Re: [PATCH v7 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-05-29 Thread Joerg Roedel 
On Fri, May 18, 2018 at 04:02:46PM -0500, Gary R Hook wrote:
> "Preferred", perhaps. Neither is incorrect. And really, the Makefile/Kconfig
> choice is somewhat separate from the organization issue.
> 
> So I've made the changes for this. Now I'm waiting on Joerg to make a
> decision on the code/file organization. I still prefer a separate file for
> the debug fs code.

The Kconfig option looks nicer to me, please use it. Then you can also
put the code into a separate file.


Joerg

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Re: [PATCH v7 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-05-24 Thread Gary R Hook 

On 05/18/2018 04:02 PM, Gary R Hook wrote:

On 05/18/2018 11:49 AM, Randy Dunlap wrote:

I think the Kconfig option would have been the correct choice.


"Preferred", perhaps. Neither is incorrect. And really, the 
Makefile/Kconfig choice is somewhat separate from the organization issue.


So I've made the changes for this. Now I'm waiting on Joerg to make a 
decision on the code/file organization. I still prefer a separate file 
for the debug fs code.


Joerg:

*poke*

Any thoughts on this?
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Re: [PATCH v7 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-05-18 Thread Gary R Hook 

On 05/18/2018 11:49 AM, Randy Dunlap wrote:

On 05/18/2018 08:20 AM, Gary R Hook wrote:

On 05/15/2018 08:46 AM, Joerg Roedel wrote:

On Mon, May 14, 2018 at 03:00:50PM -0500, Gary R Hook wrote:

This was brought up a few weeks ago in, I believe, version 3 of this patch.
That question was discussed (because that's what I did the first time out),
and _someone_ _else_ asked about why I didn't just do it the way I've done
it here.


You don't have this problem if you put the code in amd_iommu.c in an
IOMMU_DEBUGFS ifdef.


Of course. My preference, however, is a separate file to avoid size creep. 
That's why I've done it this way.

To whit: there have been threads discussing the advisability/acceptability of 
using #ifdefs for debug code. My take-away was to avoid them. Perhaps I 
misunderstood.

So: I don't understand your comment. Is this an observation, or is it an 
imperative statement? I'd like for a maintainer to clearly indicate what is 
acceptable, and I'll do it.




Hi,
I looked back at Robin Murphy's comments on April 17:


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 ;)



I think the Kconfig option would have been the correct choice.


"Preferred", perhaps. Neither is incorrect. And really, the 
Makefile/Kconfig choice is somewhat separate from the organization issue.


So I've made the changes for this. Now I'm waiting on Joerg to make a 
decision on the code/file organization. I still prefer a separate file 
for the debug fs code.


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Re: [PATCH v7 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-05-18 Thread Randy Dunlap 
On 05/18/2018 08:20 AM, Gary R Hook wrote:
> On 05/15/2018 08:46 AM, Joerg Roedel wrote:
>> On Mon, May 14, 2018 at 03:00:50PM -0500, Gary R Hook wrote:
>>> This was brought up a few weeks ago in, I believe, version 3 of this patch.
>>> That question was discussed (because that's what I did the first time out),
>>> and _someone_ _else_ asked about why I didn't just do it the way I've done
>>> it here.
>>
>> You don't have this problem if you put the code in amd_iommu.c in an
>> IOMMU_DEBUGFS ifdef.
> 
> Of course. My preference, however, is a separate file to avoid size creep. 
> That's why I've done it this way.
> 
> To whit: there have been threads discussing the advisability/acceptability of 
> using #ifdefs for debug code. My take-away was to avoid them. Perhaps I 
> misunderstood.
> 
> So: I don't understand your comment. Is this an observation, or is it an 
> imperative statement? I'd like for a maintainer to clearly indicate what is 
> acceptable, and I'll do it.
> 
> 

Hi,
I looked back at Robin Murphy's comments on April 17:


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 ;)



I think the Kconfig option would have been the correct choice.

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Re: [PATCH v7 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-05-18 Thread Gary R Hook 

On 05/15/2018 08:46 AM, Joerg Roedel wrote:

On Mon, May 14, 2018 at 03:00:50PM -0500, Gary R Hook wrote:

This was brought up a few weeks ago in, I believe, version 3 of this patch.
That question was discussed (because that's what I did the first time out),
and _someone_ _else_ asked about why I didn't just do it the way I've done
it here.


You don't have this problem if you put the code in amd_iommu.c in an
IOMMU_DEBUGFS ifdef.


Of course. My preference, however, is a separate file to avoid size 
creep. That's why I've done it this way.


To whit: there have been threads discussing the 
advisability/acceptability of using #ifdefs for debug code. My take-away 
was to avoid them. Perhaps I misunderstood.


So: I don't understand your comment. Is this an observation, or is it an 
imperative statement? I'd like for a maintainer to clearly indicate what 
is acceptable, and I'll do it.


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Re: [PATCH v7 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-05-15 Thread Joerg Roedel 
On Mon, May 14, 2018 at 03:00:50PM -0500, Gary R Hook wrote:
> This was brought up a few weeks ago in, I believe, version 3 of this patch.
> That question was discussed (because that's what I did the first time out),
> and _someone_ _else_ asked about why I didn't just do it the way I've done
> it here.

You don't have this problem if you put the code in amd_iommu.c in an
IOMMU_DEBUGFS ifdef.



Joerg
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Re: [PATCH v7 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-05-14 Thread Randy Dunlap 
On 05/14/2018 01:00 PM, Gary R Hook wrote:
> On 05/14/2018 12:50 PM, Randy Dunlap wrote:
>> On 05/14/2018 10:20 AM, Gary R Hook wrote:
>>> Implement a skeleton framework for debugfs support in the
>>> AMD IOMMU.
>>>
>>> Signed-off-by: Gary R Hook 
>>> ---
>>>   drivers/iommu/Makefile    |    5 +
>>>   drivers/iommu/amd_iommu_debugfs.c |   39 
>>> +
>>>   drivers/iommu/amd_iommu_init.c    |    6 --
>>>   drivers/iommu/amd_iommu_proto.h   |    6 ++
>>>   drivers/iommu/amd_iommu_types.h   |    3 +++
>>>   5 files changed, 57 insertions(+), 2 deletions(-)
>>>   create mode 100644 drivers/iommu/amd_iommu_debugfs.c
>>>
>>> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
>>> index 74cfbc392862..dd980f7dd8b6 100644
>>> --- a/drivers/iommu/Makefile
>>> +++ b/drivers/iommu/Makefile
>>> @@ -30,3 +30,8 @@ obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
>>>   obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o
>>>   obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
>>>   obj-$(CONFIG_QCOM_IOMMU) += qcom_iommu.o
>>> +
>>> +# This ensures that only the required files are compiled
>>> +ifeq ($(CONFIG_IOMMU_DEBUGFS), y)
>>
>> Most Makefiles don't use a space before the 'y', but since you tested it,
>> I guess either way works.
> 
> Pretty sure whitespace isn't used as a delimiter in this construct. I could 
> be mistaken. But yes, it's perfectly serviceable.
> 
>> But why do this in the Makefile at all?  Why not just add another Kconfig
>> symbol and simplify the Makefile?
>>
>>> +obj-$(CONFIG_AMD_IOMMU) += amd_iommu_debugfs.o
>>> +endif
> 
> 
> This was brought up a few weeks ago in, I believe, version 3 of this patch. 
> That question was discussed (because that's what I did the first time out), 
> and _someone_ _else_ asked about why I didn't just do it the way I've done it 
> here.

Sorry I missed it.  I would have been glad to chime in at that time.

> Everyone has a preference.
> 
> I chose to simplify the choices and avoid multiple symbols, instead opting 
> for two switches: choose your device, and decide on Debug FS enablement for 
> it. IMO Very simple.
> 
> I can't fathom a scenario where this wouldn't work. Is there one?

Probably not.

But we used to have ugly, messy, convoluted makefiles with very little config 
help.
Then we got better kconfig tools (well, arguably :) and then the makefiles were
cleaned up and simplified a lot (or A LOT!).  We shouldn't want to go back 
there.

-- 
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Re: [PATCH v7 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-05-14 Thread Gary R Hook 

On 05/14/2018 12:50 PM, Randy Dunlap wrote:

On 05/14/2018 10:20 AM, Gary R Hook wrote:

Implement a skeleton framework for debugfs support in the
AMD IOMMU.

Signed-off-by: Gary R Hook 
---
  drivers/iommu/Makefile|5 +
  drivers/iommu/amd_iommu_debugfs.c |   39 +
  drivers/iommu/amd_iommu_init.c|6 --
  drivers/iommu/amd_iommu_proto.h   |6 ++
  drivers/iommu/amd_iommu_types.h   |3 +++
  5 files changed, 57 insertions(+), 2 deletions(-)
  create mode 100644 drivers/iommu/amd_iommu_debugfs.c

diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 74cfbc392862..dd980f7dd8b6 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -30,3 +30,8 @@ obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
  obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o
  obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
  obj-$(CONFIG_QCOM_IOMMU) += qcom_iommu.o
+
+# This ensures that only the required files are compiled
+ifeq ($(CONFIG_IOMMU_DEBUGFS), y)


Most Makefiles don't use a space before the 'y', but since you tested it,
I guess either way works.


Pretty sure whitespace isn't used as a delimiter in this construct. I 
could be mistaken. But yes, it's perfectly serviceable.



But why do this in the Makefile at all?  Why not just add another Kconfig
symbol and simplify the Makefile?


+obj-$(CONFIG_AMD_IOMMU) += amd_iommu_debugfs.o
+endif



This was brought up a few weeks ago in, I believe, version 3 of this 
patch. That question was discussed (because that's what I did the first 
time out), and _someone_ _else_ asked about why I didn't just do it the 
way I've done it here.


Everyone has a preference.

I chose to simplify the choices and avoid multiple symbols, instead 
opting for two switches: choose your device, and decide on Debug FS 
enablement for it. IMO Very simple.


I can't fathom a scenario where this wouldn't work. Is there one?
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Re: [PATCH v7 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-05-14 Thread Randy Dunlap 
On 05/14/2018 10:20 AM, Gary R Hook wrote:
> Implement a skeleton framework for debugfs support in the
> AMD IOMMU.
> 
> Signed-off-by: Gary R Hook 
> ---
>  drivers/iommu/Makefile|5 +
>  drivers/iommu/amd_iommu_debugfs.c |   39 
> +
>  drivers/iommu/amd_iommu_init.c|6 --
>  drivers/iommu/amd_iommu_proto.h   |6 ++
>  drivers/iommu/amd_iommu_types.h   |3 +++
>  5 files changed, 57 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/iommu/amd_iommu_debugfs.c
> 
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index 74cfbc392862..dd980f7dd8b6 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -30,3 +30,8 @@ obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
>  obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o
>  obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
>  obj-$(CONFIG_QCOM_IOMMU) += qcom_iommu.o
> +
> +# This ensures that only the required files are compiled
> +ifeq ($(CONFIG_IOMMU_DEBUGFS), y)

Most Makefiles don't use a space before the 'y', but since you tested it,
I guess either way works.

But why do this in the Makefile at all?  Why not just add another Kconfig
symbol and simplify the Makefile?

> +obj-$(CONFIG_AMD_IOMMU) += amd_iommu_debugfs.o
> +endif

-- 
~Randy
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[PATCH v7 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

2018-05-14 Thread Gary R Hook 
Implement a skeleton framework for debugfs support in the
AMD IOMMU.

Signed-off-by: Gary R Hook 
---
 drivers/iommu/Makefile|5 +
 drivers/iommu/amd_iommu_debugfs.c |   39 +
 drivers/iommu/amd_iommu_init.c|6 --
 drivers/iommu/amd_iommu_proto.h   |6 ++
 drivers/iommu/amd_iommu_types.h   |3 +++
 5 files changed, 57 insertions(+), 2 deletions(-)
 create mode 100644 drivers/iommu/amd_iommu_debugfs.c

diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 74cfbc392862..dd980f7dd8b6 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -30,3 +30,8 @@ obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
 obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o
 obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
 obj-$(CONFIG_QCOM_IOMMU) += qcom_iommu.o
+
+# This ensures that only the required files are compiled
+ifeq ($(CONFIG_IOMMU_DEBUGFS), y)
+obj-$(CONFIG_AMD_IOMMU) += amd_iommu_debugfs.o
+endif
diff --git a/drivers/iommu/amd_iommu_debugfs.c 
b/drivers/iommu/amd_iommu_debugfs.c
new file mode 100644
index ..6dff98552969
--- /dev/null
+++ b/drivers/iommu/amd_iommu_debugfs.c
@@ -0,0 +1,39 @@
+// 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];
+
+   mutex_lock(_iommu_debugfs_lock);
+   if (!amd_iommu_debugfs)
+   amd_iommu_debugfs = iommu_debugfs_new_driver_dir("amd");
+   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..39053f11dda3 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_DEBUGFS
+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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