Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-30 Thread Gary R Hook 

On 04/17/2018 12:38 PM, Hook, Gary wrote:

On 4/13/2018 8:08 PM, Mehta, Sohil wrote:

On Fri, 2018-04-06 at 08:17 -0500, Gary R Hook wrote:

+
+
+    mutex_lock(_iommu_debugfs_lock);
+    if (!amd_iommu_debugfs) {
+    d_top = iommu_debugfs_setup();
+    if (d_top)
+    amd_iommu_debugfs =
debugfs_create_dir("amd", d_top);
+    }
+    mutex_unlock(_iommu_debugfs_lock);



You can do the above only once if you iterate over the IOMMUs here
  instead of doing it in amd_iommu_init.


I'm not sure it matters, given the finite number of IOMMUs in a system, 
and the fact that this work is done exactly once. However, removal of a 
lock is fine thing, so I'll move this around.


After thinking about this, and looking at the code, I've decided to 
leave this alone.


v4 is on its way.


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Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-18 Thread Yang, Shunyong 
Hi, Gary,

On Wed, 2018-04-18 at 16:51 -0400, Hook, Gary wrote:
> On 4/18/2018 4:16 PM, Mehta, Sohil wrote:
> > 
> > On Wed, 2018-04-18 at 08:31 +, Yang, Shunyong wrote:
> > > 
> > > Maybe the original design is to call debugfs_initialized() before
> > > calling debugfs_create_xxx()?
> > I am unaware of the original design. Someone else would probably
> > have
> > more context. However, looking at other places in the kernel where
> > debugfs_create_xx() is used, the common convention seems to be to
> > avoid
> > calling debugfs_initialized().
> > 
> >   Sohil
> > 
> debugfs_initialized() was introduced in commit c0f92ba99 back in 
> 2.6.30-rc1. It was intended as a helper, not as a gatekeeper, which
> is 
> why one doesn't see it used. Given that my use in this proposed patch
> is 
> straightforward, I'm not seeing the need here. I had just seen some 
> other code that used it, and copied the model.
> 
> Unless someone comes along to say, yes, use it, I'll not.
> 

I agree with you and Sohil on removing the unnecessary function
calling.

Thanks.
Shunyong.


> Gary
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Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-18 Thread Hook, Gary 

On 4/18/2018 4:16 PM, Mehta, Sohil wrote:

On Wed, 2018-04-18 at 08:31 +, Yang, Shunyong wrote:

Maybe the original design is to call debugfs_initialized() before
calling debugfs_create_xxx()?


I am unaware of the original design. Someone else would probably have
more context. However, looking at other places in the kernel where
debugfs_create_xx() is used, the common convention seems to be to avoid
calling debugfs_initialized().

  Sohil



debugfs_initialized() was introduced in commit c0f92ba99 back in 
2.6.30-rc1. It was intended as a helper, not as a gatekeeper, which is 
why one doesn't see it used. Given that my use in this proposed patch is 
straightforward, I'm not seeing the need here. I had just seen some 
other code that used it, and copied the model.


Unless someone comes along to say, yes, use it, I'll not.

Gary
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Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-18 Thread Mehta, Sohil 
On Wed, 2018-04-18 at 08:31 +, Yang, Shunyong wrote:
> Maybe the original design is to call debugfs_initialized() before
> calling debugfs_create_xxx()?

I am unaware of the original design. Someone else would probably have
more context. However, looking at other places in the kernel where
debugfs_create_xx() is used, the common convention seems to be to avoid
calling debugfs_initialized().

 Sohil
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Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-18 Thread Yang, Shunyong 
Hi, Sohil

On Wed, 2018-04-18 at 07:27 +, Mehta, Sohil wrote:
> On Wed, 2018-04-18 at 05:58 +, Yang, Shunyong wrote:
> > 
> > Hi, Gary and Sohil,
> > 
> > On Tue, 2018-04-17 at 13:38 -0400, Hook, Gary wrote:
> > > 
> > > On 4/13/2018 8:08 PM, Mehta, Sohil wrote:
> > > > 
> > > >  
> > > > On Fri, 2018-04-06 at 08:17 -0500, Gary R Hook wrote:
> > > > > 
> > > > >  
> > > > >   
> > > > > +
> > > > > +void amd_iommu_debugfs_setup(struct amd_iommu *iommu)
> > > > > +{
> > > > > + char name[MAX_NAME_LEN + 1];
> > > > > + struct dentry *d_top;
> > > > > +
> > > > > + if (!debugfs_initialized())
> > > > Probably not needed.
> > > Right.
> > When will this check is needed?
> > IMO, this function is to check debugfs ready status before we want
> > to
> > use debugfs. I just want to understand when we should use
> > debugfs_initialized();
> > 
> You are right debugfs_initialized() can be used to check if debugfs
> is
> ready. However in this case we can also rely on debugfs_create_dir()
> which is called in iommu_debufs_setup().
> 
> debugfs_create_dir() says:
> 
>  * If debugfs is not enabled in the kernel, the value -%ENODEV will
> be
>  * returned.

It seems "If debugfs is not enabled in the kernel"
means CONFIG_DEBUG_FS is not configured. Following is the code of no
such config.

  static inline struct dentry *debugfs_create_dir(const char *name,
struct dentry *parent)
  {
return ERR_PTR(-ENODEV);
  }

Looking into the code, debugfs_initialized() return the value of
debugfs_registered. debugfs_registered is set to true after
debugfs_init() has been called.
However, debugfs_create_dir() doesn't call debugfs_initialized() or
check debugfs_registered value.
So, there is tiny different of checking status by debugfs_create_dir()
and debugfs_initialized(). Although it can achieve functionality here.

Maybe the original design is to call debugfs_initialized() before
calling debugfs_create_xxx()?

Thanks.
Shunyong.

> 
> Sohil
> 
> > 
> > Thanks.
> > Shunyong.
> > 
> > > 
> > >  
> > > > 
> > > >  
> > > >  
> > > > > 
> > > > >  
> > > > > + return;
> > > > > +
> > > > > + mutex_lock(_iommu_debugfs_lock);
> > > > > + if (!amd_iommu_debugfs) {
> > > > > + d_top = iommu_debugfs_setup();
> > > > > + if (d_top)
> > > > > + amd_iommu_debugfs =
> > > > > debugfs_create_dir("amd", d_top);
> > > > > + }
> > > > > + mutex_unlock(_iommu_debugfs_lock);
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Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-18 Thread Mehta, Sohil 
On Wed, 2018-04-18 at 05:58 +, Yang, Shunyong wrote:
> Hi, Gary and Sohil,
> 
> On Tue, 2018-04-17 at 13:38 -0400, Hook, Gary wrote:
> > On 4/13/2018 8:08 PM, Mehta, Sohil wrote:
> > > 
> > > On Fri, 2018-04-06 at 08:17 -0500, Gary R Hook wrote:
> > > > 
> > > >   
> > > > +
> > > > +void amd_iommu_debugfs_setup(struct amd_iommu *iommu)
> > > > +{
> > > > + char name[MAX_NAME_LEN + 1];
> > > > + struct dentry *d_top;
> > > > +
> > > > + if (!debugfs_initialized())
> > > Probably not needed.
> > Right.
> 
> When will this check is needed?
> IMO, this function is to check debugfs ready status before we want to
> use debugfs. I just want to understand when we should use
> debugfs_initialized();
> 

You are right debugfs_initialized() can be used to check if debugfs is
ready. However in this case we can also rely on debugfs_create_dir()
which is called in iommu_debufs_setup().

debugfs_create_dir() says:

 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 * returned.

Sohil

> Thanks.
> Shunyong.
> 
> > 
> > > 
> > > 
> > > > 
> > > > + return;
> > > > +
> > > > + mutex_lock(_iommu_debugfs_lock);
> > > > + if (!amd_iommu_debugfs) {
> > > > + d_top = iommu_debugfs_setup();
> > > > + if (d_top)
> > > > + amd_iommu_debugfs =
> > > > debugfs_create_dir("amd", d_top);
> > > > + }
> > > > + mutex_unlock(_iommu_debugfs_lock);
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Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-18 Thread Yang, Shunyong 
Hi, Gary and Sohil,

On Tue, 2018-04-17 at 13:38 -0400, Hook, Gary wrote:
> On 4/13/2018 8:08 PM, Mehta, Sohil wrote:
> > 
> > On Fri, 2018-04-06 at 08:17 -0500, Gary R Hook wrote:
> > > 
> > >   
> > > +
> > > +void amd_iommu_debugfs_setup(struct amd_iommu *iommu)
> > > +{
> > > + char name[MAX_NAME_LEN + 1];
> > > + struct dentry *d_top;
> > > +
> > > + if (!debugfs_initialized())
> > Probably not needed.
> Right.

When will this check is needed?
IMO, this function is to check debugfs ready status before we want to
use debugfs. I just want to understand when we should use
debugfs_initialized();

Thanks.
Shunyong.

> 
> > 
> > 
> > > 
> > > + return;
> > > +
> > > + mutex_lock(_iommu_debugfs_lock);
> > > + if (!amd_iommu_debugfs) {
> > > + d_top = iommu_debugfs_setup();
> > > + if (d_top)
> > > + amd_iommu_debugfs =
> > > debugfs_create_dir("amd", d_top);
> > > + }
> > > + mutex_unlock(_iommu_debugfs_lock);
> > 
> > You can do the above only once if you iterate over the IOMMUs here
> >   instead of doing it in amd_iommu_init.
> I'm not sure it matters, given the finite number of IOMMUs in a
> system, 
> and the fact that this work is done exactly once. However, removal of
> a 
> lock is fine thing, so I'll move this around.
> 
> > 
> > 
> > > 
> > > + if (amd_iommu_debugfs) {
> > > + snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu-
> > > > 
> > > > index);
> > > + iommu->debugfs = debugfs_create_dir(name,
> > > + amd_iommu_de
> > > bugf
> > > s);
> > > + if (!iommu->debugfs) {
> > > + debugfs_remove_recursive(amd_iommu_debug
> > > fs);
> > > + amd_iommu_debugfs = NULL;
> > > + }
> > > + }
> > > +}
> > -Sohil
> > 
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Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-17 Thread Robin Murphy 

On 17/04/18 18:42, Hook, Gary wrote:

On 4/16/2018 8:52 PM, Mehta, Sohil wrote:

On Fri, 2018-04-06 at 08:17 -0500, Gary R Hook wrote:


diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 5eb1121d54b9..0ca250f626d9 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_IOMMU_IOVA) += iova.o
  obj-$(CONFIG_OF_IOMMU) += of_iommu.o
  obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o
  obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o amd_iommu_init.o
+obj-$(CONFIG_IOMMU_DEBUG) += amd_iommu_debugfs.o


Compiling amd_iommu_debugfs.c seems to depend only
on CONFIG_IOMMU_DEBUG. Can we prevent the code within
amd_iommu_debugfs.c from getting compiled when either CONFIG_AMD_IOMMU
or CONFIG_IOMMU_DEBUG is disabled?


That's a good point. My intention was that only one switch was required 
to incorporate any DebugFS support, but I see now that I didn't consider 
all of the cases.


It appears that a per-device switch is also necessary. Unless someone 
has a better idea.


Well, you could do a makefile-level dependency i.e.:

ifeq ($(CONFIG_IOMMU_DEBUG), y)
obj-$(CONFIG_AMD_IOMMU) += amd_iommu_debugfs.o
obj-$(CONFIG_BLAH_IOMMU) += blah_iommu_debugfs.o
...
endif

Or alternatively have an intermediate silent Kconfig option:

config AMD_IOMMU_DEBUG
def_bool y
depends on AMD_IOMMU && IOMMU_DEBUG

The makefile option is arguably ugly, but does at least scale better ;)

Robin.


  obj-$(CONFIG_AMD_IOMMU_V2) += amd_iommu_v2.o
  obj-$(CONFIG_ARM_SMMU) += arm-smmu.o
  obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o


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Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-17 Thread Hook, Gary 

On 4/16/2018 8:52 PM, Mehta, Sohil wrote:

On Fri, 2018-04-06 at 08:17 -0500, Gary R Hook wrote:


diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 5eb1121d54b9..0ca250f626d9 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_IOMMU_IOVA) += iova.o
  obj-$(CONFIG_OF_IOMMU) += of_iommu.o
  obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o
  obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o amd_iommu_init.o
+obj-$(CONFIG_IOMMU_DEBUG) += amd_iommu_debugfs.o


Compiling amd_iommu_debugfs.c seems to depend only
on CONFIG_IOMMU_DEBUG. Can we prevent the code within
amd_iommu_debugfs.c from getting compiled when either CONFIG_AMD_IOMMU
or CONFIG_IOMMU_DEBUG is disabled?


That's a good point. My intention was that only one switch was required 
to incorporate any DebugFS support, but I see now that I didn't consider 
all of the cases.


It appears that a per-device switch is also necessary. Unless someone 
has a better idea.



  obj-$(CONFIG_AMD_IOMMU_V2) += amd_iommu_v2.o
  obj-$(CONFIG_ARM_SMMU) += arm-smmu.o
  obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o


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Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-17 Thread Hook, Gary 

On 4/13/2018 8:08 PM, Mehta, Sohil wrote:

On Fri, 2018-04-06 at 08:17 -0500, Gary R Hook wrote:
  
+

+void amd_iommu_debugfs_setup(struct amd_iommu *iommu)
+{
+   char name[MAX_NAME_LEN + 1];
+   struct dentry *d_top;
+
+   if (!debugfs_initialized())


Probably not needed.


Right.




+   return;
+
+   mutex_lock(_iommu_debugfs_lock);
+   if (!amd_iommu_debugfs) {
+   d_top = iommu_debugfs_setup();
+   if (d_top)
+   amd_iommu_debugfs =
debugfs_create_dir("amd", d_top);
+   }
+   mutex_unlock(_iommu_debugfs_lock);



You can do the above only once if you iterate over the IOMMUs here
  instead of doing it in amd_iommu_init.


I'm not sure it matters, given the finite number of IOMMUs in a system, 
and the fact that this work is done exactly once. However, removal of a 
lock is fine thing, so I'll move this around.





+   if (amd_iommu_debugfs) {
+   snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu-

index);

+   iommu->debugfs = debugfs_create_dir(name,
+   amd_iommu_debugf
s);
+   if (!iommu->debugfs) {
+   debugfs_remove_recursive(amd_iommu_debugfs);
+   amd_iommu_debugfs = NULL;
+   }
+   }
+}


-Sohil



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Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-16 Thread Mehta, Sohil 
On Fri, 2018-04-06 at 08:17 -0500, Gary R Hook wrote:
> 
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index 5eb1121d54b9..0ca250f626d9 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -11,6 +11,7 @@ obj-$(CONFIG_IOMMU_IOVA) += iova.o
>  obj-$(CONFIG_OF_IOMMU) += of_iommu.o
>  obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o
>  obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o amd_iommu_init.o
> +obj-$(CONFIG_IOMMU_DEBUG) += amd_iommu_debugfs.o

Compiling amd_iommu_debugfs.c seems to depend only
on CONFIG_IOMMU_DEBUG. Can we prevent the code within
amd_iommu_debugfs.c from getting compiled when either CONFIG_AMD_IOMMU
or CONFIG_IOMMU_DEBUG is disabled?

>  obj-$(CONFIG_AMD_IOMMU_V2) += amd_iommu_v2.o
>  obj-$(CONFIG_ARM_SMMU) += arm-smmu.o
>  obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o
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Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-13 Thread Mehta, Sohil 
On Fri, 2018-04-06 at 08:17 -0500, Gary R Hook wrote:
> 
> +
> +void amd_iommu_debugfs_setup(struct amd_iommu *iommu)
> +{
> + char name[MAX_NAME_LEN + 1];
> + struct dentry *d_top;
> +
> + if (!debugfs_initialized())

Probably not needed.

> + return;
> +
> + mutex_lock(_iommu_debugfs_lock);
> + if (!amd_iommu_debugfs) {
> + d_top = iommu_debugfs_setup();
> + if (d_top)
> + amd_iommu_debugfs =
> debugfs_create_dir("amd", d_top);
> + }
> + mutex_unlock(_iommu_debugfs_lock);


You can do the above only once if you iterate over the IOMMUs here
 instead of doing it in amd_iommu_init.

> + if (amd_iommu_debugfs) {
> + snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu-
> >index);
> + iommu->debugfs = debugfs_create_dir(name,
> + amd_iommu_debugf
> s);
> + if (!iommu->debugfs) {
> + debugfs_remove_recursive(amd_iommu_debugfs);
> + amd_iommu_debugfs = NULL;
> + }
> + }
> +}

-Sohil
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[PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-04-06 Thread Gary R Hook 
Implement a skeleton framework for debugfs support in the
AMD IOMMU.


Signed-off-by: Gary R Hook 
---
 drivers/iommu/Makefile|1 +
 drivers/iommu/amd_iommu_debugfs.c |   45 +
 drivers/iommu/amd_iommu_init.c|6 +++--
 drivers/iommu/amd_iommu_proto.h   |6 +
 drivers/iommu/amd_iommu_types.h   |3 ++
 5 files changed, 59 insertions(+), 2 deletions(-)
 create mode 100644 drivers/iommu/amd_iommu_debugfs.c

diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 5eb1121d54b9..0ca250f626d9 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_IOMMU_IOVA) += iova.o
 obj-$(CONFIG_OF_IOMMU) += of_iommu.o
 obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o
 obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o amd_iommu_init.o
+obj-$(CONFIG_IOMMU_DEBUG) += amd_iommu_debugfs.o
 obj-$(CONFIG_AMD_IOMMU_V2) += amd_iommu_v2.o
 obj-$(CONFIG_ARM_SMMU) += arm-smmu.o
 obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o
diff --git a/drivers/iommu/amd_iommu_debugfs.c 
b/drivers/iommu/amd_iommu_debugfs.c
new file mode 100644
index ..282100a655b3
--- /dev/null
+++ b/drivers/iommu/amd_iommu_debugfs.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AMD IOMMU driver
+ *
+ * Copyright (C) 2018 Advanced Micro Devices, Inc.
+ *
+ * Author: Gary R Hook 
+ */
+
+#include 
+#include 
+#include 
+#include "amd_iommu_proto.h"
+#include "amd_iommu_types.h"
+
+static struct dentry *amd_iommu_debugfs;
+static DEFINE_MUTEX(amd_iommu_debugfs_lock);
+
+#defineMAX_NAME_LEN20
+
+void amd_iommu_debugfs_setup(struct amd_iommu *iommu)
+{
+   char name[MAX_NAME_LEN + 1];
+   struct dentry *d_top;
+
+   if (!debugfs_initialized())
+   return;
+
+   mutex_lock(_iommu_debugfs_lock);
+   if (!amd_iommu_debugfs) {
+   d_top = iommu_debugfs_setup();
+   if (d_top)
+   amd_iommu_debugfs = debugfs_create_dir("amd", d_top);
+   }
+   mutex_unlock(_iommu_debugfs_lock);
+   if (amd_iommu_debugfs) {
+   snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu->index);
+   iommu->debugfs = debugfs_create_dir(name,
+   amd_iommu_debugfs);
+   if (!iommu->debugfs) {
+   debugfs_remove_recursive(amd_iommu_debugfs);
+   amd_iommu_debugfs = NULL;
+   }
+   }
+}
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 904c575d1677..031e6dbb8345 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -2721,6 +2721,7 @@ int __init amd_iommu_enable_faulting(void)
  */
 static int __init amd_iommu_init(void)
 {
+   struct amd_iommu *iommu;
int ret;
 
ret = iommu_go_to_state(IOMMU_INITIALIZED);
@@ -2730,14 +2731,15 @@ static int __init amd_iommu_init(void)
disable_iommus();
free_iommu_resources();
} else {
-   struct amd_iommu *iommu;
-
uninit_device_table_dma();
for_each_iommu(iommu)
iommu_flush_all_caches(iommu);
}
}
 
+   for_each_iommu(iommu)
+   amd_iommu_debugfs_setup(iommu);
+
return ret;
 }
 
diff --git a/drivers/iommu/amd_iommu_proto.h b/drivers/iommu/amd_iommu_proto.h
index 640c286a0ab9..daf7f38531f9 100644
--- a/drivers/iommu/amd_iommu_proto.h
+++ b/drivers/iommu/amd_iommu_proto.h
@@ -33,6 +33,12 @@ extern void amd_iommu_uninit_devices(void);
 extern void amd_iommu_init_notifier(void);
 extern int amd_iommu_init_api(void);
 
+#ifdef CONFIG_IOMMU_DEBUG
+void amd_iommu_debugfs_setup(struct amd_iommu *iommu);
+#else
+static inline void amd_iommu_debugfs_setup(struct amd_iommu *iommu) {}
+#endif
+
 /* Needed for interrupt remapping */
 extern int amd_iommu_prepare(void);
 extern int amd_iommu_enable(void);
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index 1c9b080276c9..2ca0959ae9e6 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -593,6 +593,9 @@ struct amd_iommu {
 
u32 flags;
volatile u64 __aligned(8) cmd_sem;
+
+   /* DebugFS Info */
+   struct dentry *debugfs;
 };
 
 static inline struct amd_iommu *dev_to_amd_iommu(struct device *dev)

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