From: David Christensen <d...@linux.vnet.ibm.com> The SPAPR v2 IOMMU used on bare-metal PowerNV systems requires that a DMA window be defined before mapping/unmapping memory. The current VFIO code dynamically resizes this DMA window every time a new memory request is made, which requires that all existing memory be unmapped/remapped. While this strategy worked in DPDK 17.11 and earlier where memory was statically allocated during startup, it is potentially dangerous in DPDK 18.11 and later where memory can be allocated during runtime, temporarily invalidating IOVA memory used by hardware.
This new code statically sizes the DMA window at startup, based on the amount of memory installed in the system, avoiding the need to unmap memory during runtime. --- v7: - No patch changes, fixed email patch description v6: - Fix build error on Linux kernels prior to 4.2.0 - Rebased on 20.11-rc3 v5: - Modify get_highest_mem_addr to return error, not address - Add comment regarding sPAPR v1/v2 default window and why it needs to be removed - Added indent to second line of vfio_spapr_dma_mem_map() definition v4: - Move file reading code out of vfio_spapr_window_size_walk() v3: - Rebase for 20.08 v2: - Drop patch to wrap ppc64 code with ifdef's - Add warning when external memory detected - Change VA memory size detection to scan memseg list when setting DMA window for IOVA=VA - Add explicit error message when attempting to map outside the DMA window David Christensen (1): vfio: modify spapr iommu support to use static window sizing lib/librte_eal/linux/eal_vfio.c | 430 +++++++++++++++----------------- 1 file changed, 207 insertions(+), 223 deletions(-) -- 2.18.4
