linux-kernel - [PATCH 0/7] iommu/vt-d: Support performance monitoring for IOMMU

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Message-Id: <20230111202504.378258-1-kan.liang@linux.intel.com>
Date:   Wed, 11 Jan 2023 12:24:57 -0800
From:   kan.liang@...ux.intel.com
To:     joro@...tes.org, will@...nel.org, baolu.lu@...ux.intel.com,
        dwmw2@...radead.org, robin.murphy@....com, robert.moore@...el.com,
        rafael.j.wysocki@...el.com, lenb@...nel.org, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Cc:     Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH 0/7] iommu/vt-d: Support performance monitoring for IOMMU

From: Kan Liang <kan.liang@...ux.intel.com>

A performance monitoring infrastructure, perfmon, is introduced with
the VT-d Spec 4.0. The purpose of perfmon is to support collection of
information about key events occurring during operation of the remapping
hardware, to aid performance tuning and debug. The patch series is to
support the perfmon for IOMMU.

To facilitate the perfmon support, the patch series also supports two
new generic features of VT-d Spec 4.0.
- Support the 'size' field to retrieve the accurate size of the register
  set for each dmar device from DRHD. (Patch 1) 
- Support the new Enhanced Command Interface. (Patch 3)

With the patch series, users can collect the performance data of IOMMU
via Linux perf tool. For example,

 $ perf stat -e dmar0/iommu_requests,filter_ats=0/ -a sleep 1

 Performance counter stats for 'system wide':

              2135      dmar0/iommu_requests,filter_ats=0/

       1.001087695 seconds time elapsed

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/dmar0/format/
event  event_group  filter_ats  filter_page_table

The supported events can be found at the events folder

 $ ls /sys/bus/event_source/devices/dmar0/events/
ats_blocked        int_cache_hit_nonposted  iommu_mrds
pasid_cache_lookup
ctxt_cache_hit     int_cache_hit_posted     iommu_requests
pg_req_posted
ctxt_cache_lookup  int_cache_lookup         iotlb_hit
pw_occupancy
fs_nonleaf_hit     iommu_clocks             iotlb_lookup
ss_nonleaf_hit
fs_nonleaf_lookup  iommu_mem_blocked        pasid_cache_hit
ss_nonleaf_lookup

Kan Liang (7):
  iommu/vt-d: Support size of the register set in DRHD
  iommu/vt-d: Retrieve IOMMU perfmon capability information
  iommu/vt-d: Support Enhanced Command Interface
  iommu/vt-d: Add IOMMU perfmon support
  iommu/vt-d: Support cpumask for IOMMU perfmon
  iommu/vt-d: Add IOMMU perfmon overflow handler support
  iommu/vt-d: Enable IOMMU perfmon support

 .../sysfs-bus-event_source-devices-iommu      |  32 +
 drivers/iommu/intel/Kconfig                   |   9 +
 drivers/iommu/intel/Makefile                  |   1 +
 drivers/iommu/intel/dmar.c                    | 100 ++-
 drivers/iommu/intel/iommu.c                   |   3 +
 drivers/iommu/intel/iommu.h                   | 113 ++-
 drivers/iommu/intel/perfmon.c                 | 836 ++++++++++++++++++
 drivers/iommu/intel/perfmon.h                 |  65 ++
 drivers/iommu/intel/svm.c                     |   2 +-
 include/acpi/actbl1.h                         |   2 +-
 include/linux/cpuhotplug.h                    |   1 +
 include/linux/dmar.h                          |   1 +
 12 files changed, 1155 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-event_source-devices-iommu
 create mode 100644 drivers/iommu/intel/perfmon.c
 create mode 100644 drivers/iommu/intel/perfmon.h

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