Messages in this thread |  | | Subject | Re: [RFC 05/19] s390/zcrypt: base implementation of AP matrix device driver | From | Tony Krowiak <> | Date | Fri, 17 Nov 2017 16:13:45 -0500 |
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On 11/16/2017 11:47 AM, Cornelia Huck wrote: > On Thu, 16 Nov 2017 09:25:27 -0500 > Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote: > >> On 11/16/2017 07:35 AM, Cornelia Huck wrote: >>> On Thu, 16 Nov 2017 13:02:26 +0100 >>> Pierre Morel <pmorel@linux.vnet.ibm.com> wrote: >>> >>>> On 14/11/2017 17:37, Tony Krowiak wrote: >>>>> On 11/14/2017 07:40 AM, Cornelia Huck wrote: >>>>>> On Fri, 13 Oct 2017 13:38:50 -0400 >>>>>> Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote: >>>>>>> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig >>>>>>> index 48af970..411c19a 100644 >>>>>>> --- a/arch/s390/Kconfig >>>>>>> +++ b/arch/s390/Kconfig >>>>>>> @@ -722,6 +722,19 @@ config VFIO_CCW >>>>>>> To compile this driver as a module, choose M here: the >>>>>>> module will be called vfio_ccw. >>>>>>> +config VFIO_AP_MATRIX >>>>>>> + def_tristate m >>>>>>> + prompt "Support for Adjunct Processor Matrix device interface" >>>>>>> + depends on ZCRYPT >>>>>>> + select VFIO >>>>>>> + select MDEV >>>>>>> + select VFIO_MDEV >>>>>>> + select VFIO_MDEV_DEVICE >>>>>>> + select IOMMU_API >>>>>> I think the more common pattern is to depend on the VFIO configs >>>>>> instead of selecting them. >>>>> It's ironic because I originally changed from using 'depends on' and >>>>> changed it based on review comments made >>>>> on our internal mailing list. I'll go with 'depends on'. >>>> Is doing like the others a sufficient good reason? >>>> What if the first who did this did not really think about it? >>>> >>>> When an administrator configure the kernel what does he think? >>>> >>>> - I want to have AP through AP_VFIO in my guests >>>> and he get implicitly VFIO >>>> or >>>> - I want to have VFIO >>>> and he has to explicitly add AP_VFIO too >>>> >>>> It seems to me that the first is much more user friendly. >>>> >>>> Please tell me if I missed something. dependencies? collateral damages? >>>> my logic is wrong? >>> Using select for anything that's not a simple infrastructure dependency >>> may lead into trouble (we've had issues in the past where options tried >>> to enable other options but missed dependencies). >>> >>> If a user wants to use vfio-ap, I think it is reasonable to expect them >>> to figure out that they need both ap and vfio for that. >>> >>> [And config help has gotten much better than it was years ago; it's not >>> that hard to figure out what is actually needed.] >> Is it sufficient to specify 'depends on ZCRYPT && VFIO_MDEV_DEVICE' >> since 'VFIO_MDEV_DEVICE depends on VFIO && VFIO_MDEV' and 'VFIO_MDEV >> depends on VFIO' and 'VFIO depends on IOMMU_API'? > Perhaps ZCRYPT && VFIO_MDEV && VFIO_MDEV_DEVICE, to make it a bit more > obvious? Sure, why not. > > [Also, is IOMMU_API only needed to satisfy dependencies?] Yes, VFIO is dependent upon it. >
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