On 2017年01月17日 22:44, Michael S. Tsirkin wrote:
On Tue, Jan 17, 2017 at 12:01:00PM +0800, Jason Wang wrote:We allow vhost to clear VIRITO_F_IOMMU_PLATFORM which is wrong since VIRTIO_F_IOMMU_PLATFORM is mandatory for security. Fixing this by enforce it after vdc->get_features(). Signed-off-by: Jason Wang <jasow...@redhat.com> --- hw/virtio/virtio-bus.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c index d31cc00..a886011 100644 --- a/hw/virtio/virtio-bus.c +++ b/hw/virtio/virtio-bus.c @@ -47,6 +47,7 @@ void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp) VirtioBusState *bus = VIRTIO_BUS(qbus); VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus); VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev); + bool has_iommu = virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM);DPRINTF("%s: plug device.\n", qbus->name); @@ -63,8 +64,8 @@ void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp)klass->device_plugged(qbus->parent, errp); }- if (klass->get_dma_as != NULL &&- virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) { + if (klass->get_dma_as != NULL && has_iommu) { + virtio_add_feature(&vdev->host_features, VIRTIO_F_IOMMU_PLATFORM); vdev->dma_as = klass->get_dma_as(qbus->parent); } else { vdev->dma_as = &address_space_memory;I suspect that's not enough, we must also fail or disable vhost (depending on the options), otherwise things won't work.
Looks like with the patch, VIRTIO_F_IOMMU_PLATFORM will be passed to vhost_set_features(). So if vhost backend does not support it, it will fall back to userspace (This may not work for vhost-user, but it's a bug existed even before this patch).
Thanks
