From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:35242 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727224AbgLVPhs (ORCPT ); Tue, 22 Dec 2020 10:37:48 -0500 Subject: Re: [PATCH v4] s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated References: <20201221185625.24914-1-akrowiak@linux.ibm.com> <20201222050521.46af2bf1.pasic@linux.ibm.com> From: Tony Krowiak Message-ID: <853da84f-092b-6b94-62d5-628f440abc40@linux.ibm.com> Date: Tue, 22 Dec 2020 10:37:01 -0500 MIME-Version: 1.0 In-Reply-To: <20201222050521.46af2bf1.pasic@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US List-ID: To: Halil Pasic 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 12/21/20 11:05 PM, Halil Pasic wrote: > 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? I don't think it matters much since NOTIFY_OK and NOTIFY_DONE have no further effect on processing of the notification queue, but I believe you are correct, this is a change from what we originally had. I can restore the original return values if you'd prefer. > > Otherwise LGTM! > > Regards, > Halil > >> +notify_done: >> + mutex_unlock(&matrix_dev->lock); >> + return notify_rc; >> } >> > [..]