These patches create a top-level function to create a debugfs directory
for the IOMMU, under which 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_DEBUG to globally allow or
disallow debugfs code to be built.
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 the IOMMU
iommu/amd: Add basic debugfs infrastructure for AMD IOMMU
drivers/iommu/Kconfig | 11 +++++++
drivers/iommu/Makefile | 6 ++++
drivers/iommu/amd_iommu_debugfs.c | 42 ++++++++++++++++++++++++++++
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 | 55 +++++++++++++++++++++++++++++++++++++
include/linux/iommu.h | 4 +++
8 files changed, 131 insertions(+), 2 deletions(-)
create mode 100644 drivers/iommu/amd_iommu_debugfs.c
create mode 100644 drivers/iommu/iommu-debugfs.c
--
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 patch adds a top-level function that will create the (above)
directory, under which a driver may create a hw-specific directory for
its use. The function
iommu_debugfs_setup()
returns a pointer to the new dentry structure created for
/sys/kernel/debug/iommu, or NULL in the event of a failure. An IOMMU
driver should call this function first, and then create a directory
beneath it. A driver implementation might look something like:
static struct dentry *my_debugfs;
struct dentry *d_top;
if (!my_debugfs) {
d_top = iommu_debugfs_setup();
if (d_top)
my_debugfs = debugfs_create_dir("vendor", d_top);
}
Since the IOMMU driver can not be removed from the running system, this
patch only provides an "on" function.
Signed-off-by: Gary R Hook <[email protected]>
---
drivers/iommu/Kconfig | 11 ++++++++
drivers/iommu/Makefile | 1 +
drivers/iommu/iommu-debugfs.c | 55 +++++++++++++++++++++++++++++++++++++++++
include/linux/iommu.h | 4 +++
4 files changed, 71 insertions(+)
create mode 100644 drivers/iommu/iommu-debugfs.c
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index f3a21343e636..81a6c281e69f 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -60,6 +60,17 @@ config IOMMU_IO_PGTABLE_ARMV7S_SELFTEST
endmenu
+config IOMMU_DEBUGFS
+ bool "Enable 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..409691ca0ff9
--- /dev/null
+++ b/drivers/iommu/iommu-debugfs.c
@@ -0,0 +1,55 @@
+// 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;
+
+/*
+ * 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 top-level function that will create the (above) directory, under a
+ * driver may create a hw-specific directory for its use. The function
+ *
+ * iommu_debugfs_setup()
+ *
+ * returns a pointer to the new dentry structure created for
+ * /sys/kernel/debug/iommu, or NULL in the event of a failure. An IOMMU
+ * driver should call this function first, and then create a directory
+ * beneath it. A driver implementation might look something like:
+ *
+ * static struct dentry *my_debugfs;
+ *
+ * struct dentry *d_top;
+ * if (!my_debugfs) {
+ * d_top = iommu_debugfs_setup();
+ * if (d_top)
+ * my_debugfs = debugfs_create_dir("vendor", d_top);
+ * }
+ *
+ * Since the IOMMU driver can not be removed from the running system, there
+ * is no need for an "off" function.
+ */
+struct dentry *iommu_debugfs_setup(void)
+{
+ if (!iommu_debugfs_dir) {
+ iommu_debugfs_dir = debugfs_create_dir("iommu", NULL);
+ if (iommu_debugfs_dir)
+ pr_warn("WARNING: IOMMU DEBUGFS SUPPORT HAS BEEN ENABLED IN THIS KERNEL\n");
+ }
+
+ return iommu_debugfs_dir;
+}
+EXPORT_SYMBOL_GPL(iommu_debugfs_setup);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 19938ee6eb31..e5657c70f90c 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -698,4 +698,8 @@ const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
#endif /* CONFIG_IOMMU_API */
+#ifdef CONFIG_IOMMU_DEBUGFS
+struct dentry *iommu_debugfs_setup(void);
+#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 | 42 +++++++++++++++++++++++++++++++++++++
drivers/iommu/amd_iommu_init.c | 6 ++++-
drivers/iommu/amd_iommu_proto.h | 6 +++++
drivers/iommu/amd_iommu_types.h | 3 +++
5 files changed, 60 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..34bb65cbd798
--- /dev/null
+++ b/drivers/iommu/amd_iommu_debugfs.c
@@ -0,0 +1,42 @@
+// 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];
+ struct dentry *d_top;
+
+ mutex_lock(&amd_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(&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)
On Mon, Apr 30, 2018 at 02:58:49PM -0500, 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 patch adds a top-level function that will create the (above)
> directory, under which a driver may create a hw-specific directory for
> its use. The function
>
> iommu_debugfs_setup()
That function should be called in iommu core-code, in case we want to
export some generic information from there.
Each driver then calls a separate function like
dentry = iommu_debugfs_driver_dir("amd_iommu");
to create a driver-specific directory.
> +config IOMMU_DEBUGFS
> + bool "Enable IOMMU internals in DebugFS"
s/Enable/Export/
> + * static struct dentry *my_debugfs;
> + *
> + * struct dentry *d_top;
Missing newline
> + * if (!my_debugfs) {
> + * d_top = iommu_debugfs_setup();
> + * if (d_top)
> + * my_debugfs = debugfs_create_dir("vendor", d_top);
> + * }
> + *
> + * Since the IOMMU driver can not be removed from the running system, there
> + * is no need for an "off" function.
> + */
> +struct dentry *iommu_debugfs_setup(void)
> +{
> + if (!iommu_debugfs_dir) {
> + iommu_debugfs_dir = debugfs_create_dir("iommu", NULL);
> + if (iommu_debugfs_dir)
> + pr_warn("WARNING: IOMMU DEBUGFS SUPPORT HAS BEEN ENABLED IN THIS KERNEL\n");
This warning needs to be a lot bigger. See the trace_printk() warning
for an example of what I have in mind.