From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:48326 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726560AbgFJOiH (ORCPT ); Wed, 10 Jun 2020 10:38:07 -0400 Subject: Re: [PATCH] s390: protvirt: virtio: Refuse device without IOMMU References: <1591794711-5915-1-git-send-email-pmorel@linux.ibm.com> <20200610152431.358fded7.cohuck@redhat.com> From: Pierre Morel Message-ID: <54b28498-a6a7-4be2-9d2c-aef46c7fc642@linux.ibm.com> Date: Wed, 10 Jun 2020 16:37:55 +0200 MIME-Version: 1.0 In-Reply-To: <20200610152431.358fded7.cohuck@redhat.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: Cornelia Huck Cc: linux-kernel@vger.kernel.org, pasic@linux.ibm.com, borntraeger@de.ibm.com, frankja@linux.ibm.com, mst@redhat.com, jasowang@redhat.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org, virtualization@lists.linux-foundation.org On 2020-06-10 15:24, Cornelia Huck wrote: > On Wed, 10 Jun 2020 15:11:51 +0200 > Pierre Morel wrote: > >> Protected Virtualisation protects the memory of the guest and >> do not allow a the host to access all of its memory. >> >> Let's refuse a VIRTIO device which does not use IOMMU >> protected access. >> >> Signed-off-by: Pierre Morel >> --- >> drivers/s390/virtio/virtio_ccw.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c >> index 5730572b52cd..06ffbc96587a 100644 >> --- a/drivers/s390/virtio/virtio_ccw.c >> +++ b/drivers/s390/virtio/virtio_ccw.c >> @@ -986,6 +986,11 @@ static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status) >> if (!ccw) >> return; >> >> + /* Protected Virtualisation guest needs IOMMU */ >> + if (is_prot_virt_guest() && >> + !__virtio_test_bit(vdev, VIRTIO_F_IOMMU_PLATFORM)) >> + status &= ~VIRTIO_CONFIG_S_FEATURES_OK; >> + > > set_status seems like an odd place to look at features; shouldn't that > rather be done in finalize_features? Right, looks better to me too. What about: diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c index 06ffbc96587a..227676297ea0 100644 --- a/drivers/s390/virtio/virtio_ccw.c +++ b/drivers/s390/virtio/virtio_ccw.c @@ -833,6 +833,11 @@ static int virtio_ccw_finalize_features(struct virtio_device *vdev) ret = -ENOMEM; goto out_free; } + + if (is_prot_virt_guest() && + !__virtio_test_bit(vdev, VIRTIO_F_IOMMU_PLATFORM)) + return -EIO; + /* Give virtio_ring a chance to accept features. */ vring_transport_features(vdev); Thanks, Regards, Pierre -- Pierre Morel IBM Lab Boeblingen