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Mon, 7 Sep 2020 22:37:17 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4E9964C073; Mon, 7 Sep 2020 22:37:16 +0000 (GMT) Received: from oc2783563651 (unknown [9.145.173.93]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 7 Sep 2020 22:37:16 +0000 (GMT) Date: Tue, 8 Sep 2020 00:37:14 +0200 From: Halil Pasic 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.dropbear.id.au, linuxram@us.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com Subject: Re: [PATCH v11 2/2] s390: virtio: PV needs VIRTIO I/O device protection Message-ID: <20200908003714.6233107d.pasic@linux.ibm.com> In-Reply-To: <1599471547-28631-3-git-send-email-pmorel@linux.ibm.com> References: <1599471547-28631-1-git-send-email-pmorel@linux.ibm.com> <1599471547-28631-3-git-send-email-pmorel@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-09-07_11:2020-09-07,2020-09-07 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 malwarescore=0 mlxscore=0 clxscore=1015 spamscore=0 lowpriorityscore=0 priorityscore=1501 mlxlogscore=999 suspectscore=0 adultscore=0 impostorscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009070218 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, 7 Sep 2020 11:39:07 +0200 Pierre Morel wrote: > If protected virtualization is active on s390, VIRTIO has only retricted > access to the guest memory. > Define CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS and export > arch_has_restricted_virtio_memory_access to advertize VIRTIO if that's > the case, preventing a host error on access attempt. The description is a little inaccurate, but I don't care hence the r-b. The function arch_has_restricted_virtio_memory_access() returning true can not prevent the host from attempting to access memory if it decides to do so. And as far as I know there was no host error on access attempt. The page gets exported, and the host will operate on the encrypted page. But in the end we do run into trouble, which is usually fatal for the guest (not the host). What we actually do here is the following. If we detect an ill configured device we fail it (device status field), because attempting to drive it is a recipe for disaster. > > Signed-off-by: Pierre Morel > Reviewed-by: Cornelia Huck Reviewed-by: Halil Pasic