* [PATCH v4 1/8] iommu/amd: Refactor AMD IOMMU debugfs initial setup
2025-03-17 11:58 [PATCH v4 0/8] Introduce debugfs support in IOMMU Dheeraj Kumar Srivastava
@ 2025-03-17 11:58 ` Dheeraj Kumar Srivastava
2025-03-17 11:58 ` [PATCH v4 2/8] iommu/amd: Add debugfs support to dump IOMMU MMIO registers Dheeraj Kumar Srivastava
` (6 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Dheeraj Kumar Srivastava @ 2025-03-17 11:58 UTC (permalink / raw)
To: joro, will, robin.murphy, linux-kernel, iommu
Cc: suravee.suthikulpanit, vasant.hegde, Dheeraj Kumar Srivastava
Rearrange initial setup of AMD IOMMU debugfs to segregate per IOMMU
setup and setup which is common for all IOMMUs. This ensures that common
debugfs paths (introduced in subsequent patches) are created only once
instead of being created for each IOMMU.
With the change, there is no need to use lock as amd_iommu_debugfs_setup()
will be called only once during AMD IOMMU initialization. So remove lock
acquisition in amd_iommu_debugfs_setup().
Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
---
drivers/iommu/amd/amd_iommu.h | 4 ++--
drivers/iommu/amd/debugfs.c | 16 +++++++---------
drivers/iommu/amd/init.c | 5 ++---
3 files changed, 11 insertions(+), 14 deletions(-)
diff --git a/drivers/iommu/amd/amd_iommu.h b/drivers/iommu/amd/amd_iommu.h
index 68debf5ee2d7..58308ed12d83 100644
--- a/drivers/iommu/amd/amd_iommu.h
+++ b/drivers/iommu/amd/amd_iommu.h
@@ -28,9 +28,9 @@ void *__init iommu_alloc_4k_pages(struct amd_iommu *iommu,
gfp_t gfp, size_t size);
#ifdef CONFIG_AMD_IOMMU_DEBUGFS
-void amd_iommu_debugfs_setup(struct amd_iommu *iommu);
+void amd_iommu_debugfs_setup(void);
#else
-static inline void amd_iommu_debugfs_setup(struct amd_iommu *iommu) {}
+static inline void amd_iommu_debugfs_setup(void) {}
#endif
/* Needed for interrupt remapping */
diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
index 545372fcc72f..ff9520e002be 100644
--- a/drivers/iommu/amd/debugfs.c
+++ b/drivers/iommu/amd/debugfs.c
@@ -13,20 +13,18 @@
#include "amd_iommu.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)
+void amd_iommu_debugfs_setup(void)
{
+ 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);
+ amd_iommu_debugfs = debugfs_create_dir("amd", iommu_debugfs_dir);
- snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu->index);
- iommu->debugfs = debugfs_create_dir(name, amd_iommu_debugfs);
+ for_each_iommu(iommu) {
+ snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu->index);
+ iommu->debugfs = debugfs_create_dir(name, amd_iommu_debugfs);
+ }
}
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index cb536d372b12..1bd24c0d5fb5 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3400,7 +3400,6 @@ int amd_iommu_enable_faulting(unsigned int cpu)
*/
static int __init amd_iommu_init(void)
{
- struct amd_iommu *iommu;
int ret;
ret = iommu_go_to_state(IOMMU_INITIALIZED);
@@ -3414,8 +3413,8 @@ static int __init amd_iommu_init(void)
}
#endif
- for_each_iommu(iommu)
- amd_iommu_debugfs_setup(iommu);
+ if (!ret)
+ amd_iommu_debugfs_setup();
return ret;
}
--
2.25.1
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH v4 2/8] iommu/amd: Add debugfs support to dump IOMMU MMIO registers
2025-03-17 11:58 [PATCH v4 0/8] Introduce debugfs support in IOMMU Dheeraj Kumar Srivastava
2025-03-17 11:58 ` [PATCH v4 1/8] iommu/amd: Refactor AMD IOMMU debugfs initial setup Dheeraj Kumar Srivastava
@ 2025-03-17 11:58 ` Dheeraj Kumar Srivastava
2025-03-19 16:50 ` Vasant Hegde
2025-03-17 11:58 ` [PATCH v4 3/8] iommu/amd: Add debugfs support to dump IOMMU Capability registers Dheeraj Kumar Srivastava
` (5 subsequent siblings)
7 siblings, 1 reply; 11+ messages in thread
From: Dheeraj Kumar Srivastava @ 2025-03-17 11:58 UTC (permalink / raw)
To: joro, will, robin.murphy, linux-kernel, iommu
Cc: suravee.suthikulpanit, vasant.hegde, Dheeraj Kumar Srivastava
Analyzing IOMMU MMIO registers gives a view of what IOMMU is
configured with on the system and is helpful to debug issues
with IOMMU.
eg.
