From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 1/2] virtio: Reduce BUG if total_sg > virtqueue size to WARN. Date: Fri, 11 Aug 2017 00:41:47 +0300 Message-ID: <20170811003621-mutt-send-email-mst@kernel.org> References: <20170810164035.19963-1-rjones@redhat.com> <20170810164035.19963-2-rjones@redhat.com> <20170811001447-mutt-send-email-mst@kernel.org> <20170810213038.GC20914@redhat.com> <20170811003107-mutt-send-email-mst@kernel.org> <20170810213511.GB10017@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20170810213511.GB10017@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: "Richard W.M. Jones" Cc: jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, pbonzini@redhat.com, hch@lst.de List-Id: linux-scsi@vger.kernel.org On Thu, Aug 10, 2017 at 10:35:11PM +0100, Richard W.M. Jones wrote: > On Fri, Aug 11, 2017 at 12:31:44AM +0300, Michael S. Tsirkin wrote: > > Then we probably should fail probe if vq size is too small. > > What does this mean? > > Rich. We must prevent driver from submitting s/g lists > vq size to device. Either tell linux to avoid s/g lists that are too long, or simply fail request if this happens, or refuse to attach driver to device. Later option would look something like this within probe: for (i = VIRTIO_SCSI_VQ_BASE; i < num_vqs; i++) if (vqs[i]->num < MAX_SG_USED_BY_LINUX) goto err; I don't know what's MAX_SG_USED_BY_LINUX though. > -- > Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones > Read my programming and virtualization blog: http://rwmj.wordpress.com > virt-builder quickly builds VMs from scratch > http://libguestfs.org/virt-builder.1.html