From: Jason Gunthorpe <jgg@nvidia.com>
To: Tony Krowiak <akrowiak@linux.ibm.com>
Cc: jjherne@linux.ibm.com, linux-s390@vger.kernel.org,
linux-kernel@vger.kernel.org, borntraeger@de.ibm.com,
cohuck@redhat.com, pasic@linux.vnet.ibm.com,
alex.williamson@redhat.com, kwankhede@nvidia.com,
frankja@linux.ibm.com, david@redhat.com, imbrenda@linux.ibm.com,
hca@linux.ibm.com
Subject: Re: [PATCH v4 2/2] s390/vfio-ap: control access to PQAP(AQIC) interception handler
Date: Tue, 25 May 2021 12:11:17 -0300 [thread overview]
Message-ID: <20210525151117.GB1002214@nvidia.com> (raw)
In-Reply-To: <6542986f-b20e-3f41-b96c-70f0ce42af2d@linux.ibm.com>
On Tue, May 25, 2021 at 11:08:22AM -0400, Tony Krowiak wrote:
> > Why can't you put the locks in the right order? It looked trivial, I'm confused.
>
> Because the handle_pqap() function in priv.c does not have access to the
> matrix_dev lock.
Based on the sketch made the handle_pqap() should only handle the
arch.crypto.rwsem.
When it calls the hook it gets the matrix dev
This sets the lock order as always: rwsem then matrix_dev
Of the other two places:
@@ -352,8 +352,7 @@ static int vfio_ap_mdev_create(struct mdev_device *mdev)
+ down_write(&&vcpu->kvm->arch.crypto.rwsem);
mutex_lock(&matrix_dev->lock);
Obviously correct
@@ -1202,7 +1203,9 @@ static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev)
mutex_lock(&matrix_dev->lock);
vfio_ap_mdev_reset_queues(matrix_mdev->mdev);
+ down_write(&matrix_mdev->kvm->arch.crypto.rwsem);
matrix_mdev->kvm->arch.crypto.pqap_hook = NULL;
+ up_write(&matrix_mdev->kvm->arch.crypto.rwsem);
This is inverted
Just move the down_write up two lines
What is missing?
Jason
next prev parent reply other threads:[~2021-05-25 15:11 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-21 19:36 [PATCH v4 0/2] s390/vfio-ap: fix memory leak in mdev remove callback Tony Krowiak
2021-05-21 19:36 ` [PATCH v4 1/2] " Tony Krowiak
2021-05-25 13:03 ` Halil Pasic
2021-05-25 13:22 ` Tony Krowiak
2021-05-26 12:37 ` Tony Krowiak
2021-05-21 19:36 ` [PATCH v4 2/2] s390/vfio-ap: control access to PQAP(AQIC) interception handler Tony Krowiak
2021-05-23 22:57 ` Jason Gunthorpe
2021-05-25 14:59 ` Tony Krowiak
2021-05-25 15:00 ` Jason Gunthorpe
2021-05-24 14:37 ` Jason J. Herne
2021-05-25 13:16 ` Tony Krowiak
2021-05-25 13:19 ` Jason Gunthorpe
2021-05-25 15:08 ` Tony Krowiak
2021-05-25 15:11 ` Jason Gunthorpe [this message]
2021-05-25 15:56 ` Tony Krowiak
2021-05-25 16:29 ` Jason Gunthorpe
2021-05-27 2:28 ` Tony Krowiak
2021-05-27 11:24 ` Jason Gunthorpe
2021-05-25 13:24 ` Jason J. Herne
2021-05-25 13:26 ` Jason Gunthorpe
2021-05-25 14:07 ` Jason J. Herne
2021-05-25 14:16 ` Jason Gunthorpe
2021-06-14 7:51 ` [PATCH v4 0/2] s390/vfio-ap: fix memory leak in mdev remove callback Christian Borntraeger
2021-06-16 14:24 ` Tony Krowiak
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