Re: [PATCH v6 17/25] iommu/qcom_iommu: Add an IOMMU_IDENTITIY_DOMAIN

[Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx>]

On 2023/8/3 8:08, Jason Gunthorpe wrote:
> This brings back the ops->detach_dev() code that commit
> 1b932ceddd19 ("iommu: Remove detach_dev callbacks") deleted and turns it
> into an IDENTITY domain.
>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> ---
>   drivers/iommu/arm/arm-smmu/qcom_iommu.c | 39 +++++++++++++++++++++++++
>   1 file changed, 39 insertions(+)
>
> diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> index a503ed758ec302..9d7b9d8b4386d4 100644
> --- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> +++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> @@ -387,6 +387,44 @@ static int qcom_iommu_attach_dev(struct iommu_domain *domain, struct device *dev
>   	return 0;
>   }
>   
> +static int qcom_iommu_identity_attach(struct iommu_domain *identity_domain,
> +				      struct device *dev)
> +{
> +	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
> +	struct qcom_iommu_domain *qcom_domain;
> +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> +	struct qcom_iommu_dev *qcom_iommu = to_iommu(dev);
> +	unsigned int i;
> +
> +	if (domain == identity_domain || !domain)
> +		return 0;
> +
> +	qcom_domain = to_qcom_iommu_domain(domain);
> +	if (WARN_ON(!qcom_domain->iommu))
> +		return -EINVAL;
> +
> +	pm_runtime_get_sync(qcom_iommu->dev);
> +	for (i = 0; i < fwspec->num_ids; i++) {
> +		struct qcom_iommu_ctx *ctx = to_ctx(qcom_domain, fwspec->ids[i]);
> +
> +		/* Disable the context bank: */
> +		iommu_writel(ctx, ARM_SMMU_CB_SCTLR, 0);
> +
> +		ctx->domain = NULL;

Does setting ctx->domain to NULL still match this semantics?

> +	}
> +	pm_runtime_put_sync(qcom_iommu->dev);
> +	return 0;
> +}
> +
> +static struct iommu_domain_ops qcom_iommu_identity_ops = {
> +	.attach_dev = qcom_iommu_identity_attach,
> +};
> +
> +static struct iommu_domain qcom_iommu_identity_domain = {
> +	.type = IOMMU_DOMAIN_IDENTITY,
> +	.ops = &qcom_iommu_identity_ops,
> +};
> +
>   static int qcom_iommu_map(struct iommu_domain *domain, unsigned long iova,
>   			  phys_addr_t paddr, size_t pgsize, size_t pgcount,
>   			  int prot, gfp_t gfp, size_t *mapped)
> @@ -553,6 +591,7 @@ static int qcom_iommu_of_xlate(struct device *dev, struct of_phandle_args *args)
>   }
>   
>   static const struct iommu_ops qcom_iommu_ops = {
> +	.identity_domain = &qcom_iommu_identity_domain,
>   	.capable	= qcom_iommu_capable,
>   	.domain_alloc	= qcom_iommu_domain_alloc,
>   	.probe_device	= qcom_iommu_probe_device,

Anyway,

Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Best regards,
baolu