From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     Nicolin Chen <nicolinc@nvidia.com>,
        "jgg@nvidia.com" <jgg@nvidia.com>,
        "joro@8bytes.org" <joro@8bytes.org>,
        "will@kernel.org" <will@kernel.org>,
        "robin.murphy@arm.com" <robin.murphy@arm.com>,
        "alex.williamson@redhat.com" <alex.williamson@redhat.com>,
        "shuah@kernel.org" <shuah@kernel.org>
CC:     "Liu, Yi L" <yi.l.liu@intel.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "iommu@lists.linux.dev" <iommu@lists.linux.dev>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>,
        "baolu.lu@linux.intel.com" <baolu.lu@linux.intel.com>
Subject: RE: [PATCH v2 02/10] iommu: Introduce a new
 iommu_group_replace_domain() API
Thread-Topic: [PATCH v2 02/10] iommu: Introduce a new
 iommu_group_replace_domain() API
Thread-Index: AQHZOzoL2+M6IjP2sU+QmVuzFLJejK7F7DaQ
Date:   Thu, 9 Feb 2023 02:55:24 +0000
Message-ID: <BN9PR11MB5276859C11057878722F30988CD99@BN9PR11MB5276.namprd11.prod.outlook.com>
References: <cover.1675802050.git.nicolinc@nvidia.com>
 <fa81379dca611c1d9f50f9d8cd2bca0d4ec7f965.1675802050.git.nicolinc@nvidia.com>
In-Reply-To: <fa81379dca611c1d9f50f9d8cd2bca0d4ec7f965.1675802050.git.nicolinc@nvidia.com>
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> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Wednesday, February 8, 2023 5:18 AM
>=20
> +int iommu_group_replace_domain(struct iommu_group *group,
> +			       struct iommu_domain *new_domain)
> +{
> +	int ret;
> +
> +	if (!new_domain)
> +		return -EINVAL;

Is there value of allowing NULL new domain so this plays like
iommu_detach_group() then iommufd only needs call one
function in both attach/detach path?

> +
> +	mutex_lock(&group->mutex);
> +	ret =3D __iommu_group_set_domain(group, new_domain);
> +	if (ret)
> +		__iommu_group_set_domain(group, group->domain);
> +	mutex_unlock(&group->mutex);
> +	return ret;
> +}
> +EXPORT_SYMBOL_NS_GPL(iommu_group_replace_domain,
> IOMMUFD_INTERNAL);
> +
>  static int iommu_group_do_set_platform_dma(struct device *dev, void
> *data)
>  {
>  	const struct iommu_ops *ops =3D dev_iommu_ops(dev);
> --
> 2.39.1
>=20