Re: [PATCH v10 04/26] s390: vfio-ap: base implementation of VFIO AP device driver

[Cornelia Huck <cohuck@redhat.com>]

On Wed, 12 Sep 2018 15:42:54 -0400
Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote:

> From: Tony Krowiak <akrowiak@linux.ibm.com>
> 
> Introduces a new AP device driver. This device driver
> is built on the VFIO mediated device framework. The framework
> provides sysfs interfaces that facilitate passthrough
> access by guests to devices installed on the linux host.
> 
> The VFIO AP device driver will serve two purposes:
> 
> 1. Provide the interfaces to reserve AP devices for exclusive
>    use by KVM guests. This is accomplished by unbinding the
>    devices to be reserved for guest usage from the zcrypt
>    device driver and binding them to the VFIO AP device driver.
> 
> 2. Implements the functions, callbacks and sysfs attribute
>    interfaces required to create one or more VFIO mediated
>    devices each of which will be used to configure the AP
>    matrix for a guest and serve as a file descriptor
>    for facilitating communication between QEMU and the
>    VFIO AP device driver.
> 
> When the VFIO AP device driver is initialized:
> 
> * It registers with the AP bus for control of type 10 (CEX4
>   and newer) AP queue devices. This limitation was imposed
>   due to:
> 
>   1. A desire to keep the code as simple as possible;
> 
>   2. Some older models are no longer supported by the kernel
>      and others are getting close to end of service.
> 
>   The probe and remove callbacks will be provided to support
>   the binding/unbinding of AP queue devices to/from the VFIO
>   AP device driver.
> 
> * Creates a matrix device, /sys/devices/vfio_ap/matrix,
>   to serve as the parent of the mediated devices created, one
>   for each guest, and to hold the APQNs of the AP devices bound to
>   the VFIO AP device driver.
> 
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
> Tested-by: Michael Mueller <mimu@linux.ibm.com>
> Tested-by: Farhan Ali <alifm@linux.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

Christian's S-o-b looks a bit odd here; OTOH, it's probably him anyway
who will queue the patches in the end :)

> ---
>  MAINTAINERS                           |   10 +++
>  arch/s390/Kconfig                     |   11 +++
>  drivers/iommu/Kconfig                 |    8 ++
>  drivers/s390/crypto/Makefile          |    4 +
>  drivers/s390/crypto/vfio_ap_drv.c     |  134 +++++++++++++++++++++++++++++++++
>  drivers/s390/crypto/vfio_ap_private.h |   34 ++++++++
>  6 files changed, 201 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/s390/crypto/vfio_ap_drv.c
>  create mode 100644 drivers/s390/crypto/vfio_ap_private.h

Reviewed-by: Cornelia Huck <cohuck@redhat.com>