[PATCH v2 00/10] IOMMU memory observability

[Pasha Tatashin]

From: Pasha Tatashin <tatashin@xxxxxxxxxx>

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Changelog
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v2:
- Added Reviewed-by Janne Grunau
- Sync with 6.7.0-rc3, 3b47bc037bd44f142ac09848e8d3ecccc726be99
- Separated form the series patches:
vhost-vdpa: account iommu allocations
https://lore.kernel.org/all/20231130200447.2319543-1-pasha.tatashin@xxxxxxxxxx
vfio: account iommu allocations
https://lore.kernel.org/all/20231130200900.2320829-1-pasha.tatashin@xxxxxxxxxx
as suggested by Jason Gunthorpe
- Fixed SPARC build issue detected by kernel test robot
- Drop the following patches as they do account iommu page tables:
iommu/dma: 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
as suggested by Robin Murphy. These patches are not related to IOMMU
page tables. We might need to do a separate work to support DMA
observability.
- Remove support iommu/io-pgtable-arm-v7s as the 2nd level pages are
under a page size, thanks Robin Murphy for pointing this out.

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Description
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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].
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[1] https://github.com/soleen/iova_stress
[2] https://lpc.events/event/17/contributions/1466
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Previous versions
v1: https://lore.kernel.org/all/20231128204938.1453583-1-pasha.tatashin@xxxxxxxxxx
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Pasha Tatashin (10):
  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/exynos: 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

 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/exynos-iommu.c            |  14 +-
 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.c          |   7 +-
 drivers/iommu/io-pgtable-dart.c         |  37 ++--
 drivers/iommu/iommu-pages.h             | 231 ++++++++++++++++++++++++
 drivers/iommu/rockchip-iommu.c          |  14 +-
 drivers/iommu/sun50i-iommu.c            |   7 +-
 drivers/iommu/tegra-smmu.c              |  18 +-
 include/linux/mmzone.h                  |   5 +-
 mm/vmstat.c                             |   3 +
 22 files changed, 390 insertions(+), 185 deletions(-)
 create mode 100644 drivers/iommu/iommu-pages.h

-- 
2.43.0.rc2.451.g8631bc7472-goog