-> To get mmio registers value at offset 0x18 for iommu<x> (say, iommu00)
# echo "0x18" > /sys/kernel/debug/iommu/amd/iommu00/mmio
# cat /sys/kernel/debug/iommu/amd/iommu00/mmio
Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
---
drivers/iommu/amd/debugfs.c | 47 +++++++++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)
diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
index ff9520e002be..c61d52420c5f 100644
--- a/drivers/iommu/amd/debugfs.c
+++ b/drivers/iommu/amd/debugfs.c
@@ -15,6 +15,50 @@
static struct dentry *amd_iommu_debugfs;
#define MAX_NAME_LEN 20
+#define OFS_IN_SZ 8
+
+static int mmio_offset = -1;
+
+static ssize_t iommu_mmio_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct seq_file *m = filp->private_data;
+ struct amd_iommu *iommu = m->private;
+ int ret;
+
+ mmio_offset = -1;
+
+ if (cnt > OFS_IN_SZ)
+ return -EINVAL;
+
+ ret = kstrtou32_from_user(ubuf, cnt, 0, &mmio_offset);
+ if (ret)
+ return ret;
+
+ if (mmio_offset > iommu->mmio_phys_end - 4) {
+ mmio_offset = -1;
+ return -EINVAL;
+ }
+
+ return cnt;
+}
+
+static int iommu_mmio_show(struct seq_file *m, void *unused)
+{
+ struct amd_iommu *iommu = m->private;
+ u64 value;
+
+ if (mmio_offset < 0) {
+ seq_puts(m, "Please provide mmio register's offset\n");
+ return 0;
+ }
+
+ value = readq(iommu->mmio_base + mmio_offset);
+ seq_printf(m, "Offset:0x%x Value:0x%016llx\n", mmio_offset, value);
+
+ return 0;
+}
+DEFINE_SHOW_STORE_ATTRIBUTE(iommu_mmio);
void amd_iommu_debugfs_setup(void)
{
@@ -26,5 +70,8 @@ void amd_iommu_debugfs_setup(void)
for_each_iommu(iommu) {
snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu->index);
iommu->debugfs = debugfs_create_dir(name, amd_iommu_debugfs);
+
+ debugfs_create_file("mmio", 0644, iommu->debugfs, iommu,
+ &iommu_mmio_fops);
}
}
--
2.25.1
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH v4 2/8] iommu/amd: Add debugfs support to dump IOMMU MMIO registers
2025-03-17 11:58 ` [PATCH v4 2/8] iommu/amd: Add debugfs support to dump IOMMU MMIO registers Dheeraj Kumar Srivastava
@ 2025-03-19 16:50 ` Vasant Hegde
2025-04-08 5:41 ` Dheeraj Kumar Srivastava
0 siblings, 1 reply; 11+ messages in thread
From: Vasant Hegde @ 2025-03-19 16:50 UTC (permalink / raw)
To: Dheeraj Kumar Srivastava, joro, will, robin.murphy, linux-kernel, iommu
Cc: suravee.suthikulpanit
Dheeraj,
On 3/17/2025 5:28 PM, Dheeraj Kumar Srivastava wrote:
> Analyzing IOMMU MMIO registers gives a view of what IOMMU is
> configured with on the system and is helpful to debug issues
> with IOMMU.
>
> eg.
> -> To get mmio registers value at offset 0x18 for iommu<x> (say, iommu00)
> # echo "0x18" > /sys/kernel/debug/iommu/amd/iommu00/mmio
> # cat /sys/kernel/debug/iommu/amd/iommu00/mmio
>
> Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
> ---
> drivers/iommu/amd/debugfs.c | 47 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 47 insertions(+)
>
> diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
> index ff9520e002be..c61d52420c5f 100644
> --- a/drivers/iommu/amd/debugfs.c
> +++ b/drivers/iommu/amd/debugfs.c
> @@ -15,6 +15,50 @@
> static struct dentry *amd_iommu_debugfs;
>
> #define MAX_NAME_LEN 20
> +#define OFS_IN_SZ 8
> +
> +static int mmio_offset = -1;
Somehow I missed to catch this earlier. Here you have global variable but mmio
is defined per IOMMU. Shouldn't we track it per IOMMU ?
-Vasant
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v4 2/8] iommu/amd: Add debugfs support to dump IOMMU MMIO registers
2025-03-19 16:50 ` Vasant Hegde
@ 2025-04-08 5:41 ` Dheeraj Kumar Srivastava
0 siblings, 0 replies; 11+ messages in thread
From: Dheeraj Kumar Srivastava @ 2025-04-08 5:41 UTC (permalink / raw)
To: Vasant Hegde, joro, will, robin.murphy, linux-kernel, iommu
Cc: suravee.suthikulpanit
Hi Vasant,
On 3/19/2025 10:20 PM, Vasant Hegde wrote:
> Dheeraj,
>
>
> On 3/17/2025 5:28 PM, Dheeraj Kumar Srivastava wrote:
>> Analyzing IOMMU MMIO registers gives a view of what IOMMU is
>> configured with on the system and is helpful to debug issues
>> with IOMMU.
>>
>> eg.
