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Message-ID: <20180924134931.6c67a3d2.cohuck@redhat.com>
Date: Mon, 24 Sep 2018 13:49:31 +0200
From: Cornelia Huck <cohuck@...hat.com>
To: Tony Krowiak <akrowiak@...ux.vnet.ibm.com>
Cc: linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, freude@...ibm.com, schwidefsky@...ibm.com,
heiko.carstens@...ibm.com, borntraeger@...ibm.com,
kwankhede@...dia.com, bjsdjshi@...ux.vnet.ibm.com,
pbonzini@...hat.com, alex.williamson@...hat.com,
pmorel@...ux.vnet.ibm.com, alifm@...ux.vnet.ibm.com,
mjrosato@...ux.vnet.ibm.com, jjherne@...ux.vnet.ibm.com,
thuth@...hat.com, pasic@...ux.vnet.ibm.com, berrange@...hat.com,
fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com,
frankja@...ux.ibm.com, Tony Krowiak <akrowiak@...ux.ibm.com>
Subject: Re: [PATCH v10 00/26] guest dedicated crypto adapters
On Wed, 12 Sep 2018 15:42:50 -0400
Tony Krowiak <akrowiak@...ux.vnet.ibm.com> wrote:
> Abstract:
> ========
>
> On s390, we have cryptographic coprocessor cards, which are modeled on
> Linux as devices on the AP bus. Each card can be partitioned into domains
> which can be thought of as a set of hardware registers for processing
> crypto commands. Crypto commands are sent to a specific domain within a
> card is via a queue which is identified as 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)
>
> 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
> most of the rest.
>
> 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
> parent node for mdev devices.
>
> If you now want to give the tuples (4,1) and (4,2), you need to do the
> following:
>
> - Make sure the queues (4,1) and (4,2) belong to vfio_ap (see patches
> #5 and #6)
> - Create the mediated device.
> - Assign card 4 and domains 1 and 2 to the mediated device
> - Optionally activate the mediated device.
>
> QEMU will now simply consume the mediated device and things should work.
>
> For a complete description of the architecture and concepts underlying
> the design, see the Documentation/s390/vfio-ap.txt file included with this
> patch set.
I did not spot anything major, and if v11 addresses the issues raised
by various reviewers I don't see why it should not be merged (interface
looks sane). I skipped looking at the vsie stuff, though ;)
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