[PATCH v7 4/5] iommu: Use EINVAL for incompatible device/domain in ->attach_dev

[Will Deacon]

On Mon, Oct 17, 2022 at 04:02:21PM -0700, Nicolin Chen wrote:
> Following the new rules in include/linux/iommu.h kdocs, update all drivers
> ->attach_dev callback functions to return EINVAL in the failure paths that
> are related to domain incompatibility.
> 
> Also, drop adjacent error prints to prevent a kernel log spam.
> 
> Reviewed-by: Jean-Philippe Brucker <jean-philippe at linaro.org>
> Reviewed-by: Lu Baolu <baolu.lu at linux.intel.com>
> Reviewed-by: Kevin Tian <kevin.tian at intel.com>
> Reviewed-by: Jason Gunthorpe <jgg at nvidia.com>
> Signed-off-by: Nicolin Chen <nicolinc at nvidia.com>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 11 +----------
>  drivers/iommu/arm/arm-smmu/arm-smmu.c       |  3 ---
>  drivers/iommu/arm/arm-smmu/qcom_iommu.c     |  7 +------
>  drivers/iommu/intel/iommu.c                 | 10 +++-------
>  drivers/iommu/ipmmu-vmsa.c                  |  2 --
>  drivers/iommu/omap-iommu.c                  |  2 +-
>  drivers/iommu/sprd-iommu.c                  |  4 +---
>  drivers/iommu/tegra-gart.c                  |  2 +-
>  drivers/iommu/virtio-iommu.c                |  3 +--
>  9 files changed, 9 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index ba47c73f5b8c..01fd7df16cb9 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2430,23 +2430,14 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
>  			goto out_unlock;
>  		}
>  	} else if (smmu_domain->smmu != smmu) {
> -		dev_err(dev,
> -			"cannot attach to SMMU %s (upstream of %s)\n",
> -			dev_name(smmu_domain->smmu->dev),
> -			dev_name(smmu->dev));
> -		ret = -ENXIO;
> +		ret = -EINVAL;
>  		goto out_unlock;
>  	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
>  		   master->ssid_bits != smmu_domain->s1_cfg.s1cdmax) {
> -		dev_err(dev,
> -			"cannot attach to incompatible domain (%u SSID bits != %u)\n",
> -			smmu_domain->s1_cfg.s1cdmax, master->ssid_bits);
>  		ret = -EINVAL;
>  		goto out_unlock;
>  	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
>  		   smmu_domain->stall_enabled != master->stall_enabled) {
> -		dev_err(dev, "cannot attach to stall-%s domain\n",
> -			smmu_domain->stall_enabled ? "enabled" : "disabled");
>  		ret = -EINVAL;
>  		goto out_unlock;
>  	}

I think it would be helpful to preserve these messages using
dev_err_ratelimited() so that attach failure can be diagnosed without
having to hack the messages back into the driver.

With that:

Acked-by: Will Deacon <will at kernel.org>

Will