iproc based PCI RC and Stingray SOC has limitaiton of addressing only 512GB memory at once. IOVA allocation honors device's coherent_dma_mask/dma_mask. In PCI case, current code honors DMA mask set by EP, there is no concept of PCI host bridge dma-mask, should be there and hence could truly reflect the limitation of PCI host bridge. However assuming Linux takes care of largest possible dma_mask, still the limitation could exist, because of the way memory banks are implemented. for e.g. memory banks: <0x00000000 0x80000000 0x0 0x80000000>, /* 2G @ 2G */ <0x00000008 0x80000000 0x3 0x80000000>, /* 14G @ 34G */ <0x00000090 0x00000000 0x4 0x00000000>, /* 16G @ 576G */ <0x000000a0 0x00000000 0x4 0x00000000>; /* 16G @ 640G */ When run User space (SPDK) which internally uses vfio in order to access PCI EndPoint directly. Vfio uses huge-pages which could come from 640G/0x000000a0. And the way vfio maps the hugepage is to have phys addr as iova, and ends up calling VFIO_IOMMU_MAP_DMA ends up calling iommu_map, inturn arm_lpae_map mapping iovas out of range. So the way kernel allocates IOVA (where it honours device dma_mask) and the way userspace gets IOVA is different. dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>; will not work. Instead we have to go for scattered dma-ranges leaving holes. Hence, we have to reserve IOVA allocations for inbound memory. The patch-set caters to only addressing IOVA allocation problem. Changes since v7: - Robin's comment addressed where he wanted to remove depedency between IOMMU and OF layer. - Bjorn Helgaas's comments addressed. Changes since v6: - Robin's comments addressed. Changes since v5: Changes since v4: Changes since v3: Changes since v2: - minor changes, redudant checkes removed - removed internal review Changes since v1: - address Rob's comments. - Add a get_dma_ranges() function to of_bus struct.. - Convert existing contents of of_dma_get_range function to of_bus_default_dma_get_ranges and adding that to the default of_bus struct. - Make of_dma_get_range call of_bus_match() and then bus->get_dma_ranges. Oza Pawandeep (3): OF/PCI: expose inbound memory interface to PCI RC drivers. IOMMU/PCI: reserve IOVA for inbound memory for PCI masters PCI: add support for inbound windows resources drivers/iommu/dma-iommu.c | 44 ++++++++++++++++++++-- drivers/of/of_pci.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++ drivers/pci/probe.c | 30 +++++++++++++-- include/linux/of_pci.h | 7 ++++ include/linux/pci.h | 1 + 5 files changed, 170 insertions(+), 8 deletions(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