>> -> To get mmio registers value at offset 0x18 for iommu<x> (say, iommu00)
>> # echo "0x18" > /sys/kernel/debug/iommu/amd/iommu00/mmio
>> # cat /sys/kernel/debug/iommu/amd/iommu00/mmio
>>
>> Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
>> ---
>> drivers/iommu/amd/debugfs.c | 47 +++++++++++++++++++++++++++++++++++++
>> 1 file changed, 47 insertions(+)
>>
>> diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
>> index ff9520e002be..c61d52420c5f 100644
>> --- a/drivers/iommu/amd/debugfs.c
>> +++ b/drivers/iommu/amd/debugfs.c
>> @@ -15,6 +15,50 @@
>> static struct dentry *amd_iommu_debugfs;
>>
>> #define MAX_NAME_LEN 20
>> +#define OFS_IN_SZ 8
>> +
>> +static int mmio_offset = -1;
>
>
> Somehow I missed to catch this earlier. Here you have global variable but mmio
> is defined per IOMMU. Shouldn't we track it per IOMMU ?
Yes correct we need to maintain per iommu global variables for mmio and
capability registers offset. I have sent v5 addressing this. Please find
some time to review it.
Thanks
Dheeraj
>
> -Vasant
>
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v4 3/8] iommu/amd: Add debugfs support to dump IOMMU Capability registers
2025-03-17 11:58 [PATCH v4 0/8] Introduce debugfs support in IOMMU Dheeraj Kumar Srivastava
2025-03-17 11:58 ` [PATCH v4 1/8] iommu/amd: Refactor AMD IOMMU debugfs initial setup Dheeraj Kumar Srivastava
2025-03-17 11:58 ` [PATCH v4 2/8] iommu/amd: Add debugfs support to dump IOMMU MMIO registers Dheeraj Kumar Srivastava
@ 2025-03-17 11:58 ` Dheeraj Kumar Srivastava
2025-03-17 11:58 ` [PATCH v4 4/8] iommu/amd: Add debugfs support to dump IOMMU command buffer Dheeraj Kumar Srivastava
` (4 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Dheeraj Kumar Srivastava @ 2025-03-17 11:58 UTC (permalink / raw)
To: joro, will, robin.murphy, linux-kernel, iommu
Cc: suravee.suthikulpanit, vasant.hegde, Dheeraj Kumar Srivastava
IOMMU Capability registers defines capabilities of IOMMU and information
needed for initialising MMIO registers and device table. This is useful
to dump these registers for debugging IOMMU related issues.
e.g.
-> To get capability registers value at offset 0x10 for iommu<x> (say,
iommu00)
# echo "0x10" > /sys/kernel/debug/iommu/amd/iommu00/capability
# cat /sys/kernel/debug/iommu/amd/iommu00/capability
Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
---
drivers/iommu/amd/debugfs.c | 49 +++++++++++++++++++++++++++++++++++++
1 file changed, 49 insertions(+)
diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
index c61d52420c5f..33ffa1c7a511 100644
--- a/drivers/iommu/amd/debugfs.c
+++ b/drivers/iommu/amd/debugfs.c
@@ -18,6 +18,7 @@ static struct dentry *amd_iommu_debugfs;
#define OFS_IN_SZ 8
static int mmio_offset = -1;
+static int cap_offset = -1;
static ssize_t iommu_mmio_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
@@ -60,6 +61,52 @@ static int iommu_mmio_show(struct seq_file *m, void *unused)
}
DEFINE_SHOW_STORE_ATTRIBUTE(iommu_mmio);
+static ssize_t iommu_capability_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ int ret;
+
+ cap_offset = -1;
+
+ if (cnt > OFS_IN_SZ)
+ return -EINVAL;
+
+ ret = kstrtou32_from_user(ubuf, cnt, 0, &cap_offset);
+ if (ret)
+ return ret;
+
+ /* Capability register at offset 0x14 is the last IOMMU capability register. */
+ if (cap_offset > 0x14) {
+ cap_offset = -1;
+ return -EINVAL;
+ }
+
+ return cnt;
+}
+
+static int iommu_capability_show(struct seq_file *m, void *unused)
+{
+ struct amd_iommu *iommu = m->private;
+ u32 value;
+ int err;
+
+ if (cap_offset < 0) {
+ seq_puts(m, "Please provide capability register's offset in the range [0x00 - 0x14]\n");
+ return 0;
+ }
+
+ err = pci_read_config_dword(iommu->dev, iommu->cap_ptr + cap_offset, &value);
+ if (err) {
+ seq_printf(m, "Not able to read capability register at 0x%x\n", cap_offset);
+ return 0;
+ }
+
+ seq_printf(m, "Offset:0x%x Value:0x%08x\n", cap_offset, value);
+
+ return 0;
+}
+DEFINE_SHOW_STORE_ATTRIBUTE(iommu_capability);
+
void amd_iommu_debugfs_setup(void)
{
struct amd_iommu *iommu;
@@ -73,5 +120,7 @@ void amd_iommu_debugfs_setup(void)
debugfs_create_file("mmio", 0644, iommu->debugfs, iommu,
&iommu_mmio_fops);
+ debugfs_create_file("capability", 0644, iommu->debugfs, iommu,
+ &iommu_capability_fops);
}
}
--
2.25.1
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH v4 4/8] iommu/amd: Add debugfs support to dump IOMMU command buffer
2025-03-17 11:58 [PATCH v4 0/8] Introduce debugfs support in IOMMU Dheeraj Kumar Srivastava
` (2 preceding siblings ...)
