[PATCH kernel v3 0/6] powerpc/powernv/iommu: Optimize memory use

Alexey Kardashevskiy
2018-07-04T06:13:43Z

This patchset aims to reduce actual memory use for guests with
sparse memory. The pseries guest uses dynamic DMA windows to map
the entire guest RAM but it only actually maps onlined memory
which may be not be contiguous. I hit this when tried passing
through NVLink2-connected GPU RAM of NVIDIA V100 and trying to
map this RAM at the same offset as in the real hardware
forced me to rework I handle these windows.

This moves userspace-to-host-physical translation table
(iommu_table::it_userspace) from VFIO TCE IOMMU subdriver to
the platform code and reuses the already existing multilevel
TCE table code which we have for the hardware tables.
At last in 6/6 I switch to on-demand allocation so we do not
allocate huge chunks of the table if we do not have to;
there is some math in 6/6.

Changes:
v3:
* rebased on v4.18-rc3 and fixed compile error in 6/6

v2:
* bugfix and error handling in 6/6

This is based on sha1
021c917 Linus Torvalds "Linux 4.18-rc3".

Please comment. Thanks.

Alexey Kardashevskiy (6):
powerpc/powernv: Remove useless wrapper
powerpc/powernv: Move TCE manupulation code to its own file
KVM: PPC: Make iommu_table::it_userspace big endian
powerpc/powernv: Add indirect levels to it_userspace
powerpc/powernv: Rework TCE level allocation
powerpc/powernv/ioda: Allocate indirect TCE levels on demand

arch/powerpc/platforms/powernv/Makefile | 2 +-
arch/powerpc/include/asm/iommu.h | 11 +-
arch/powerpc/platforms/powernv/pci.h | 44 ++-
arch/powerpc/kvm/book3s_64_vio.c | 11 +-
arch/powerpc/kvm/book3s_64_vio_hv.c | 18 +-
arch/powerpc/platforms/powernv/pci-ioda-tce.c | 399 ++++++++++++++++++++++++++
arch/powerpc/platforms/powernv/pci-ioda.c | 184 ++----------
arch/powerpc/platforms/powernv/pci.c | 158 ----------
drivers/vfio/vfio_iommu_spapr_tce.c | 65 +----
9 files changed, 478 insertions(+), 414 deletions(-)
create mode 100644 arch/powerpc/platforms/powernv/pci-ioda-tce.c

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2.11.0