From d55f518248f263bb8d0852f98e47102ea09d4f89 Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Mon, 21 Sep 2020 14:25:03 +0200 Subject: virtio: skip legacy support check on machine types less than 5.1 Commit 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on") added a check that returns an error if legacy support is on, but the device does not support legacy. Unfortunately some devices were wrongly declared legacy capable even if they were not (e.g vhost-vsock). To avoid migration issues, we add a virtio-device property (x-disable-legacy-check) to skip the legacy error, printing a warning instead, for machine types < 5.1. Cc: qemu-stable@nongnu.org Fixes: 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on") Suggested-by: Dr. David Alan Gilbert Suggested-by: Cornelia Huck Reviewed-by: Cornelia Huck Signed-off-by: Stefano Garzarella Message-Id: <20200921122506.82515-2-sgarzare@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/virtio.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'hw/virtio/virtio.c') diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 3a3d012d9f..a2edb4f386 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -3304,6 +3304,11 @@ bool virtio_legacy_allowed(VirtIODevice *vdev) } } +bool virtio_legacy_check_disabled(VirtIODevice *vdev) +{ + return vdev->disable_legacy_check; +} + hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n) { return vdev->vq[n].vring.desc; @@ -3713,6 +3718,8 @@ static Property virtio_properties[] = { DEFINE_VIRTIO_COMMON_FEATURES(VirtIODevice, host_features), DEFINE_PROP_BOOL("use-started", VirtIODevice, use_started, true), DEFINE_PROP_BOOL("use-disabled-flag", VirtIODevice, use_disabled_flag, true), + DEFINE_PROP_BOOL("x-disable-legacy-check", VirtIODevice, + disable_legacy_check, false), DEFINE_PROP_END_OF_LIST(), }; -- cgit 1.4.1 From 2d69eba5fe52045b2c8b0d04fd3806414352afc1 Mon Sep 17 00:00:00 2001 From: Li Qiang Date: Sat, 19 Sep 2020 01:27:06 -0700 Subject: virtio: update MemoryRegionCaches when guest set bad features Current the 'virtio_set_features' only update the 'MemorRegionCaches' when the 'virtio_set_features_nocheck' return '0' which means it is not bad features. However the guest can still trigger the access of the used vring after set bad features. In this situation it will cause assert failure in 'ADDRESS_SPACE_ST_CACHED'. Buglink: https://bugs.launchpad.net/qemu/+bug/1890333 Fixes: db812c4073c7 ("virtio: update MemoryRegionCaches when guest negotiates features") Reported-by: Alexander Bulekov Signed-off-by: Li Qiang Message-Id: <20200919082706.6703-1-liq3ea@163.com> Reviewed-by: Paolo Bonzini Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/virtio.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) (limited to 'hw/virtio/virtio.c') diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index a2edb4f386..6f8f865aff 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -2963,17 +2963,16 @@ int virtio_set_features(VirtIODevice *vdev, uint64_t val) return -EINVAL; } ret = virtio_set_features_nocheck(vdev, val); - if (!ret) { - if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) { - /* VIRTIO_RING_F_EVENT_IDX changes the size of the caches. */ - int i; - for (i = 0; i < VIRTIO_QUEUE_MAX; i++) { - if (vdev->vq[i].vring.num != 0) { - virtio_init_region_cache(vdev, i); - } + if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) { + /* VIRTIO_RING_F_EVENT_IDX changes the size of the caches. */ + int i; + for (i = 0; i < VIRTIO_QUEUE_MAX; i++) { + if (vdev->vq[i].vring.num != 0) { + virtio_init_region_cache(vdev, i); } } - + } + if (!ret) { if (!virtio_device_started(vdev, vdev->status) && !virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) { vdev->start_on_kick = true; -- cgit 1.4.1