From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:30720 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725850AbgLVEGL (ORCPT ); Mon, 21 Dec 2020 23:06:11 -0500 Date: Tue, 22 Dec 2020 05:05:21 +0100 From: Halil Pasic Subject: Re: [PATCH v4] s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated Message-ID: <20201222050521.46af2bf1.pasic@linux.ibm.com> In-Reply-To: <20201221185625.24914-1-akrowiak@linux.ibm.com> References: <20201221185625.24914-1-akrowiak@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit List-ID: To: Tony Krowiak Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, stable@vger.kernel.org, borntraeger@de.ibm.com, cohuck@redhat.com, kwankhede@nvidia.com, pbonzini@redhat.com, alex.williamson@redhat.com, pasic@linux.vnet.ibm.com On Mon, 21 Dec 2020 13:56:25 -0500 Tony Krowiak wrote: > The vfio_ap device driver registers a group notifier with VFIO when the > file descriptor for a VFIO mediated device for a KVM guest is opened to > receive notification that the KVM pointer is set (VFIO_GROUP_NOTIFY_SET_KVM > event). When the KVM pointer is set, the vfio_ap driver takes the > following actions: > 1. Stashes the KVM pointer in the vfio_ap_mdev struct that holds the state > of the mediated device. > 2. Calls the kvm_get_kvm() function to increment its reference counter. > 3. Sets the function pointer to the function that handles interception of > the instruction that enables/disables interrupt processing. > 4. Sets the masks in the KVM guest's CRYCB to pass AP resources through to > the guest. > > In order to avoid memory leaks, when the notifier is called to receive > notification that the KVM pointer has been set to NULL, the vfio_ap device > driver should reverse the actions taken when the KVM pointer was set. > > Fixes: 258287c994de ("s390: vfio-ap: implement mediated device open callback") > Cc: stable@vger.kernel.org > Signed-off-by: Tony Krowiak > Reviewed-by: Halil Pasic > Reviewed-by: Cornelia Huck [..] > static int vfio_ap_mdev_group_notifier(struct notifier_block *nb, > unsigned long action, void *data) > { > - int ret; > + int ret, notify_rc = NOTIFY_DONE; > struct ap_matrix_mdev *matrix_mdev; > > if (action != VFIO_GROUP_NOTIFY_SET_KVM) > return NOTIFY_OK; > > matrix_mdev = container_of(nb, struct ap_matrix_mdev, group_notifier); > + mutex_lock(&matrix_dev->lock); > > if (!data) { > - matrix_mdev->kvm = NULL; > - return NOTIFY_OK; > + if (matrix_mdev->kvm) > + vfio_ap_mdev_unset_kvm(matrix_mdev); > + notify_rc = NOTIFY_OK; > + goto notify_done; > } > > ret = vfio_ap_mdev_set_kvm(matrix_mdev, data); > if (ret) > - return NOTIFY_DONE; > + goto notify_done; > > /* If there is no CRYCB pointer, then we can't copy the masks */ > if (!matrix_mdev->kvm->arch.crypto.crycbd) > - return NOTIFY_DONE; > + goto notify_done; > > kvm_arch_crypto_set_masks(matrix_mdev->kvm, matrix_mdev->matrix.apm, > matrix_mdev->matrix.aqm, > matrix_mdev->matrix.adm); > > - return NOTIFY_OK; Shouldn't there be an + notify_rc = NOTIFY_OK; here? I mean you initialize notify_rc to NOTIFY_DONE, in the !data branch on success you set notify_rc to NOTIFY_OK, but in the !!data branch it just stays NOTIFY_DONE. Or am I missing something? Otherwise LGTM! Regards, Halil > +notify_done: > + mutex_unlock(&matrix_dev->lock); > + return notify_rc; > } > [..]