linux-kernel - Re: [PATCH v7 4/5] iommu: Use EINVAL for incompatible device/domain in ->attach

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Message-ID: <20221107152645.GD21002@willie-the-truck>
Date:   Mon, 7 Nov 2022 15:26:45 +0000
From:   Will Deacon <will@...nel.org>
To:     Nicolin Chen <nicolinc@...dia.com>
Cc:     joro@...tes.org, robin.murphy@....com, jgg@...dia.com,
        kevin.tian@...el.com, quic_jjohnson@...cinc.com,
        suravee.suthikulpanit@....com, robdclark@...il.com,
        dwmw2@...radead.org, baolu.lu@...ux.intel.com,
        yong.wu@...iatek.com, matthias.bgg@...il.com, orsonzhai@...il.com,
        baolin.wang@...ux.alibaba.com, zhang.lyra@...il.com,
        thierry.reding@...il.com, vdumpa@...dia.com, jonathanh@...dia.com,
        jean-philippe@...aro.org, tglx@...utronix.de,
        shameerali.kolothum.thodi@...wei.com,
        christophe.jaillet@...adoo.fr, yangyicong@...ilicon.com,
        yangyingliang@...wei.com, quic_saipraka@...cinc.com,
        jon@...id-run.com, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        linux-tegra@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v7 4/5] iommu: Use EINVAL for incompatible device/domain
 in ->attach_dev

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@...aro.org>
> Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>
> Reviewed-by: Kevin Tian <kevin.tian@...el.com>
> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
> Signed-off-by: Nicolin Chen <nicolinc@...dia.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@...nel.org>

Will