On Thu, 26 Aug 2021 15:34:15 +0200
Christoph Hellwig <hch@xxxxxx> wrote:
> +#ifdef CONFIG_VFIO_NOIOMMU
> +static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev)
> {
> struct iommu_group *iommu_group;
> struct vfio_group *group;
> + int ret;
> +
> + iommu_group = iommu_group_alloc();
> + if (IS_ERR(iommu_group))
> + return ERR_CAST(iommu_group);
>
> - iommu_group = vfio_iommu_group_get(dev);
> + iommu_group_set_name(iommu_group, "vfio-noiommu");
> + iommu_group_set_iommudata(iommu_group, &noiommu, NULL);
> + ret = iommu_group_add_device(iommu_group, dev);
> + if (ret)
> + goto out_put_group;
> +
> + group = vfio_create_group(iommu_group);
> + if (IS_ERR(group)) {
> + ret = PTR_ERR(group);
> + goto out_remove_device;
> + }
> +
> + return group;
> +
> +out_remove_device:
> + iommu_group_remove_device(dev);
> +out_put_group:
> + iommu_group_put(iommu_group);
> + return ERR_PTR(ret);
> +}
> +#endif
> +
> +static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
> +{
> + struct iommu_group *iommu_group;
> + struct vfio_group *group;
> +
> + iommu_group = iommu_group_get(dev);
> +#ifdef CONFIG_VFIO_NOIOMMU
> + if (!iommu_group && noiommu && !iommu_present(dev->bus)) {
> + /*
> + * With noiommu enabled, create an IOMMU group for devices that
> + * don't already have one and don't have an iommu_ops on their
> + * bus. Taint the kernel because we're about to give a DMA
> + * capable device to a user without IOMMU protection.
> + */
> + group = vfio_noiommu_group_alloc(dev);
> + if (group) {
> + add_taint(TAINT_USER, LOCKDEP_STILL_OK);
> + dev_warn(dev, "Adding kernel taint for vfio-noiommu group on device\n");
> + }
Perhaps what Kevin was pointing out here in the previous version,
vfio_noiommu_group_alloc() returns a pointer, so this should test
!IS_ERR(group). Thanks,
Alex
