From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44906) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZXmle-0006MP-HR for qemu-devel@nongnu.org; Fri, 04 Sep 2015 04:54:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZXmlb-0002nF-1Y for qemu-devel@nongnu.org; Fri, 04 Sep 2015 04:54:42 -0400 Received: from e06smtp12.uk.ibm.com ([195.75.94.108]:42766) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZXmla-0002mP-OR for qemu-devel@nongnu.org; Fri, 04 Sep 2015 04:54:38 -0400 Received: from /spool/local by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 4 Sep 2015 09:54:37 +0100 Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 0FE372190069 for ; Fri, 4 Sep 2015 09:54:07 +0100 (BST) Received: from d06av12.portsmouth.uk.ibm.com (d06av12.portsmouth.uk.ibm.com [9.149.37.247]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t848sYq735520748 for ; Fri, 4 Sep 2015 08:54:34 GMT Received: from d06av12.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av12.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t848sXRQ006435 for ; Fri, 4 Sep 2015 02:54:34 -0600 From: Cornelia Huck Date: Fri, 4 Sep 2015 10:54:28 +0200 Message-Id: <1441356869-57861-4-git-send-email-cornelia.huck@de.ibm.com> In-Reply-To: <1441356869-57861-1-git-send-email-cornelia.huck@de.ibm.com> References: <1441356869-57861-1-git-send-email-cornelia.huck@de.ibm.com> Subject: [Qemu-devel] [PATCH 3/4] virtio-ccw: feature bits > 31 handling List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Cornelia Huck , borntraeger@de.ibm.com, jasowang@redhat.com, mst@redhat.com We currently switch off the VERSION_1 feature bit if the guest has not negotiated at least revision 1. As no feature bits beyond 31 are valid however unless VERSION_1 has been negotiated, make sure that legacy guests never see a feature bit beyond 31. Signed-off-by: Cornelia Huck --- hw/s390x/virtio-ccw.c | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-) diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c index 85e2a5d..eed7b3e 100644 --- a/hw/s390x/virtio-ccw.c +++ b/hw/s390x/virtio-ccw.c @@ -468,15 +468,12 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw) NULL); if (features.index == 0) { features.features = (uint32_t)vdev->host_features; - } else if (features.index == 1) { - features.features = (uint32_t)(vdev->host_features >> 32); + } else if ((features.index == 1) && (dev->revision >= 1)) { /* - * Don't offer version 1 to the guest if it did not - * negotiate at least revision 1. + * Only offer feature bits beyond 31 if the guest has + * negotiated at least revision 1. */ - if (dev->revision <= 0) { - features.features &= ~(1 << (VIRTIO_F_VERSION_1 - 32)); - } + features.features = (uint32_t)(vdev->host_features >> 32); } else { /* Return zeroes if the guest supports more feature bits. */ features.features = 0; @@ -515,14 +512,12 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw) virtio_set_features(vdev, (vdev->guest_features & 0xffffffff00000000ULL) | features.features); - } else if (features.index == 1) { + } else if ((features.index == 1) && (dev->revision >= 1)) { /* - * The guest should not set version 1 if it didn't - * negotiate a revision >= 1. + * If the guest did not negotiate at least revision 1, + * we did not offer it any feature bits beyond 31. Such a + * guest passing us any bit here is therefore buggy. */ - if (dev->revision <= 0) { - features.features &= ~(1 << (VIRTIO_F_VERSION_1 - 32)); - } virtio_set_features(vdev, (vdev->guest_features & 0x00000000ffffffffULL) | ((uint64_t)features.features << 32)); -- 2.3.8