[PATCH v4 00/10] IOMMU memory observability

Pasha Tatashin pasha.tatashin at soleen.com
Wed Feb 7 09:40:52 PST 2024

- Synced with v6.8-rc3 
- Updated commit log for "iommu: account IOMMU allocated memory" as
  suggested by Michal Koutný
- Added more Acked-bys David Rientjes and Thierry Reding
- Added Tested-by Bagas Sanjaya.

- Sync with v6.7-rc7
- Addressed comments from David Rientjes: s/pages/page/, added
  unlikely() into the branches, expanded comment for
- Added Acked-bys: David Rientjes

- Added Reviewed-by Janne Grunau
- Sync with 6.7.0-rc3
- Separated form the series patches:
vhost-vdpa: account iommu allocations
vfio: account iommu allocations
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
- Remove support iommu/io-pgtable-arm-v7s as the 2nd level pages are
under a page size, thanks Robin Murphy for pointing this out.

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:
Node N SecPageTables:    422204 kB

Contains IOMMU and KVM memory in the given NUMA node.

Per-node IOMMU only observability:
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
Previous versions
v1: https://lore.kernel.org/all/20231128204938.1453583-1-pasha.tatashin@soleen.com
v2: https://lore.kernel.org/linux-mm/20231130201504.2322355-1-pasha.tatashin@soleen.com
v3: https://lore.kernel.org/all/20231226200205.562565-1-pasha.tatashin@soleen.com

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/io-pgtable-dart: use page allocation function provided by
  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: 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          |  15 +-
 drivers/iommu/io-pgtable-dart.c         |  37 ++--
 drivers/iommu/iommu-pages.h             | 236 ++++++++++++++++++++++++
 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, 397 insertions(+), 191 deletions(-)
 create mode 100644 drivers/iommu/iommu-pages.h


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