* [PATCH] iommu/arm-smmu-v3: Add tracepoint for EVTQ events
@ 2026-06-13 13:00 Chen Jun
2026-06-23 15:31 ` Robin Murphy
0 siblings, 1 reply; 3+ messages in thread
From: Chen Jun @ 2026-06-13 13:00 UTC (permalink / raw)
To: will, robin.murphy, joro, linux-kernel, linux-arm-kernel
Cc: chenjun102, zhangyuwei20
Events reported by the SMMU can severely impact accelerator
performance. Currently, only events that the SMMU fails to handle are
printed to the kernel log, leaving most events invisible to users.
To analyze and optimize accelerator performance, complete visibility
into all SMMU-reported events is required.
Add a tracepoint in the EVTQ interrupt handler to capture every
event record reported by the SMMU. This allows users to collect all
event information via ftrace/perf for further analysis, complementing
the existing event decoder and error dump which only cover a subset
of events.
Signed-off-by: Chen Jun <chenjun102@huawei.com>
---
drivers/iommu/arm/arm-smmu-v3/Makefile | 2 +-
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 ++
drivers/iommu/arm/arm-smmu-v3/trace.c | 9 ++++
drivers/iommu/arm/arm-smmu-v3/trace.h | 53 +++++++++++++++++++++
4 files changed, 66 insertions(+), 1 deletion(-)
create mode 100644 drivers/iommu/arm/arm-smmu-v3/trace.c
create mode 100644 drivers/iommu/arm/arm-smmu-v3/trace.h
diff --git a/drivers/iommu/arm/arm-smmu-v3/Makefile b/drivers/iommu/arm/arm-smmu-v3/Makefile
index 493a659cc66b..63a8d71bfc93 100644
--- a/drivers/iommu/arm/arm-smmu-v3/Makefile
+++ b/drivers/iommu/arm/arm-smmu-v3/Makefile
@@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_ARM_SMMU_V3) += arm_smmu_v3.o
-arm_smmu_v3-y := arm-smmu-v3.o
+arm_smmu_v3-y := arm-smmu-v3.o trace.o
arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_IOMMUFD) += arm-smmu-v3-iommufd.o
arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_SVA) += arm-smmu-v3-sva.o
arm_smmu_v3-$(CONFIG_TEGRA241_CMDQV) += tegra241-cmdqv.o
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index e8d7dbe495f0..85e6c25b73ed 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -34,6 +34,8 @@
#include "arm-smmu-v3.h"
#include "../../dma-iommu.h"
+#include "trace.h"
+
static bool disable_msipolling;
module_param(disable_msipolling, bool, 0444);
MODULE_PARM_DESC(disable_msipolling,
@@ -2271,6 +2273,7 @@ static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
do {
while (!queue_remove_raw(q, evt)) {
+ trace_smmu_evtq_event(smmu, evt);
arm_smmu_decode_event(smmu, evt, &event);
if (arm_smmu_handle_event(smmu, evt, &event))
arm_smmu_dump_event(smmu, evt, &event, &rs);
diff --git a/drivers/iommu/arm/arm-smmu-v3/trace.c b/drivers/iommu/arm/arm-smmu-v3/trace.c
new file mode 100644
index 000000000000..77378698b1a3
--- /dev/null
+++ b/drivers/iommu/arm/arm-smmu-v3/trace.c
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ARM SMMUv3 trace support
+ *
+ * Copyright (c) 2026 OpenCloudOS / openEuler
+ */
+
+#define CREATE_TRACE_POINTS
+#include "trace.h"
diff --git a/drivers/iommu/arm/arm-smmu-v3/trace.h b/drivers/iommu/arm/arm-smmu-v3/trace.h
new file mode 100644
index 000000000000..7cec8d41745e
--- /dev/null
+++ b/drivers/iommu/arm/arm-smmu-v3/trace.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * ARM SMMUv3 trace support
+ *
+ * Copyright (c) 2026 OpenCloudOS / openEuler
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM arm_smmu_v3
+
+#if !defined(_TRACE_ARM_SMMU_V3_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_ARM_SMMU_V3_H
+
+#include <linux/tracepoint.h>
+
+#include "arm-smmu-v3.h"
+
+TRACE_EVENT(smmu_evtq_event,
+
+ TP_PROTO(struct arm_smmu_device *smmu, u64 *evt),
+
+ TP_ARGS(smmu, evt),
+
+ TP_STRUCT__entry(
+ __string(iommu, dev_name(smmu->dev))
+ __field(u64, evt0)
+ __field(u64, evt1)
