Messages in this thread | | | Subject | Re: [PATCH v5 11/13] KVM: s390: implement mediated device open callback | From | Tony Krowiak <> | Date | Wed, 30 May 2018 10:33:13 -0400 |
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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? > > Pierre > > > ...snip... > >
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