linux-kernel - RE: [PATCH v2] iommu: Check dev->iommu in iommu_dev

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Date:   Fri, 12 Feb 2021 14:54:47 +0000
From:   Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>
CC:     "joro@...tes.org" <joro@...tes.org>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "jean-philippe@...aro.org" <jean-philippe@...aro.org>,
        "will@...nel.org" <will@...nel.org>,
        "Zengtao (B)" <prime.zeng@...ilicon.com>,
        "linuxarm@...neuler.org" <linuxarm@...neuler.org>
Subject: RE: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions

Hi Robin/Joerg,

> -----Original Message-----
> From: Shameer Kolothum [mailto:shameerali.kolothum.thodi@...wei.com]
> Sent: 01 February 2021 12:41
> To: linux-kernel@...r.kernel.org; iommu@...ts.linux-foundation.org
> Cc: joro@...tes.org; robin.murphy@....com; jean-philippe@...aro.org;
> will@...nel.org; Zengtao (B) <prime.zeng@...ilicon.com>;
> linuxarm@...neuler.org
> Subject: [Linuxarm] [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx
> functions
> 
> The device iommu probe/attach might have failed leaving dev->iommu
> to NULL and device drivers may still invoke these functions resulting
> in a crash in iommu vendor driver code. Hence make sure we check that.
> 
> Also added iommu_ops to the "struct dev_iommu" and set it if the dev
> is successfully associated with an iommu.
> 
> Fixes: a3a195929d40 ("iommu: Add APIs for multiple domains per device")
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
> ---
> v1 --> v2:
>  -Added iommu_ops to struct dev_iommu based on the discussion with Robin.
>  -Rebased against iommu-tree core branch.

A gentle ping on this...

Thanks,
Shameer

> ---
>  drivers/iommu/iommu.c | 19 +++++++------------
>  include/linux/iommu.h |  2 ++
>  2 files changed, 9 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index fd76e2f579fe..6023d0b7c542 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -217,6 +217,7 @@ static int __iommu_probe_device(struct device *dev,
> struct list_head *group_list
>  	}
> 
>  	dev->iommu->iommu_dev = iommu_dev;
> +	dev->iommu->ops = iommu_dev->ops;
> 
>  	group = iommu_group_get_for_dev(dev);
>  	if (IS_ERR(group)) {
> @@ -2865,10 +2866,8 @@ EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);
>   */
>  int iommu_dev_enable_feature(struct device *dev, enum
> iommu_dev_features feat)
>  {
> -	const struct iommu_ops *ops = dev->bus->iommu_ops;
> -
> -	if (ops && ops->dev_enable_feat)
> -		return ops->dev_enable_feat(dev, feat);
> +	if (dev->iommu && dev->iommu->ops->dev_enable_feat)
> +		return dev->iommu->ops->dev_enable_feat(dev, feat);
> 
>  	return -ENODEV;
>  }
> @@ -2881,10 +2880,8 @@
> EXPORT_SYMBOL_GPL(iommu_dev_enable_feature);
>   */
>  int iommu_dev_disable_feature(struct device *dev, enum
> iommu_dev_features feat)
>  {
> -	const struct iommu_ops *ops = dev->bus->iommu_ops;
> -
> -	if (ops && ops->dev_disable_feat)
> -		return ops->dev_disable_feat(dev, feat);
> +	if (dev->iommu && dev->iommu->ops->dev_disable_feat)
> +		return dev->iommu->ops->dev_disable_feat(dev, feat);
> 
>  	return -EBUSY;
>  }
> @@ -2892,10 +2889,8 @@
> EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
> 
>  bool iommu_dev_feature_enabled(struct device *dev, enum
> iommu_dev_features feat)
>  {
> -	const struct iommu_ops *ops = dev->bus->iommu_ops;
> -
> -	if (ops && ops->dev_feat_enabled)
> -		return ops->dev_feat_enabled(dev, feat);
> +	if (dev->iommu && dev->iommu->ops->dev_feat_enabled)
> +		return dev->iommu->ops->dev_feat_enabled(dev, feat);
> 
>  	return false;
>  }
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 524ffc2ff64f..ff0c76bdfb67 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -354,6 +354,7 @@ struct iommu_fault_param {
>   * @fault_param: IOMMU detected device fault reporting data
>   * @fwspec:	 IOMMU fwspec data
>   * @iommu_dev:	 IOMMU device this device is linked to
> + * @ops:	 iommu-ops for talking to the iommu_dev
>   * @priv:	 IOMMU Driver private data
>   *
>   * TODO: migrate other per device data pointers under iommu_dev_data,
> e.g.
> @@ -364,6 +365,7 @@ struct dev_iommu {
>  	struct iommu_fault_param	*fault_param;
>  	struct iommu_fwspec		*fwspec;
>  	struct iommu_device		*iommu_dev;
> +	const struct iommu_ops		*ops;
>  	void				*priv;
>  };
> 
> --
> 2.17.1
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