Re: [RFC PATCH v2 14/22] iommufd: Add TIO calls

[Aneesh Kumar K.V <aneesh.kumar@kernel.org>]

Alexey Kardashevskiy <aik@amd.com> writes:

....

> +int iommufd_vdevice_tsm_bind_ioctl(struct iommufd_ucmd *ucmd)
> +{
> +	struct iommu_vdevice_tsm_bind *cmd = ucmd->cmd;
> +	struct iommufd_viommu *viommu;
> +	struct iommufd_vdevice *vdev;
> +	struct iommufd_device *idev;
> +	struct tsm_tdi *tdi;
> +	int rc = 0;
> +
> +	viommu = iommufd_get_viommu(ucmd, cmd->viommu_id);
> +	if (IS_ERR(viommu))
> +		return PTR_ERR(viommu);
>

Would this require an IOMMU_HWPT_ALLOC_NEST_PARENT page table
allocation? How would this work in cases where there's no need to set up
Stage 1 IOMMU tables?

Alternatively, should we allocate an IOMMU_HWPT_ALLOC_NEST_PARENT with a
Stage 1 disabled translation config? (In the ARM case, this could mean
marking STE entries as Stage 1 bypass and Stage 2 translate.)

Also, if a particular setup doesn't require creating IOMMU
entries because the entire guest RAM is identity-mapped in the IOMMU, do
we still need to make tsm_tdi_bind use this abstraction in iommufd?


> +
> +	idev = iommufd_get_device(ucmd, cmd->dev_id);
> +	if (IS_ERR(idev)) {
> +		rc = PTR_ERR(idev);
> +		goto out_put_viommu;
> +	}
> +
> +	vdev = container_of(iommufd_get_object(ucmd->ictx, cmd->vdevice_id,
> +					       IOMMUFD_OBJ_VDEVICE),
> +			    struct iommufd_vdevice, obj);
> +	if (IS_ERR(idev)) {
> +		rc = PTR_ERR(idev);
> +		goto out_put_dev;
> +	}
> +
> +	tdi = tsm_tdi_get(idev->dev);
> +	if (!tdi) {
> +		rc = -ENODEV;
> +		goto out_put_vdev;
> +	}
> +
> +	rc = tsm_tdi_bind(tdi, vdev->id, cmd->kvmfd);
> +	if (rc)
> +		goto out_put_tdi;
> +
> +	vdev->tsm_bound = true;
> +
> +	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
> +out_put_tdi:
> +	tsm_tdi_put(tdi);
> +out_put_vdev:
> +	iommufd_put_object(ucmd->ictx, &vdev->obj);
> +out_put_dev:
> +	iommufd_put_object(ucmd->ictx, &idev->obj);
> +out_put_viommu:
> +	iommufd_put_object(ucmd->ictx, &viommu->obj);
> +	return rc;
> +}

-aneesh