2025-03-17 11:58 ` [PATCH v4 3/8] iommu/amd: Add debugfs support to dump IOMMU Capability registers Dheeraj Kumar Srivastava
@ 2025-03-17 11:58 ` Dheeraj Kumar Srivastava
2025-03-17 11:58 ` [PATCH v4 5/8] iommu/amd: Add support for device id user input Dheeraj Kumar Srivastava
` (3 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Dheeraj Kumar Srivastava @ 2025-03-17 11:58 UTC (permalink / raw)
To: joro, will, robin.murphy, linux-kernel, iommu
Cc: suravee.suthikulpanit, vasant.hegde, Dheeraj Kumar Srivastava
IOMMU driver sends command to IOMMU hardware via command buffer. In cases
where IOMMU hardware fails to process commands in command buffer, dumping
it is a valuable input to debug the issue.
IOMMU hardware processes command buffer entry at offset equals to the head
pointer. Dumping just the entry at the head pointer may not always be
useful. The current head may not be pointing to the entry of the command
buffer which is causing the issue. IOMMU Hardware may have processed the
entry and updated the head pointer. So dumping the entire command buffer
gives a broad understanding of what hardware was/is doing. The command
buffer dump will have all entries from start to end of the command buffer.
Along with that, it will have a head and tail command buffer pointer
register dump to facilitate where the IOMMU driver and hardware are in
the command buffer for injecting and processing the entries respectively.
Command buffer is a per IOMMU data structure. So dumping on per IOMMU
basis.
eg.
-> To get command buffer dump for iommu<x> (say, iommu00)
#cat /sys/kernel/debug/iommu/amd/iommu00/cmdbuf
Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
---
drivers/iommu/amd/amd_iommu_types.h | 7 +++++++
drivers/iommu/amd/debugfs.c | 26 ++++++++++++++++++++++++++
drivers/iommu/amd/iommu.c | 7 -------
3 files changed, 33 insertions(+), 7 deletions(-)
diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index 23caea22f8dc..022e32f0a877 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -893,6 +893,13 @@ struct dev_table_entry {
};
};
+/*
+ * Structure defining one entry in the command buffer
+ */
+struct iommu_cmd {
+ u32 data[4];
+};
+
/*
* Structure to sture persistent DTE flags from IVHD
*/
diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
index 33ffa1c7a511..d211c1343f93 100644
--- a/drivers/iommu/amd/debugfs.c
+++ b/drivers/iommu/amd/debugfs.c
@@ -107,6 +107,30 @@ static int iommu_capability_show(struct seq_file *m, void *unused)
}
DEFINE_SHOW_STORE_ATTRIBUTE(iommu_capability);
+static int iommu_cmdbuf_show(struct seq_file *m, void *unused)
+{
+ struct amd_iommu *iommu = m->private;
+ struct iommu_cmd *cmd;
+ unsigned long flag;
+ u32 head, tail;
+ int i;
+
+ raw_spin_lock_irqsave(&iommu->lock, flag);
+ head = readl(iommu->mmio_base + MMIO_CMD_HEAD_OFFSET);
+ tail = readl(iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);
+ seq_printf(m, "CMD Buffer Head Offset:%d Tail Offset:%d\n",
+ (head >> 4) & 0x7fff, (tail >> 4) & 0x7fff);
+ for (i = 0; i < CMD_BUFFER_ENTRIES; i++) {
+ cmd = (struct iommu_cmd *)(iommu->cmd_buf + i * sizeof(*cmd));
+ seq_printf(m, "%3d: %08x %08x %08x %08x\n", i, cmd->data[0],
+ cmd->data[1], cmd->data[2], cmd->data[3]);
+ }
+ raw_spin_unlock_irqrestore(&iommu->lock, flag);
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(iommu_cmdbuf);
+
void amd_iommu_debugfs_setup(void)
{
struct amd_iommu *iommu;
@@ -122,5 +146,7 @@ void amd_iommu_debugfs_setup(void)
&iommu_mmio_fops);
debugfs_create_file("capability", 0644, iommu->debugfs, iommu,
&iommu_capability_fops);
+ debugfs_create_file("cmdbuf", 0444, iommu->debugfs, iommu,
+ &iommu_cmdbuf_fops);
}
}
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index cd5116d8c3b2..5c51ffe7c956 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -62,13 +62,6 @@ static const struct iommu_dirty_ops amd_dirty_ops;
int amd_iommu_max_glx_val = -1;
-/*
- * general struct to manage commands send to an IOMMU
- */
-struct iommu_cmd {
- u32 data[4];
-};
-
/*
* AMD IOMMU allows up to 2^16 different protection domains. This is a bitmap
* to know which ones are already in use.
--
2.25.1
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH v4 5/8] iommu/amd: Add support for device id user input
2025-03-17 11:58 [PATCH v4 0/8] Introduce debugfs support in IOMMU Dheeraj Kumar Srivastava
` (3 preceding siblings ...)
