Here is an attempt to support bigger DMA space for devices supporting DMA masks less than 59 bits (GPUs come into mind first). POWER9 PHBs have an option to map 2 windows at 0 and select a windows based on DMA address being below or above 4GB.
This adds the "iommu=iommu_bypass" kernel parameter and supports VFIO+pseries machine - current this requires telling upstream+unmodified QEMU about this via -global spapr-pci-host-bridge.dma64_win_addr=0x100000000 or per-phb property. 4/4 advertises the new option but there is no automation around it in QEMU (should it be?). For now it is either 1<<59 or 4GB mode; dynamic switching is not supported (could be via sysfs). This is a rebased version of https://lore.kernel.org/kvm/20191202015953.127902-1-...@ozlabs.ru/ The main change since v1 is that now it is 7 patches with clearer separation of steps. This is based on 6c90b86a745a "Merge tag 'mmc-v5.6-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc" Please comment. Thanks. Alexey Kardashevskiy (7): powerpc/powernv/ioda: Move TCE bypass base to PE powerpc/powernv/ioda: Rework for huge DMA window at 4GB powerpc/powernv/ioda: Allow smaller TCE table levels powerpc/powernv/phb4: Use IOMMU instead of bypassing powerpc/iommu: Add a window number to iommu_table_group_ops::get_table_size powerpc/powernv/phb4: Add 4GB IOMMU bypass mode vfio/spapr_tce: Advertise and allow a huge DMA windows at 4GB arch/powerpc/include/asm/iommu.h | 3 + arch/powerpc/include/asm/opal-api.h | 9 +- arch/powerpc/include/asm/opal.h | 2 + arch/powerpc/platforms/powernv/pci.h | 4 +- include/uapi/linux/vfio.h | 2 + arch/powerpc/platforms/powernv/npu-dma.c | 1 + arch/powerpc/platforms/powernv/opal-call.c | 2 + arch/powerpc/platforms/powernv/pci-ioda-tce.c | 4 +- arch/powerpc/platforms/powernv/pci-ioda.c | 234 ++++++++++++++---- drivers/vfio/vfio_iommu_spapr_tce.c | 17 +- 10 files changed, 213 insertions(+), 65 deletions(-) -- 2.17.1