+ __field(u64, evt2)
+ __field(u64, evt3)
+ ),
+
+ TP_fast_assign(
+ __assign_str(iommu);
+ __entry->evt0 = evt[0];
+ __entry->evt1 = evt[1];
+ __entry->evt2 = evt[2];
+ __entry->evt3 = evt[3];
+ ),
+
+ TP_printk("%s evt: 0x%016llx 0x%016llx 0x%016llx 0x%016llx",
+ __get_str(iommu),
+ __entry->evt0, __entry->evt1,
+ __entry->evt2, __entry->evt3)
+);
+
+#endif /* _TRACE_ARM_SMMU_V3_H */
+
+/* This part must be outside protection */
+#undef TRACE_INCLUDE_PATH
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_PATH ../../drivers/iommu/arm/arm-smmu-v3/
+#define TRACE_INCLUDE_FILE trace
+#include <trace/define_trace.h>
--
2.22.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] iommu/arm-smmu-v3: Add tracepoint for EVTQ events
2026-06-13 13:00 [PATCH] iommu/arm-smmu-v3: Add tracepoint for EVTQ events Chen Jun
@ 2026-06-23 15:31 ` Robin Murphy
2026-06-24 8:43 ` chenjun (AM)
0 siblings, 1 reply; 3+ messages in thread
From: Robin Murphy @ 2026-06-23 15:31 UTC (permalink / raw)
To: Chen Jun, will, joro, linux-kernel, linux-arm-kernel; +Cc: zhangyuwei20
On 13/06/2026 2:00 pm, Chen Jun wrote:
> Events reported by the SMMU can severely impact accelerator
> performance. Currently, only events that the SMMU fails to handle are
> printed to the kernel log, leaving most events invisible to users.
> To analyze and optimize accelerator performance, complete visibility
> into all SMMU-reported events is required.
What events, exactly? AFAICS the only events we should expect to handle
"invisibly", without being some unexpected error condition worth
screaming about, would be stalls for SVA page faults, and if SVA isn't
generically accounting page faults itself then I would imagine it
probably should.
Thanks,
Robin.
> Add a tracepoint in the EVTQ interrupt handler to capture every
> event record reported by the SMMU. This allows users to collect all
> event information via ftrace/perf for further analysis, complementing
> the existing event decoder and error dump which only cover a subset
> of events.
>
> Signed-off-by: Chen Jun <chenjun102@huawei.com>
> ---
> drivers/iommu/arm/arm-smmu-v3/Makefile | 2 +-
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 ++
> drivers/iommu/arm/arm-smmu-v3/trace.c | 9 ++++
> drivers/iommu/arm/arm-smmu-v3/trace.h | 53 +++++++++++++++++++++
> 4 files changed, 66 insertions(+), 1 deletion(-)
> create mode 100644 drivers/iommu/arm/arm-smmu-v3/trace.c
> create mode 100644 drivers/iommu/arm/arm-smmu-v3/trace.h
>
> diff --git a/drivers/iommu/arm/arm-smmu-v3/Makefile b/drivers/iommu/arm/arm-smmu-v3/Makefile
> index 493a659cc66b..63a8d71bfc93 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/Makefile
> +++ b/drivers/iommu/arm/arm-smmu-v3/Makefile
> @@ -1,6 +1,6 @@
> # SPDX-License-Identifier: GPL-2.0
> obj-$(CONFIG_ARM_SMMU_V3) += arm_smmu_v3.o
> -arm_smmu_v3-y := arm-smmu-v3.o
> +arm_smmu_v3-y := arm-smmu-v3.o trace.o
> arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_IOMMUFD) += arm-smmu-v3-iommufd.o
> arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_SVA) += arm-smmu-v3-sva.o
> arm_smmu_v3-$(CONFIG_TEGRA241_CMDQV) += tegra241-cmdqv.o
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index e8d7dbe495f0..85e6c25b73ed 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -34,6 +34,8 @@
> #include "arm-smmu-v3.h"
> #include "../../dma-iommu.h"
>
> +#include "trace.h"
> +
> static bool disable_msipolling;
> module_param(disable_msipolling, bool, 0444);
> MODULE_PARM_DESC(disable_msipolling,
> @@ -2271,6 +2273,7 @@ static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
>
> do {
> while (!queue_remove_raw(q, evt)) {
> + trace_smmu_evtq_event(smmu, evt);
> arm_smmu_decode_event(smmu, evt, &event);
> if (arm_smmu_handle_event(smmu, evt, &event))
