[PATCH 00/16] IOMMU memory observability

[Pasha Tatashin]

From: Pasha Tatashin <tatashin@xxxxxxxxxx>

IOMMU subsystem may contain state that is in gigabytes. Majority of that
state is iommu page tables. Yet, there is currently, no way to observe
how much memory is actually used by the iommu subsystem.

This patch series solves this problem by adding both observability to
all pages that are allocated by IOMMU, and also accountability, so
admins can limit the amount if via cgroups.

The system-wide observability is using /proc/meminfo:
SecPageTables:    438176 kB

Contains IOMMU and KVM memory.

Per-node observability:
/sys/devices/system/node/nodeN/meminfo
Node N SecPageTables:    422204 kB

Contains IOMMU and KVM memory memory in the given NUMA node.

Per-node IOMMU only observability:
/sys/devices/system/node/nodeN/vmstat
nr_iommu_pages 105555

Contains number of pages IOMMU allocated in the given node.

Accountability: using sec_pagetables cgroup-v2 memory.stat entry.

With the change, iova_stress[1] stops as limit is reached:

# ./iova_stress
iova space:     0T      free memory:   497G
iova space:     1T      free memory:   495G
iova space:     2T      free memory:   493G
iova space:     3T      free memory:   491G

stops as limit is reached.

This series encorporates suggestions that came from the discussion
at LPC [2].

[1] https://github.com/soleen/iova_stress
[2] https://lpc.events/event/17/contributions/1466

Pasha Tatashin (16):
  iommu/vt-d: add wrapper functions for page allocations
  iommu/amd: use page allocation function provided by iommu-pages.h
  iommu/io-pgtable-arm: use page allocation function provided by
    iommu-pages.h
  iommu/io-pgtable-dart: use page allocation function provided by
    iommu-pages.h
  iommu/io-pgtable-arm-v7s: use page allocation function provided by
    iommu-pages.h
  iommu/dma: use page allocation function provided by iommu-pages.h
  iommu/exynos: use page allocation function provided by iommu-pages.h
  iommu/fsl: use page allocation function provided by iommu-pages.h
  iommu/iommufd: use page allocation function provided by iommu-pages.h
  iommu/rockchip: use page allocation function provided by iommu-pages.h
  iommu/sun50i: use page allocation function provided by iommu-pages.h
  iommu/tegra-smmu: use page allocation function provided by
    iommu-pages.h
  iommu: observability of the IOMMU allocations
  iommu: account IOMMU allocated memory
  vhost-vdpa: account iommu allocations
  vfio: account iommu allocations

 Documentation/admin-guide/cgroup-v2.rst |   2 +-
 Documentation/filesystems/proc.rst      |   4 +-
 drivers/iommu/amd/amd_iommu.h           |   8 -
 drivers/iommu/amd/init.c                |  91 +++++-----
 drivers/iommu/amd/io_pgtable.c          |  13 +-
 drivers/iommu/amd/io_pgtable_v2.c       |  20 +-
 drivers/iommu/amd/iommu.c               |  13 +-
 drivers/iommu/dma-iommu.c               |   8 +-
 drivers/iommu/exynos-iommu.c            |  14 +-
 drivers/iommu/fsl_pamu.c                |   5 +-
 drivers/iommu/intel/dmar.c              |  10 +-
 drivers/iommu/intel/iommu.c             |  47 ++---
 drivers/iommu/intel/iommu.h             |   2 -
 drivers/iommu/intel/irq_remapping.c     |  10 +-
 drivers/iommu/intel/pasid.c             |  12 +-
 drivers/iommu/intel/svm.c               |   7 +-
 drivers/iommu/io-pgtable-arm-v7s.c      |   9 +-
 drivers/iommu/io-pgtable-arm.c          |   7 +-
 drivers/iommu/io-pgtable-dart.c         |  37 ++--
 drivers/iommu/iommu-pages.h             | 231 ++++++++++++++++++++++++
 drivers/iommu/iommufd/iova_bitmap.c     |   6 +-
 drivers/iommu/rockchip-iommu.c          |  14 +-
 drivers/iommu/sun50i-iommu.c            |   7 +-
 drivers/iommu/tegra-smmu.c              |  18 +-
 drivers/vfio/vfio_iommu_type1.c         |   8 +-
 drivers/vhost/vdpa.c                    |   3 +-
 include/linux/mmzone.h                  |   5 +-
 mm/vmstat.c                             |   3 +
 28 files changed, 415 insertions(+), 199 deletions(-)
 create mode 100644 drivers/iommu/iommu-pages.h

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2.43.0.rc2.451.g8631bc7472-goog