Re: [PATCH v5 11/13] KVM: s390: implement mediated device open callback
From: Pierre Morel
Date: Tue Jun 05 2018 - 08:20:08 EST
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)
+{
+ÂÂÂ atomic_inc(&kvm->arch.crypto.aprefs);
+}
+EXPORT_SYMBOL(kvm_ap_refcount_inc);
+
+void kvm_ap_refcount_dec(struct kvm *kvm)
+{
+ÂÂÂ 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.
--
Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany