From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:58612 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387915AbfITOY3 (ORCPT ); Fri, 20 Sep 2019 10:24:29 -0400 Subject: Re: [PATCH v6 04/10] s390: vfio-ap: filter CRYCB bits for unavailable queue devices References: <1568410018-10833-1-git-send-email-akrowiak@linux.ibm.com> <1568410018-10833-5-git-send-email-akrowiak@linux.ibm.com> <20190919123434.28a29c00.pasic@linux.ibm.com> From: Tony Krowiak Message-ID: <3c81ae10-79fc-d845-571f-66cb84e1227a@linux.ibm.com> Date: Fri, 20 Sep 2019 10:24:19 -0400 MIME-Version: 1.0 In-Reply-To: <20190919123434.28a29c00.pasic@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Halil Pasic Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, freude@linux.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com, mjrosato@linux.ibm.com, pmorel@linux.ibm.com, alex.williamson@redhat.com, kwankhede@nvidia.com, jjherne@linux.ibm.com On 9/19/19 6:34 AM, Halil Pasic wrote: > On Fri, 13 Sep 2019 17:26:52 -0400 > Tony Krowiak wrote: > >> +static void vfio_ap_mdev_get_crycb_matrix(struct ap_matrix_mdev *matrix_mdev) >> +{ >> + unsigned long apid, apqi; >> + unsigned long masksz = BITS_TO_LONGS(AP_DEVICES) * >> + sizeof(unsigned long); >> + >> + memset(matrix_mdev->crycb.apm, 0, masksz); >> + memset(matrix_mdev->crycb.apm, 0, masksz); >> + memcpy(matrix_mdev->crycb.adm, matrix_mdev->matrix.adm, masksz); >> + >> + for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, >> + matrix_mdev->matrix.apm_max + 1) { >> + for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, >> + matrix_mdev->matrix.aqm_max + 1) { >> + if (vfio_ap_find_queue(AP_MKQID(apid, apqi))) { >> + if (!test_bit_inv(apid, matrix_mdev->crycb.apm)) >> + set_bit_inv(apid, >> + matrix_mdev->crycb.apm); >> + if (!test_bit_inv(apqi, matrix_mdev->crycb.aqm)) >> + set_bit_inv(apqi, >> + matrix_mdev->crycb.aqm); >> + } >> + } >> + } >> +} > > Even with the discussed typo fixed (zero crycb.aqm) this procedure does > not make sense to me. :( > > If in doubt please consider the following example: > matrix_mdev->matrix.apm and matrix_mdev->matrix.aqm have both just bits > 0 and 1 set (i.e. first byte 0xC0 the rest of the bytes 0x0). Queues > bound to the vfio_ap driver (0,0), (0,1), (1,0); not bound to vfio_ap is > however (1,1). If I read this correctly this filtering logic would grant > access to (1,1) which seems to contradict with the stated intention. Yep, I see your point. I'll have to rework this code. > > Regards, > Halil > > >