2025-03-17 11:58 ` [PATCH v4 4/8] iommu/amd: Add debugfs support to dump IOMMU command buffer Dheeraj Kumar Srivastava
@ 2025-03-17 11:58 ` Dheeraj Kumar Srivastava
2025-03-17 11:58 ` [PATCH v4 6/8] iommu/amd: Add debugfs support to dump device table Dheeraj Kumar Srivastava
` (2 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Dheeraj Kumar Srivastava @ 2025-03-17 11:58 UTC (permalink / raw)
To: joro, will, robin.murphy, linux-kernel, iommu
Cc: suravee.suthikulpanit, vasant.hegde, Dheeraj Kumar Srivastava
Dumping IOMMU data structures like device table, IRT, etc., for all devices
on the system will be a lot of data dumped in a file. Also, user may want
to dump and analyze these data structures just for one or few devices. So
dumping IOMMU data structures like device table, IRT etc for all devices
is not a good approach.
Add "device id" user input to be used for dumping IOMMU data structures
like device table, IRT etc in AMD IOMMU debugfs.
eg.
1. # echo 0000:01:00.0 > /sys/kernel/debug/iommu/amd/devid
# cat /sys/kernel/debug/iommu/amd/devid
Output : 0000:01:00.0
2. # echo 01:00.0 > /sys/kernel/debug/iommu/amd/devid
# cat /sys/kernel/debug/iommu/amd/devid
Output : 0000:01:00.0
Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
---
drivers/iommu/amd/debugfs.c | 78 +++++++++++++++++++++++++++++++++++++
1 file changed, 78 insertions(+)
diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
index d211c1343f93..de030801e236 100644
--- a/drivers/iommu/amd/debugfs.c
+++ b/drivers/iommu/amd/debugfs.c
@@ -16,9 +16,11 @@ static struct dentry *amd_iommu_debugfs;
#define MAX_NAME_LEN 20
#define OFS_IN_SZ 8
+#define DEVID_IN_SZ 16
static int mmio_offset = -1;
static int cap_offset = -1;
+static int sbdf = -1;
static ssize_t iommu_mmio_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
@@ -131,6 +133,80 @@ static int iommu_cmdbuf_show(struct seq_file *m, void *unused)
}
DEFINE_SHOW_ATTRIBUTE(iommu_cmdbuf);
+static ssize_t devid_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct amd_iommu_pci_seg *pci_seg;
+ int seg, bus, slot, func;
+ struct amd_iommu *iommu;
+ char *srcid_ptr;
+ u16 devid;
+ int i;
+
+ sbdf = -1;
+
+ if (cnt >= DEVID_IN_SZ)
+ return -EINVAL;
+
+ srcid_ptr = memdup_user_nul(ubuf, cnt);
+ if (IS_ERR(srcid_ptr))
+ return PTR_ERR(srcid_ptr);
+
+ i = sscanf(srcid_ptr, "%x:%x:%x.%x", &seg, &bus, &slot, &func);
+ if (i != 4) {
+ i = sscanf(srcid_ptr, "%x:%x.%x", &bus, &slot, &func);
+ if (i != 3) {
+ kfree(srcid_ptr);
+ return -EINVAL;
+ }
+ seg = 0;
+ }
+
+ devid = PCI_DEVID(bus, PCI_DEVFN(slot, func));
+
+ /* Check if user device id input is a valid input */
+ for_each_pci_segment(pci_seg) {
+ if (pci_seg->id != seg)
+ continue;
+ if (devid > pci_seg->last_bdf) {
+ kfree(srcid_ptr);
+ return -EINVAL;
+ }
+ iommu = pci_seg->rlookup_table[devid];
+ if (!iommu) {
+ kfree(srcid_ptr);
+ return -ENODEV;
+ }
+ break;
+ }
+
+ if (pci_seg->id != seg) {
+ kfree(srcid_ptr);
+ return -EINVAL;
+ }
+
+ sbdf = PCI_SEG_DEVID_TO_SBDF(seg, devid);
+
+ kfree(srcid_ptr);
+
+ return cnt;
+}
+
+static int devid_show(struct seq_file *m, void *unused)
+{
+ u16 devid;
+
+ if (sbdf >= 0) {
+ devid = PCI_SBDF_TO_DEVID(sbdf);
+ seq_printf(m, "%04x:%02x:%02x:%x\n", PCI_SBDF_TO_SEGID(sbdf),
+ PCI_BUS_NUM(devid), PCI_SLOT(devid), PCI_FUNC(devid));
+ } else
+ seq_puts(m, "No or Invalid input provided\n");
+
+ return 0;
+}
+DEFINE_SHOW_STORE_ATTRIBUTE(devid);
+
void amd_iommu_debugfs_setup(void)
{
struct amd_iommu *iommu;
@@ -149,4 +225,6 @@ void amd_iommu_debugfs_setup(void)
debugfs_create_file("cmdbuf", 0444, iommu->debugfs, iommu,
&iommu_cmdbuf_fops);
}
+ debugfs_create_file("devid", 0644, amd_iommu_debugfs, NULL,
+ &devid_fops);
}
--
2.25.1
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH v4 6/8] iommu/amd: Add debugfs support to dump device table
2025-03-17 11:58 [PATCH v4 0/8] Introduce debugfs support in IOMMU Dheeraj Kumar Srivastava
` (4 preceding siblings ...)
