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SubjectRe: [PATCH v3 05/14] s390: vfio-ap: base implementation of VFIO AP device driver
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On 03/15/2018 09:25 AM, Pierre Morel wrote:
> On 14/03/2018 19:25, Tony Krowiak wrote:
>> 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 default AP
>> 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. 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 /sys/devices/vfio-ap/matrix device to hold
>> the APQNs of the AP devices bound to the VFIO
>> AP device driver and serves as the parent of the
>> mediated devices created for each guest.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>
>> ---
>> MAINTAINERS | 2 +
>> arch/s390/Kconfig | 11 +++
>> drivers/s390/crypto/Makefile | 4 +
>> drivers/s390/crypto/vfio_ap_drv.c | 135
>> +++++++++++++++++++++++++++++++++
>> drivers/s390/crypto/vfio_ap_private.h | 22 ++++++
>> include/uapi/linux/vfio.h | 2 +
>> 6 files changed, 176 insertions(+), 0 deletions(-)
>> create mode 100644 drivers/s390/crypto/vfio_ap_drv.c
>> create mode 100644 drivers/s390/crypto/vfio_ap_private.h
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 72742d5..f129253 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -11884,6 +11884,8 @@ W:
>> http://www.ibm.com/developerworks/linux/linux390/
>> S: Supported
>> F: arch/s390/include/asm/kvm/kvm-ap.h
>> F: arch/s390/kvm/kvm-ap.c
>> +F: drivers/s390/crypto/vfio_ap_drv.c
>> +F: drivers/s390/crypto/vfio_ap_private.h
>>
>> S390 ZFCP DRIVER
>> M: Steffen Maier <maier@linux.vnet.ibm.com>
>> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
>> index cbe1d97..58509db 100644
>> --- a/arch/s390/Kconfig
>> +++ b/arch/s390/Kconfig
>> @@ -771,6 +771,17 @@ config VFIO_CCW
>> To compile this driver as a module, choose M here: the
>> module will be called vfio_ccw.
>>
>> +config VFIO_AP
>> + def_tristate m
> not sure it must be module by default.
> I would not set it by default.
Connie also asked about this in the last review, so I will go ahead
and change it.
>
>> + prompt "VFIO support for AP devices"
>> + depends on ZCRYPT && VFIO_MDEV_DEVICE
>
> VFIO_MDEV_DEVICE is a general feature *needed* by VFIO_AP
> and has no use case by its own. If it is set it is obviously because some
> mediated device drivers needs it.
> while ZCRYPT is a Z feature which may be set without VFIO_AP.
>
> So you need:
>
> config VFIO_AP
> def_tristate n
> prompt "VFIO support for AP devices"
> depends on ZCRYPT
> select VFIO_MDEV
> select VFIO_MDEV_DEVICE
> ...
I was thinking the same just yesterday and I agree, this makes sense.
>
>
>
> Pierre
>

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