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

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Message-ID: <358b4b68-1bfb-4a5c-960d-d442271c5852@linux.ibm.com>
Date:   Wed, 24 Feb 2021 18:44:39 -0500
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     Christian Borntraeger <borntraeger@...ibm.com>,
        Halil Pasic <pasic@...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 2/24/21 11:10 AM, Christian Borntraeger wrote:
>
> 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?

I was locked out of email due to expiration of my w3 password.
I am working on the response now.