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Re: [PATCH 1/2] iommu/tegra: Add support for struct iommu_device

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  Re: [PATCH 1/2] iommu/tegra: Add support for struct iommu_device Jon Hunter <jonathanh@nvidia.com> - 2017-08-30 13:10 +0200
    Re: [PATCH 1/2] iommu/tegra: Add support for struct iommu_device Joerg Roedel <joro@8bytes.org> - 2017-08-30 14:10 +0200
      Re: [PATCH 1/2] iommu/tegra: Add support for struct iommu_device Jon Hunter <jonathanh@nvidia.com> - 2017-08-30 16:30 +0200
        Re: [PATCH 1/2] iommu/tegra: Add support for struct iommu_device Joerg Roedel <joro@8bytes.org> - 2017-08-30 17:40 +0200
          Re: [PATCH 1/2] iommu/tegra: Add support for struct iommu_device Jon Hunter <jonathanh@nvidia.com> - 2017-08-30 19:00 +0200
          Re: [PATCH 1/2] iommu/tegra: Add support for struct iommu_device Jon Hunter <jonathanh@nvidia.com> - 2017-08-31 12:30 +0200

#1723205 — Re: [PATCH 1/2] iommu/tegra: Add support for struct iommu_device

On 09/08/17 23:29, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
> 
> Add a struct iommu_device to each tegra-smmu and register it
> with the iommu-core. Also link devices added to the driver
> to their respective hardware iommus.
> 
> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
>  drivers/iommu/tegra-smmu.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> index faa9c1e..2802e12 100644
> --- a/drivers/iommu/tegra-smmu.c
> +++ b/drivers/iommu/tegra-smmu.c
> @@ -36,6 +36,8 @@ struct tegra_smmu {
>  	struct list_head list;
>  
>  	struct dentry *debugfs;
> +
> +	struct iommu_device iommu;	/* IOMMU Core code handle */
>  };
>  
>  struct tegra_smmu_as {
> @@ -720,6 +722,9 @@ static int tegra_smmu_add_device(struct device *dev)
>  			 * first match.
>  			 */
>  			dev->archdata.iommu = smmu;
> +
> +			iommu_device_link(&smmu->iommu, dev);
> +
>  			break;
>  		}
>  
> @@ -737,6 +742,11 @@ static int tegra_smmu_add_device(struct device *dev)
>  
>  static void tegra_smmu_remove_device(struct device *dev)
>  {
> +	struct tegra_smmu *smmu = dev->archdata.iommu;
> +
> +	if (smmu)
> +		iommu_device_unlink(&smmu->iommu, dev);
> +
>  	dev->archdata.iommu = NULL;
>  	iommu_group_remove_device(dev);
>  }
> @@ -943,6 +953,18 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
>  	if (err < 0)
>  		return ERR_PTR(err);
>  
> +	err = iommu_device_sysfs_add(&smmu->iommu, dev, NULL, dev_name(dev));
> +	if (err)
> +		return ERR_PTR(err);
> +
> +	iommu_device_set_ops(&smmu->iommu, &tegra_smmu_ops);
> +
> +	err = iommu_device_register(&smmu->iommu);
> +	if (err) {
> +		iommu_device_sysfs_remove(&smmu->iommu);
> +		return ERR_PTR(err);
> +	}
> +
>  	if (IS_ENABLED(CONFIG_DEBUG_FS))
>  		tegra_smmu_debugfs_init(smmu);
>  
> @@ -951,6 +973,9 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
>  
>  void tegra_smmu_remove(struct tegra_smmu *smmu)
>  {
> +	iommu_device_unregister(&smmu->iommu);
> +	iommu_device_sysfs_remove(&smmu->iommu);
> +
>  	if (IS_ENABLED(CONFIG_DEBUG_FS))
>  		tegra_smmu_debugfs_exit(smmu);
>  }
> 

With next-20170829 I am seeing several Tegra boards crashing [0][1] on
boot in tegra_smmu_probe() and the bisect is point to this commit. Looks
like there maybe a sequence problem between calls to bus_set_iommu() and
iommu_device_add_sysfs() which results in a NULL pointer dereference.

You can see the full crash log here [1].

Cheers
Jon

[0] https://nvtb.github.io//linux-next/
[1]
https://nvtb.github.io//linux-next/test_next-20170829/20170829024534/boot/tegra124-jetson-tk1/tegra124-jetson-tk1/tegra_defconfig_log.txt

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#1723239

Hi Jon,

On Wed, Aug 30, 2017 at 12:04:38PM +0100, Jon Hunter wrote:
> With next-20170829 I am seeing several Tegra boards crashing [0][1] on
> boot in tegra_smmu_probe() and the bisect is point to this commit. Looks
> like there maybe a sequence problem between calls to bus_set_iommu() and
> iommu_device_add_sysfs() which results in a NULL pointer dereference.

Thanks for the report. Can you please test whether the patch below
fixes the problem?

