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
vendor-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 v8:
- Change Kconfig to use both an IOMMU boolean and a vendor-specific
boolean; ensure big warning messages
- Make the function that creates a vendor directory more concise
Changes since v7:
- Change the Kconfig approach to use a hidden boolean for a
specific device
- Change some #ifdefs to reference the new boolean
Changes since v6:
- Rely on default Kconfig value for a bool
- comment/doc fixes
- use const where appropriate
- fix inline declaration
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 | 22 ++++++++++++
drivers/iommu/Makefile | 2 +
drivers/iommu/amd_iommu_debugfs.c | 33 +++++++++++++++++++
drivers/iommu/amd_iommu_init.c | 6 ++-
drivers/iommu/amd_iommu_proto.h | 6 +++
drivers/iommu/amd_iommu_types.h | 5 +++
drivers/iommu/iommu-debugfs.c | 66 +++++++++++++++++++++++++++++++++++++
drivers/iommu/iommu.c | 2 +
include/linux/iommu.h | 7 ++++
9 files changed, 147 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 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 | 10 ++++++
drivers/iommu/Makefile | 1 +
drivers/iommu/iommu-debugfs.c | 66 +++++++++++++++++++++++++++++++++++++++++
drivers/iommu/iommu.c | 2 +
include/linux/iommu.h | 7 ++++
5 files changed, 86 insertions(+)
create mode 100644 drivers/iommu/iommu-debugfs.c
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index c76157e57f6b..f9af25ac409f 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -60,6 +60,16 @@ config IOMMU_IO_PGTABLE_ARMV7S_SELFTEST
endmenu
+config IOMMU_DEBUGFS
+ bool "Export IOMMU internals in DebugFS"
+ depends on DEBUG_FS
+ 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..3b1bf88fd1b0
--- /dev/null
+++ b/drivers/iommu/iommu-debugfs.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * IOMMU debugfs core infrastructure
+ *
+ * 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>
+
+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);
+ 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.
+ *
+ * Return: upon success, a pointer to the dentry for the new directory.
+ * NULL in case of failure.
+ */
+struct dentry *iommu_debugfs_new_driver_dir(const char *vendor)
+{
+ return debugfs_create_dir(vendor, iommu_debugfs_dir);
+}
+EXPORT_SYMBOL_GPL(iommu_debugfs_new_driver_dir);
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 63b37563db7e..d227b864a109 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1748,6 +1748,8 @@ 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..7447b0b0579a 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -698,4 +698,11 @@ const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
#endif /* CONFIG_IOMMU_API */
+#ifdef CONFIG_IOMMU_DEBUGFS
+extern struct dentry *iommu_debugfs_dir;
+void iommu_debugfs_setup(void);
+#else
+static inline void iommu_debugfs_setup(void) {}
+#endif
+
#endif /* __LINUX_IOMMU_H */
Implement a skeleton framework for debugfs support in the AMD
IOMMU. Add an AMD-specific Kconfig boolean that depends upon
general enablement of DebugFS in the IOMMU.
Signed-off-by: Gary R Hook <[email protected]>
---
drivers/iommu/Kconfig | 12 ++++++++++++
drivers/iommu/Makefile | 1 +
drivers/iommu/amd_iommu_debugfs.c | 33 +++++++++++++++++++++++++++++++++
drivers/iommu/amd_iommu_init.c | 6 ++++--
drivers/iommu/amd_iommu_proto.h | 6 ++++++
drivers/iommu/amd_iommu_types.h | 5 +++++
6 files changed, 61 insertions(+), 2 deletions(-)
create mode 100644 drivers/iommu/amd_iommu_debugfs.c
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index f9af25ac409f..5a9cef113763 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -146,6 +146,18 @@ config AMD_IOMMU_V2
hardware. Select this option if you want to use devices that support
the PCI PRI and PASID interface.
+config AMD_IOMMU_DEBUGFS
+ bool "Enable AMD IOMMU internals in DebugFS"
+ depends on AMD_IOMMU && IOMMU_DEBUGFS
+ ---help---
+ !!!WARNING!!! !!!WARNING!!! !!!WARNING!!! !!!WARNING!!!
+
+ DO NOT ENABLE THIS OPTION UNLESS YOU REALLY, -REALLY- KNOW WHAT YOU ARE DOING!!!
+ Exposes AMD IOMMU device internals in DebugFS.
+
+ This option is -NOT- intended for production environments, and should
+ not generally be enabled.
