Messages in this thread | | | Subject | Re: [PATCH v6 1/2] s390/vfio-ap: clean up mdev resources when remove callback invoked | From | Christian Borntraeger <> | Date | Mon, 21 Jun 2021 18:04:54 +0200 |
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On 21.06.21 17:57, Tony Krowiak wrote: > The mdev remove callback for the vfio_ap device driver bails out with > -EBUSY if the mdev is in use by a KVM guest (i.e., the KVM pointer in the > struct ap_matrix_mdev is not NULL). The intended purpose was > to prevent the mdev from being removed while in use. There are two > problems with this scenario: > > 1. Returning a non-zero return code from the remove callback does not > prevent the removal of the mdev. > > 2. The KVM pointer in the struct ap_matrix_mdev will always be NULL because > the remove callback will not get invoked until the mdev fd is closed. > When the mdev fd is closed, the mdev release callback is invoked and > clears the KVM pointer from the struct ap_matrix_mdev. > > Let's go ahead and remove the check for KVM in the remove callback and > allow the cleanup of mdev resources to proceed. > > Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com> > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> > Cc: stable@vger.kernel.org
This one is already queued on
https://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git/log/?h=fixes
Jason. Do you want this in stable? Then we should write a mail after merging. > --- > drivers/s390/crypto/vfio_ap_ops.c | 10 ---------- > 1 file changed, 10 deletions(-) > > diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c > index b2c7e10dfdcd..122c85c22469 100644 > --- a/drivers/s390/crypto/vfio_ap_ops.c > +++ b/drivers/s390/crypto/vfio_ap_ops.c > @@ -366,16 +366,6 @@ static int vfio_ap_mdev_remove(struct mdev_device *mdev) > struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); > > mutex_lock(&matrix_dev->lock); > - > - /* > - * If the KVM pointer is in flux or the guest is running, disallow > - * un-assignment of control domain. > - */ > - if (matrix_mdev->kvm_busy || matrix_mdev->kvm) { > - mutex_unlock(&matrix_dev->lock); > - return -EBUSY; > - } > - > vfio_ap_mdev_reset_queues(mdev); > list_del(&matrix_mdev->node); > kfree(matrix_mdev); >
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