diff options
| author | Cornelia Huck <cornelia.huck@de.ibm.com> | 2015-09-11 15:16:43 +0200 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2015-09-24 13:42:17 +0300 |
| commit | b4f8f9df152fca0e79b7a3ca40a3eea700a40855 (patch) | |
| tree | 76dbd80abf6d613093e28ed7f350cc5bda016bc8 /hw | |
| parent | 79cd0c80f82215a32890e3d30ff621b32ece5156 (diff) | |
virtio-ccw: feature bits > 31 handling
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.
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw')
| -rw-r--r-- | hw/s390x/virtio-ccw.c | 21 |
1 files changed, 8 insertions, 13 deletions
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c index 85e2a5d29e..eed7b3e0f6 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)); |