From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:45776 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728481AbgFPL6D (ORCPT ); Tue, 16 Jun 2020 07:58:03 -0400 Date: Tue, 16 Jun 2020 13:57:26 +0200 From: Halil Pasic Subject: Re: [PATCH v2 1/1] s390: virtio: let arch accept devices without IOMMU feature Message-ID: <20200616135726.04fa8314.pasic@linux.ibm.com> In-Reply-To: References: <1592224764-1258-1-git-send-email-pmorel@linux.ibm.com> <1592224764-1258-2-git-send-email-pmorel@linux.ibm.com> <20200616115202.0285aa08.pasic@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Pierre Morel Cc: linux-kernel@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, mst@redhat.com, jasowang@redhat.com, cohuck@redhat.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org, virtualization@lists.linux-foundation.org, thomas.lendacky@amd.com, David Gibson , Ram Pai , Heiko Carstens , Vasily Gorbik On Tue, 16 Jun 2020 12:52:50 +0200 Pierre Morel wrote: > >> int virtio_finalize_features(struct virtio_device *dev) > >> { > >> int ret = dev->config->finalize_features(dev); > >> @@ -179,6 +184,10 @@ int virtio_finalize_features(struct virtio_device *dev) > >> if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) > >> return 0; > >> > >> + if (arch_needs_iommu_platform(dev) && > >> + !virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) > >> + return -EIO; > >> + > > > > Why EIO? > > Because I/O can not occur correctly? > I am open to suggestions. We use -ENODEV if feature when the device rejects the features we tried to negotiate (see virtio_finalize_features()) and -EINVAL when the F_VERSION_1 and the virtio-ccw revision ain't coherent (in virtio_ccw_finalize_features()). Any of those seems more fitting that EIO to me. BTW does the error code itself matter in any way, or is it just OK vs some error? Regards, Halil