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# 46284c6c 31-Jan-2023 Kan Liang <kan.liang@linux.intel.com>

iommu/vt-d: Support cpumask for IOMMU perfmon

The perf subsystem assumes that all counters are by default per-CPU. So
the user space tool reads a counter from each CPU. However, the IOMMU
counters a

iommu/vt-d: Support cpumask for IOMMU perfmon

The perf subsystem assumes that all counters are by default per-CPU. So
the user space tool reads a counter from each CPU. However, the IOMMU
counters are system-wide and can be read from any CPU. Here we use a CPU
mask to restrict counting to one CPU to handle the issue. (with CPU
hotplug notifier to choose a different CPU if the chosen one is taken
off-line).

The CPU is exposed to /sys/bus/event_source/devices/dmar*/cpumask for
the user space perf tool.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20230128200428.1459118-6-kan.liang@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

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# 7232ab8b 31-Jan-2023 Kan Liang <kan.liang@linux.intel.com>

iommu/vt-d: Add IOMMU perfmon support

Implement the IOMMU performance monitor capability, which supports the
collection of information about key events occurring during operation of
the remapping ha

iommu/vt-d: Add IOMMU perfmon support

Implement the IOMMU performance monitor capability, which supports the
collection of information about key events occurring during operation of
the remapping hardware, to aid performance tuning and debug.

The IOMMU perfmon support is implemented as part of the IOMMU driver and
interfaces with the Linux perf subsystem.

The IOMMU PMU has the following unique features compared with the other
PMUs.
- Support counting. Not support sampling.
- Does not support per-thread counting. The scope is system-wide.
- Support per-counter capability register. The event constraints can be
enumerated.
- The available event and event group can also be enumerated.
- Extra Enhanced Commands are introduced to control the counters.

Add a new variable, struct iommu_pmu *pmu, to in the struct intel_iommu
to track the PMU related information.

Add iommu_pmu_register() and iommu_pmu_unregister() to register and
unregister a IOMMU PMU. The register function setup the IOMMU PMU ops
and invoke the standard perf_pmu_register() interface to register a PMU
in the perf subsystem. This patch only exposes the functions. The
following patch will enable them in the IOMMU driver.

The IOMMU PMUs can be found under /sys/bus/event_source/devices/dmar*

The available filters and event format can be found at the format folder

$ ls /sys/bus/event_source/devices/dmar1/format/
event event_group filter_ats filter_ats_en filter_page_table
filter_page_table_en

The supported events can be found at the events folder

$ ls /sys/bus/event_source/devices/dmar1/events/
ats_blocked fs_nonleaf_hit int_cache_hit_posted
iommu_mem_blocked iotlb_hit pasid_cache_lookup ss_nonleaf_hit
ctxt_cache_hit fs_nonleaf_lookup int_cache_lookup
iommu_mrds iotlb_lookup pg_req_posted ss_nonleaf_lookup
ctxt_cache_lookup int_cache_hit_nonposted iommu_clocks
iommu_requests pasid_cache_hit pw_occupancy

The command below illustrates filter usage with a simple example.

$ perf stat -e dmar1/iommu_requests,filter_ats_en=0x1,filter_ats=0x1/
-a sleep 1

Performance counter stats for 'system wide':

368,947 dmar1/iommu_requests,filter_ats_en=0x1,filter_ats=0x1/

1.002592074 seconds time elapsed

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20230128200428.1459118-5-kan.liang@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

show more ...