2025-03-17 11:58 ` [PATCH v4 5/8] iommu/amd: Add support for device id user input Dheeraj Kumar Srivastava
@ 2025-03-17 11:58 ` Dheeraj Kumar Srivastava
2025-03-17 11:58 ` [PATCH v4 7/8] iommu/amd: Add debugfs support to dump IRT Table Dheeraj Kumar Srivastava
2025-03-17 11:58 ` [PATCH v4 8/8] iommu/amd: Add documentation for AMD IOMMU debugfs support Dheeraj Kumar Srivastava
7 siblings, 0 replies; 11+ messages in thread
From: Dheeraj Kumar Srivastava @ 2025-03-17 11:58 UTC (permalink / raw)
To: joro, will, robin.murphy, linux-kernel, iommu
Cc: suravee.suthikulpanit, vasant.hegde, Dheeraj Kumar Srivastava
IOMMU uses device table data structure to get per-device information for
DMA remapping, interrupt remapping, and other functionalities. It's a
valuable data structure to visualize for debugging issues related to
IOMMU.
eg.
-> To dump device table entry for a particular device
#echo 0000:c4:00.0 > /sys/kernel/debug/iommu/amd/devid
#cat /sys/kernel/debug/iommu/amd/devtbl
or
#echo c4:00.0 > /sys/kernel/debug/iommu/amd/devid
#cat /sys/kernel/debug/iommu/amd/devtbl
Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
---
drivers/iommu/amd/debugfs.c | 49 +++++++++++++++++++++++++++++++++++++
1 file changed, 49 insertions(+)
diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
index de030801e236..4ea50e5625fa 100644
--- a/drivers/iommu/amd/debugfs.c
+++ b/drivers/iommu/amd/debugfs.c
@@ -207,6 +207,53 @@ static int devid_show(struct seq_file *m, void *unused)
}
DEFINE_SHOW_STORE_ATTRIBUTE(devid);
+static void dump_dte(struct seq_file *m, struct amd_iommu_pci_seg *pci_seg, u16 devid)
+{
+ struct dev_table_entry *dev_table;
+ struct amd_iommu *iommu;
+
+ iommu = pci_seg->rlookup_table[devid];
+ if (!iommu)
+ return;
+
+ dev_table = get_dev_table(iommu);
+ if (!dev_table) {
+ seq_puts(m, "Device table not found");
+ return;
+ }
+
+ seq_printf(m, "%-12s %16s %16s %16s %16s iommu\n", "DeviceId",
+ "QWORD[3]", "QWORD[2]", "QWORD[1]", "QWORD[0]");
+ seq_printf(m, "%04x:%02x:%02x:%x ", pci_seg->id, PCI_BUS_NUM(devid),
+ PCI_SLOT(devid), PCI_FUNC(devid));
+ for (int i = 3; i >= 0; --i)
+ seq_printf(m, "%016llx ", dev_table[devid].data[i]);
+ seq_printf(m, "iommu%d\n", iommu->index);
+}
+
+static int iommu_devtbl_show(struct seq_file *m, void *unused)
+{
+ struct amd_iommu_pci_seg *pci_seg;
+ u16 seg, devid;
+
+ if (sbdf < 0) {
+ seq_puts(m, "Please provide valid device id input\n");
+ return 0;
+ }
+ seg = PCI_SBDF_TO_SEGID(sbdf);
+ devid = PCI_SBDF_TO_DEVID(sbdf);
+
+ for_each_pci_segment(pci_seg) {
+ if (pci_seg->id != seg)
+ continue;
+ dump_dte(m, pci_seg, devid);
+ break;
+ }
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(iommu_devtbl);
+
void amd_iommu_debugfs_setup(void)
{
struct amd_iommu *iommu;
@@ -227,4 +274,6 @@ void amd_iommu_debugfs_setup(void)
}
debugfs_create_file("devid", 0644, amd_iommu_debugfs, NULL,
&devid_fops);
+ debugfs_create_file("devtbl", 0444, amd_iommu_debugfs, NULL,
+ &iommu_devtbl_fops);
}
--
2.25.1
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH v4 7/8] iommu/amd: Add debugfs support to dump IRT Table
2025-03-17 11:58 [PATCH v4 0/8] Introduce debugfs support in IOMMU Dheeraj Kumar Srivastava
` (5 preceding siblings ...)
2025-03-17 11:58 ` [PATCH v4 6/8] iommu/amd: Add debugfs support to dump device table Dheeraj Kumar Srivastava
@ 2025-03-17 11:58 ` Dheeraj Kumar Srivastava
2025-03-17 11:58 ` [PATCH v4 8/8] iommu/amd: Add documentation for AMD IOMMU debugfs support Dheeraj Kumar Srivastava
7 siblings, 0 replies; 11+ messages in thread
From: Dheeraj Kumar Srivastava @ 2025-03-17 11:58 UTC (permalink / raw)
To: joro, will, robin.murphy, linux-kernel, iommu
Cc: suravee.suthikulpanit, vasant.hegde, Dheeraj Kumar Srivastava
In cases where we have an issue in the device interrupt path with IOMMU
interrupt remapping enabled, dumping valid IRT table entries for the device
is very useful and good input for debugging the issue.
eg.