> arm_smmu_dump_event(smmu, evt, &event, &rs);
> diff --git a/drivers/iommu/arm/arm-smmu-v3/trace.c b/drivers/iommu/arm/arm-smmu-v3/trace.c
> new file mode 100644
> index 000000000000..77378698b1a3
> --- /dev/null
> +++ b/drivers/iommu/arm/arm-smmu-v3/trace.c
> @@ -0,0 +1,9 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * ARM SMMUv3 trace support
> + *
> + * Copyright (c) 2026 OpenCloudOS / openEuler
> + */
> +
> +#define CREATE_TRACE_POINTS
> +#include "trace.h"
> diff --git a/drivers/iommu/arm/arm-smmu-v3/trace.h b/drivers/iommu/arm/arm-smmu-v3/trace.h
> new file mode 100644
> index 000000000000..7cec8d41745e
> --- /dev/null
> +++ b/drivers/iommu/arm/arm-smmu-v3/trace.h
> @@ -0,0 +1,53 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * ARM SMMUv3 trace support
> + *
> + * Copyright (c) 2026 OpenCloudOS / openEuler
> + */
> +
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM arm_smmu_v3
> +
> +#if !defined(_TRACE_ARM_SMMU_V3_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_ARM_SMMU_V3_H
> +
> +#include <linux/tracepoint.h>
> +
> +#include "arm-smmu-v3.h"
> +
> +TRACE_EVENT(smmu_evtq_event,
> +
> + TP_PROTO(struct arm_smmu_device *smmu, u64 *evt),
> +
> + TP_ARGS(smmu, evt),
> +
> + TP_STRUCT__entry(
> + __string(iommu, dev_name(smmu->dev))
> + __field(u64, evt0)
> + __field(u64, evt1)
> + __field(u64, evt2)
> + __field(u64, evt3)
> + ),
> +
> + TP_fast_assign(
> + __assign_str(iommu);
> + __entry->evt0 = evt[0];
> + __entry->evt1 = evt[1];
> + __entry->evt2 = evt[2];
> + __entry->evt3 = evt[3];
> + ),
> +
> + TP_printk("%s evt: 0x%016llx 0x%016llx 0x%016llx 0x%016llx",
> + __get_str(iommu),
> + __entry->evt0, __entry->evt1,
> + __entry->evt2, __entry->evt3)
> +);
> +
> +#endif /* _TRACE_ARM_SMMU_V3_H */
> +
> +/* This part must be outside protection */
> +#undef TRACE_INCLUDE_PATH
> +#undef TRACE_INCLUDE_FILE
> +#define TRACE_INCLUDE_PATH ../../drivers/iommu/arm/arm-smmu-v3/
> +#define TRACE_INCLUDE_FILE trace
> +#include <trace/define_trace.h>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] iommu/arm-smmu-v3: Add tracepoint for EVTQ events
2026-06-23 15:31 ` Robin Murphy
@ 2026-06-24 8:43 ` chenjun (AM)
0 siblings, 0 replies; 3+ messages in thread
From: chenjun (AM) @ 2026-06-24 8:43 UTC (permalink / raw)
To: Robin Murphy, will@kernel.org, joro@8bytes.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Cc: zhangyuwei (G)
在 2026/6/23 23:31, Robin Murphy 写道:
> On 13/06/2026 2:00 pm, Chen Jun wrote:
>> Events reported by the SMMU can severely impact accelerator
>> performance. Currently, only events that the SMMU fails to handle are
>> printed to the kernel log, leaving most events invisible to users.
>> To analyze and optimize accelerator performance, complete visibility
>> into all SMMU-reported events is required.
>
> What events, exactly? AFAICS the only events we should expect to handle
> "invisibly", without being some unexpected error condition worth
> screaming about, would be stalls for SVA page faults, and if SVA isn't
> generically accounting page faults itself then I would imagine it
> probably should.
>
> Thanks,
> Robin.
>
AF and WP faults are common occurrences. and they can significantly
impact SMMU performance. If we can determine exactly at which address
and what type of page fault occurred, it would help us avoid SVA page
fault events through other means. Also, I don't see any separate
accounting for page fault events in the SVA flow.
Thanks
Chen Jun
>> Add a tracepoint in the EVTQ interrupt handler to capture every
>> event record reported by the SMMU. This allows users to collect all
>> event information via ftrace/perf for further analysis, complementing
>> the existing event decoder and error dump which only cover a subset
>> of events.
