linux-kernel - Re: [PATCH v4 3/7] s390: ap: associate a ap_vfio

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Message-Id: <d1d19f9e-40c1-e648-fcfb-4f05c75961e9@linux.ibm.com>
Date:   Wed, 27 Feb 2019 11:21:32 +0100
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     Cornelia Huck <cohuck@...hat.com>
Cc:     borntraeger@...ibm.com, alex.williamson@...hat.com,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org, frankja@...ux.ibm.com, akrowiak@...ux.ibm.com,
        pasic@...ux.ibm.com, david@...hat.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, freude@...ux.ibm.com, mimu@...ux.ibm.com
Subject: Re: [PATCH v4 3/7] s390: ap: associate a ap_vfio_queue and a matrix
 mdev

On 27/02/2019 10:32, Cornelia Huck wrote:
> On Fri, 22 Feb 2019 16:29:56 +0100
> Pierre Morel <pmorel@...ux.ibm.com> wrote:
> 
>> We need to associate the ap_vfio_queue, which will hold the
>> per queue information for interrupt with a matrix mediated device
>> which hold the configuration and the way to the CRYCB.
>>
>> Let's do this when assigning a APID or a APQI to the mediated device
>> and clear the relation when unassigning.
>>
>> Queuing the devices on a list of free devices and testing the
>> matrix_mdev pointer to the associated matrix allow us to know
>> if the queue is associated to the matrix device and associated
>> or not to a mediated device.
>>
>> When resetting an AP queue we must wait until there are no more
>> messages in the message queue before considering the queue is really
>> in a clean state.
>>
>> Let's do it and wait until the status response code indicate the
>> queue is empty after issuing a PAPQ/ZAPQ instruction.
> 
> I'm a bit confused about the context where that list moving etc. is
> supposed to take place.
> 
> When are we assigning/deassigning? Is there even supposed to be any
> activity that we need to zap on the queues?
> 
> Do we need any serialization/locking on the lists?

Did I really forget this!?

Yes, thanks.

Regards,
Pierre


-- 
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany