These patches create a top-level function, called at IOMMU initialization,
to create a debugfs directory for the IOMMU. Under this directory drivers
may create and populate-specific directories for their device internals.
Patch 1: general IOMMU enablement
Patch 2: basic AMD enablement to demonstrate linkage with patch 1
Introduce a new Kconfig parameter IOMMU_DEBUGFS to globally allow/disallow
debugfs code to be built.
The Makefile structure is intended to allow the use of a single switch for
turning on DebugFS.
Changes since v5:
- Added parameters names in declarations/definitions
- Reformatted an inline definition
Changes since v4:
- Guard vendor-specific debugfs files in the Makefile
- Call top-level routine from iommu_init()
- Add function for instantiating a driver-specific directory
- Change AMD driver code to use this new format
Changes since v3:
- Remove superfluous calls to debugfs_initialized()
- Emit a warning exactly one time
- Change the Kconfig name to IOMMU_DEBUGFS
- Change the way debugfs modules are made
Changes since v2:
- Move a declaration to outside an ifdef
- Remove a spurious blank line
Changes since v1:
- Remove debug cruft
- Remove cruft produced by design change
- Change the lock to a mutex
- Coding style fixes
- Add a comment to document the framework
---
Gary R Hook (2):
iommu - Enable debugfs exposure of IOMMU driver internals
iommu/amd: Add basic debugfs infrastructure for AMD IOMMU
drivers/iommu/Kconfig | 11 ++++++
drivers/iommu/Makefile | 6 +++
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 ++
drivers/iommu/iommu-debugfs.c | 70 +++++++++++++++++++++++++++++++++++++
drivers/iommu/iommu.c | 2 +
include/linux/iommu.h | 10 +++++
9 files changed, 151 insertions(+), 2 deletions(-)
create mode 100644 drivers/iommu/amd_iommu_debugfs.c
create mode 100644 drivers/iommu/iommu-debugfs.c
--
Signature
Provide base enablement for using debugfs to expose internal data of an
IOMMU driver. When called, create the /sys/kernel/debug/iommu directory.
Emit a strong warning at boot time to indicate that this feature is
enabled.
This function is called from iommu_init, and creates the initial DebugFS
directory. Drivers may then call iommu_debugfs_new_driver_dir() to
instantiate a device-specific directory to expose internal data.
It will return a pointer to the new dentry structure created in
/sys/kernel/debug/iommu, or NULL in the event of a failure.
Since the IOMMU driver can not be removed from the running system, there
is no need for an "off" function.
Signed-off-by: Gary R Hook <[email protected]>
---
drivers/iommu/Kconfig | 11 ++++++
drivers/iommu/Makefile | 1 +
drivers/iommu/iommu-debugfs.c | 70 +++++++++++++++++++++++++++++++++++++++++
drivers/iommu/iommu.c | 2 +
include/linux/iommu.h | 10 ++++++
5 files changed, 94 insertions(+)
create mode 100644 drivers/iommu/iommu-debugfs.c
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index f3a21343e636..ff511fa8ca7d 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -60,6 +60,17 @@ config IOMMU_IO_PGTABLE_ARMV7S_SELFTEST
endmenu
+config IOMMU_DEBUGFS
+ bool "Export IOMMU internals in DebugFS"
+ depends on DEBUG_FS
+ default n
+ help
+ Allows exposure of IOMMU device internals. This option enables
+ the use of debugfs by IOMMU drivers as required. Devices can,
+ at initialization time, cause the IOMMU code to create a top-level
+ debug/iommu directory, and then populate a subdirectory with
+ entries as required.
+
config IOMMU_IOVA
tristate
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 1fb695854809..74cfbc392862 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -2,6 +2,7 @@
obj-$(CONFIG_IOMMU_API) += iommu.o
obj-$(CONFIG_IOMMU_API) += iommu-traces.o
obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
+obj-$(CONFIG_IOMMU_DEBUGFS) += iommu-debugfs.o
obj-$(CONFIG_IOMMU_DMA) += dma-iommu.o
obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o
diff --git a/drivers/iommu/iommu-debugfs.c b/drivers/iommu/iommu-debugfs.c
new file mode 100644
index 000000000000..9df3b44aef55
--- /dev/null
+++ b/drivers/iommu/iommu-debugfs.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * IOMMU driver
+ *
+ * Copyright (C) 2018 Advanced Micro Devices, Inc.
+ *
+ * Author: Gary R Hook <[email protected]>
+ */
+
+#include <linux/pci.h>
+#include <linux/iommu.h>
+#include <linux/debugfs.h>
+
+static struct dentry *iommu_debugfs_dir;
+
+/**
+ * iommu_debugfs_setup - create the top-level iommu directory in debugfs
+ *
+ * Provide base enablement for using debugfs to expose internal data of an
+ * IOMMU driver. When called, this function creates the
+ * /sys/kernel/debug/iommu directory.
+ *
+ * Emit a strong warning at boot time to indicate that this feature is
+ * enabled.
+ *
+ * This function is called from iommu_init; drivers may then call
+ * iommu_debugfs_new_driver_dir() to instantiate a vendor-specific
+ * directory to be used to expose internal data.
+ */
+void iommu_debugfs_setup(void)
+{
+ if (!iommu_debugfs_dir) {
+ iommu_debugfs_dir = debugfs_create_dir("iommu", NULL);
+ if (iommu_debugfs_dir) {
+ pr_warn("\n");
+ pr_warn("*************************************************************\n");
+ pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n");
+ pr_warn("** **\n");
+ pr_warn("** IOMMU DebugFS SUPPORT HAS BEEN ENABLED IN THIS KERNEL **\n");
+ pr_warn("** **\n");
+ pr_warn("** This means that this kernel is built to expose internal **\n");
+ pr_warn("** IOMMU data structures, which may compromise security on **\n");
+ pr_warn("** your system. **\n");
+ pr_warn("** **\n");
+ pr_warn("** If you see this message and you are not debugging the **\n");
+ pr_warn("** kernel, report this immediately to your vendor! **\n");
+ pr_warn("** **\n");
+ pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n");
+ pr_warn("*************************************************************\n");
+ }
+ }
+}
+
+/**
+ * iommu_debugfs_new_driver_dir - create a vendor directory under debugfs/iommu
+ * @vendor: name of the vendor-specific subdirectory to create
+ *
+ * This function is called by an IOMMU driver to create the top-level debugfs
+ * directory for that driver. The return value is the dentry for the requested
+ * vendor directory, or NULL in case of failure.
+ */
+struct dentry *iommu_debugfs_new_driver_dir(char *vendor)
+{
+ struct dentry *d_new;
+
+ d_new = debugfs_create_dir(vendor, iommu_debugfs_dir);
+
+ return d_new;
+}
+EXPORT_SYMBOL_GPL(iommu_debugfs_new_driver_dir);
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index d2aa23202bb9..350819f1c5e1 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1747,6 +1747,8 @@ static int __init iommu_init(void)
NULL, kernel_kobj);
BUG_ON(!iommu_group_kset);
+ iommu_debugfs_setup();
+
return 0;
}
core_initcall(iommu_init);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 19938ee6eb31..25018ac0fdab 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -698,4 +698,14 @@ const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
#endif /* CONFIG_IOMMU_API */
+#ifdef CONFIG_IOMMU_DEBUGFS
+void iommu_debugfs_setup(void);
+struct dentry *iommu_debugfs_new_driver_dir(char *vendor);
+#else
+static inline void iommu_debugfs_setup(void) {}
+static inline struct dentry *iommu_debugfs_new_driver_dir(char *vendor) { \
+ return NULL; \
+}
+#endif
+
#endif /* __LINUX_IOMMU_H */
Implement a skeleton framework for debugfs support in the
AMD IOMMU.
Signed-off-by: Gary R Hook <[email protected]>
---
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 000000000000..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 <[email protected]>
+ */
+
+#include <linux/debugfs.h>
+#include <linux/iommu.h>
+#include <linux/pci.h>
+#include "amd_iommu_proto.h"
+#include "amd_iommu_types.h"
+
+static struct dentry *amd_iommu_debugfs;
+static DEFINE_MUTEX(amd_iommu_debugfs_lock);
+
+#define MAX_NAME_LEN 20
+
+void amd_iommu_debugfs_setup(struct amd_iommu *iommu)
+{
+ char name[MAX_NAME_LEN + 1];
+
+ mutex_lock(&amd_iommu_debugfs_lock);
+ if (!amd_iommu_debugfs)
+ amd_iommu_debugfs = iommu_debugfs_new_driver_dir("amd");
+ mutex_unlock(&amd_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)
Hi Gary,
Just a few trivial nitpicks below, otherwise:
Reviewed-by: Robin Murphy <[email protected]>
On 11/05/18 15:34, Gary R Hook wrote:
> Provide base enablement for using debugfs to expose internal data of an
> IOMMU driver. When called, create the /sys/kernel/debug/iommu directory.
>
> Emit a strong warning at boot time to indicate that this feature is
> enabled.
>
> This function is called from iommu_init, and creates the initial DebugFS
> directory. Drivers may then call iommu_debugfs_new_driver_dir() to
> instantiate a device-specific directory to expose internal data.
> It will return a pointer to the new dentry structure created in
> /sys/kernel/debug/iommu, or NULL in the event of a failure.
>
> Since the IOMMU driver can not be removed from the running system, there
> is no need for an "off" function.
>
> Signed-off-by: Gary R Hook <[email protected]>
> ---
> drivers/iommu/Kconfig | 11 ++++++
> drivers/iommu/Makefile | 1 +
> drivers/iommu/iommu-debugfs.c | 70 +++++++++++++++++++++++++++++++++++++++++
> drivers/iommu/iommu.c | 2 +
> include/linux/iommu.h | 10 ++++++
> 5 files changed, 94 insertions(+)
> create mode 100644 drivers/iommu/iommu-debugfs.c
>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index f3a21343e636..ff511fa8ca7d 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -60,6 +60,17 @@ config IOMMU_IO_PGTABLE_ARMV7S_SELFTEST
>
> endmenu
>
> +config IOMMU_DEBUGFS
> + bool "Export IOMMU internals in DebugFS"
> + depends on DEBUG_FS
> + default n
bool implicitly defaults to n anyway, so you don't really need to say it.
> + help
> + Allows exposure of IOMMU device internals. This option enables
> + the use of debugfs by IOMMU drivers as required. Devices can,
> + at initialization time, cause the IOMMU code to create a top-level
> + debug/iommu directory, and then populate a subdirectory with
> + entries as required.
> +
> config IOMMU_IOVA
> tristate
>
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index 1fb695854809..74cfbc392862 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -2,6 +2,7 @@
> obj-$(CONFIG_IOMMU_API) += iommu.o
> obj-$(CONFIG_IOMMU_API) += iommu-traces.o
> obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
> +obj-$(CONFIG_IOMMU_DEBUGFS) += iommu-debugfs.o
> obj-$(CONFIG_IOMMU_DMA) += dma-iommu.o
> obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
> obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o
> diff --git a/drivers/iommu/iommu-debugfs.c b/drivers/iommu/iommu-debugfs.c
> new file mode 100644
> index 000000000000..9df3b44aef55
> --- /dev/null
> +++ b/drivers/iommu/iommu-debugfs.c
> @@ -0,0 +1,70 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * IOMMU driver
"driver"? ;) I'd have thought something like "IOMMU debugfs core
infrastructure", but arguably it's self-evident enough that it doesn't
necessarily need describing at all.
> + *
> + * Copyright (C) 2018 Advanced Micro Devices, Inc.
> + *
> + * Author: Gary R Hook <[email protected]>
> + */
> +
> +#include <linux/pci.h>
> +#include <linux/iommu.h>
> +#include <linux/debugfs.h>
> +
> +static struct dentry *iommu_debugfs_dir;
> +
> +/**
> + * iommu_debugfs_setup - create the top-level iommu directory in debugfs
> + *
> + * Provide base enablement for using debugfs to expose internal data of an
> + * IOMMU driver. When called, this function creates the
> + * /sys/kernel/debug/iommu directory.
> + *
> + * Emit a strong warning at boot time to indicate that this feature is
> + * enabled.
> + *
> + * This function is called from iommu_init; drivers may then call
> + * iommu_debugfs_new_driver_dir() to instantiate a vendor-specific
> + * directory to be used to expose internal data.
> + */
> +void iommu_debugfs_setup(void)
> +{
> + if (!iommu_debugfs_dir) {
> + iommu_debugfs_dir = debugfs_create_dir("iommu", NULL);
> + if (iommu_debugfs_dir) {
> + pr_warn("\n");
> + pr_warn("*************************************************************\n");
> + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n");
> + pr_warn("** **\n");
> + pr_warn("** IOMMU DebugFS SUPPORT HAS BEEN ENABLED IN THIS KERNEL **\n");
> + pr_warn("** **\n");
> + pr_warn("** This means that this kernel is built to expose internal **\n");
> + pr_warn("** IOMMU data structures, which may compromise security on **\n");
> + pr_warn("** your system. **\n");
> + pr_warn("** **\n");
> + pr_warn("** If you see this message and you are not debugging the **\n");
> + pr_warn("** kernel, report this immediately to your vendor! **\n");
> + pr_warn("** **\n");
> + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n");
> + pr_warn("*************************************************************\n");
> + }
> + }
> +}
> +
> +/**
> + * iommu_debugfs_new_driver_dir - create a vendor directory under debugfs/iommu
> + * @vendor: name of the vendor-specific subdirectory to create
> + *
> + * This function is called by an IOMMU driver to create the top-level debugfs
> + * directory for that driver. The return value is the dentry for the requested
> + * vendor directory, or NULL in case of failure.
According to kernel-doc.rst, return values should be in a dedicated
section (i.e. "Return: The dentry...") rather than as part of the
function description.
> + */
> +struct dentry *iommu_debugfs_new_driver_dir(char *vendor)
const char *?
> +{
> + struct dentry *d_new;
> +
> + d_new = debugfs_create_dir(vendor, iommu_debugfs_dir);
> +
> + return d_new;
> +}
> +EXPORT_SYMBOL_GPL(iommu_debugfs_new_driver_dir);
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index d2aa23202bb9..350819f1c5e1 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1747,6 +1747,8 @@ static int __init iommu_init(void)
> NULL, kernel_kobj);
> BUG_ON(!iommu_group_kset);
>
> + iommu_debugfs_setup();
> +
> return 0;
> }
> core_initcall(iommu_init);
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 19938ee6eb31..25018ac0fdab 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -698,4 +698,14 @@ const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
>
> #endif /* CONFIG_IOMMU_API */
>
> +#ifdef CONFIG_IOMMU_DEBUGFS
> +void iommu_debugfs_setup(void);
> +struct dentry *iommu_debugfs_new_driver_dir(char *vendor);
> +#else
> +static inline void iommu_debugfs_setup(void) {}
> +static inline struct dentry *iommu_debugfs_new_driver_dir(char *vendor) { \
Since this is a function, not a macro, it doesn't really need the line
continuations.
Robin.
> + return NULL; \
> +}
> +#endif
> +
> #endif /* __LINUX_IOMMU_H */
>
> _______________________________________________
> iommu mailing list
> [email protected]
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
>
On 05/11/2018 10:22 AM, Robin Murphy wrote:
> Hi Gary,
>
> Just a few trivial nitpicks below, otherwise:
>
> Reviewed-by: Robin Murphy <[email protected]>
>
> On 11/05/18 15:34, Gary R Hook wrote:
>> Provide base enablement for using debugfs to expose internal data of an
>> IOMMU driver. When called, create the /sys/kernel/debug/iommu directory.
>>
>> Emit a strong warning at boot time to indicate that this feature is
>> enabled.
>>
>> This function is called from iommu_init, and creates the initial DebugFS
>> directory. Drivers may then call iommu_debugfs_new_driver_dir() to
>> instantiate a device-specific directory to expose internal data.
>> It will return a pointer to the new dentry structure created in
>> /sys/kernel/debug/iommu, or NULL in the event of a failure.
>>
>> Since the IOMMU driver can not be removed from the running system, there
>> is no need for an "off" function.
>>
>> Signed-off-by: Gary R Hook <[email protected]>
>> ---
>> drivers/iommu/Kconfig | 11 ++++++
>> drivers/iommu/Makefile | 1 +
>> drivers/iommu/iommu-debugfs.c | 70
>> +++++++++++++++++++++++++++++++++++++++++
>> drivers/iommu/iommu.c | 2 +
>> include/linux/iommu.h | 10 ++++++
>> 5 files changed, 94 insertions(+)
>> create mode 100644 drivers/iommu/iommu-debugfs.c
>>
>> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
>> index f3a21343e636..ff511fa8ca7d 100644
>> --- a/drivers/iommu/Kconfig
>> +++ b/drivers/iommu/Kconfig
>> @@ -60,6 +60,17 @@ config IOMMU_IO_PGTABLE_ARMV7S_SELFTEST
>> endmenu
>> +config IOMMU_DEBUGFS
>> + bool "Export IOMMU internals in DebugFS"
>> + depends on DEBUG_FS
>> + default n
>
> bool implicitly defaults to n anyway, so you don't really need to say it.
Roger.
>
>> + help
>> + Allows exposure of IOMMU device internals. This option enables
>> + the use of debugfs by IOMMU drivers as required. Devices can,
>> + at initialization time, cause the IOMMU code to create a top-level
>> + debug/iommu directory, and then populate a subdirectory with
>> + entries as required.
>> +
>> config IOMMU_IOVA
>> tristate
>> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
>> index 1fb695854809..74cfbc392862 100644
>> --- a/drivers/iommu/Makefile
>> +++ b/drivers/iommu/Makefile
>> @@ -2,6 +2,7 @@
>> obj-$(CONFIG_IOMMU_API) += iommu.o
>> obj-$(CONFIG_IOMMU_API) += iommu-traces.o
>> obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
>> +obj-$(CONFIG_IOMMU_DEBUGFS) += iommu-debugfs.o
>> obj-$(CONFIG_IOMMU_DMA) += dma-iommu.o
>> obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
>> obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o
>> diff --git a/drivers/iommu/iommu-debugfs.c
>> b/drivers/iommu/iommu-debugfs.c
>> new file mode 100644
>> index 000000000000..9df3b44aef55
>> --- /dev/null
>> +++ b/drivers/iommu/iommu-debugfs.c
>> @@ -0,0 +1,70 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * IOMMU driver
>
> "driver"? ;) I'd have thought something like "IOMMU debugfs core
> infrastructure", but arguably it's self-evident enough that it doesn't
> necessarily need describing at all.
Changed to your suggestion
>
>> + *
>> + * Copyright (C) 2018 Advanced Micro Devices, Inc.
>> + *
>> + * Author: Gary R Hook <[email protected]>
>> + */
>> +
>> +#include <linux/pci.h>
>> +#include <linux/iommu.h>
>> +#include <linux/debugfs.h>
>> +
>> +static struct dentry *iommu_debugfs_dir;
>> +
>> +/**
>> + * iommu_debugfs_setup - create the top-level iommu directory in debugfs
>> + *
>> + * Provide base enablement for using debugfs to expose internal data
>> of an
>> + * IOMMU driver. When called, this function creates the
>> + * /sys/kernel/debug/iommu directory.
>> + *
>> + * Emit a strong warning at boot time to indicate that this feature is
>> + * enabled.
>> + *
>> + * This function is called from iommu_init; drivers may then call
>> + * iommu_debugfs_new_driver_dir() to instantiate a vendor-specific
>> + * directory to be used to expose internal data.
>> + */
>> +void iommu_debugfs_setup(void)
>> +{
>> + if (!iommu_debugfs_dir) {
>> + iommu_debugfs_dir = debugfs_create_dir("iommu", NULL);
>> + if (iommu_debugfs_dir) {
>> + pr_warn("\n");
>> +
>> pr_warn("*************************************************************\n");
>>
>> + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE
>> NOTICE **\n");
>> +
>> pr_warn("**
>> **\n");
>> + pr_warn("** IOMMU DebugFS SUPPORT HAS BEEN ENABLED IN
>> THIS KERNEL **\n");
>> +
>> pr_warn("**
>> **\n");
>> + pr_warn("** This means that this kernel is built to
>> expose internal **\n");
>> + pr_warn("** IOMMU data structures, which may compromise
>> security on **\n");
>> + pr_warn("** your
>> system. **\n");
>> +
>> pr_warn("**
>> **\n");
>> + pr_warn("** If you see this message and you are not
>> debugging the **\n");
>> + pr_warn("** kernel, report this immediately to your
>> vendor! **\n");
>> +
>> pr_warn("**
>> **\n");
>> + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE
>> NOTICE **\n");
>> +
>> pr_warn("*************************************************************\n");
>>
>> + }
>> + }
>> +}
>> +
>> +/**
>> + * iommu_debugfs_new_driver_dir - create a vendor directory under
>> debugfs/iommu
>> + * @vendor: name of the vendor-specific subdirectory to create
>> + *
>> + * This function is called by an IOMMU driver to create the top-level
>> debugfs
>> + * directory for that driver. The return value is the dentry for the
>> requested
>> + * vendor directory, or NULL in case of failure.
>
> According to kernel-doc.rst, return values should be in a dedicated
> section (i.e. "Return: The dentry...") rather than as part of the
> function description.
A style change that happened along the way; my model was apparently
older code. I've adjusted for this new style.
>
>> + */
>> +struct dentry *iommu_debugfs_new_driver_dir(char *vendor)
>
> const char *?
Sure thing.
>
>> +{
>> + struct dentry *d_new;
>> +
>> + d_new = debugfs_create_dir(vendor, iommu_debugfs_dir);
>> +
>> + return d_new;
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_debugfs_new_driver_dir);
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index d2aa23202bb9..350819f1c5e1 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -1747,6 +1747,8 @@ static int __init iommu_init(void)
>> NULL, kernel_kobj);
>> BUG_ON(!iommu_group_kset);
>> + iommu_debugfs_setup();
>> +
>> return 0;
>> }
>> core_initcall(iommu_init);
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index 19938ee6eb31..25018ac0fdab 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -698,4 +698,14 @@ const struct iommu_ops
>> *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
>> #endif /* CONFIG_IOMMU_API */
>> +#ifdef CONFIG_IOMMU_DEBUGFS
>> +void iommu_debugfs_setup(void);
>> +struct dentry *iommu_debugfs_new_driver_dir(char *vendor);
>> +#else
>> +static inline void iommu_debugfs_setup(void) {}
>> +static inline struct dentry *iommu_debugfs_new_driver_dir(char
>> *vendor) { \
>
> Since this is a function, not a macro, it doesn't really need the line
> continuations.
Yep. Done. And moved the curly brace to the next line.
>
> Robin.
>
>> + return NULL; \
>> +}
>> +#endif
>> +
>> #endif /* __LINUX_IOMMU_H */
>>
>> _______________________________________________
>> iommu mailing list
>> [email protected]
>> https://lists.linuxfoundation.org/mailman/listinfo/iommu
>>