>>
>> Signed-off-by: Chen Jun <chenjun102@huawei.com>
>> ---
>> drivers/iommu/arm/arm-smmu-v3/Makefile | 2 +-
>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 ++
>> drivers/iommu/arm/arm-smmu-v3/trace.c | 9 ++++
>> drivers/iommu/arm/arm-smmu-v3/trace.h | 53 +++++++++++++++++++++
>> 4 files changed, 66 insertions(+), 1 deletion(-)
>> create mode 100644 drivers/iommu/arm/arm-smmu-v3/trace.c
>> create mode 100644 drivers/iommu/arm/arm-smmu-v3/trace.h
>>
>> diff --git a/drivers/iommu/arm/arm-smmu-v3/Makefile b/drivers/iommu/arm/arm-smmu-v3/Makefile
>> index 493a659cc66b..63a8d71bfc93 100644
>> --- a/drivers/iommu/arm/arm-smmu-v3/Makefile
>> +++ b/drivers/iommu/arm/arm-smmu-v3/Makefile
>> @@ -1,6 +1,6 @@
>> # SPDX-License-Identifier: GPL-2.0
>> obj-$(CONFIG_ARM_SMMU_V3) += arm_smmu_v3.o
>> -arm_smmu_v3-y := arm-smmu-v3.o
>> +arm_smmu_v3-y := arm-smmu-v3.o trace.o
>> arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_IOMMUFD) += arm-smmu-v3-iommufd.o
>> arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_SVA) += arm-smmu-v3-sva.o
>> arm_smmu_v3-$(CONFIG_TEGRA241_CMDQV) += tegra241-cmdqv.o
>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> index e8d7dbe495f0..85e6c25b73ed 100644
>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> @@ -34,6 +34,8 @@
>> #include "arm-smmu-v3.h"
>> #include "../../dma-iommu.h"
>>
>> +#include "trace.h"
>> +
>> static bool disable_msipolling;
>> module_param(disable_msipolling, bool, 0444);
>> MODULE_PARM_DESC(disable_msipolling,
>> @@ -2271,6 +2273,7 @@ static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
>>
>> do {
>> while (!queue_remove_raw(q, evt)) {
>> + trace_smmu_evtq_event(smmu, evt);
>> arm_smmu_decode_event(smmu, evt, &event);
>> if (arm_smmu_handle_event(smmu, evt, &event))
>> arm_smmu_dump_event(smmu, evt, &event, &rs);
>> diff --git a/drivers/iommu/arm/arm-smmu-v3/trace.c b/drivers/iommu/arm/arm-smmu-v3/trace.c
>> new file mode 100644
>> index 000000000000..77378698b1a3
>> --- /dev/null
>> +++ b/drivers/iommu/arm/arm-smmu-v3/trace.c
>> @@ -0,0 +1,9 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * ARM SMMUv3 trace support
>> + *
>> + * Copyright (c) 2026 OpenCloudOS / openEuler
>> + */
>> +
>> +#define CREATE_TRACE_POINTS
>> +#include "trace.h"
>> diff --git a/drivers/iommu/arm/arm-smmu-v3/trace.h b/drivers/iommu/arm/arm-smmu-v3/trace.h
>> new file mode 100644
>> index 000000000000..7cec8d41745e
>> --- /dev/null
>> +++ b/drivers/iommu/arm/arm-smmu-v3/trace.h
>> @@ -0,0 +1,53 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * ARM SMMUv3 trace support
>> + *
>> + * Copyright (c) 2026 OpenCloudOS / openEuler
>> + */
>> +
>> +#undef TRACE_SYSTEM
>> +#define TRACE_SYSTEM arm_smmu_v3
>> +
>> +#if !defined(_TRACE_ARM_SMMU_V3_H) || defined(TRACE_HEADER_MULTI_READ)
>> +#define _TRACE_ARM_SMMU_V3_H
>> +
>> +#include <linux/tracepoint.h>
>> +
>> +#include "arm-smmu-v3.h"
>> +
>> +TRACE_EVENT(smmu_evtq_event,
>> +
>> + TP_PROTO(struct arm_smmu_device *smmu, u64 *evt),
>> +
>> + TP_ARGS(smmu, evt),
>> +
>> + TP_STRUCT__entry(
>> + __string(iommu, dev_name(smmu->dev))
>> + __field(u64, evt0)
>> + __field(u64, evt1)
>> + __field(u64, evt2)
>> + __field(u64, evt3)
>> + ),
>> +
>> + TP_fast_assign(
>> + __assign_str(iommu);
>> + __entry->evt0 = evt[0];
>> + __entry->evt1 = evt[1];
>> + __entry->evt2 = evt[2];
>> + __entry->evt3 = evt[3];
>> + ),
>> +
>> + TP_printk("%s evt: 0x%016llx 0x%016llx 0x%016llx 0x%016llx",
>> + __get_str(iommu),
>> + __entry->evt0, __entry->evt1,
>> + __entry->evt2, __entry->evt3)
>> +);
>> +
>> +#endif /* _TRACE_ARM_SMMU_V3_H */
>> +
>> +/* This part must be outside protection */
>> +#undef TRACE_INCLUDE_PATH
>> +#undef TRACE_INCLUDE_FILE
>> +#define TRACE_INCLUDE_PATH ../../drivers/iommu/arm/arm-smmu-v3/
>> +#define TRACE_INCLUDE_FILE trace
>> +#include <trace/define_trace.h>
>
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-06-13 13:00 [PATCH] iommu/arm-smmu-v3: Add tracepoint for EVTQ events Chen Jun
2026-06-23 15:31 ` Robin Murphy
2026-06-24 8:43 ` chenjun (AM)
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