-> To dump irte entries for a particular device
#echo "c4:00.0" > /sys/kernel/debug/iommu/amd/devid
#cat /sys/kernel/debug/iommu/amd/irqtbl | less
or
#echo "0000:c4:00.0" > /sys/kernel/debug/iommu/amd/devid
#cat /sys/kernel/debug/iommu/amd/irqtbl | less
Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
---
drivers/iommu/amd/debugfs.c | 89 +++++++++++++++++++++++++++++++++++++
1 file changed, 89 insertions(+)
diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
index 4ea50e5625fa..cd74a10109dc 100644
--- a/drivers/iommu/amd/debugfs.c
+++ b/drivers/iommu/amd/debugfs.c
@@ -11,6 +11,7 @@
#include <linux/pci.h>
#include "amd_iommu.h"
+#include "../irq_remapping.h"
static struct dentry *amd_iommu_debugfs;
@@ -254,6 +255,92 @@ static int iommu_devtbl_show(struct seq_file *m, void *unused)
}
DEFINE_SHOW_ATTRIBUTE(iommu_devtbl);
+static void dump_128_irte(struct seq_file *m, struct irq_remap_table *table)
+{
+ struct irte_ga *ptr, *irte;
+ int index;
+
+ for (index = 0; index < MAX_IRQS_PER_TABLE; index++) {
+ ptr = (struct irte_ga *)table->table;
+ irte = &ptr[index];
+
+ if (AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir) &&
+ !irte->lo.fields_vapic.valid)
+ continue;
+ else if (!irte->lo.fields_remap.valid)
+ continue;
+ seq_printf(m, "IRT[%04d] %016llx %016llx\n", index, irte->hi.val, irte->lo.val);
+ }
+}
+
+static void dump_32_irte(struct seq_file *m, struct irq_remap_table *table)
+{
+ union irte *ptr, *irte;
+ int index;
+
+ for (index = 0; index < MAX_IRQS_PER_TABLE; index++) {
+ ptr = (union irte *)table->table;
+ irte = &ptr[index];
+
+ if (!irte->fields.valid)
+ continue;
+ seq_printf(m, "IRT[%04d] %08x\n", index, irte->val);
+ }
+}
+
+static void dump_irte(struct seq_file *m, u16 devid, struct amd_iommu_pci_seg *pci_seg)
+{
+ struct irq_remap_table *table;
+ unsigned long flags;
+
+ table = pci_seg->irq_lookup_table[devid];
+ if (!table) {
+ seq_printf(m, "IRQ lookup table not set for %04x:%02x:%02x:%x\n",
+ pci_seg->id, PCI_BUS_NUM(devid), PCI_SLOT(devid), PCI_FUNC(devid));
+ return;
+ }
+
+ seq_printf(m, "DeviceId %04x:%02x:%02x:%x\n", pci_seg->id, PCI_BUS_NUM(devid),
+ PCI_SLOT(devid), PCI_FUNC(devid));
+
+ raw_spin_lock_irqsave(&table->lock, flags);
+ if (AMD_IOMMU_GUEST_IR_GA(amd_iommu_guest_ir))
+ dump_128_irte(m, table);
+ else
+ dump_32_irte(m, table);
+ seq_puts(m, "\n");
+ raw_spin_unlock_irqrestore(&table->lock, flags);
+}
+
+static int iommu_irqtbl_show(struct seq_file *m, void *unused)
+{
+ struct amd_iommu_pci_seg *pci_seg;
+ u16 devid, seg;
+
+ if (!irq_remapping_enabled) {
+ seq_puts(m, "Interrupt remapping is disabled\n");
+ return 0;
+ }
+
+ if (sbdf < 0) {
+ seq_puts(m, "Please provide valid device id input\n");
+ return 0;
+ }
+
+ seg = PCI_SBDF_TO_SEGID(sbdf);
+ devid = PCI_SBDF_TO_DEVID(sbdf);
+
+ for_each_pci_segment(pci_seg) {
+ if (pci_seg->id != seg)
+ continue;
+ dump_irte(m, devid, pci_seg);
+ break;
+ }
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(iommu_irqtbl);
+
void amd_iommu_debugfs_setup(void)
{
struct amd_iommu *iommu;
@@ -276,4 +363,6 @@ void amd_iommu_debugfs_setup(void)
&devid_fops);
debugfs_create_file("devtbl", 0444, amd_iommu_debugfs, NULL,
&iommu_devtbl_fops);
+ debugfs_create_file("irqtbl", 0444, amd_iommu_debugfs, NULL,
+ &iommu_irqtbl_fops);
}
--
2.25.1
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH v4 8/8] iommu/amd: Add documentation for AMD IOMMU debugfs support
2025-03-17 11:58 [PATCH v4 0/8] Introduce debugfs support in IOMMU Dheeraj Kumar Srivastava
` (6 preceding siblings ...)
2025-03-17 11:58 ` [PATCH v4 7/8] iommu/amd: Add debugfs support to dump IRT Table Dheeraj Kumar Srivastava
@ 2025-03-17 11:58 ` Dheeraj Kumar Srivastava
7 siblings, 0 replies; 11+ messages in thread
From: Dheeraj Kumar Srivastava @ 2025-03-17 11:58 UTC (permalink / raw)
To: joro, will, robin.murphy, linux-kernel, iommu
Cc: suravee.suthikulpanit, vasant.hegde, Dheeraj Kumar Srivastava
Add documentation describing how to use AMD IOMMU debugfs support to
dump IOMMU data structures - IRT table, Device table, Registers (MMIO and
Capability) and command buffer.
Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
---
Documentation/ABI/testing/debugfs-amd-iommu | 114 ++++++++++++++++++++
1 file changed, 114 insertions(+)
create mode 100644 Documentation/ABI/testing/debugfs-amd-iommu
diff --git a/Documentation/ABI/testing/debugfs-amd-iommu b/Documentation/ABI/testing/debugfs-amd-iommu
new file mode 100644
index 000000000000..49efc74c8e6f
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-amd-iommu
@@ -0,0 +1,114 @@
+What: /sys/kernel/debug/iommu/amd/iommu<x>/mmio
+Date: September 2024
+Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
+Description:
+ This is an input read/write access file. In this file, the user input
+ mmio register offset for iommu<x> to print corresponding mmio register
+ of iommu<x>.
+
+ Example:
+ $ echo "0x18" > /sys/kernel/debug/iommu/amd/iommu00/mmio
+ $ cat /sys/kernel/debug/iommu/amd/iommu00/mmio
+
+ Output:
+ Offset:0x18 Value:0x000c22000003f48d
+
+What: /sys/kernel/debug/iommu/amd/iommu<x>/capability
+Date: September 2024
+Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
+Description:
+ This is an input read/write access file. In this file, the user input
+ capability register offset for iommu<x> to print corresponding capability
+ register of iommu<x>.
+
+ Example:
+ $ echo "0x10" > /sys/kernel/debug/iommu/amd/iommu00/capability
+ $ cat /sys/kernel/debug/iommu/amd/iommu00/capability
+
+ Output:
+ Offset:0x10 Value:0x00203040
+
+What: /sys/kernel/debug/iommu/amd/iommu<x>/cmdbuf
+Date: September 2024
+Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
+Description:
+ This file is an output read only file that contains iommu<x> command
+ buffer entries.
+
+ Examples:
+ $ cat /sys/kernel/debug/iommu/amd/iommu<x>/cmdbuf
+
+ Output:
+ CMD Buffer Head Offset:339 Tail Offset:339
+ 0: 00835001 10000001 00003c00 00000000
+ 1: 00000000 30000005 fffff003 7fffffff
+ 2: 00835001 10000001 00003c01 00000000
+ 3: 00000000 30000005 fffff003 7fffffff
+ 4: 00835001 10000001 00003c02 00000000
+ 5: 00000000 30000005 fffff003 7fffffff
+ 6: 00835001 10000001 00003c03 00000000
+ 7: 00000000 30000005 fffff003 7fffffff
+ 8: 00835001 10000001 00003c04 00000000
+ 9: 00000000 30000005 fffff003 7fffffff
+ 10: 00835001 10000001 00003c05 00000000
+ 11: 00000000 30000005 fffff003 7fffffff
+ [...]
+
+What: /sys/kernel/debug/iommu/amd/devid
+Date: September 2024
+Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
+Description:
+ This is an input read/write file that takes device id user input.
+ This input can be used for dumping iommu data structures like
+ interrupt remapping table, device table etc.
+
+ Example:
+ 1.
+ $ echo 0000:01:00.0 > /sys/kernel/debug/iommu/amd/devid
+ $ cat /sys/kernel/debug/iommu/amd/devid
+
+ Output:
+ 0000:01:00.0
+
+ 2.
+ $ echo 01:00.0 > /sys/kernel/debug/iommu/amd/devid
+ $ cat /sys/kernel/debug/iommu/amd/devid
+
+ Output:
+ 0000:01:00.0
+
+What: /sys/kernel/debug/iommu/amd/devtbl
+Date: September 2024
+Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
+Description:
+ This is an output read only file that contains device table entry for
+ the device id input given in /sys/kernel/debug/iommu/amd/devid.
+
+ Example:
+ $ cat /sys/kernel/debug/iommu/amd/devtbl
+
+ Output:
+ DeviceId QWORD[3] QWORD[2] QWORD[1] QWORD[0] iommu
+ 0000:01:00.0 0000000000000000 20000001373b8013 0000000000000038 6000000114d7b603 iommu3
+
+What: /sys/kernel/debug/iommu/amd/irqtbl
+Date: September 2024
+Contact: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
+Description:
+ This is an output read only file that contains IRT table valid entries
+ for the device id input given in /sys/kernel/debug/iommu/amd/devid.
+
+ Example:
+ $ cat /sys/kernel/debug/iommu/amd/irqtbl
+
+ Output:
+ DeviceId 0000:01:00.0
+ IRT[0000] 0000000000000020 0000000000000241
+ IRT[0001] 0000000000000020 0000000000000841
+ IRT[0002] 0000000000000020 0000000000002041
+ IRT[0003] 0000000000000020 0000000000008041
+ IRT[0004] 0000000000000020 0000000000020041
+ IRT[0005] 0000000000000020 0000000000080041
+ IRT[0006] 0000000000000020 0000000000200041
+ IRT[0007] 0000000000000020 0000000000800041
+ [...]
--
2.25.1
^ permalink raw reply [flat|nested] 11+ messages in thread