Messages in this thread | | | Subject | Re: [PATCH v5 11/13] KVM: s390: implement mediated device open callback | From | Tony Krowiak <> | Date | Wed, 6 Jun 2018 10:28:17 -0400 |
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On 06/05/2018 08:19 AM, Pierre Morel wrote: > On 30/05/2018 16:33, Tony Krowiak wrote: >> On 05/24/2018 05:08 AM, Pierre Morel wrote: >>> On 23/05/2018 16:45, Tony Krowiak wrote: >>>> On 05/16/2018 04:03 AM, Pierre Morel wrote: >>>>> On 07/05/2018 17:11, Tony Krowiak wrote: >>>>>> Implements the open callback on the mediated matrix device. >>>>>> The function registers a group notifier to receive notification >>>>>> of the VFIO_GROUP_NOTIFY_SET_KVM event. When notified, >>>>>> the vfio_ap device driver will get access to the guest's >>>>>> kvm structure. With access to this structure the driver will: >>>>>> >>>>>> 1. Ensure that only one mediated device is opened for the guest >>> >>> You should explain why. >>> >>>>>> >>>>>> 2. Configure access to the AP devices for the guest. >>>>>> >>> ...snip... >>>>>> +void kvm_ap_refcount_inc(struct kvm *kvm) >>>>>> +{ >>>>>> + atomic_inc(&kvm->arch.crypto.aprefs); >>>>>> +} >>>>>> +EXPORT_SYMBOL(kvm_ap_refcount_inc); >>>>>> + >>>>>> +void kvm_ap_refcount_dec(struct kvm *kvm) >>>>>> +{ >>>>>> + atomic_dec(&kvm->arch.crypto.aprefs); >>>>>> +} >>>>>> +EXPORT_SYMBOL(kvm_ap_refcount_dec); >>>>> >>>>> Why are these functions inside kvm-ap ? >>>>> Will anyone use this outer of vfio-ap ? >>>> >>>> As I've stated before, I made the choice to contain all interfaces >>>> that >>>> access KVM in kvm-ap because I don't think it is appropriate for >>>> the device >>>> driver to have to have "knowledge" of the inner workings of KVM. >>>> Why does >>>> it matter whether any entity outside of the vfio_ap device driver >>>> calls >>>> these functions? I could ask a similar question if the interfaces were >>>> contained in vfio-ap; what if another device driver needs access to >>>> these >>>> interfaces? >>> >>> This is very driver specific and only used during initialization. >>> It is not a common property of the cryptographic interface. >>> >>> I really think you should handle this inside the driver. >> >> We are going to have to agree to disagree on this one. Is it not >> possible >> that future drivers - e.g., when full virtualization is implemented - >> will >> require access to KVM? > > I do not think that an access to KVM is required for full virtualization.
You may be right, but at this point, there is no guarantee. I stand by my design on this one.
> > >
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