From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2A494C61DA4 for ; Thu, 9 Mar 2023 10:44:31 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1paDkb-0008B6-BW; Thu, 09 Mar 2023 05:43:57 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1paDka-0008Ao-2V for qemu-devel@nongnu.org; Thu, 09 Mar 2023 05:43:56 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1paDkY-0000aV-FG for qemu-devel@nongnu.org; Thu, 09 Mar 2023 05:43:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1678358632; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4LbPNDz/A2letSB/0ETL2iW7R/GejqNgSANH0zkTZSM=; b=I4A2KuKXjuRNyx54sIVutuhJR2U45SQnYPDIiDsrC1bfoF33+dsd0KoRNSaOOLZEje/WrN UokFH6yNGaPUtTq9/KjMipJChKuwUbc98l853WWSflszR6Qxh2Faw49ROUKa414ijSAWLr P/2NYxIu5dV4BUV8+OStpFlA/V+2yWc= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-553-px_opmpON3mpv-Ne5LGNtQ-1; Thu, 09 Mar 2023 05:43:49 -0500 X-MC-Unique: px_opmpON3mpv-Ne5LGNtQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E043D8588E0; Thu, 9 Mar 2023 10:43:48 +0000 (UTC) Received: from localhost (dhcp-192-239.str.redhat.com [10.33.192.239]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 62E261121314; Thu, 9 Mar 2023 10:43:48 +0000 (UTC) From: Cornelia Huck To: Carlos =?utf-8?Q?L=C3=B3pez?= , qemu-devel@nongnu.org Cc: Carlos =?utf-8?Q?L=C3=B3pez?= , Halil Pasic , Eric Farman , "Michael S. Tsirkin" , Richard Henderson , David Hildenbrand , Ilya Leoshkevich , Christian Borntraeger , Thomas Huth , "open list:virtio-ccw" Subject: Re: [PATCH] virtio: refresh vring region cache after updating a virtqueue size In-Reply-To: <20230302101447.4499-1-clopez@suse.de> Organization: Red Hat GmbH References: <20230302101447.4499-1-clopez@suse.de> User-Agent: Notmuch/0.37 (https://notmuchmail.org) Date: Thu, 09 Mar 2023 11:43:46 +0100 Message-ID: <875ybajjbx.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Received-SPF: pass client-ip=170.10.129.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Mar 02 2023, Carlos L=C3=B3pez wrote: > When a virtqueue size is changed by the guest via > virtio_queue_set_num(), its region cache is not automatically updated. > If the size was increased, this could lead to accessing the cache out > of bounds. For example, in vring_get_used_event(): > > static inline uint16_t vring_get_used_event(VirtQueue *vq) > { > return vring_avail_ring(vq, vq->vring.num); > } > > static inline uint16_t vring_avail_ring(VirtQueue *vq, int i) > { > VRingMemoryRegionCaches *caches =3D vring_get_region_caches(vq); > hwaddr pa =3D offsetof(VRingAvail, ring[i]); > > if (!caches) { > return 0; > } > > return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa); > } > > vq->vring.num will be greater than caches->avail.len, which will > trigger a failed assertion down the call path of > virtio_lduw_phys_cached(). > > Fix this by calling virtio_queue_update_rings() after > virtio_queue_set_num() if we are not already calling > virtio_queue_set_rings(). Don't we instead need to call virtio_init_region_cache() to update the caches? virtio_queue_set_rings() will calculate avail and used from desc, which looks wrong for modern devices. > > Signed-off-by: Carlos L=C3=B3pez > --- > hw/s390x/virtio-ccw.c | 1 + > hw/virtio/virtio-mmio.c | 5 ++--- > hw/virtio/virtio-pci.c | 1 + > 3 files changed, 4 insertions(+), 3 deletions(-) > > diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c > index e33e5207ab..89891ac58a 100644 > --- a/hw/s390x/virtio-ccw.c > +++ b/hw/s390x/virtio-ccw.c > @@ -237,6 +237,7 @@ static int virtio_ccw_set_vqs(SubchDev *sch, VqInfoBl= ock *info, > return -EINVAL; > } > virtio_queue_set_num(vdev, index, num); > + virtio_queue_update_rings(vdev, index); Note that this is the non-legacy path. > } else if (virtio_queue_get_num(vdev, index) > num) { > /* Fail if we don't have a big enough queue. */ > return -EINVAL; > diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c > index 23ba625eb6..c74822308f 100644 > --- a/hw/virtio/virtio-mmio.c > +++ b/hw/virtio/virtio-mmio.c > @@ -350,10 +350,9 @@ static void virtio_mmio_write(void *opaque, hwaddr o= ffset, uint64_t value, > case VIRTIO_MMIO_QUEUE_NUM: > trace_virtio_mmio_queue_write(value, VIRTQUEUE_MAX_SIZE); > virtio_queue_set_num(vdev, vdev->queue_sel, value); > + virtio_queue_update_rings(vdev, vdev->queue_sel); >=20=20 > - if (proxy->legacy) { > - virtio_queue_update_rings(vdev, vdev->queue_sel); > - } else { > + if (!proxy->legacy) { > proxy->vqs[vdev->queue_sel].num =3D value; > } > break; > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > index 247325c193..a0a2f2c965 100644 > --- a/hw/virtio/virtio-pci.c > +++ b/hw/virtio/virtio-pci.c > @@ -1554,6 +1554,7 @@ static void virtio_pci_common_write(void *opaque, h= waddr addr, > proxy->vqs[vdev->queue_sel].num =3D val; > virtio_queue_set_num(vdev, vdev->queue_sel, > proxy->vqs[vdev->queue_sel].num); > + virtio_queue_update_rings(vdev, vdev->queue_sel); > break; > case VIRTIO_PCI_COMMON_Q_MSIX: > vector =3D virtio_queue_vector(vdev, vdev->queue_sel);