Re: [PATCH v4 3/3] iommu/tegra-smmu: Add PCI support

From: Thierry Reding <thierry.reding@gmail.com>
To: Nicolin Chen <nicoleotsuka@gmail.com>
Cc: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	jonathanh@nvidia.com, linux-tegra@vger.kernel.org,
	digetx@gmail.com
Subject: Re: [PATCH v4 3/3] iommu/tegra-smmu: Add PCI support
Date: Mon, 5 Oct 2020 12:04:19 +0200	[thread overview]
Message-ID: <20201005100419.GK425362@ulmo> (raw)
In-Reply-To: <20201002060807.32138-4-nicoleotsuka@gmail.com>

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On Thu, Oct 01, 2020 at 11:08:07PM -0700, Nicolin Chen wrote:
> This patch simply adds support for PCI devices.
> 
> Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
> ---
> 
> Changelog
> v3->v4
>  * Dropped !iommu_present() check
>  * Added CONFIG_PCI check in the exit path
> v2->v3
>  * Replaced ternary conditional operator with if-else in .device_group()
>  * Dropped change in tegra_smmu_remove()
> v1->v2
>  * Added error-out labels in tegra_smmu_probe()
>  * Dropped pci_request_acs() since IOMMU core would call it.
> 
>  drivers/iommu/tegra-smmu.c | 37 +++++++++++++++++++++++++++----------
>  1 file changed, 27 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> index 02d02b0c55c4..b701a7b55e84 100644
> --- a/drivers/iommu/tegra-smmu.c
> +++ b/drivers/iommu/tegra-smmu.c
> @@ -10,6 +10,7 @@
>  #include <linux/kernel.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/pci.h>
>  #include <linux/platform_device.h>
>  #include <linux/slab.h>
>  #include <linux/spinlock.h>
> @@ -865,7 +866,11 @@ static struct iommu_group *tegra_smmu_device_group(struct device *dev)
>  	group->smmu = smmu;
>  	group->soc = soc;
>  
> -	group->group = iommu_group_alloc();
> +	if (dev_is_pci(dev))
> +		group->group = pci_device_group(dev);
> +	else
> +		group->group = generic_device_group(dev);
> +
>  	if (IS_ERR(group->group)) {
>  		devm_kfree(smmu->dev, group);
>  		mutex_unlock(&smmu->lock);
> @@ -1069,22 +1074,32 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
>  	iommu_device_set_fwnode(&smmu->iommu, dev->fwnode);
>  
>  	err = iommu_device_register(&smmu->iommu);
> -	if (err) {
> -		iommu_device_sysfs_remove(&smmu->iommu);
> -		return ERR_PTR(err);
> -	}
> +	if (err)
> +		goto err_sysfs;
>  
>  	err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
> -	if (err < 0) {
> -		iommu_device_unregister(&smmu->iommu);
> -		iommu_device_sysfs_remove(&smmu->iommu);
> -		return ERR_PTR(err);
> -	}
> +	if (err < 0)
> +		goto err_unregister;
> +
> +#ifdef CONFIG_PCI
> +	err = bus_set_iommu(&pci_bus_type, &tegra_smmu_ops);
> +	if (err < 0)
> +		goto err_bus_set;
> +#endif
>  
>  	if (IS_ENABLED(CONFIG_DEBUG_FS))
>  		tegra_smmu_debugfs_init(smmu);
>  
>  	return smmu;
> +
> +err_bus_set: __maybe_unused;
> +	bus_set_iommu(&platform_bus_type, NULL);
> +err_unregister:
> +	iommu_device_unregister(&smmu->iommu);
> +err_sysfs:
> +	iommu_device_sysfs_remove(&smmu->iommu);

Can you please switch to label names that are more consistent with the
others in this driver? Notably the ones in tegra_smmu_domain_alloc().
The idea is to describe in the name of the label what's happening at the
label. Something like this, for example:

unset_platform_bus:
	bus_set_iommu(&platform_bus_type, NULL);
unregister:
	iommu_device_unregister(&smmu->iommu);
remove_sysfs:
	iommu_device_sysfs_remove(&smmu->iommu);

Thierry

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