Thanks,

	Joerg

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 2802e12e6a54..48ffbe95a663 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -949,10 +949,6 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
 
 	tegra_smmu_ahb_enable();
 
-	err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
-	if (err < 0)
-		return ERR_PTR(err);
-
 	err = iommu_device_sysfs_add(&smmu->iommu, dev, NULL, dev_name(dev));
 	if (err)
 		return ERR_PTR(err);
@@ -965,6 +961,10 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
 		return ERR_PTR(err);
 	}
 
+	err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
+	if (err < 0)
+		return ERR_PTR(err);
+
 	if (IS_ENABLED(CONFIG_DEBUG_FS))
 		tegra_smmu_debugfs_init(smmu);
 

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#1723386

Hi Joerg,

On 30/08/17 13:09, Joerg Roedel wrote:
> Hi Jon,
> 
> On Wed, Aug 30, 2017 at 12:04:38PM +0100, Jon Hunter wrote:
>> With next-20170829 I am seeing several Tegra boards crashing [0][1] on
>> boot in tegra_smmu_probe() and the bisect is point to this commit. Looks
>> like there maybe a sequence problem between calls to bus_set_iommu() and
>> iommu_device_add_sysfs() which results in a NULL pointer dereference.
> 
> Thanks for the report. Can you please test whether the patch below
> fixes the problem?
> 
> Thanks,
> 
> 	Joerg
> 
> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> index 2802e12e6a54..48ffbe95a663 100644
> --- a/drivers/iommu/tegra-smmu.c
> +++ b/drivers/iommu/tegra-smmu.c
> @@ -949,10 +949,6 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
>  
>  	tegra_smmu_ahb_enable();
>  
> -	err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
> -	if (err < 0)
> -		return ERR_PTR(err);
> -
>  	err = iommu_device_sysfs_add(&smmu->iommu, dev, NULL, dev_name(dev));
>  	if (err)
>  		return ERR_PTR(err);
> @@ -965,6 +961,10 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
>  		return ERR_PTR(err);
>  	}
>  
> +	err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
> +	if (err < 0)
> +		return ERR_PTR(err);
> +

Yes I can confirm that this fixes the crash. I assume that you will fix
the error path for bus_set_iommu() above as I believe now it needs to
call iommu_device_sysfs_remove().

Cheers!
Jon

-- 
nvpublic

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#1723463

Hi Jon,

On Wed, Aug 30, 2017 at 03:22:05PM +0100, Jon Hunter wrote:
> Yes I can confirm that this fixes the crash. I assume that you will fix
> the error path for bus_set_iommu() above as I believe now it needs to
> call iommu_device_sysfs_remove().

Thanks for testing the patch. I updated the error-path and put the
commit below into the iommu-tree:

From 96302d89a03524e04d46ec82c6730881bb755923 Mon Sep 17 00:00:00 2001
From: Joerg Roedel <jroedel@suse.de>
Date: Wed, 30 Aug 2017 15:06:43 +0200
Subject: [PATCH] arm/tegra: Call bus_set_iommu() after iommu_device_register()

The bus_set_iommu() function will call the add_device()
call-back which needs the iommu to be registered.

Reported-by: Jon Hunter <jonathanh@nvidia.com>
Fixes: 0b480e447006 ('iommu/tegra: Add support for struct iommu_device')
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/tegra-smmu.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 2802e12e6a54..3b6449e2cbf1 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -949,10 +949,6 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
 
 	tegra_smmu_ahb_enable();
 
-	err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
-	if (err < 0)
-		return ERR_PTR(err);
-
 	err = iommu_device_sysfs_add(&smmu->iommu, dev, NULL, dev_name(dev));
 	if (err)
 		return ERR_PTR(err);
@@ -965,6 +961,13 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
 		return ERR_PTR(err);
 	}
 
+	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 (IS_ENABLED(CONFIG_DEBUG_FS))
 		tegra_smmu_debugfs_init(smmu);
 
-- 
2.13.5

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#1723502

On 30/08/17 16:30, Joerg Roedel wrote:
> Hi Jon,
> 
> On Wed, Aug 30, 2017 at 03:22:05PM +0100, Jon Hunter wrote:
>> Yes I can confirm that this fixes the crash. I assume that you will fix
>> the error path for bus_set_iommu() above as I believe now it needs to
>> call iommu_device_sysfs_remove().
> 
> Thanks for testing the patch. I updated the error-path and put the
> commit below into the iommu-tree:
Great! Thanks, Jon

-- 
nvpublic

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#1724082

Hi Joerg,

On 30/08/17 16:30, Joerg Roedel wrote:
> Hi Jon,
> 
> On Wed, Aug 30, 2017 at 03:22:05PM +0100, Jon Hunter wrote:
>> Yes I can confirm that this fixes the crash. I assume that you will fix
>> the error path for bus_set_iommu() above as I believe now it needs to
>> call iommu_device_sysfs_remove().
> 
> Thanks for testing the patch. I updated the error-path and put the
> commit below into the iommu-tree:
Today's -next is still failing and I don't see this fix in your public
tree yet [0]. Can you push this out?

Cheers
Jon

[0] https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git/

-- 
nvpublic

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