linux-kernel - Re: [PATCH v2 1/1] s390/vfio-ap: fix circular lockdep when setting/clearing crypto masks

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Message-ID: <e07d6f8e-f29e-7c4e-4226-5a5c072e7ae6@de.ibm.com>
Date:   Wed, 24 Feb 2021 17:10:40 +0100
From:   Christian Borntraeger <borntraeger@...ibm.com>
To:     Halil Pasic <pasic@...ux.ibm.com>,
        Tony Krowiak <akrowiak@...ux.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, stable@...r.kernel.org, cohuck@...hat.com,
        kwankhede@...dia.com, pbonzini@...hat.com,
        alex.williamson@...hat.com, pasic@...ux.vnet.ibm.com
Subject: Re: [PATCH v2 1/1] s390/vfio-ap: fix circular lockdep when
 setting/clearing crypto masks



On 23.02.21 10:48, Halil Pasic wrote:
> On Mon, 15 Feb 2021 20:15:47 -0500
> Tony Krowiak <akrowiak@...ux.ibm.com> wrote:
> 
>> This patch fixes a circular locking dependency in the CI introduced by
>> commit f21916ec4826 ("s390/vfio-ap: clean up vfio_ap resources when KVM
>> pointer invalidated"). The lockdep only occurs when starting a Secure
>> Execution guest. Crypto virtualization (vfio_ap) is not yet supported for
>> SE guests; however, in order to avoid CI errors, this fix is being
>> provided.
>>
>> The circular lockdep was introduced when the masks in the guest's APCB
>> were taken under the matrix_dev->lock. While the lock is definitely
>> needed to protect the setting/unsetting of the KVM pointer, it is not
>> necessarily critical for setting the masks, so this will not be done under
>> protection of the matrix_dev->lock.
> 
> 
> 
> With the one little thing I commented on below addressed: 
> Acked-by: Halil Pasic <pasic@...ux.ibm.com>  

Tony, can you comment on Halils comment or send a v3 right away?