| Message ID | 20231130201504.2322355-1-pasha.tatashin@soleen.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | IOMMU memory observability | expand |
On Thu, 30 Nov 2023, Pasha Tatashin wrote: > 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. > I think this is *very* useful to provide visibility into a significant amount of memory that we currently cannot observe on a host. It can help to uncover bugs and shed light onto a particularly large amount of memory that would otherwise be mysterious. Joerg, Will, Robin, I think this series would go through the git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git tree since it depends on a common framework for all other IOMMU implementations to then use? Any concerns about this patch series? It would be very useful for us to create visibility into this memory. Pasha: any chance of adding a selftest that can be run that will test the value of nr_iommu_pages? I could imagine in the future that a bug could be introduced where either an allocation or free is done through alloc_pages() directly and its paired alloc/free function now results in a leak or underflow. > 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 > ---------------------------------------------------------------------- > > 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 > > >
From: Pasha Tatashin <tatashin@google.com> ---------------------------------------------------------------------- Changelog ---------------------------------------------------------------------- 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@soleen.com vfio: account iommu allocations https://lore.kernel.org/all/20231130200900.2320829-1-pasha.tatashin@soleen.com 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. 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 ---------------------------------------------------------------------- Previous versions v1: https://lore.kernel.org/all/20231128204938.1453583-1-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-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