.ibm.com,
        alex.williamson@...hat.com, kwankhede@...dia.com,
        fiuczy@...ux.ibm.com, frankja@...ux.ibm.com, david@...hat.com,
        hca@...ux.ibm.com, gor@...ux.ibm.com
Subject: Re: [PATCH v12 11/17] s390/vfio-ap: allow assignment of unavailable
 AP queues to mdev device

On Tue, 24 Nov 2020 16:40:10 -0500
Tony Krowiak <akrowiak@...ux.ibm.com> wrote:

> The current implementation does not allow assignment of an AP adapter or
> domain to an mdev device if each APQN resulting from the assignment
> does not reference an AP queue device that is bound to the vfio_ap device
> driver. This patch allows assignment of AP resources to the matrix mdev as
> long as the APQNs resulting from the assignment:
>    1. Are not reserved by the AP BUS for use by the zcrypt device drivers.
>    2. Are not assigned to another matrix mdev.
> 
> The rationale behind this is twofold:
>    1. The AP architecture does not preclude assignment of APQNs to an AP
>       configuration that are not available to the system.
>    2. APQNs that do not reference a queue device bound to the vfio_ap
>       device driver will not be assigned to the guest's CRYCB, so the
>       guest will not get access to queues not bound to the vfio_ap driver.
> 
> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>

Again code looks good. I'm still worried about all the incremental
changes (good for review) and their testability.