+
# Intel IOMMU support
config DMAR_TABLE
bool
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 74cfbc392862..47fd6ea9de2d 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_AMD_IOMMU_DEBUGFS) += 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 000000000000..c6a5c737ef09
--- /dev/null
+++ b/drivers/iommu/amd_iommu_debugfs.c
@@ -0,0 +1,33 @@
+// 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 = debugfs_create_dir("amd",
+ iommu_debugfs_dir);
+ mutex_unlock(&amd_iommu_debugfs_lock);
+
+ snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu->index);
+ iommu->debugfs = debugfs_create_dir(name, amd_iommu_debugfs);
+}
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..a8cd0296fb16 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_AMD_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 986cbe0cc189..cfac9d842b0f 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -594,6 +594,11 @@ struct amd_iommu {
u32 flags;
volatile u64 __aligned(8) cmd_sem;
+
+#ifdef CONFIG_AMD_IOMMU_DEBUGFS
+ /* DebugFS Info */
+ struct dentry *debugfs;
+#endif
};
static inline struct amd_iommu *dev_to_amd_iommu(struct device *dev)
On 06/12/2018 02:41 PM, Gary R Hook wrote:
> Implement a skeleton framework for debugfs support in the AMD
> IOMMU. Add an AMD-specific Kconfig boolean that depends upon
> general enablement of DebugFS in the IOMMU.
>
> Signed-off-by: Gary R Hook <[email protected]>
Gary,
Looks good to me. Thanks.
> ---
> drivers/iommu/Kconfig | 12 ++++++++++++
> drivers/iommu/Makefile | 1 +
> drivers/iommu/amd_iommu_debugfs.c | 33 +++++++++++++++++++++++++++++++++
> drivers/iommu/amd_iommu_init.c | 6 ++++--
> drivers/iommu/amd_iommu_proto.h | 6 ++++++
> drivers/iommu/amd_iommu_types.h | 5 +++++
> 6 files changed, 61 insertions(+), 2 deletions(-)
> create mode 100644 drivers/iommu/amd_iommu_debugfs.c
>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index f9af25ac409f..5a9cef113763 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -146,6 +146,18 @@ config AMD_IOMMU_V2
> hardware. Select this option if you want to use devices that support
> the PCI PRI and PASID interface.
>
> +config AMD_IOMMU_DEBUGFS
> + bool "Enable AMD IOMMU internals in DebugFS"
> + depends on AMD_IOMMU && IOMMU_DEBUGFS
> + ---help---
> + !!!WARNING!!! !!!WARNING!!! !!!WARNING!!! !!!WARNING!!!
> +
> + DO NOT ENABLE THIS OPTION UNLESS YOU REALLY, -REALLY- KNOW WHAT YOU ARE DOING!!!
> + Exposes AMD IOMMU device internals in DebugFS.
> +
> + This option is -NOT- intended for production environments, and should
> + not generally be enabled.
> +
> # Intel IOMMU support
> config DMAR_TABLE
> bool
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index 74cfbc392862..47fd6ea9de2d 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_AMD_IOMMU_DEBUGFS) += 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
--
~Randy
On Tue, Jun 12, 2018 at 04:41:12PM -0500, Gary R Hook wrote:
> Gary R Hook (2):
> iommu - Enable debugfs exposure of IOMMU driver internals
> iommu/amd: Add basic debugfs infrastructure for AMD IOMMU
Applied, thanks Gary.
Hi Gary,
On Tue, Jun 12, 2018 at 11:42 PM Gary R Hook <[email protected]> wrote:
> Implement a skeleton framework for debugfs support in the AMD
> IOMMU. Add an AMD-specific Kconfig boolean that depends upon
> general enablement of DebugFS in the IOMMU.
>
> Signed-off-by: Gary R Hook <[email protected]>
This is now commit 7d0f5fd3e4d68742 ("iommu/amd: Add basic debugfs
infrastructure for AMD IOMMU").
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -146,6 +146,18 @@ config AMD_IOMMU_V2
> hardware. Select this option if you want to use devices that support
> the PCI PRI and PASID interface.
>
> +config AMD_IOMMU_DEBUGFS
> + bool "Enable AMD IOMMU internals in DebugFS"
> + depends on AMD_IOMMU && IOMMU_DEBUGFS
> + ---help---
> + !!!WARNING!!! !!!WARNING!!! !!!WARNING!!! !!!WARNING!!!
> +
> + DO NOT ENABLE THIS OPTION UNLESS YOU REALLY, -REALLY- KNOW WHAT YOU ARE DOING!!!
> + Exposes AMD IOMMU device internals in DebugFS.
> +
> + This option is -NOT- intended for production environments, and should
> + not generally be enabled.
If it is that bad, shouldn't this option be protected by some Kconfig
trickery to avoid it being enabled in allmodconfig/allyesconfig builds?
I forgot the way to do that, so some CCs added.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
On Mon, Aug 27, 2018 at 08:56:50AM +0200, Geert Uytterhoeven wrote:
> If it is that bad, shouldn't this option be protected by some Kconfig
> trickery to avoid it being enabled in allmodconfig/allyesconfig builds?
It is fine to have it in allmodconfig/allyesconfig, I just don't want
any distro-kernel enable it so that these internals become a user-space
ABI or leak security sensitive data on everyones system. This is
intended to be a pure debugging feature for development.
Regards,
Joerg