Re: [PATCH v2 2/4] virtio-iommu: Default to bypass during boot

[Cornelia Huck]

On Thu, Jan 27 2022, Jean-Philippe Brucker <jean-philippe@linaro.org> wrote:

> @@ -988,9 +1025,9 @@ static void virtio_iommu_device_realize(DeviceState 
> *dev, Error **errp)
>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_INPUT_RANGE);
>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_DOMAIN_RANGE);
>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_MAP_UNMAP);
> -    virtio_add_feature(&s->features, VIRTIO_IOMMU_F_BYPASS);
>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_MMIO);
>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_PROBE);
> +    virtio_add_feature(&s->features, VIRTIO_IOMMU_F_BYPASS_CONFIG);

Hm. In the other patch, you say that you don't support cross-version
migration (I assume across QEMU versions?) Because changing the feature
set will be guest-visible, and would need some compat handling if you
plan to support this.