Re: [PATCH v8 6/7] iommu/vt-d: Add trace events for device dma map/unmap

[Steven Rostedt]

On Fri, 30 Aug 2019 15:17:17 +0800
Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> wrote:

> This adds trace support for the Intel IOMMU driver. It
> also declares some events which could be used to trace
> the events when an IOVA is being mapped or unmapped in
> a domain.
> 
> Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
> Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Reviewed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> ---
>  drivers/iommu/Makefile             |  1 +
>  drivers/iommu/intel-trace.c        | 14 +++++
>  include/trace/events/intel_iommu.h | 84 ++++++++++++++++++++++++++++++
>  3 files changed, 99 insertions(+)
>  create mode 100644 drivers/iommu/intel-trace.c
>  create mode 100644 include/trace/events/intel_iommu.h
> 
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index f13f36ae1af6..bfe27b2755bd 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -17,6 +17,7 @@ obj-$(CONFIG_ARM_SMMU) += arm-smmu.o
>  obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o
>  obj-$(CONFIG_DMAR_TABLE) += dmar.o
>  obj-$(CONFIG_INTEL_IOMMU) += intel-iommu.o intel-pasid.o
> +obj-$(CONFIG_INTEL_IOMMU) += intel-trace.o
>  obj-$(CONFIG_INTEL_IOMMU_DEBUGFS) += intel-iommu-debugfs.o
>  obj-$(CONFIG_INTEL_IOMMU_SVM) += intel-svm.o
>  obj-$(CONFIG_IPMMU_VMSA) += ipmmu-vmsa.o
> diff --git a/drivers/iommu/intel-trace.c b/drivers/iommu/intel-trace.c
> new file mode 100644
> index 000000000000..bfb6a6e37a88
> --- /dev/null
> +++ b/drivers/iommu/intel-trace.c
> @@ -0,0 +1,14 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Intel IOMMU trace support
> + *
> + * Copyright (C) 2019 Intel Corporation
> + *
> + * Author: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> + */
> +
> +#include <linux/string.h>
> +#include <linux/types.h>
> +
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/intel_iommu.h>
> diff --git a/include/trace/events/intel_iommu.h b/include/trace/events/intel_iommu.h
> new file mode 100644
> index 000000000000..9c28e6cae86f
> --- /dev/null
> +++ b/include/trace/events/intel_iommu.h
> @@ -0,0 +1,84 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Intel IOMMU trace support
> + *
> + * Copyright (C) 2019 Intel Corporation
> + *
> + * Author: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> + */
> +#ifdef CONFIG_INTEL_IOMMU
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM intel_iommu
> +
> +#if !defined(_TRACE_INTEL_IOMMU_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_INTEL_IOMMU_H
> +
> +#include <linux/tracepoint.h>
> +#include <linux/intel-iommu.h>
> +
> +DECLARE_EVENT_CLASS(dma_map,
> +	TP_PROTO(struct device *dev, dma_addr_t dev_addr, phys_addr_t phys_addr,
> +		 size_t size),
> +
> +	TP_ARGS(dev, dev_addr, phys_addr, size),
> +
> +	TP_STRUCT__entry(
> +		__string(dev_name, dev_name(dev))
> +		__field(dma_addr_t, dev_addr)
> +		__field(phys_addr_t, phys_addr)
> +		__field(size_t,	size)
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(dev_name, dev_name(dev));
> +		__entry->dev_addr = dev_addr;
> +		__entry->phys_addr = phys_addr;
> +		__entry->size = size;
> +	),
> +
> +	TP_printk("dev=%s dev_addr=0x%llx phys_addr=0x%llx size=%zu",
> +		  __get_str(dev_name),
> +		  (unsigned long long)__entry->dev_addr,
> +		  (unsigned long long)__entry->phys_addr,
> +		  __entry->size)
> +);
> +
> +DEFINE_EVENT(dma_map, bounce_map_single,
> +	TP_PROTO(struct device *dev, dma_addr_t dev_addr, phys_addr_t phys_addr,
> +		 size_t size),
> +	TP_ARGS(dev, dev_addr, phys_addr, size)
> +);

Do you plan on adding more events to these classes? This patch has two
distinct DECLARE_EVENT_CLASS() calls, and each has one DEFINE_EVENT()
for them.

It's fine to do this, but I'm curious to why you did not use
the "TRACE_EVENT()" macro, which basically is just a single
DECLARE_EVENT_CLASS() followed by a single DEFINE_EVENT(). In other
words, you just open coded TRACE_EVENT().

-- Steve

> +
> +DECLARE_EVENT_CLASS(dma_unmap,
> +	TP_PROTO(struct device *dev, dma_addr_t dev_addr, size_t size),
> +
> +	TP_ARGS(dev, dev_addr, size),
> +
> +	TP_STRUCT__entry(
> +		__string(dev_name, dev_name(dev))
> +		__field(dma_addr_t, dev_addr)
> +		__field(size_t,	size)
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(dev_name, dev_name(dev));
> +		__entry->dev_addr = dev_addr;
> +		__entry->size = size;
> +	),
> +
> +	TP_printk("dev=%s dev_addr=0x%llx size=%zu",
> +		  __get_str(dev_name),
> +		  (unsigned long long)__entry->dev_addr,
> +		  __entry->size)
> +);
> +
> +DEFINE_EVENT(dma_unmap, bounce_unmap_single,
> +	TP_PROTO(struct device *dev, dma_addr_t dev_addr, size_t size),
> +	TP_ARGS(dev, dev_addr, size)
> +);
> +
> +#endif /* _TRACE_INTEL_IOMMU_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> +#endif /* CONFIG_INTEL_IOMMU */