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    SubjectRe: [RFC 00/19] KVM: s390/crypto/vfio: guest dedicated crypto adapters
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    adding qemu devel and add Daniel and Erik from libvirt to keep them in the loop. 

    On 10/29/2017 12:11 PM, Cornelia Huck wrote:
    > On Fri, 13 Oct 2017 13:38:45 -0400
    > Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote:
    >
    >> Tony Krowiak (19):
    >> KVM: s390: SIE considerations for AP Queue virtualization
    >> KVM: s390: refactor crypto initialization
    >> s390/zcrypt: new AP matrix bus
    >> s390/zcrypt: create an AP matrix device on the AP matrix bus
    >> s390/zcrypt: base implementation of AP matrix device driver
    >> s390/zcrypt: register matrix device with VFIO mediated device
    >> framework
    >> KVM: s390: introduce AP matrix configuration interface
    >> s390/zcrypt: support for assigning adapters to matrix mdev
    >> s390/zcrypt: validate adapter assignment
    >> s390/zcrypt: sysfs interfaces supporting AP domain assignment
    >> s390/zcrypt: validate domain assignment
    >> s390/zcrypt: sysfs support for control domain assignment
    >> s390/zcrypt: validate control domain assignment
    >> KVM: s390: Connect the AP mediated matrix device to KVM
    >> s390/zcrypt: introduce ioctl access to VFIO AP Matrix driver
    >> KVM: s390: interface to configure KVM guest's AP matrix
    >> KVM: s390: validate input to AP matrix config interface
    >> KVM: s390: New ioctl to configure KVM guest's AP matrix
    >> s390/facilities: enable AP facilities needed by guest
    >
    > I'll try to summarize all of this in my own words, both to make sure I
    > understand the design correctly and to give others a different view on
    > this.
    >
    > [I'm completely disregarding control domains here.]
    >
    > On s390, we have cryptographic coprocessor cards, which are modeled on
    > Linux as devices on the AP bus. There's also a concept called domains,
    > which means an individual queue of a crypto device is basically a
    > (card,domain) tuple. We model this something like the following
    > (assuming we have access to cards 3 and 4 and domains 1 and 2):
    >
    > AP -> card3 -> queue (3,1)
    > -> queue (3,2)
    > -> card4 -> queue (4,1)
    > -> queue (4,2)
    >
    > (The AP bus is a bit different for backwards compat.)
    >
    > If we want to virtualize this, we can use a feature provided by the
    > hardware. We basically attach a satellite control block to our main
    > hardware virtualization control block and the hardware takes care of
    > (mostly) everything.
    >
    > For this control block, we don't specify explicit tuples, but a list of
    > cards and a list of domains. The guest will get access to the cross
    > product.
    >
    > Because of this, we need to take care that the lists provided to
    > different guests don't overlap; i.e., we need to enforce sane
    > configurations. Otherwise, one guest may get access to things like
    > secret keys for another guest.
    >
    > The idea of this patch set is to introduce a new device, the matrix
    > device. This matrix device hangs off a different root and acts as the
    > node where mdev devices hang off.
    >
    > If you now want to give the tuples (4,1) and (4,2), you need to do the
    > following:
    >
    > - Unbind the (4,1) and (4,2) tuples from their ap bus driver.
    > - Bind the (4,1) and (4,2) tuples to the ap matrix driver.
    > - Create the mediated device.
    > - Assign card 4 and domains 1 and 2.
    >
    > QEMU will now simply consume the mediated device and things should work.
    >

    This is probably the shortest possible summary I can imagine.
    Tony can you double check if it matches your understanding as well?

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