On Tue, Jun 22, 2021 at 6:31 PM Christian König <christian.koenig@xxxxxxx> wrote: > > > > Am 22.06.21 um 17:28 schrieb Jason Gunthorpe: > > On Tue, Jun 22, 2021 at 05:24:08PM +0200, Christian König wrote: > > > >>>> I will take two GAUDI devices and use one as an exporter and one as an > >>>> importer. I want to see that the solution works end-to-end, with real > >>>> device DMA from importer to exporter. > >>> I can tell you it doesn't. Stuffing physical addresses directly into > >>> the sg list doesn't involve any of the IOMMU code so any configuration > >>> that requires IOMMU page table setup will not work. > >> Sure it does. See amdgpu_vram_mgr_alloc_sgt: > >> > >> amdgpu_res_first(res, offset, length, &cursor); > > ^^^^^^^^^^ > > > > I'm not talking about the AMD driver, I'm talking about this patch. > > > > + bar_address = hdev->dram_pci_bar_start + > > + (pages[cur_page] - prop->dram_base_address); > > + sg_dma_address(sg) = bar_address; > > Yeah, that is indeed not working. > > Oded you need to use dma_map_resource() for this. > > Christian. Yes, of course. But will it be enough ? Jason said that supporting IOMMU isn't nice when we don't have struct pages. I fail to understand the connection, I need to dig into this. Oded > > > > > > > Jason >
