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

Alexey Kardashevskiy
2018-07-13T05:26:51Z

On Wed, 4 Jul 2018 16:13:43 +1000
Alexey Kardashevskiy <aik@ozlabs.ru> wrote:

> 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.

Ping?

>
>
>
> 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

--
Alexey