Re: [PATCH v5 00/11] IOMMU memory observability

[Linu Cherian]

On 2024-02-22 at 23:09:26, Pasha Tatashin (pasha.tatashin@xxxxxxxxxx) wrote:
> ----------------------------------------------------------------------
> Changelog
> ----------------------------------------------------------------------
> v5:
> - Synced with v6.8-rc5
> - Added: Acked-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> - Added: Acked-by: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
> - Addressed review comments from Robin Murphy:
>   Updated the header comment in iommu-pages.h
>   Removed __iommu_alloc_pages_node(), invoke
>   iommu_alloc_pages_node directly.
>   Removed unused: __iommu_alloc_page_node()
>   Removed __iommu_free_page()
>   Renamed: iommu_free_pages_list() -> iommu_put_pages_list()
>   Added missing iommu_put_pages_list() to dma-iommu.c in
>   iommu/dma: use iommu_put_pages_list() to releae freelist
> 
> v4:
> - 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.
> 
> v3:
> - Sync with v6.7-rc7
> - Addressed comments from David Rientjes: s/pages/page/, added
>   unlikely() into the branches, expanded comment for
>   iommu_free_pages_list().
> - Added Acked-bys: David Rientjes
> 
> v2:
> - Added Reviewed-by Janne Grunau
> - Sync with 6.7.0-rc3
> - 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.
> 
> ----------------------------------------------------------------------
> Description
> ----------------------------------------------------------------------
> 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.

Can you please clarify what does KVM memory refers to here ?
Does it mean the VFIO map / virtio-iommu invoked ones for a guest VM?  

> 
> Per-node observability:
> /sys/devices/system/node/nodeN/meminfo
> Node N SecPageTables:    422204 kB
> 
> Contains IOMMU and KVM 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
> ----------------------------------------------------------------------
> Previous versions
> v1: https://lore.kernel.org/all/20231128204938.1453583-1-pasha.tatashin@xxxxxxxxxx
> v2: https://lore.kernel.org/linux-mm/20231130201504.2322355-1-pasha.tatashin@xxxxxxxxxx
> v3: https://lore.kernel.org/all/20231226200205.562565-1-pasha.tatashin@xxxxxxxxxx
> v4: https://lore.kernel.org/all/20240207174102.1486130-1-pasha.tatashin@xxxxxxxxxx
> ----------------------------------------------------------------------
> 
> Pasha Tatashin (11):
>   iommu/vt-d: add wrapper functions for page allocations
>   iommu/dma: use iommu_put_pages_list() to releae freelist
>   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/dma-iommu.c               |   7 +-
>  drivers/iommu/exynos-iommu.c            |  14 +-
>  drivers/iommu/intel/dmar.c              |  16 +-
>  drivers/iommu/intel/iommu.c             |  47 ++----
>  drivers/iommu/intel/iommu.h             |   2 -
>  drivers/iommu/intel/irq_remapping.c     |  16 +-
>  drivers/iommu/intel/pasid.c             |  18 +--
>  drivers/iommu/intel/svm.c               |  11 +-
>  drivers/iommu/io-pgtable-arm.c          |  15 +-
>  drivers/iommu/io-pgtable-dart.c         |  37 ++---
>  drivers/iommu/iommu-pages.h             | 186 ++++++++++++++++++++++++
>  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 +
>  23 files changed, 361 insertions(+), 206 deletions(-)
>  create mode 100644 drivers/iommu/iommu-pages.h
> 
> -- 
> 2.44.0.rc0.258.g7320e95886-goog
>